Apple II+ clone repair: I thought this would be easy... I was wrong
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- Опубліковано 15 жов 2024
- In the early 80s, the Apple II had was selling well but it was expensive. This is where foreign companies stepped in and started making clones. These machines were much cheaper but also illegal due to them using copied ROMs.
Here we have one of these clones but this machine is broken, very broken. So let's try to get it working.
Small correction: It turns out Franklin did not have a clean-room ROM, and were eventually found to be infringing. There isn't much detail about why Franklin was able to sell computers until 1988. See the pinned comment for more.
Part 0: • 0068 This computer is ... (SMMC video featuring this computer)
Part 1: This part!
Part 2: • Apple II+ clone repair...
-- Links
News report on these illegal clone computers:
• 1985 New Tech Times on...
Scan of schematics and photos of the clone PCB:
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-- Tools
Deoxit D5:
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O-Ring Pick Set: (I use these to lift chips off boards)
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Elenco Electronics LP-560 Logic Probe:
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Hakko FR301 Desoldering Iron:
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Rigol DS1054Z Four Channel Oscilloscope:
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Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:
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TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)
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EEVBlog 121GW Multimeter:
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DSLogic Basic Logic Analyzer:
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Magnetic Screw Holder:
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Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
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RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)
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Plato (Clone) Side Cutters: (order five)
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Heat Sinks:
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Little squeezy bottles: (available elsewhere too)
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--- Links
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--- Instructional videos
My video on damage-free chip removal:
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--- Music
Intro music and other tracks by:
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Small correction: It turns out Franklin did not have a clean-room ROM, and were eventually found to be infringing. I can't find exact specifics about this as even Wikipedia lacks citations, but this seems to be the general consensus. Even this article specifically about the case lacks detail: en.wikipedia.org/wiki/Apple_Computer,_Inc._v._Franklin_Computer_Corp.
It talks about how Apple "won" in 1983 but Franklin continued to sell its very compatible Franklin Ace line until 1988, when "Apple was able to force Franklin to withdraw its clones by 1988." That doesn't exactly make sense to me -- so If anyone can dig up more detail about how Franklin continued to sell large numbers of machines with supposedly infringing code, I'd love to know.
I never really saw a Franklin in the wild. I remember there was a shop by me that sold the Pineapple or something similar.
The case was famous. They had a guy read the fuses of a ROM with a microscope in order to show that this was really text and should fall under copyright law.
The answer, if MAME is anything to go by, is that they replaced the infringing ROM with a cleanroom one for their later models.
At the time Franklin started making their computer, there was a legal precedent for code that was in memory chips not being subject to copyright law. I believe the original case involved a pinball machine. This is why Franklin copied the ROMs and won the first few rounds against Apple. Eventually, the courts figured out that of course the code should be protected, no matter what form it took. Franklin at that point was forced to change its EPROMs, They rewrote the routines, keeping only the entry points which an app would call. Unfortunately, since Apple had published the entire code, some programs would jump into the middle of a routine if they only wanted to do the last part of its function. This kind of thing made it impossible to be 100% compatible without copying all of the code in the EPROMs. Luckily, a lot of programs only called the entry points and ran fine on the later Franklin machines.
I know it's just anecdotal, but my aunt and uncle had a Franklin Ace 1000 back in the day, and I specifically remember them saying that Apple successfully sued Franklin after proving that the ROM's were 100% identical to Apple's, including the name Apple itself appearing in the code. I also remember much more recently someone (not the comment below, but someone on Facebook) saying that Franklin and other clone dealers switched to selling Apple ROM kits as "spare parts", with a nudge and a wink about how to achieve 100% compatibility. I was just a kid in the 80's, though, so I never dealt with any of this more directly than using my aunt and uncle's Franklin, since we didn't have a computer.
It seems like *someone* must have hardcopy documentation about the exact chain of events, though.
back in the day, you could buy bare boards for apple and ibm clones from ads in the back of magazines. that's how some engineers at a place i worked acquired machines; buying a computer required approvals, but buying parts was just buying parts.
If only modern PCBs weren't as complicated. Imagine buying the parts for a full machine via a loophole.
@@SockyNoobwould you please elaborate? I don't understand the difference. As in older PCs had the system burnt into the boards?
@@Loki- Loki, modern computer components like motherboards aren't user serviceable. They're all surface mounted parts, microscopic traces, many layered PCB's, etc. You're only buying major components like graphics cards and connecting them together when you "build" a computer today and when you "repair" one, you're just swapping out one of these major components. In the Apple II days the motherboard was simple and as seen on this channel, easily user serviceable with fairly basic skills and tools.
People could buy a board and source all the components to solder on it and assemble their own, which people did back in the day (and people do today when they buy something like a modern replacement C64 board for an example and populate it with all the necessary parts).
yeah double sided boards compared to modern 8 layer stuff....yeah copy that
This was exactly how my Dad and I built our ][+ clone. I actually had started wire-wrapping one -- my dad worked at a famous research facility where they had an Apple CIG (Computer Interest Group), and they had a wirewrap board with a large manual of wire-wrap co-ordinates. I would come home from school and start wire-wrapping, and my dad was supposed to check my work -- but he soon tired of that, and then was able to a clone board, and those guys troubleshooted it during lunch hours. I still have it, it's got a few cool set of hacks. I need to pull it out of storage and check and see if it works. I did this some time ago and it was still working.
When I was studying in the University I had a classmate from Taiwan who import these Apple 2 clones from Taiwan and sell them in campus. How he did it was the motherboards and chassis were imported separately, and there were no ROMs on the motherboards, which made them legal since they were just parts. Once the parts were received, he then programmed the EPROMs and assembled them into full units. It was so profitable that he eventually dropped out of school and went on setting up his own business selling Apple and PC clones.
Here's an old trick I've done to find shorts like that on a board. Put a power supply though a small resistor on the two shorted lines. (5V and a 100 ohm is a good start.)
Now probe voltages across those two lines... when the voltage difference is the smallest, you're at the short!
As a VERY LAST MEASURE, On boards that were quite frustrating, and had put enough time into them that "it just didn't matter any more" and "zapped" the problem with high current.. would blow the short... or sometimes the trace near the short.
I've also used this in car wiring, also, to find a short to ground in a RV on the interrior lighting. (found a "shiner" on the power wire, in a conduit.) Used 12V and a turn signal bulb for current limited voltage there.
50:20 Address line A3 is on cart slot pin 5. Data line D2 is on cart slot pin 47, which is *almost* directly opposite.
I would check all of the cart slot connectors, in case a pin is bent.
Or maybe there is something conductive sitting in the bottom of one of the connector slots? (like a piece of wire, or solder blob).
It's also quite possible somebody was messing with the board before, and put the wrong TTL chip into the wrong socket.
I was going to suggest a possible short due to touching connector fingers in the cart slot, too.
I think Adrian intentionaly put the solder blob and will say that it fell when he changed the transistor😂
I haven't shouted at the TV so much in ages... 🤣 Badly defined logic levels where the line settles quickly to an intermediate voltage and stays there until the next transition (as per the weird scope trace) is almost always a short to another signal. You effectively had four steady signal levels on that trace, depending on which of the signals was high or low. Finding the fault is a case of either visual examination and / or using a meter on a low ohms range wherever those two signals are close together on a chip or on the board and looking for the reading that's closest to zero ohms. I first learned this trick back in the late 1970's debugging memory cards with lots of RAM chips. The fault is unlikely to be a chip - most likely a solder splash, or a fine copper whisker caused by a bad etch of the PCB. Back in the day, not all PCBs were tested for shorts between traces before assembly.
A splash or a whisker sounds like the kind of problem that would be there from day 1, but presumably this system was working before it went into a few decades of storage.
@Sashazur There is a phenomenon known as "tin whiskers". These can grow over time, and were sometimes a problem in older electronics, even forming inside components after some years. And we don't know if this system was ever fully working, but I would also suspect that it was.
45:58 When you say the expansion connector is not the problem, my experience as a diagnostician is that a lot of times it turns out to be the thing you thought it couldn’t be. My Spidey sense is tingling, and I would probably get a magnifier and a high-powered light, and make sure that there is nothing conductive that got pushed down into one of the expansion connectors. I can just see a little bit of material from an edge connector flaking off and getting down in there.
With A3 and D2 being almost directly across from each other on the peripheral I/O connectors, that would actually be one of the first places I would look. Could be a damaged connector, soldering error, or even a board etching issue .
Could be a leg of a component fell into one of the expansion connectors, and as was said, when Adrian probed both the address and data lines it looked like he did it on the back of the expansion connector and they did look opposite to each other.
Dave of eevblog has a method he uses with a high precision voltmeter to measure resistance and triangulate on the short. You could also pull all of the chips that touch those lines and apply 5V across and use a FLIR to find the hot spot.
Another option is to try an ESR meter which typically measure down to 0.01 ohms and they usually have a button to zero out the leads. This would be better than burning out a track with 5V power and you wouldn’t need to remove all the chips to test for the short.
This looks like a copy of an early generation Unitron (Taiwan) board. The case and keyboard look very much like those used by the Unitron branded computers built in Brazil. There are additional half moon/bow tie jumpers below the EPROMS (and a thru hole jumper above the LS139 at F2) to convert the board from 6 x 2716 to 3 x 2732 installed in F0/D0/E0. We used to find these PCBs in almost every electronics shop in the area. I built and repaired dozens of these. Most people could never get the oscillator running reliably, and often had to pad the oscillator with an added 50pF trimmer at location A1.
A tip that might help in situations where you have a large set of things that might be causing a problem: instead of checking the chips one at a time for an offender, you might be able to check a half at a time. Remove half of the chips connected, test. If the issue persists, put them back, and remove the other half. That'll either rule out everything or narrow it down to half the chips. Then, repeat splitting the suspect group in half again. Instead of having to test each item one at a time, it becomes a power of two. Uses math to help rule things out quicker.
Binary search to find a binary problem. 😁
Kinda like a physical merge sort...
Exactly. This is called a "binary search" and works for a lot of search tasks. It's a massive time-saver.
Unless you have two failed chips, one in each half.
@@pedro_8240 then you divide it in half a different way.
19:20 - Using arrows to pinpoint what section on schematics Adrian was measuring is AWESOME!
I lived in Hong Kong in the mid 1980s. There were a tremendous number of Apple II clones as well as clones of all the peripheral cards. There was a 3 story shopping mall in the New Territories that had 100s of shops selling Apple II clones and copied software. The entire shopping mall was devoted to clone computers and software. Needless to say, I shopped there often.
I'm thoroughly enjoying this video and writing this around the 32 minute mark when you say the chips are a hodge podge. It occurs to me that this system may not have been built in a factory, but by an end user (or the seller) using one of those bare PCBs and grabbing whatever chips they could find. Back then, there may have been local electronic shops that didn't have large lots of parts, and maybe the builder had to go to multiple physical or mail order shops to get what they needed and/or whatever they had on hand.
Yep, and those memory chips used to cost $5 dollars each back in the day.
This video is about 40 years too late to help troubleshoot the Apple clone I tried to make in the early 80s. I could solder and follow simple schematics, but without any real troubleshooting tools, it was way too difficult. I finally threw in the towel. It may have been this very same board.
I was kind-of wondering if this computer was a hobbyist's machine that never functioned. I was also wondering if Apple was seeding boards into the community that had shorts just to keep people from building clones. Perhaps a little too Machiavellian.
I would suspect that A LOT of those hobbiest bare-board builds were never working nor completed and just stayed in a basement shelf for decades.
@@haweater1555 I'm sure I wasn't the only one who ran into problems trying to build one. My brother was more of an electronics wiz than I. Neither of us could get it going. We didn't have anywhere near the same troubleshooting tools that Adrian has. As well as the knowledge, I might add.
Oh that resonates so hard; I tried to build a floppy disk controller for my Nascom 2 and it worked just extremely briefly, but not having access to a scope it was impossible to debug and I didn’t touch hardware for many decades. Today I wish I had tried harder to find someone to help.
I've never used an Apple II (I grew up a C64 guy) and I don't understand half of what you're saying, but these videos are truly fascinating to me. Watching your troubleshooting process and enthusiasm for older tech is very inspiring. Keep up the good work!
Look for mashed contacts on the expansion slots. If a board was put in wrong it could have mashed the socket contact down and maybe is now shorting to something it is not supposed to be touching.
Thanks for leaving IN the mistakes. I enjoy watching the process and learn a bunch of good techniques. Like I wouldn’t have considered that heating the transistor would bring it back to life. I used what I learned to bring my Nascom 2 back to life. Turns out I must have removed a bodge wire I installed 40 years ago, but tracing the signals methodically lead me right to a missing connection.
The Franklin Ace 1000 was actually an illegal clone. It was allowed to stay on the market while Apple Computer, Inc. v. Franklin Computer Corp. was on appeal, partly because the initial court rulings were that compiled code could not be copyrighted. (The Franklin Ace 500 and the Franklin Ace 2000 used cleanroom-implemented ROMs. I believe this was a result of other court rulings that compiled code could be copyrighted.) Eventually, Franklin and Apple settled, with Franklin being barred from ever selling computers (including PC compatibles) as part of the settlement.
One way other Apple clones got around the import bans is that they were imported without ROMs, and ROMs were either installed by the seller or end user.
I thought Apple eventually bought Franklin as their educational division.
@@SockyNoob No. Franklin actually morphed into a different company. They went into electronic publishing and made some devices associated with that. They made things like pocket spellers and pocket Bibles. The company definitely existed into the early 2000's and may still exist in some form today.
And the instructions for ROMless clones said to go find an authorized Apple dealer that will sell you the genuine ROM as a replacement part (before Apple caught on and jacked the price up for this chip to reflect the intellectual property contained inside).
@@haweater1555 You didn't need to buy them. Could just copy them on a eprom reader/writer. i.imgur.com/RDxFJeQ.jpg
Oh man! It was really fun to watch you troubleshoot. You are a great entertainment genius :-)
Especially because I'm currently desperate for a similar board (a MEWA-48 / GTAC-2 / West PC-800)...
I'm really looking forward to Part 2, in which you'll hopefully track down the error...
Your way of troubleshooting helps me a lot with my repair!
Thanks and greetings from Germany
I had an Apple II clone bought in the mid 80s. I actually bought it from a shop teacher at our school. I’m not sure that would fly today! It worked for years and I used through out university. I typed my these in Wordstar on the CPM card and print pad on my Epson MX80.
The 13 year old in me loves the idea of buying a clone Apple PC board, spending months buying the parts from Jameco and soldering them onto the board, and then one day going to a friend's house to illegally copy the ROMs in his Apple II.
I'm really sad that I missed the Wild West era of computing... although I've still managed to work on stuff that would make Apple mad at me all the same. 😂
Jameco! First "computer" I ever had (because I could afford it) was a kit called a Jolt I bought from them. A Fairchild F8, second sourced by Mostek (of 6502 fame), was the computer chip. 1K RAM, 1K ROM. Jolt was a closeout, at a fraction of the price, after the product flopped, and the company that made them evaporated.
@@kennethflorek8532 I ordered tons of stuff from Jameco out of Popular Electronics. I remember buying sixteen 2114 static RAM chips at *five dollars each* to get another 8K. It was the biggest investment I had made since buying the computer.
There was a store in Toronto called "Parts Galore".
They sold everything you needed to build your own.
It’s always fun watching you go step by step through the diagnostic procedure. Looking forward to the next episode.
Back in '80 or '81, my father and went to various stores and bought all the parts needed to assemble a clone at a fraction of the cost of an Apple. it has the same case, keyboard doesn't have short cut functions. Motherboard had a Unitron branding on it if i recall. it was very close to the board you have there. It took us about 2 weeks to complete the soldering with only a couple hours a day for one of us to work on it. We knew people with equipment to burn eproms back then, so, we had copies of the originals, we also had the modified beep tone and banner, which I'm sure are still in it. I loved the Apple ][ era. (also had a TRS-80 Model 1 L2 with floppies and a modem. my father would use it to connect to the main frame at work to look at issues. i would use it to play text based games and Adventure!. )
One of My first Apple computer was a Taiwanese Apple II clone clone called the Unitron u2200. Basically a desktop case with detachable keyboard/speaker. With 64k ram, 6 expansion slots and 6502 & Z80 CPU. I'm sure they were legal to sell as we had these in my high school computer labs here in Australia before they were sold off and replaced with twin disc drive MAC SE computers.
Thank you for changing the color of the oscilloscope trace! Colorblind folks everywhere salute you!
adrian: "this could be a ROM problem"
my brain: "pROMblem, hehe hehe he"
Great video! Excited to see you figure this one out.
Although it may take longer, rather than using one probe to bounce between pins on a logic IC, I prefer to use 3 or 4 channels on my scope to look at multiple inputs (if necessary) and an output.
For example, to make sure a bus transceiver is working properly, I’ll measure and trigger on the direction input pin as well as an input/output pair of pins. This lets me see if one side of the IC is weak and not fully driving the busses. Because either side of the bus transceiver has other sources that could drive the busses, without seeing a pair of pins at the same time on the screen to compare, it’s difficult to prove full functionality.
I used this approach on a Nintendo VS arcade PCB and identified almost a dozen bad logic ICs. It helped to pull up data sheets for each IC and use the pin out and truth table to verify proper operation, marking the schematic as a checklist as I worked my way through.
Lovely throwback for me, I used to watch (and try to help) my father way back in 1981 repairing these. He was an electrical engineer. Thanks for these videos 😁
Having repaired a genuine Apple ][ Plus (rev RFI) that I purchased last year which had 11 separate faults I’m really enjoying this video and I’m looking forward to the next one (or two). I only used a logic probe and multimeter to find all faults and didn’t need to crack out the scope. Not all faults will necessarily be chips or components. I had several that were due to corrosion of pins. That book you used is awesome and was the one I used as it has all Apple ][ plus circuit revisions (just have to make sure you are using the right revision). In your case there is that extra difficulty factor of it being a clone with some variations from the book.
I have an unpopulated main board for the Pete Perkins Apple II clone. Was really hoping that was it, but alas its a different illegal copy! Still cool to see, especially love seeing how the layouts between this one and the board I have are so different.
Love Apple content Adrian and the channel in general! Been watching for almost 4 years now! Keep up the good vids and I'll keep sharing with everyone I know.
A Franklin was the first computer I ever used. This was at a “intro to computing” summer camp in 1984. Great memories playing Karateka.
I just recently found this channel. Love it. The one where you found that game in that crt menu was neat... I'd like to see a video about Easter Eggs hidden in old computers. Software and hardware.
A Huntron tracker or curve tracer can identify bad output drivers of an IC without power applied to the IC.
You can also disconnect the clock, power up the board and use a logic pulser and logic probe to test logic ICs.
It a pain and time consuming, but doable.
It would be so awesome if classic computers schematics were translated into open board view. Have you ever seen Louis Rossman use the software he can click on any point in a board view and see where the pins go and even what should be on that pin. Hope someone sends you a Coleco Adam in the near future!
Amiga PCB Explorer does this for the Amigas
Wow! A Laser! Haven't seen one of those since summer computer class in '92 where we learned to write a dice-roller in BASIC.
Fantastic that you put the board scans online, it looks to make fault finding and modding a breeze using the GIMP scans front and back overlay.
Amazingly, my first computer was a clone of this clone. Brazilian company Dismac made Apple II plus clones with the same keyboard layout as this one, and the motherboard looks very much like it as well!
I'm betting some of those confiscated clones that Apple acquired probably had some stuff that Apply thought "hey this is pretty good, we'll take that idea for ourselves. I mean come on what they going to do 'sue us'?" :D
Thanks for keeping me entertained on the North Sea ferry service from Shetland to Aberdeen in the UK! Man shorts between data/address bus lines what a pain, maybe there's somewhere those traces run together or maybe that prototyping area has a bridge, oof could be lots of things, good luck, I'm looking forward to pt2, hopefully I'll be watching on dry land next time!
At swap events in the SF Bay Area (in the early and mid 80's) you could walk through and buy all the parts, choose your case style and keyboard, power supply, etc. and then take it home to put together. Even ROM sets were available for as little as $ 5. I had a case that said Banana on it.
This video made my stomach tickle because I literally loved that time when pretty much everything was "home brew". The community was much more tightly knit and everyone was willing to share. GREAT video!
Like the "Lazy Susan" to rotate items while recording.
Poor Susan, why does she get such a bad rap.
There are several methods for locating a low-resistance short on a large pcb. One way is to use a DMM that can display tenths or even hundredths of an ohm. Accuracy is not that important. You probe those two signals at various points on the board. As you get closer to the short, the resistance will drop. This relies on making consistent contacts with the two signals with your probes, since any resistance in the contact will add to your measurement. A different technique gets around this issue. If you have a bench power supply, set the voltage to something like 0.3 volts. This will prevent damage to any chips in case the short suddenly clears. Now set the current limit to 50 mA. If your short is on the order of 1 ohm,
that should give 50 mV across it, which many meters can display. Now apply the voltage across the two shorted signals, then probe the same signals at various pts on the board. The lowest voltage reading should be right where they are shorted. You may get the same reading at multiple locations for one of the probes. This indicates that the power supply connection point is electrically between the short and the probe locations. Both of these techniques rely on the pcb traces having resistance that adds to the resistance at the actual short as you get further from it.
I have a multi-board Space Invaders machine where the CPU reset pin was shorted to Address line 15 of the CPU. A15 isn't used by the software but was pulsing due to the CPU reset watchdog circuit. That was fun to track down!
Love seeing the Laser 128EX again. My brother and I used to write so many programs for that thing. We had these program "wars" where one would build a base in graphics, then the next would animate breaking or taking that base over and so on. We got fairly decent at moving pixels around. Good times.
Involved with computer since "before computers" but never Apple. Not because they don't RoCk. You gotz to pick a side to play on :) Thank you for teaching me all this old-school Apple core stuff.
In the 80s I had one of the Apple versions and I sold it to a local school. I got plenty of money for it. Which enabled me to find anorther computer to find that needed repair.
Watching this video has helped me (through your repetition) understand some basic fault-finding techniques. I have a PPG Waveterm A - a 6809 based German Music Computer from 1984 - which has developed a fault. I live in a city half-way round the world from where it was manufactured & there aren't too many people who own these things - let alone are prepared to take on repairs. But I now feel confident I have better knowledge & tools to find out what's wrong with it - I think it's the floppy controller.
If all the chips are socketed, make sure to check for pins bent under or sideways. The previous owner may have caused a new problem while troubleshooting an existing one, and you're discovering it now. I've seen a bent-under pin soldered to a plated through-hole pad that worked (not socketed) but in the process of getting bent under it cut cleanly through an unrelated surface trace running under the chip. Fun to find, relatively easy to fix.
Is it really hacker space? Or an area not removed to patch gotchas in the design? I see those and/or ic patterns to be able to patch a board...
@@thinking-laaf If you mean the grid of feed-thru holes, I remember seeing those years ago. Yes, they were there to allow adding components and "bodge" wires to implement ECOs (Engineering Change Orders) as needed.
I hope it's not a sliver of solder across a trace or pin. Those can be exceedingly hard to find.
If you can pull ALL of the chips off, you might be able to burn open a short by applying, say 24Vdc at a high available current. A sliver of solder will open (like a fuse) if you push enough current through it. This is extremely risky, but it can work.
You can do the above trick at a lower, safer current if you have access to infrared camera equipment, push in the power and look for a hot spot.
Good luck!
Question: I've personally seen an identical machine which had an "Apple computer" motherboard inside. How was that even possible?
When I was a kid, I bought an Apple 2 clone like the one you have there with the keypad. That was many decades ago and it's since long gone (I had bought an Apple //e afterwards). Apple clones were on the market before IBM PC clones existed. Most of these Apple clones are long long gone. I found and picked up an Apple 2 clone (no keypad) which is so blatant that it actually says "apple computer" in apple's font on the badge. It's pretty funny.
Can you safely put enough current through the two shorted pins that a thermal camera would pick up the hot track?
When I was in high school, my got a board like that and made his own Apple II along with a custom plexiglass case that held two floppy drives. I never heard about Apple selling kits, but it was clearly one of those kits.
I like the credits during the intro... It makes the entire video watchable until the end. 👍
Really enjoyed this video, thank you.
Amazing work. I wish I could diagnose and fault find as quickly as you do!
I've fixed a couple of Atari S.Ts with various issues but what takes you minutes takes me days.
What it taught me was I really need to get better with my scope!
I had a Redstone ][+ clone with the Z80 CPM and 80 column display card. 1st computer was the MicroAce, a Sinclair ZX80 clone, then a Tandy 1000, a PC clone. Send in the clones ! Fun times.
What usually happens (Not sure back then, but certainly these days), is that the company (in this case Apple) will send out to a variety of suppliers a request for an example product that meets the specifications that Apple sends to them (Such as the Apple IIe case).
The suppliers then either come back with an example product or a 'can't supply', Apple then looks at each example that comes back to determine which supplier (or suppliers) they will use for the final product.
Now, the losing suppliers should then destroy the specifications that were sent to them, but hey, they just spent all this money setting up tooling to make the example product, like they are really going to let all that tooling go to waste.
So, they when Apple finally releases the product to retail, the suppliers who didn't win the contract and who didn't destroy the specifications, start manufacturing 3rd party products, just not officially endorsed or badged.
This then means that companies like Laser, etc... have a ready to go product that they can utilise.
Other ways it occurs is buying the retail product and then getting all the measurements, etc... to create your own clone of a particular part of it.
This is good example to use multimeter with mV scale and use it as short circuit finder. Using LM317.
I was frequenting a Dutch electronic store which sold blank apple and later ibm pc PCBs like hotcakes. As there were only standard TTL ICs on those boards, people could just build them. The only proprietary chips were the roms, but nothing an eprom could replace...
i purchased just such a bare board from the back of Byte magazine around 1984 ish. Soldered up my own Apple II. A friend had a real machine and worked at a company that could make my ROM's. Tons of fun.
Back in the days when Apple made the most expandable machines... And today you often can't even change the harddisks or add more memory.
and repairable.
You used an unapproved apple screw, your operating system is disabled.
and they even take away ports (e.g., audio out port) and have a penchant for their own proprietary connectors where they could easily go with industry standard choices (e.g., the power connector)
@@TheSulrossmagsafe is the best thing apple has ever done (the MacBook one. The iPhone magsafe is stupid)
Yeah, we need a new Steve Wozniak. 😊
Congratulations for the tenacity Adam, I would check on the new pcb without components if there is already a short circuit! At this point it could be a manufacturing defect of the pcb. greetings from italy.😅
I worked for a UK company that made Apple II clones as well as a range of expansion cards. I think they reverse engineered the roms and did a clean room implementation. They certainly sold them for quite a few years before moving into other products.
Apple II has interleaved memory access. With the bus transceiver disconnected, you will still see activity on the address lines because the video generation logic generates addresses on the odd phase of the clock. The whole purpose of the bus transceivers is to ensure the CPU is off the bus during video/slot DMA.
When @jdmcs was working on his identical unbranded Apple II clone on a live stream, it too was displaying garbage on the screen until I suggested in the comments to connect the keyboard. After he did that, it just worked. It seems like before the keyboard was connected, it was running a self diagnostic.
As a test, replace chip f14. This is the 74ls259, which is not only controlling the display modes, speaker and tape but is also connected to the game io connector c040. Maybe a dodgy apple paddle ot joystick fried the chip. There is no chip protection. Also f14 is connected to a3
If it wasn't 53 minutes long, I would have linked this to the definition of "cliffhanger" :-) Can't wait for the next one! Absolute brilliant detective work and love your reaction upon realizing there's a short between two data lines in a rat's nest. I'd trace out the lines on the schematics using two different colors and a 3rd for the chips in which they interact or intersect, but I'm sure you have a better way of doing it. and I can't wait to see it
The video circuit drives the address lines during the low phase of the clock, Adrian.
I lived in Hong Kong in the early 80s and you could buy Apple ][ boards in Apliu Street, which was/is big electronics flea market. Helped to launch me into a career in computing. Taught me how to solder pretty well too!
Now I'm very curious about how this will end, but I'm sure you will fix it!
Question: the component tester that comes out around 20:20, is it the same that can be had for cheap on AliExpress? I see them there for about 12-15 euros (prob. the same in dollars). As we can see here it correctly recognises a transistor, which is good, but how well does it do with other components and ICs? Basically what I'm asking is should I buy it or save up for something better? Just a hobbyist with limited means here.
You need a Toneohm! Low-ohms meter with a tone output, so you can chase around the board with the probes looking for the nearest place to the short just by listening to the tone. It's indispensable on the repair bench.
Really enjoyed that. Oddly relaxing. I suppose because you were doing all the hard work ;)
The one thing I seriously want to do is fabricate clones of some motherboards that used the NiCd batteries and have them use coin cells in place of them or only a header for a 4.5V battery holder. For example, the one Jetway 3/486 board I have (or had, cannot recall if I still have it or not since I cleared some clutter out of my room recently) was under heavy battery leakage/corrosion and a lot of traces were damaged and repairing it was complicated and it almost worked. I have a working one that had 2 small drips, but I got it cleared up and it runs great.
Heck, even for OEM system motherboards, I would do the same thing.
It's like working on old bootleg arcade boards, like Krazy Kong: You're on your own!
Here is how you quickly find a short like the A3 to D2. Pick a ROM and take a resistance reading. It won't be 0 ohms, but something like 0.6 ohms. Then keep one probe on D2 and find A3 on another chip and take another resistance reading. If the resistance reading is higher, as in 0.7 ohms, you got physically farther from the short. If it's 0.5 ohms, you got closer. Keep going until you get the lowest number you can. Then keep that end of the meter lead on D2 on the chip with the lowest resistance number, then start over with A3. Move the meter lead to A3 on other chips, take a ohm reading, and find the point you got the lowest reading. It will often be near your D2 point. At then point you have the lowest ohm reading, is really close to your short.
If you break up the board into a search grid, you can speed up the process more. If you get a higher ohm reading on a chip on the upper left of the PCB then the lower right, then focus on the lower right.
That said, before doing the above, I check the user damageable things first. Like the card connectors. If the two shorted pins are near each other on a connector or cable, then they could have been damaged or shorted.
I've since come to appreciate the computer as itself. Back in t he day, I hated Apples, because I was in the 'Trs80 camp'. With age does come wisdom. It's no longer Hatfield vs. McKoys. I still like Z80 better than 6502, but it is no longer Evil Innate. - Well at least from a hardware standpoint. Company wise, that's another story.
Awesome. Never got anything this harry, but did encounter defective delay lines to memory chips on TRS-80 model-2's and thought abought solder shorting two pins of dip sockets.
The 2SC1815 transistor is a Japanese TO-92 pinout, with
E C B
But the 2N3904 is E B C.
That seems to be the reason why it tested good but didn't work in circuit. They should be replaced with the 2N3904 which has slightly better switching specifications.
Thanks.
I wouldn't be surprised if this was bought as a kit, and the builder didn't have the skills to successfully get it working
Those two lines are across from each other and suspiciously close on the slots. Maybe there's something in or under one of the slots?
Amazing video, going to watch part 2 now! :)
Just a thought... If jou remove the bus transceiver would it be safe to pull the address line high and the dataline low with a power supply. It would be like voltage injection, the short would get hot....
I was thinking the same exact thing. Start with current limited and slowly turn it up. Use the FLIR to see the exact path to the short start to warm up. My non-electrical engineer guess is a solder blob down in one of the expansion ports.. Probably not it, but it's fun to guess!
I had an illegal Apple II+ when I was a kid. I used it most of the way through college. It had the actual Apple ROMs in it. No clean room stuff for me. Mine was kind of interesting in that it also had a Z80 and could also boot to CPM. I didn't have any CPM software at the time, so I never booted to it after I first got it. It was pretty reliable. I managed to get all my college papers done on it. I used AceWriter for that.
Do you recall if it has the Z80 on a card or was it somehow integrated into the motherboard?
@@adriansdigitalbasement it was integrated into the motherboard. It seems like there was a key combination when you turned on the computer to go to cpm. If there was no Apple ROMs, it booted straight to cpm.
@@Slim_Chiply that's a really cool "feature-add" over Apple's stuff. On a real Apple II you had to buy an extra card, but not on the clone. Neat!
@@adriansdigitalbasement There were a few with the integrated Z80. I had one that had the ROM on a card that plugged into slot 1. There was no slot 4, and the RAM was a single row of eight socketed chips (64K). It said "EASY ][" at the top of the screen instead of "APPLE ][", and there were macros for common BASIC commands as well as all the Demosoft apps. The keyboard was similar to the one in the video.
I'd watch how you word the title, I could see "Illegal" and "Apple" getting you a cease and desist from them, or a knock on the door from the FBI coming to confiscate your 40 year old clone computers. Someone at Apple, watching your video, pounding their fist "Nein! Nein! Nein!" 😆
I’d use the term “unauthorized” if it were me. Apple isn’t known to be nice.
Exactly, this includes the guy that was buying up all the Lisa computers from them, upgrading them and reselling them. It's not about the technology, it's about making money.
Nein! Nein! Nein!😃
The likely explanation a bad solder joint on the transistor.
IIRC Franklin survived to become the same company behind the Franklin electronic dictionaries and ebook readers
you can hear Adrians sanity slowly dissappear as the repair keeps getting more difficult LOL
Possibly a ram chip for bit 2, that would use both the address line 3 and data line for bit 2.
There's a multiplexer between the address bus and DRAM, so no way to have a short there.
Many of the signals you indicated as being fine looked like total crap to me. That stepping effect on the signals I would associate with bad crosstalk or high resistance shorts. Given the age of the board and the sloppy construction, I might think of oxidation or contaminants from degrading solder flux. I would wash that board really well, clean off all the solder, and then try the continuity tests over.
There were Apple clones named peach, orange and even banana.
They were in magazines like Computer Shopper, Byte etc and they were all over the SF Bay Area here where I live and Apple was suing these clone makers like crazy back then.
I'm expecting those other transistors to be bad as well. They're generic PNP replacements, but probably came from the bottom of the barrel. Is that the reason for the socketed transistors near the crystal? If they worked when it was new, what could cause them to fail? Maybe it could have been bad packaging that corroded internally after time, who knows.
And I'm pretty sure the clone Apple II that I have is also this same board, so I'm downloading that schematic, because I'm pretty sure that I tried it and it didn't work, and I'm going to have to fix it. Thanks for sharing the info!
I wonder if the clone you are working on started as a bare board too ? That would explain all the different dates on the chips. (?)
My dad told me once that there were vendors that sold the motherboards without ROMs as "replacement motherboards" for defective Apples and you just needed ROMS
Very interesting troubleshooting, Adrian!
You should totally put that unpopulated motherboard in a glass display to hang on a wall. Absolutely beautiful.
Hi Adrian, great try on the clone board. I saw a solder run at 49.58 minutes, 5th (?) chip down in the center of the board. A little later it's not there so part of your multiple failures? Good luck.
Is voltage injection + a thermal camera safe on older boards like this to find a short?