Commodore Amiga A3640 Repair / Recap - 68040
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- Опубліковано 17 жов 2024
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Repair of a Commodore A3640 from Andy over on my Patreon Discord.
#commodore #amiga #repair
![Little Guys Ep 11 - Where No PC Has Gone Before [Stryker SDC]](/img/n.gif)
The other thing I obviously did here - at the point it wasn't working at all, or giving display problems - feel the temperature of each of the chips on the A3640. That could help you work out if one has died! Something strange - did anyone notice the walls in Doom seemed sloped lol? NOTE: The other difference between 040 and 060, the 060 needs an extra 74F257 and resistors and caps I think! Those probably come fitted on an 040 to 060 adapter, and they are on the A3660 from Chucky. In order to use the MAPROM feature you need to load the Kickstart via command line (as I tried in the next A3640 video!) NOTE: When I cleaned up around C105 you can see the wire is loose! I spotted that later, removed the cap again, soldered it back down, and refitted the cap again! That was done just before it went back - after the video was complete!
The old saying still holds true "THOU SHALL TEST VOLTAGES". As for recapping sometimes people do more damage than good these old boards are fragile so they require a very delicate touch.
Absolutely! However, I use this PSU and motherboard all the time, so I didnt expect that to be the issue! If those parts came as a system, it would be the first thing to check =D
Great video, I find it so awesome that people are making new replacement boards for things like this. Thanks for posting!
As always excellent work and an excellent video - FWIW: I particularly like you include your thought processes in your videos, and even your errors when they crop up along with why they were errors. Very helpful for learning, thanks.
On the subject of learning I guess the primary issue with this board is the person who previously recapped it could have done with a bit more practice?
Thank you very much! =D Yes, the original caps were perhaps removed a bit too quickly, resulting in pad loss. That said, sometimes you lose a pad no matter how careful you are etc, just due to capacitor leakage.
This just makes me want a video game in which you fly your spaceship over a huge Amiga motherboard, dodging power connectors and CF cards, while bad electrolytic caps shoot globs of electrolyte at your ship, and they’ll weaken the shields and slow down the ship until you get back to base to clean it off with vinegar and IPA. 😀 Crazy, huh? 🙂 Oh, and those LEDs on the accelerator card turn into powerful turbo lasers that’ll blast your ship to bits!
Amiga game: Vyrus
=D
That frontier elite intro is classic! just heariing brings back memories..... It was a long time ago but... if memory serves some of the missing FPU instructions were emulated in an 040 version of the MATHIEEEdoubtrans.library located on one of the workbench 3.0 install disks which I had to copy over and if I remember right had to rename, please forgive my old mind if am wrong... I ran an /x BBS on an A4000 for a few years - good times...
Yes, I found the FPU stuff worked there when you have the 040 library installed! I worked that out in the A3660 board build that's coming up!
I used to love magic menu 😊
Saving rare treasure... good job.
Hollow soldertips can be quite handy and used to remove excess solder.
Great work gadget. I can recommend Pattex Repair Extreme or UHU Repair Extreme for fixing capacitors and other stuff on boards. I don't like hot glue.
Wow, that was a tricky one to pin down.
Recently fixed a A3640, had one broken trace due to corrosion.
I assume someone's already mentioned this but anyway always check for dry solder joints especially cracked ones that can always be an issue if you've done just ignore this
The beachball test on the 040 is normally lightning fast with FPU enabled in AIBB. It should not go to black screen. Maybe faulty FPU?
I mentioned this in the pinned comment I think, and in the premiere chat - I was lacking the correct 040 library at the time! Without that library it will black screen on that test! I re-visit this in the next video (A3660 PCB build - using the 040 shown in this video).
I've told you before - MuMapROM util to put boot roms into fast RAM. If you are using MMULib, you have to install it (choose simple option, Expert install has 100s of options). Original 68040.library had huge bugs, which is why Thomas Richter wrote a replacement.
He maintains MMULib to enable a user to implement a custom version of 680X0,.library to do that and more to this day, 25 years plus of commitment. Most modern Workbench (3.1.4) will actually complain if you don't have a 680X0.library on the system (but will still boot).
Thanks - I didn't remember lol! I did however cover this a bit in the next video (build off that PCB shown in this video).
28:31 Depends on the type of flux. Amtech NC-559-V2-TF (my favourite) doesn't burn up, it's consistently in liquid state regardless of the temperature used. It's very sticky and hard to clean though. Ultrasonic with distilled water and Flux-Off Aqueous is recommended. That's what I use.
Thanks, I will give that a try =D
Coldspray and a hairdryer can be used to pinpoint intermittent problems caused by soldercracks.
Thanks - Yes, I've used both of those many times over the years =D
Nice man
Is that a XC68040RC25M? The text is in a weird place and in a strange font. Has someone added that after it left the factory?
Honestly no idea! I suspect it may have been relabelled! Runs fine though!
should there be a lead running from the chip resistor beside R401
No lol - but thanks for pointing out =D
Nice, good job.
Is there a petition anywhere for AmigaKit to use more amps capable connectors? I'd sign it, my A4000 also has significant voltage drop on their connector.
Haha =D It has opened my eyes! I think I have the exact same problem on the A2000 cable too. Since I have on occasion had the same "video cutting out" behaviour on my A2000 boards. Always when first connecting up. I suspect I will need to start storing the adapters in a sealed bag to stop oxidisation.
I remember on irc a person called zorak wrote a small program for me to put in devs that sped up my hd speed on my 040
Yes, the “real” 68040 has the FPU instructions, but the 68LC040 does not. I don’t know about any MMU, though, or if the ‘LC040 had the 6-stage instruction pipeline or not.
This is a "real" 040 - it has the FPU (not an LC), but lacks the transcendental functions. It failed to do anything when I tested using the benchmark there because I was lacking the 040 library. The LC would have had the same 6 stage pipeline I'me sure.
You can use my Sprintfiles and sprint layout to check where pins goes on the 3640 :)
Awesome - I wasn't aware of that =D Great work on the A3660 remake, it's gorgeous!
If you want a challenge, I have a rev 2.1 (not a typo) a3640 that needs some help. I wish there was more information on a3640 repair but it seems to be mainly around re-cap and damaged traces in those areas. This board had no such issues from what I could see under the microscope, but does have some older GALs. I know the GALs had to be upgraded for use in the a3000 due to timing issues. I would even include a 040 to 060 upgrade board for the a3640 for you to show and keep for your channel.
I had a 040 at 40mhz with 128mb ram on my A1200 with a power computing idie power flyer the system ran pretty damn quick for what it was 🙂
Can you please contact me with regards to some faulty boards, A2000, Blizzard boards, and a splash of disk drives and A1200 boards with issues.
I don't do customer repairs sorry!
Thou shalt check voltages
Yeah, not the sort of thing you expect to need to check when you know your PSU and board is good etc. I suspect the voltage drop had gradually increased over time without me noticing it up until this CPU card repair =/
24:44 it looks like you soldered your tinned via to the pad of capacitor C105.
Yes, that's correct! Initially I was trying to avoid that - but after doing it remembered that's where the connection from the cap goes to anyway! It goes to that via!
01:02:10 Did you just skip over the slow part (the planet surface, most demanding)? :)
Haha, yes - it was the most boring lol. The frame rate was perfect - trust me ;)
Chris can i give you a link a non working taito type X2 on ebay
I don't have the funds and resources to tackle an X2 atm. It's PC based architecture, but I would need a better scope, better logic analyser, access to spare parts / parts boards etc etc.
Now days a $5 ESP32 can run Doom at 20fps.
Why didn't you put new pads on i would never do this hack job
It's all a question of your own personal preference. How do you fit a pad there - we didn't have the original pad and trace to epoxy down (which would often be my preference). When there is no pad, your options are to use a wire and secure the cap with epoxy or hot glue, or cut a small pad from copper tape or something and try and epoxy that down, but it will not hold in place very well, and likely need a wire to join the pad up to where ever it goes anyway.