Commodore Amiga 500 Junk PSU Repair (Heavy Brick Model)
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- Опубліковано 28 сер 2024
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A simple repair to a PSU that had been scrapped. What makes this model nice is the simplicity of it! If the transformer doesn't fail, you will always be able to repair this model easily.
Thanks to Hey Birt! for the connectors!
/ @heybirt
#commodore #amiga #repair - Наука та технологія
Thanks to Hey Birt! for the connectors!
ua-cam.com/channels/2V0T-vGOewtuCW3pazzczQ.html
Excellent repair - I've always found British plugs to be fascinating.
1 amp! - it's been a long long time since i seen one of those.....i believe they are/were used in shaver adapters.
In Russia regulations prohibit tinning wires in screw-based termination points. Reasoning is that wire gets aluminum-like strength characteristics when tinned making it a more like "buttery" than "springy" and it is a bad thing for a non-springed screw terminal. Official recommendation is to clamp the end of a multi-core wire with a special metal cap using resp. crimping tool.
Thanks for the info there =D Yes, that was why I pointed out it might not be deemed safe! This PSU is staying with me anyway, and many of the other devices I have probably have the leads soldered from decades ago!
@@GadgetUK164 Alexey is right there. Copper and tin are both just too soft for the force coming from the screw so it losens and leads to arcing. In Germany we have a regulation that a short metal pipe has to be used and clamped down on flexible wiring, unless it is one solid copper conductor.
Also what confuses me, I have three of the same A500 PSUs here and they are labelled as "5v/2.5A" with the exact same electronics inside. I even had to repair one of them because the schottky diode of the big regulator (which is for 5V) blew. So I know this model of PSU inside out.
So all those decades I was thhinking the heavier transformer ones are the 2.5A types and the lighter full switchmode models are 4.5A
@@amurtigress_mobile365 In the USA its the same thing - my understanding was as well in a fault situation the wire would heat up so much its at risk of falling off the terminal as well.
7:58 I recommend not tinning the ends of the wires for screw terminals, as solder is a soft metal. Over time, soft metal can work its way free from a screw terminal. Instead, use crimped ferrules (this is what appliance manufacturers will often do for UK plugs).
Great vid, the power you're supplying is electrifying!
Chris what can I say what a terrible plug!!😂
a T12 soldering iron will make your life so much easier, even a cheap one, you wont go back to that old antec iron, if memory serves the really bad psu's were the really light high frequency switching ones that came out with the a500+ my memory maybe wrong but I think they were marked as 2 or 2.5 amps on the bottom - they used to blow quite often so we used to give out 4.5 amp after market ones when they did
I have a Hakko now, but still use the Antex for something things too.
I don't know how much electronics you know but multi-stranded wire is used due to skin effect. Electricity runs down the outside of a wire and the more current that is passed down a wire the closer to the centre of the wire the electricity penetrates too. If the electricity reaches the centre it causes the wire to heat up . Being multi-stranded there is more surface area and therefore more amperage can be delivered to the device without the wire heating up. However if you don't tin the end of the wire when you screw it down the wire splays out. Which means most of the strands don't make a proper contact this again can cause the wire to heat up at that point.
Thanks for the info there =D
I was about to say 'at least it's not resin potted' and then you compared it with one that is! The cases from those potted ones can be handy to rebuild a new power supply inside, if you manage to crack the seam, and drill a hole in the top to put a screwdriver through to try to separate the resin 'brick' from the plastic. You can then use the hole for an LED.
CPC sell a plastic-cased transformer that fits the C64 bricks exactly, with enough room for a small board for the cap and rectifier, and enough room for a little switching regulator board for the 5V line. Then glue the case back together. I built one like this for my C64 and of course it runs a million degrees cooler.
Nice idea =D
Great repair job, have you ever done one of the solid filled ones? Can you dissolve the filling material?
Many years ago I went into one I think! I think they are very similar (if not worse) than the C64 ones! I might go into that one I have at some point as I think it does need recapping.
@@GadgetUK164 I would be interested to watch that episode.
nice i picked up one of these the other week on the bay not had chance to service it yet think i paid 15 or 20 with postage but its in really nice condition so didn't mind paying a little more than usual
1A fuse. LMAO! What were they thinking! Great stuff as usual!
I know lol! Don't remember ever seeing a 1A fuse in a mains plug before tbh!
@@GadgetUK164 theyre usually used in Shaver adapters. 1A would be enough current, but the inrush of the transformer probably popped it
Ive just got given back my Amiga 500 from my Dad. Does anyone know what UK plug adapter would fit the bs5733 adapter to the mains. Im at a loss as it has 3 thin pins but cant see anything to marry it up. Cheers
Same treatment to mine recently except the connector, plug on it was horrific, also didn't bother with recapping, just had to epoxy two of the screw posts, absolute beefcake of a transformer, might recap in the future but didn't seem to need it. the A500 itself however may be worthwhile.
you should get some liquid poly cement for these small case bumps. it literally elts the plastic back together.
I remember when you used to buy an electronic item and had to buy the plug separate... lol back in the old days, and people used to use tin foil round the fuse!!
In the old days I remember someone I went out with wrapping wire around a matchstick and pushing that into the socket.. and cooking dinner on an electric fire lain in its back...
blackcountryme ,,, I’m in stitches laughing,
@@briancharles3438 she was a nice girl, just a bit cavalier with anything electrical, hair tongs with the wire around the matchsticks shoved in the socket behind the chest if drawers, and smoke pouring out. Or when cooking on that electric fire, some peas fell Inthe the fire and she was using a metal fork to get them back from next to the old spring type live fire bars, not the glass covered ones...
blackcountryme is she still alive lol, sounds like a comedy sketch (quality)
I think it’s ABS plastic and if it is you can glue it with acetone. But be careful it can ruin it if you spill. Put some in a cotton swab.
Fuses for uk plugs come in 1,2,3 ,5,7,10, 13
Most commonly 1, 3, 5 and 13. 10A arent that common. I've only ever seen them in IEC cables
I've only ever seen 3, 5 and 13.
Wasn't aware tbh - only sized I've ever seen (and I've seen the insides of a lot of plugs in my time lol) are 3,5,13.
Interesting video, nice fix :) My Amiga 500 power supply is, I guess, the light one. Part number 312503- but after that has stamped numbers 03 22021*
No idea what those stamped numbers mean? The star is actually stamped as well, didn't try to censor anything :D
It's made in W. Germany.
Actually the 1A fuse is fine as the PSU is 60W rated.. so 60 / 240 * 1.25 = 0.3125Amps.. well under 1 Amp. Even C64s should have a 1A fuse, it's just because 3A is produced en-masse covering more higher rated appliances. Low powered 30 or 40 year old computers never got the correct fused fitted.
The fuse is not to protect the appliance, it is to protect the flex as we have 32A ring final circuits which are capable of providing a massive overload. The PSU is usually fused inside with a T500mA fuse. A 3A fuse should be fitted as that is what the flex will be rated for, however 1A is not a problem
... apart from inrush current. The transformer will briefly draw more current as it magnetises. This has probably popped the 1A fuse
Thanks, yeah - I didn't calculated it, just went from prior experience of putting 3A into something like that - as we typically only ever see 3,5, or 13A fuses here in old computers. I think Peter's point there about inrush is probably why it died with a 1A fuse tbh.
The new mains plug is from the same era as the PSU. LOL.
I love seeing that old Fluke 77. I was buying them used from hock shops for about $50 back in the early 90's. :)
Funny, most people always get the 'Birt' part wrong...Brit, Bart, Bird, etc... :)
LOL =D
Have you tried Plastic Weld at all Chris? It bonds plastics together
BTW: I would have done a double-check on the voltages on the pins before crimping the connector on... just in case. It’s just too easy to get all but the last two correct, then have two swapped. Then there goes your motherboard. Ouch! 🥺 Then you really will have a “terrible fire” motherboard! And, of course, if you do find a pin mis-wired, you can correct it without having to un-crimp the connector shell, as those crimp tabs will break off if you fiddle with them too many times.
Voltages were measured before I connected it up to the Amiga btw!
I have a huge brick psu...
Is it dangerous to use it for my Amiga s health?
Thanks!
If it hasn't been recapped - it's well worth getting that done (and a service of the PSU in general). You could alternatively buy a modern replacement.
A500 power bricks work better than A1200 ones especially if you're A1200 has upgrades in it.
My 600 came with a large psu like the one in your video. However it’s super light?!
Very interesting! There must be light ones in that package too! I've never seen one!
Salve potrei sapere codice transistor ic3. Grazie
Tinning multi strand cables for screw terminals is not a good dea, because when tin is under pressure it deforms over time. This will eventually cause a loose connection. With spring terminals it's not a problem AFAIK, but the combination of screw terminals and tinned multistrand wire is a bad one.
Im living in the Twilight Zone, uploaded 7 minutes ago but comments from 2 weeks ago lol (yes I know about Patreon)
LOL! Same here! :)
I always find it interesting how paranoid the British standards commission was when they introduced the mandatory AC plugs with built in fuses.
As paranoid as it may seem, these plugs have saved many lives!
Not paranoia, the fuses are necessary on a ring circuit that is rated for 32A
Now I was watching this, whilst playing battlefield 1, then it stopped .. after I finished playing it started playing again... Scared the ship out of me... Dead silent room then TV shouts booming
Haha =D
@@GadgetUK164 the game just finished, I took off my headset and the TV decided to test my heart out. I swear, I jumped out of that cheapo gaming seat
You shouldn't put solder at the end of the cables. It has the ability to shrink and when it do the screws get loose. That is why you today see these shrink end terminals instead of solder.
Thanks for the video, but you really need to layoff with all the ads.
Become a patreon then ;)
The combination of ads and Patreon are what keep the videos coming! I litterally cannot afford to run the channel without them sorry.
@@GadgetUK164
Well I need my daily dose of Gadget, n I don't want to run AdBlock cause that's not fair for UA-camrs, so I can live with the ads.
@@TheErador
Or run AdBlock for free, n never watch a ad again
I'm always slightly amazed with how huge UK plugs are. Seems like something from the 50's. ;-) Only large appliances (stoves, dishwashers, washers/dryers) have large plugs in the US.
BS1363 was introduced in 1947 and revised to include sleeved pins in 1984. It's one of the safest plugs available. Bear in mind our ring circuits can carry 32A of current.
Chris the second you said "Hey Birt" it sounded like something from a childhood TV show ua-cam.com/video/pD0CL4KJOa8/v-deo.html No disrespect intended btw.
Hey Ernie!
Man, the quality of the solder work on this thing originally is absolutely atrocious...
Meh, gut it and put a Meanwell in there. The transformer is about 50VA and if you measure the secondaries, it's something like 25-18-0-18-25 ! Obviously the manufacturer had these on the shelf from something else, and just decided to throw some switchmode regulators on the output. Typical cheap subcontracted crap.
The schematic basically comes from an ST application note in the datasheet for either the L296 (which generates the 5v here) or the L4960 (which does the +12v). I've occasionally found the crowbar SCR dead in these too
Oh, and the 7912 for the -12V output often likes to go short as well...
Thanks =D Nah, I like to keep the originals as they are - sticking a meanwell in there is like removing the engine out of an old classic car and replacing it with a modern engine.
That's interesting! I've seen the crowbar dead in a few 3rd party Amiga PSUs over the last few years too.
@@GadgetUK164 Thats fair enough, mostly for me I think the Amiga is the part worth saving... so I generally retrofit the PSU's with a Meanwell as it is an insurance for the Amiga as well. Each to their own :)
There's a few different kinds of supply.. im not sure who made this one. The switchmode ones by ISMET i dont bother fixing as they are very poor designs. There is a slim "Made in India" design which is only 22W but is very good quality. I've only come across one of the slim potted ones, made by Speedy-Tech and usually dead - I did manage to get the resin block out of one to reuse the casing!
Not a fan of the wacka-wacka guitar in the background.