17 May 2019, 01:13 | #1 |
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A2000 PSU refurbish
Just got an Amiga 2000, my first big box Amiga. Seller advised it was non functional with a green screen at boot. The battery had been removed and the area cleaned.
On receiving the unit the first thing I did was to remove the PSU and drives. The area around the battery looks clean but there was some light corrosion on the three pins on the CPU nearest the battery. Before I powered the board I thought I'd test the PSU first and I am glad I did. All the power rails are showing serious voltage fluctuation. 5v bounces between 3 and 5.5v, 12v bounces between 10 and 11.5, -12v shows between 0 and -3 and -5 is between -3 and 5v. The fan is also speeding up and slowing down so I can only guess that the line caps are completely gubbed. I have got an ATX adaptor on order but I would like to get this PSU reconditioned. To that end I'm afraid my google-fu has come up short so does anyone know th we list of caps needed to swap on these PSU's? |
17 May 2019, 07:42 | #2 |
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You already have the PSU out, so I guess you could look at the caps and make a cap list for the rest of us? :-)
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17 May 2019, 08:11 | #3 |
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Yeah, there are a few different "innards" as the PSUs were made by different no-name suppliers - I wouldn't trust any single cap kit I found anyway.
But, when I looked at the cost of properly recapping mine I just replaced the innards with an Ian Stedman ATX adaptor and spare ATX innards. Not much value in preserving retro PSU designs. |
17 May 2019, 21:14 | #4 | |
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Quote:
Model : PhiHong PSM-2000 Rev-F1 C10 100 uF 35V C12 47 uF 25V C17 220 uF 25V C18 47 uF 25V C19 47 uF 25V C20 4700 uF 16V C21 4700 uF 16V C22 1 uF 50V C23 4700 uF 10V C24 4700 uF 10V C25 4700 uF 10V C28 1 uF 50V C32 47 uF 16V C6 680 uF 200V C7 680 uF 200V |
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18 May 2019, 07:59 | #5 |
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Thank you kind sir. :-)
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18 May 2019, 08:24 | #6 |
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Phi Hong... Sounds like a quality brand. Possibly German?
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18 May 2019, 15:19 | #7 |
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In case it helps, here are the positions of the caps as well.
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21 May 2019, 19:25 | #8 |
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Well, I replaced all the caps on the PSU which made no difference to the problem. Voltage was fluctuating badly. Checked all the diodes and they seemed OK. On a passing whim I disconnected the fan and now the bloody thing works!
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21 May 2019, 19:31 | #9 |
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Caps is not just caps. Did you check datasheet of the old ones and matched new ones with better or same ripple current specs and same or little lower ESR
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23 May 2019, 00:09 | #10 | |
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Quote:
Now I have to troubleshoot the chip RAM problems. |
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23 May 2019, 00:49 | #11 |
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I replaced my PSU with an ATX one 2 years ago and I posted a tutorial on github. If you're interested, here it is:
https://github.com/tfve/a2000atx |
23 May 2019, 01:28 | #12 |
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Nice guide - great writeup.
I did the same but stupidly didn't take any pictures. What I did was put the adaptor inside the PSU case - drilled holes in the left hand side - if you look at your second to last picture it went flat against the left panel on the inside. That way the wires running out look original. Only issue with that is to try and keep the bolts flush on the outside, as on the A2000 a card in the CPU slot gets very close to the PSU. Next time I take it out I will take some photos! EDIT: oh - and be careful - anti-static bags can be conductive! |
23 May 2019, 10:32 | #13 |
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Was that yours? Yes, I had a look at that but unfortunately Ian's ATX adaptor is out of stock, I have ordered an ATX adaptor from Amigakit but they seem to be very slow to acknowledge orders these days as it has been sitting in Pending for a week now.
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23 May 2019, 10:36 | #14 | |
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Quote:
Please post some photos of your PSU when you can. Thanks for the heads up regarding the anti-static bags! |
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23 May 2019, 11:38 | #15 |
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When I did A2000 PSU replacements, I just swapped the AT/ATX PSU inside the original case and soldered the A2000 power harness to the new PSU's circuit board in place of the wires that went to the original motherboard power connector. No need for any adapters - you already have the required cable.
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23 May 2019, 13:03 | #16 |
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I have the cable but no spare PSU. Thought I could take one from one of the old PCs at work that are being disposed of but they are all HP DC8000's with proprietary PSU's that don't have a 5V line on them
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23 May 2019, 13:43 | #17 | |
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Quote:
Only things you miss out with there are the -5V line (used by some zorro expansions?) and the tick signal (if you don't want to use the video signal tick jumper option). |
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23 May 2019, 13:47 | #18 |
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Indeed. I selected a PSU with -5 and moved the tick jumper, as I didn't need a stable tick for anything.
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23 May 2019, 16:37 | #19 |
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There is a guy on Amibay selling the IanSteadman adapter as well. He is based in Germany.
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