Changing capacitors in Amiga power supplies

8bitbubsy · 22 February 2010, 13:25

I have this old trusty A500 PSU brick which always gives a good and stable voltage rail, I love it! However, it's very very old so it might be a bit sick.
I know very well the saying "Don't fix what is not broken", but capacitors are known to fail over time and especially the very old ones!

Capacitor list (POWER SUPPLY A 500 P/NO. 312 503- 03):
2x 470µF 25v electrolytic through-hole
1x 4700µF 25v electrolytic through-hole
1x 4700µF 16v electrolytic through-hole
3x 22µF 25v electrolytic through-hole

Futurlec order list:
2x 4700µF 25v
3x 22µF 50v
2x 470µF 25v

Oh, and another thing.. When this PSU has ran for half an hour or so it starts to smell like "80s bite the dust & plastic" or something like that.. It's not a fault, it's the case.. How can I remove this? Just wash it?

jbenam · 22 February 2010, 14:38

I was going to do the same thing with my A1200 brick (one of those black ones)!

Sadly it started having pretty instable voltages not too long ago (luckily I switched over to my Micronik Infinitiv PSU just some days later) and I thought of changing capacitors on it. Already got a bunch of em, but I preferred to wait for a Desoldering Gun station to do this work. Now that I have one, I might do it soon

Good luck!

Thorham · 22 February 2010, 14:54

Isn't it a better idea to buy a new peecee psu and mod it using the cable from the Amiga psu? Unless you want to keep things as original as possible, this might be a better option.

8bitbubsy · 22 February 2010, 15:03

Quote:

Originally Posted by Thorham

Isn't it a better idea to buy a new peecee psu and mod it using the cable from the Amiga psu? Unless you want to keep things as original as possible, this might be a better option.

Well.. I've tried that, but all the PSUs I have seem to have a pretty low 5v voltage rail... The original Commodore PSUs are perfect (5.04v on mine)

Thorham · 22 February 2010, 15:17

Quote:

Originally Posted by 8bitbubsy

Well.. I've tried that, but all the PSUs I have seem to have a pretty low 5v voltage rail... The original Commodore PSUs are perfect (5.04v on mine)

Oh, I didn't know that. Is that something that can cause damage to an Amiga (I us an AT PSU to power an A1200, CD rewriter and HD)?

8bitbubsy · 22 February 2010, 15:26

I doubt it, but it's not healthy in any way for it... You can get funky results and unstability, as far as I know. Always good to have a precise voltage rating

My other PSUs has like 4.66v on the 5v rail...
12.0xv and 5.0xv is perfect

Thorham · 22 February 2010, 15:38

Quote:

Originally Posted by 8bitbubsy

I doubt it, but it's not healthy in any way for it... You can get funky results and unstability, as far as I know. Always good to have a precise voltage rating

My other PSUs has like 4.66v on the 5v rail...
12.0xv and 5.0xv is perfect

Okay, thanks for letting me know

I guess I should do some measurements when I replace my dead A1200. Perhaps spending more on a high quality peecee PSU would make a difference.

Loedown · 23 February 2010, 00:05

I've had no issue with using AT style power supplies, but then again, I only use new supplies and decent branded ones, they don't cost much more and you can be assured that if the thing goes tits up, you're more likely not to blow your Amiga hardware to kingdom come. Ask me the story about my sister's PC and the amazing melting RAM chips.

Don't ask, I'll write it anyway, she left her PC on overnight and came out in the morning to find a very dead PC, so I got it and opened it up, it had blown every single card in the machine, literally blown chunks out of the chips. The RAM chips had gotten so hot that they'd melted their own solder and moved on the simms. I could only save two things from the whole system, the DVD laser and the CPU, everything else was fried. So don't use cheap power supplies.

Franchute13 · 01 February 2016, 16:02

Hi.
Use this thread to detail capacitors using this PSU
Model:
A 391 029-03_rev
Photo:
http://hostthenpost.org/uploads/7786...9398c50a9b.jpg

List:
3 x 47uFx35V 85C
1 x 82uFx35V 105C
2 x 1000uFx10V 105C
1 x 220uFx35V 105C
1 x 1uFx50V 85C
1 x 33uFx400V 85C

8bitbubsy · 01 February 2016, 16:37

Oh wow, I was younger and dumb back then, in the first post...

1) The 80s smell is not a bad thing!

2) You should use low ESR capacitors in a switching power supply. Also, futurlec.com tends to give you the cheapest capacitors ever. One time I got a batch of fake Rubycons from them with high ESR, all of them. I have a feeling that their Samxon stuff is fake too, because they have high ESR too. I've seen real Samxon stuff in some good (!) PSUs, and they look to be of more quality. Could be a different series.. Anyways, never buy from futurlec.com if you want to do a proper recap job that should last and be good.

dlfrsilver · 01 February 2016, 17:29

guys i changed the capacitors for better ones in my own PSU's and the result is very neat !!!

Don't throw away your old PSUs, restore them, buy some high quality capacitors (rubycon, or nichicon), and replace them.

It's amazing how great the display got better once i did the change on my A500 PSU

Just use a screwdriver to discharge the parts, and go disolder the old farts !

Zetr0 · 01 February 2016, 18:14

@Thread

I would humbly suggest replacing for 105c (Or higher) rated capacitors - always go for a good brand, like rubycon, nichicon or my favourite panasonic.

If your hearing a buzzing sound its quite likely the transformer coils, these can be replaced - (you would require a 2 tap module - [12v and 5v], the rest is rectified on the power supply PCB. To be honest though a "drop in" replacement might be tricky to source.

If you are having intermittent issues but still reporting good voltages = current leakage could be an issue and at that point it would prudent to replace the rectifier diodes. like for like would be the best thing here.

mech · 01 February 2016, 18:20

Quote:

Originally Posted by Zetr0

@Thread

I would humbly suggest replacing for 105c (Or higher) rated capacitors - always go for a good brand, like rubycon, nichicon or my favourite panasonic.

I second the Panasonic! their long life caps are excellent.

22 February 2010, 13:25	#1
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,584	Changing capacitors in Amiga power supplies I have this old trusty A500 PSU brick which always gives a good and stable voltage rail, I love it! However, it's very very old so it might be a bit sick. I know very well the saying "Don't fix what is not broken", but capacitors are known to fail over time and especially the very old ones! Capacitor list (POWER SUPPLY A 500 P/NO. 312 503- 03): 2x 470µF 25v electrolytic through-hole 1x 4700µF 25v electrolytic through-hole 1x 4700µF 16v electrolytic through-hole 3x 22µF 25v electrolytic through-hole Futurlec order list: 2x 4700µF 25v 3x 22µF 50v 2x 470µF 25v Oh, and another thing.. When this PSU has ran for half an hour or so it starts to smell like "80s bite the dust & plastic" or something like that.. It's not a fault, it's the case.. How can I remove this? Just wash it? Last edited by 8bitbubsy; 22 February 2010 at 13:46.

01 February 2016, 18:14	#12
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 47 Posts: 9,768	@Thread I would humbly suggest replacing for 105c (Or higher) rated capacitors - always go for a good brand, like rubycon, nichicon or my favourite panasonic. If your hearing a buzzing sound its quite likely the transformer coils, these can be replaced - (you would require a 2 tap module - [12v and 5v], the rest is rectified on the power supply PCB. To be honest though a "drop in" replacement might be tricky to source. If you are having intermittent issues but still reporting good voltages = current leakage could be an issue and at that point it would prudent to replace the rectifier diodes. like for like would be the best thing here. Last edited by Zetr0; 01 February 2016 at 18:28.

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22 February 2010, 14:38	#2
jbenam Italian Amiga Zealot Join Date: Jan 2009 Location: Italy Age: 34 Posts: 1,671	I was going to do the same thing with my A1200 brick (one of those black ones)! Sadly it started having pretty instable voltages not too long ago (luckily I switched over to my Micronik Infinitiv PSU just some days later) and I thought of changing capacitors on it. Already got a bunch of em, but I preferred to wait for a Desoldering Gun station to do this work. Now that I have one, I might do it soon Good luck!

22 February 2010, 14:54	#3
Thorham Computer Nerd Join Date: Sep 2007 Location: Rotterdam/Netherlands Age: 45 Posts: 3,249	Isn't it a better idea to buy a new peecee psu and mod it using the cable from the Amiga psu? Unless you want to keep things as original as possible, this might be a better option.

22 February 2010, 15:26	#6
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,584	I doubt it, but it's not healthy in any way for it... You can get funky results and unstability, as far as I know. Always good to have a precise voltage rating My other PSUs has like 4.66v on the 5v rail... 12.0xv and 5.0xv is perfect

23 February 2010, 00:05	#8
Loedown Precious & fragile things Join Date: Feb 2009 Location: Victoria, Australia Posts: 1,946	I've had no issue with using AT style power supplies, but then again, I only use new supplies and decent branded ones, they don't cost much more and you can be assured that if the thing goes tits up, you're more likely not to blow your Amiga hardware to kingdom come. Ask me the story about my sister's PC and the amazing melting RAM chips. Don't ask, I'll write it anyway, she left her PC on overnight and came out in the morning to find a very dead PC, so I got it and opened it up, it had blown every single card in the machine, literally blown chunks out of the chips. The RAM chips had gotten so hot that they'd melted their own solder and moved on the simms. I could only save two things from the whole system, the DVD laser and the CPU, everything else was fried. So don't use cheap power supplies.

01 February 2016, 16:02	#9
Franchute13 Registered User Join Date: Feb 2013 Location: Argentina Posts: 279	Hi. Use this thread to detail capacitors using this PSU Model: A 391 029-03_rev Photo: http://hostthenpost.org/uploads/7786...9398c50a9b.jpg List: 3 x 47uFx35V 85C 1 x 82uFx35V 105C 2 x 1000uFx10V 105C 1 x 220uFx35V 105C 1 x 1uFx50V 85C 1 x 33uFx400V 85C

01 February 2016, 16:37	#10
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,584	Oh wow, I was younger and dumb back then, in the first post... 1) The 80s smell is not a bad thing! 2) You should use low ESR capacitors in a switching power supply. Also, futurlec.com tends to give you the cheapest capacitors ever. One time I got a batch of fake Rubycons from them with high ESR, all of them. I have a feeling that their Samxon stuff is fake too, because they have high ESR too. I've seen real Samxon stuff in some good (!) PSUs, and they look to be of more quality. Could be a different series.. Anyways, never buy from futurlec.com if you want to do a proper recap job that should last and be good.

01 February 2016, 17:29	#11
dlfrsilver CaptainM68K-SPS France Join Date: Dec 2004 Location: Melun nearby Paris/France Age: 44 Posts: 9,306	guys i changed the capacitors for better ones in my own PSU's and the result is very neat !!! Don't throw away your old PSUs, restore them, buy some high quality capacitors (rubycon, or nichicon), and replace them. It's amazing how great the display got better once i did the change on my A500 PSU Just use a screwdriver to discharge the parts, and go disolder the old farts !

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