ASP34-2 REV1 recapping how-to

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sandord
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ASP34-2 REV1 recapping how-to

Post by sandord » Mon Aug 13, 2018 10:27 pm

I recapped my ASP34-2 REV 1 PSU the other day, replacing 7 capacitors and the rectifier.

I thought I'd do a quick report to share my experience with anyone who would be interested.

So, I ordered the PSU upgrade kit for my ASP34-2. I have the revision and that particular revision wasn't mentioned in the shop at the time (Chris has put it online right after I mailed a picture of it to him).

As you can see on the picture below, there's one capacity (25V 1000uF) that isn't quite met specwise by the replacement capacitor (16V 2200uF). After mailing Chris, I was ensured that is posed no problem as the other revisions all have a 16V rated capacitor in that spot.
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Here are the replacement parts from the PSU upgrade kit.
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Before starting the upgrade, I measured the PSU under load using my oscilloscope.
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I don't notice any screen dimming while disk access so I think my PSU isn't that bad as it is.

Okay, here we go.

Remove four screws as indicated:
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Put the board straight up and desolder the two indicated points to disconnect the board from the support.
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Now, the board is separed from the support.

You might want to use some desoldering ribbon to open up the holes so it'll be easier to stick the wires back in later.
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Now, remove all components (capacitors and a rectifier) as indicated:
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Again, you might want to use desoldering ribbon to keep the holes open.
I'm only using it after removing a part. I could use it to desolder the part as well but as desoldering lint can be quite expensive, I prefer removing the parts using the wiggling technique. By alternating a few times between legs, heating one while tilting the part into the opposite direction and vice-versa.
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Now, place the replacement components.

I had to bend the legs of the rectifier a bit to fit the holes but luckily, no drilling was required (some other PSU types and revisions apparently have holes that are a little smaller).
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I also had to bend the legs of the top-right capacitor because it's a bit larger than the original one and the board didn't account for the additional required space.
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Finally, refresh all remaining soldering points on the board to make sure that none of them are on the verge of breaking.

Finished!
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Finally, let's measure:
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I can’t say it made much difference, other than 12V Vpp going from 140mV to 120mV.
I guess the PSU was pretty okay to begin with. At least I’ll be safe for many years to come!

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Re: ASP34-2 REV1 recapping how-to

Post by exxos » Mon Aug 13, 2018 10:31 pm

:bravo:

Pretty much same as results as the PSU I tested. The DVE/ASP ones seem to stand the tests of time better than the SR98s. Though I haven't seen many past the SR98s to test out much.

Thanks for posting it! I'm sure will be interest to others!
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Re: ASP34-2 REV1 recapping how-to

Post by sandord » Mon Sep 24, 2018 10:31 am

When doing another PSU recap, I figured that instead of desoldering the mains wires from the PCB, it's more practical to just unscrew the rear terminals :roll: :-D

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Re: ASP34-2 REV1 recapping how-to

Post by exxos » Mon Sep 24, 2018 10:54 am

sandord wrote:
Mon Sep 24, 2018 10:31 am
When doing another PSU recap, I figured that instead of desoldering the mains wires from the PCB, it's more practical to just unscrew the rear terminals :roll: :-D
ahh, I don't do either, I struggle with it in place :)
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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