psu.why & how to replace the dreaded capacitors in ATARI ST!

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Fujiyama
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Re: psu.why & how to replace the dreaded capacitors in ATARI ST!

Postby Fujiyama » Sun Aug 06, 2017 10:47 pm

Huh? The ST power supplies aren't switched mode types?
How can you tell a switched mode and normal regulated power supply apart?
Mega STe | MonSTer with dual IDE-CF memory card adapter | STe | SM-144 |NEC Multisync 1990SXi | IDE doubler | ST_ESSC | RSVE | ICD Link II | Link '97 | HD floppy drive/AJAX | HD floppy module | Minolta PCMCIA card-drive | Realtime Clock module | Discovery cartridge | Unitor-2 | Export | Combiner | Steady Eye | Human Touch | Unicorn USB

KLund1
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Re: psu.why & how to replace the dreaded capacitors in ATARI ST!

Postby KLund1 » Tue Aug 22, 2017 11:00 pm

I have a coupe dead 1040STF PSU's I would like to bring back to life. It would be my first time doing a re-cap, but they are dead anyway, so no harm if I make a mistake. I do not know what part(s) failed, but this would be a logical first step. I will be following Exxos PSU recap page direction, and parts list.
Any word about NTE caps? I works at Fry's Electronics and we sell this line of parts. I do not know if NTE is just the distributor, or manufacturer. But, I get a discount on purchases. I do know that most of these parts have been hanging in the stores, in the original packages for several years. So no heat or humidity issues during their non use life.
Thanks
UPDATED: Falcon 030(FX-1)(CF int & removable SD), MSTE 4+PS3000 4160STE 2.06+HDFD STacy4-internal-USD 1040STFM+I.B.Driver-5.25"FDD 1040STF 1040ST 520ST-AdSpeed 400-48k 800+810x2+820+822+825+830+835+850, 800XL+IndusGT 600XL 130XE+XF551x2 Portfolio 1200XL APE(Warp+32in1 OS SuperVideo 2.1 256k RAMBO)+1050x2 USD'd+SIO2PC, PC1+PCH204+PCM124+PCF554x2

KLund1
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Re: psu.why & how to replace the dreaded capacitors in ATARI ST!

Postby KLund1 » Wed Aug 23, 2017 2:19 am

Got home and pull put the ASP34-1 bad psu I have. I did some quick multimeter testing on all the major caps. None are bulging, or leaking from under that I can see with out removing them. They all get response from the meter. The only unit I get no response from is a cap in position C2, an orange cap. it is labeled OCS 222M on one side and the other:
580-2 400V
+ ~ Y
665-1 s EW1

What dose this mean?
is this a good replacement
http://frys.com/product/1792445?site=sr ... IN_RSLT_PG
Fry's only seems to have 50v and 100V ceramic caps when i filter with 220M
UPDATED: Falcon 030(FX-1)(CF int & removable SD), MSTE 4+PS3000 4160STE 2.06+HDFD STacy4-internal-USD 1040STFM+I.B.Driver-5.25"FDD 1040STF 1040ST 520ST-AdSpeed 400-48k 800+810x2+820+822+825+830+835+850, 800XL+IndusGT 600XL 130XE+XF551x2 Portfolio 1200XL APE(Warp+32in1 OS SuperVideo 2.1 256k RAMBO)+1050x2 USD'd+SIO2PC, PC1+PCH204+PCM124+PCF554x2

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Fujiyama
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Re: psu.why & how to replace the dreaded capacitors in ATARI ST!

Postby Fujiyama » Tue Oct 17, 2017 11:59 am

Your link came up empty ("not found") but I suggest you look at the schematic for your particular power supply and find the C2 capacitor. The numbers you read seem to be production numbers.
There's recapping info for most of the Atari power supplies here, but I didn't find that specific ASP34 revision you have. Maybe the differences aren't that great.

I don't know what kind of capacitors Frys sells, but don't just settle with the cheapest generic one you can find the easiest.
I suggest you go for high quality, brand name capacitors from reputable component dealers if you want to recap. Exxos sells complete "recapping kits" where he's picked out the components you need, saving you the hassle. I think this is the one you want although there's no mention of the revision number. Better ask Exxos before you order.

Although only one capacitor in your PSU appears to be non-working I would for sure replace them all. They've all aged, their capacitor values have surely changed since they were new and you never know when the who thing breaks down, perhaps because of one capacitor which presently seems OK. Replace them all with high quality components and be done with it :D

I've just posted a "how to" guide on recapping the Mega STe power supply. Most of the information (obviously apart from the parts list) should be applicable for recapping other Atari ST power supplies as well, so I suggest reading through it if you've never done this sort of thing before (or even if you have). Good luck! :D

UPDATE: I've just downloaded the ASP-34 schematic from the above link and it reads the ASP-34-1 meaning it's your exact PSU revision.
Sorry, I should have read through your previous postings a little better because you're not referring to the usual components which need recapping (electrolytic capacitors), and I see that C2 in the schematic is valued at 0.002uF/400V (or 2nf/400V) which corresponds well with the "222M" marking you found. According to this online capacitor calculator it translates into 2.2nF/400V and I believe you're looking for a ceramic capacitor with those markings, but don't quote me on that. Maybe someone else can confirm that.
Mega STe | MonSTer with dual IDE-CF memory card adapter | STe | SM-144 |NEC Multisync 1990SXi | IDE doubler | ST_ESSC | RSVE | ICD Link II | Link '97 | HD floppy drive/AJAX | HD floppy module | Minolta PCMCIA card-drive | Realtime Clock module | Discovery cartridge | Unitor-2 | Export | Combiner | Steady Eye | Human Touch | Unicorn USB


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