Recapping for Dummies, (and troglodytes)

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PeckPeekPoke
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Recapping for Dummies, (and troglodytes)

Post by PeckPeekPoke »

Hello friends,

I am wondering if it may be a good idea to recap everything on my Atari 1040STFM and Falcon 030.
I am in the USA and occasionally purchase components from Digikey.
I've just put in an order from the Exxos shop, but didn't see any complete recap kits.
Has anyone out there already made a part-list that can be used for the order?
FOR GREAT JUSTICE. TAKE OUT EVERY ZIG
800xl+U1mb, STfm, STe, 030
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stephen_usher
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Re: Recapping for Dummies, (and troglodytes)

Post by stephen_usher »

No-one has really found the need to do a full re-cap of the STs as the components used have been pretty stable and generally don’t leak and destroy the motherboard unlike the surface mount devices on later Amigas and Macs. That’s why you don’t find kits etc.
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Steve
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Re: Recapping for Dummies, (and troglodytes)

Post by Steve »

if you need, here is a part list:

Code: Select all

Name   Voltage Capacitance Location
-----------------------------------
C1     16V     22uF        Under PSU
C2     25V     4.7uF       Under PSU
C6     25V     4.7uF       Under PSU
C7     50V     1uF         Under PSU
C11    25V     4.7uF       Under PSU
C29    16V     100uF       Under PSU
C67    16V     47uF        Under PSU
C110   16V     100uF       Mid section
C147   16V     4700uF      Mid section
C181   50V     1uF         Mid section
C117   6.3V    220uF       Near Floppy cable
C24    35V     470uF       Video section
C36    16V     100uF       Video section
C48    50V     1uF         Video section
-      50V     10uF        Video section
C50    16V     100uF       Video section
C54    16V     47uF        Near SCSI port
C78    50V     2.2uF       Near SCSI port
C56    16V     47uF        Under Floppy Drive
C57    16V     220uF       Under Floppy Drive
C83    16V     47uF        Under Floppy Drive
C84    16V     47uF        Under Floppy Drive
C88    50V     10uF        Under Floppy Drive
C91    50V     10uF        Under Floppy Drive
C92    50V     3.3uF       Under Floppy Drive
C121   16V     220uF       Under Floppy Drive
C127   50V     3.3uF       Under Floppy Drive
C138   16V     47uF        Under Floppy Drive
C141   50V     10uF        Under Floppy Drive
note: The Falcon is actually quite a difficult re-cap, the ground plane sucks away lots of your irons heat which makes some cap replacements rather difficult, especially under the PSU. If you are not sure then the easiest & most important cap is the easiest to replace, the 4700uf cap in the centre. Exxos sells a great replacement for this in his store.
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Re: Recapping for Dummies, (and troglodytes)

Post by rubber_jonnie »

In my own personal experience, generally only the PSU needs a recap in the ST range, unless you specifically encounter a problem where a cap has died.

Capacitors die for many reasons, and those in the PSU do get particularly stressed, and though I have never found one that's leaked or bulged in an ST PSU, I have found output to be incorrect/unstable until I've replaced them.

Outside of the ST world, I generally check all capacitors whenever I get in a new machine.

My A1200, which has the little aluminium dustbin types I caught just in time, but an Amstrad ALT-386 laptop was nearly a total loss due to just one of those caps leaking, and required many hours of work to bring back to life. Not only that, but the capacitors in the PSU were also leaking, but thankfully caused no damage. Leaks can be detected by the presence of a fishy odour and liquid around the bung area of the capacitor.

Similarly with my Mac Classic, they were the little aluminium dustbin types and were just starting to go as well, and are used, and fail, in a lot of Macs. Generally I try to replace those with tantalum capacitors, but the A1200 I just bought a kit and replaced like for like. Like the Amstrad, the PSU in the Mac had leaking electrolytics that required replacement.

The bottom line is that you have to assess each machine individually based on the capacitor types. Some need to have everything done, some just specifics.

I find axial to be very reliable generally as they have only a single lead coming through the bung, but age and stress does play a part.
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Re: Recapping for Dummies, (and troglodytes)

Post by PeckPeekPoke »

Thank you all for the replies :D
I have ordered the 4700uF Exxos replacement. While I was snooping around in my STs, my capacitor ESR tester detected several leaky electrolytic caps. I will stick to the philosophy of "if ain't broke don't fix it," while I work on Exxos' list of required fixes. The reason I thought of doing all the caps at once was to try to avoid repeated complete dismantling of the machines, yet if such be my fate then so be it for the love of Ataris. :geek:
My next question would be : what is the preferred brand for replacement electrolytic caps?
FOR GREAT JUSTICE. TAKE OUT EVERY ZIG
800xl+U1mb, STfm, STe, 030
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DoG
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Re: Recapping for Dummies, (and troglodytes)

Post by DoG »

Console5 in the US have cap kit for a lot of motherboards. I haven't heard anything about them so I don't know how accurate they are or how good the caps are.
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Re: Recapping for Dummies, (and troglodytes)

Post by derkom »

DoG wrote: Wed Jun 09, 2021 3:28 pm Console5 in the US have cap kit for a lot of motherboards. I haven't heard anything about them so I don't know how accurate they are or how good the caps are.
When repairing a SC1435 a couple of years ago, I got a couple of specialty bipolar caps from Console5 (seems they're the only ones stocking those), and while it's obviously a very small sample size, no complaints. Delivery was quick even across the ocean (pre-pandemic mind you), and the caps are top quality.
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Re: Recapping for Dummies, (and troglodytes)

Post by exxos »

PeckPeekPoke wrote: Wed Jun 09, 2021 2:49 pm My next question would be : what is the preferred brand for replacement electrolytic caps?
Generally I use Panasonic as they offer the best ESR specs. But don't assume one brand is better with all values. Wading through the data sheets is the only way to find best caps. Some cheap big brand names can be really bad spec wise. It's why you should study what caps you're actually buying and don't assume as they are new, they are better. Not many sellers really understand cap specs and just go for the cheapest or go with Panasonic because I quote them as being good, but epcos are better for some values. Some caps in PSUs are not good spec wise and can pop after a short while. I used to see that all the time in my old job and sadly some recapped PSUs sold use really bad caps.
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