1040 STE capacitors

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damanloox
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1040 STE capacitors

Postby damanloox » Mon Feb 19, 2018 10:23 pm

Does anybody know what capacitors (full set for recap including power supply) are required for 1040 STE (motherboard as on the picture)?
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siriushardware
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Re: 1040 STE capacitors

Postby siriushardware » Tue Feb 20, 2018 11:21 am

If you are recapping anything, generally the technique is to read the values off all the existing capacitors you see fitted and order replacements for them - same voltage (or a little bit higher is OK) and same value. The ones used in the high frequency parts of the power supply and on power supply rails on the motherboard should be 'Low ESR' types. Broadly speaking the ones which are marked 105 degrees (rather than 85 degrees) will tend to be the ones which should also be Low-ESR. I'm assuming you know enough about electronics and are sufficiently skilled at soldering and unsoldering to do this, and were just hoping that someone could provide a pre-compiled capacitor list for your motherboard and PSU. It would not take you long to record all of the capacitor component numbers, values and voltages on the motherboard yourself. And then maybe post the list here.

People like Exxos (Google is your friend) sell kits of replacement capacitors for Atari PSUs but you will need to identify the PSU type from the information on his website in order to order the right kit. Exxos also sells a brand new, superior design replacement PSU if you would prefer to go that way.

A hint, whenever you are recapping (anything) - take lots of still photos of the job from all angles and maybe a 'fly-over' video or three before you start anything just in case a wire snaps off while you are working or you get two capacitors mixed up and can't remember where they went. Personally, I remove one capacitor at a time, write the component position it came from on the body of the old capacitor and then fit the new one before proceeding to the next one. Recording the positions of the original capacitors gives you the emergency option of putting them back exactly where they came from if your new capacitors and the unit don't get along for some reason.

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Re: 1040 STE capacitors

Postby 1st1 » Tue Feb 20, 2018 11:34 am

In my experience the mainboard's capacitors in all Atari ST series computers are of good quality and did not lost relevant capacity over the past ~30 years. The only point where you have to take care are some capacitors in the power supplies. We don't have that massive problem that our friends with Amiga 600, 1200, 3000 and 4000 have.
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Dal
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Re: 1040 STE capacitors

Postby Dal » Tue Feb 20, 2018 12:42 pm

Replacing the 4700uf on the board is usually a good idea as it acts as a reservoir for the 5v line. That and the PSU caps plus the bridge rectifier is usually enough.
Mega"SST" 12, MegaSTE, STE: Desktopper case, IDE interface, UltraSatan (8GB + 512Mb) + HXC floppy emulator. Plus some STE's/STFM's

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troed
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Re: 1040 STE capacitors

Postby troed » Tue Feb 20, 2018 1:17 pm

siriushardware wrote:same voltage (or a little bit higher is OK)


How much is "a little"? I found axial 4700uF capacitors in my local electronics store and since I was ordering other stuff anyway I bought a few. They're 40V though, so pretty beefy compared to the 16V they would replace.
Last edited by troed on Tue Feb 20, 2018 3:21 pm, edited 1 time in total.

Dal
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Re: 1040 STE capacitors

Postby Dal » Tue Feb 20, 2018 1:48 pm

40V rated cap will be fine assuming it fits.
Mega"SST" 12, MegaSTE, STE: Desktopper case, IDE interface, UltraSatan (8GB + 512Mb) + HXC floppy emulator. Plus some STE's/STFM's

damanloox
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Re: 1040 STE capacitors

Postby damanloox » Tue Feb 20, 2018 2:38 pm

I only asked if anybody has a list of all caps handy as I don't have a dedicated workshop. I live in a small apartment with a 1 yr old baby and I wanted to do recap in one go (ie. disassembly/desolder/solder and reassembly)... I know I can desolder all caps, order new ones and do the recap but that means a lot of steps and disassembly/assembly multiple times as I can't really leave disassembled st on my desk (1 yr old) and I can't really store disassembled st (re: very limited storage and not-so-understanding wife)... I wish I had big American house with dedicated workshop, lots of storage and 1966 mustang Shelby GT in my garage but I don't (spending too much on ataris is probabyl one of the reasons I don't ;))

siriushardware
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Re: 1040 STE capacitors

Postby siriushardware » Tue Feb 20, 2018 3:18 pm

I share your pain, I have cramped facilities here as well.

As to size and voltage, you will typically find that (example) a modern 4700uF 35V capacitor will be about the same physical size as a 1980s 4700uF 12V or 16V capacitor. The main penalty for using a higher voltage capacitor than necessary is cost - the higher the voltage, the more a capacitor of a given value costs.

Despite that, I usually replace old capacitors with ones of similar size (therefore higher voltage rated) to keep the equipment looking 'right', and also, if the capacitor will be working in a warm environment then the more electrolyte it starts off with inside it, the better, since it will then take longer to dry out.

Maybe this is being unnecessarily far sighted. Anything I re-cap now is very likely to out-live me by a long way before it needs to be re-capped again. :(

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troed
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Re: 1040 STE capacitors

Postby troed » Tue Feb 20, 2018 3:28 pm

Dal wrote:40V rated cap will be fine assuming it fits.


:) Yeah they're a bit fatter (and slightly longer).

beefycap.jpg


Thx.
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