HELP i was trying to replace caps now i have issues!

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RS232
Posts: 42
Joined: Fri Apr 05, 2019 8:57 pm

HELP i was trying to replace caps now i have issues!

Post by RS232 » Mon Jun 10, 2019 12:24 am

I gave bbc een trying to replace the caps on my 48k spec issue 3b. Problem when powering up i get red lines then restart then copywrite notice and repeat. Finally eirther stops black screen or a few colour squares.

Any advice appreciated

Thanks!
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Lardo Boffin
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Joined: Sat Nov 26, 2016 2:42 am

Re: HELP i was trying to replace caps now i have issues!

Post by Lardo Boffin » Mon Jun 10, 2019 12:56 am

Do you have a multi-meter? If so use the continuity checker to see if the tracks are actually broken. If not then get one. :D They are cheap and extremely useful!

Did it work ok before changing the caps?

Did you change all of the caps in one go or did you do a couple and then test, and repeat until all are done? I.e. do you know changing which caps caused the issue? If so then look for damage / unwanted solder in that area.

Obvious one but have you fitted them all using the correct polarity? Its easy enough to put one in the wrong way round. I know this from experience. :oops:
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
Iss 3 ZXVid
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

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RetroTechie
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Re: HELP i was trying to replace caps now i have issues!

Post by RetroTechie » Mon Jun 10, 2019 5:23 pm

Rule #1 of modding: check that machine works before modifying anything.
Rule #2 of modding: if after that you find machine doesn't work anymore, it will be because of whatever was modified just now. Double-check, triple-check, or undo if necessary.

Sure there's ESD, pcb tracks where a crack develops while you're working on the board, etc. But in practice, I have yet to encounter a case where the above doesn't hold. Don't modify a machine which you don't know whether it works. Unless it helps to make a repair easier (composite video mod comes to mind).

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