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Re: ZX spectrum 48k repair
Posted: Fri Jun 29, 2018 6:48 pm
by 1024MAK
With your other Spectrum, is the picture like any on this
site?
Re: ZX spectrum 48k repair
Posted: Fri Jun 29, 2018 8:14 pm
by tyrell
Yes more or less !
Symptoms are large black and white vertical stripes.
(Last time I checked).
And voltages for lm1889 are in range... This shouldn't be the problem.
Re: ZX spectrum 48k repair
Posted: Sat Jun 30, 2018 3:58 pm
by tyrell
For the wrong colors, it was the ULA !
I swapped it for a working one, and the colors were back ! I have brought back one speccy to life. I even added a small switching module, which is way more power efficient than a 7805, and of course I did the composite mod.
Later I'll see if I can buy a ula (nebula ?), And fix the rom (vertical black and white striped) for the other partially working board.
Total work done on this spectrum :
- replaced almost all lower bank ram chips (used 5x4164 from a c64 and 3x4116 from retroleum).
- replaced d9
- replaced TR4
- replaced the ULA
- replaced 4 or 5 capacitors
- replaced the 7805 regulator with an UBEC module
- new keyboard membrane
- placed a socket for the lm1889
- composite mod
Re: ZX spectrum 48k repair
Posted: Sat Jun 30, 2018 9:24 pm
by 1024MAK
Good that your progress brings success
Mark
Re: ZX spectrum 48k repair
Posted: Sat Jun 30, 2018 9:54 pm
by Moggy
One more back on the road, magic.
Re: ZX spectrum 48k repair
Posted: Sun Jul 01, 2018 7:52 am
by tyrell
Moggy wrote: ↑Sat Jun 30, 2018 9:54 pm
One more back on the road, magic.
Was quite a work, but we would do anything for our speccies, right ?
Re: ZX spectrum 48k repair
Posted: Wed Jul 11, 2018 9:32 pm
by tyrell
Latest news about my second board which was not booting to basic (black and white vertical stripes).
I replaced a pair of capacitors (1 mfd) and now everything is ok !
I also replaced the ULA with Nebula.
A second board which came back from the deads
Total work done on this board :
- replaced TR4
- replaced 4 or 5 capacitors (bad caps were responsible for vertical white and black stripes)
- replaced the ULA with Nebula (retroleum)
- replaced the beeper (sound was weak)
- will replace soon the 7805 regulator with an UBEC module. These are cheap and efficient ... already placed in a speccy, in a Timex 2048 and in a c64 power supply... I highly recommend these modules ! I recommend them over the traco modules even though they are bigger, because they can deliver up to 3 amps, while the traco can only deliver 1A I think, which is not enough in case you connect several peripherals to the speccy...
Re: ZX spectrum 48k repair
Posted: Wed Jul 11, 2018 11:33 pm
by 1024MAK
Well done
Mark
Re: ZX spectrum 48k repair
Posted: Thu Jul 12, 2018 4:41 pm
by tyrell
1024MAK wrote: ↑Wed Jul 11, 2018 11:33 pm
Well done
Mark
Thanks Mark
It really was a challenge given it was the first time I was repairing speccies. I'm just stubborn and it paid off.
Re: ZX spectrum 48k repair
Posted: Wed Dec 16, 2020 12:13 pm
by ant
tyrell wrote: ↑Wed Jul 11, 2018 9:32 pm
Latest news about my second board which was not booting to basic (black and white vertical stripes).
I replaced a pair of capacitors (1 mfd) and now everything is ok !
I also replaced the ULA with Nebula.
A second board which came back from the deads
Total work done on this board :
- replaced TR4
- replaced 4 or 5 capacitors (bad caps were responsible for vertical white and black stripes)
- replaced the ULA with Nebula (retroleum)
- replaced the beeper (sound was weak)
- will replace soon the 7805 regulator with an UBEC module. These are cheap and efficient ... already placed in a speccy, in a Timex 2048 and in a c64 power supply... I highly recommend these modules ! I recommend them over the traco modules even though they are bigger, because they can deliver up to 3 amps, while the traco can only deliver 1A I think, which is not enough in case you connect several peripherals to the speccy...
Hi Tyrell, where I can see/purchase this UBEC modules? Thanks