Spectrum 128K toastrack jail bars?

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

Spectrum 128K toastrack jail bars?

Post by Lardo Boffin »

I have just finished refurbing a toastrack and the jail bars were a bit noticeable so I did the jail bar mod as shown here https://spectrumforeveryone.com/technic ... -spectrum/

It has certainly mostly got rid of the jail-bars visible on the white background when it boots up but in some games there is a very noticeable level of jail barring going on.


Note the vertical ‘stripe’:
5F51535A-D488-4D92-BCB9-EAFB1608EFEE.jpeg

Even worse on the main menu:
19ED6D29-95AF-4BC5-A940-DF02D14A7907.jpeg

Up close on a CRT TV:
621BC91C-F681-4ABD-9950-9FDE6A3CB855.jpeg

They almost look like character boundaries?

Is there anything I can do further to reduce this? It was like it from the outset and isn’t as bad as it was to start with.

I have fully recapped it and replaced the voltage regulator.

Any help appreciated thanks!
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
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1024MAK
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Location: Looking forward to summer in Somerset, UK...

Re: Spectrum 128K toastrack jail bars?

Post by 1024MAK »

Yeah, desolder C1 to C8 (including those shiny new capacitors if you used a value of less than 470nF) and fit 470nF or 1µF types instead :lol:

Note that try to keep the leads as short as possible.

Also consider doing the same with C30 and C75.

Although some of the artefacts may be due to a problem with the ULA.

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

Re: Spectrum 128K toastrack jail bars?

Post by Lardo Boffin »

1024MAK wrote: Thu Nov 19, 2020 1:43 am Yeah, desolder C1 to C8 (including those shiny new capacitors if you used a value of less than 470nF) and fit 470nF or 1uF types instead :lol:

Note that try to keep the leads as short as possible.

Also consider doing the same with C30 and C75.

Although some of the artefacts may be due to a problem with the ULA.

Mark
Thanks Mark

C7 and 8 were replaced with 1uF types. Will do the rest!
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Lardo Boffin
Posts: 2235
Joined: Sat Nov 26, 2016 2:42 am

Re: Spectrum 128K toastrack jail bars?

Post by Lardo Boffin »

Once I’ve ordered some more. Only 2 left. Typical. :evil:

1uF multi layer ceramics?
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
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1024MAK
Posts: 5332
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Spectrum 128K toastrack jail bars?

Post by 1024MAK »

Lardo Boffin wrote: Thu Nov 19, 2020 8:42 am 1uF multi-layer ceramics?
Yes!

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
Autumn is here. Bye bye summer 2024...
Lardo Boffin
Posts: 2235
Joined: Sat Nov 26, 2016 2:42 am

Re: Spectrum 128K toastrack jail bars?

Post by Lardo Boffin »

1024MAK wrote: Thu Nov 19, 2020 11:23 am
Lardo Boffin wrote: Thu Nov 19, 2020 8:42 am 1uF multi-layer ceramics?
Yes!

Mark
Thanks. Wasn’t sure about C30 and C75.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
User avatar
1024MAK
Posts: 5332
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Spectrum 128K toastrack jail bars?

Post by 1024MAK »

Lardo Boffin wrote: Thu Nov 19, 2020 12:03 pm
1024MAK wrote: Thu Nov 19, 2020 11:23 am
Lardo Boffin wrote: Thu Nov 19, 2020 8:42 am 1uF multi-layer ceramics?
Yes!

Mark
Thanks. Wasn’t sure about C30 and C75.
Use 1µF for these as well.

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
Autumn is here. Bye bye summer 2024...
Lardo Boffin
Posts: 2235
Joined: Sat Nov 26, 2016 2:42 am

Re: Spectrum 128K toastrack jail bars?

Post by Lardo Boffin »

I have replaced all the caps but it made no difference. Dodgy ULA?

Maybe time to get a vLA128?
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Lardo Boffin
Posts: 2235
Joined: Sat Nov 26, 2016 2:42 am

Re: Spectrum 128K toastrack jail bars?

Post by Lardo Boffin »

In the short term it turns out I can use my SpectraSCART with the toastrack and it produces a perfect picture.
It only produces beeper noises directly though so it looks like I need to enter the world of butchering modifying cables. :D
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Lardo Boffin
Posts: 2235
Joined: Sat Nov 26, 2016 2:42 am

Re: Spectrum 128K toastrack jail bars?

Post by Lardo Boffin »

Thanks to (a lot of) assistance from Paul Farrow one cable delicately bodged modified and I have a great picture and full sound!

5EC05A43-1273-4F70-B52F-B217F1E8F26D.jpeg

Wish I had found a longer cable for the MIC socket. Ah well, cable take 2 I guess.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
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