Hi all
I have an otherwise lovely +2A that does not produce sound on the RF out to the telly (well, it produces a hiss as though not tuned in, which it is). If I use a SCART then I get a great picture and sound. It is the later revision of the +2A that has the corrected sound circuit.
I have recapped it (including the tape drive which was fiddly) and done the RGB ghosting fix (from https://spectrumforeveryone.com/technic ... compliant/) which just involves changing a resistor.
Any idea what might be wrong? Its not a big deal as I can use scart but I am curious!
Spectrum 128K +2A RF sound issues
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Spectrum 128K +2A RF sound issues
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
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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Re: Spectrum 128K +2A RF sound issues
Maybe someone has previously removed the ceramic capacitor (C24) that feeds sound to the RF output?
Mark
Mark
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ZX81 Chip Pin-outs
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ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
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- Posts: 2160
- Joined: Sat Nov 26, 2016 2:42 am
Re: Spectrum 128K +2A RF sound issues
Thanks Mark - will have a look when I get chance.
Here is the PCB after a clean up and recap:
Here is the PCB after a clean up and recap:
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
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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- Posts: 2160
- Joined: Sat Nov 26, 2016 2:42 am
Re: Spectrum 128K +2A RF sound issues
I found C24 intact:
But while hunting for C25 I noticed C53 has been snipped off. Is that anything to do with sound or just a coincidence?
But while hunting for C25 I noticed C53 has been snipped off. Is that anything to do with sound or just a coincidence?
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
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