Re: ZX80 restoration

I noticed that the modulator was wobbly and lose.

The legs are part of the can, so they quickly take heat from soldering
irons.

What is needed is a big soldering iron with a big thermal mass.
This holds enough heat energy to keep the joint hot while the solder melts
and wets the legs and PCB.

The guy probably had a common size iron.

the Modulator is a UM1082.
I thought the ZX80 had a UM1233.

The UM1233 appeared in most 80's home micros.
I got a new unused one in front of me now.

I don't know if I'll ever need it, I just pump video straight into SCART or
S-video sockets these days.

Are they hard to get these days?

I thought NZ and the UK were the same PAL TV
standard).

http://en.wikipedia.org/wiki/PAL
http://www.ee.surrey.ac.uk/Contrib/WorldTV/broadcast.html

The UK uses PAL-I
New Zealand uses PAL B/G (VHF/UHF respectively).

Both have 25 FPS and 625 lines negative-modulated video.
However, the sound carrier offset is 6 MHz for PAL-I and 5 MHz for PAL B/G.

Since the ZX80 and ZX81 were both without sound output, I think you should
be able to use modulators for either system. If you hear unwanted stuff on
your TV, just mute it.

Secondly, upon opening up the modulator I noticed that one of the
components didn't seem properly connected.

Remove the modulator and fit a new one.
The cost in cash and time is less than trying to fix one that looks bodged.
They need some sophisticated equipment to set up, because at UHF adjustments
consist of gently tweaking coils to get the right frequency. People sell
ready-tweaked modules to avoid this chore.

Whoever did the repair before has lifted some traces.

That happens when you use an underpowered iron to (de)solder can legs.
You have to hold them on so long to heat the can legs that the PCB tracks
lift off.

Does anyone know what type of glue or resin I should be used to glue
these traces back down?

None. Use a blade to snip dud tracks off, then use wires to re-make the
connections.

Personally I would not bother fitting a new regulator, I would just feed the
video signal direct to the SCART, S-video or Composite video socket. Most
modern TVs have them, and will thus give a sharper picture.

Plus you are not wasting money and electricity on a modulator you do not
need.



.

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