Need help with VCR tuner/modulator fault

[Rommel]

An old Roxy SV-115 VCR (not too common type, is it?), playback fine but
doesn't tune in any channel. Sound and a weak picture with much of noise and
usually diagonal lines, waves and stuff can be found after a hard work.
Same with TV connected to the AV- outputs. Nevertheless, TV can be watched
through RF modulator box (don't know for sure, if this is to be mentioned,
because I'm not so familiar with these things).
Not visual damage in modulator neither tuner, I've opened both. I have also
also resoldered some connections and don't believe cold solder joint to be
one to blame. Cables are OK. Voltages going to the tuner would seem to be OK
too, as far as I know.
Strangely, when a channel seems to be near and the noisy sound comes on, it
may vary in the same pace that the digital clock in the front panel blinks.

Don't have a repair manual or schematics.

Which one, tuner or modulator, or what else could it be?

Thanks,

EK

 

[Patch]

"Rommel" <eknuutil@turkuamk.fi> wrote in message
news:btc0p9$1nme$1@bowmore.utu.fi...

An old Roxy SV-115 VCR (not too common type, is it?), playback fine but
doesn't tune in any channel. Sound and a weak picture with much of noise
and
usually diagonal lines, waves and stuff can be found after a hard work.
Same with TV connected to the AV- outputs. Nevertheless, TV can be watched
through RF modulator box (don't know for sure, if this is to be mentioned,
because I'm not so familiar with these things).
Not visual damage in modulator neither tuner, I've opened both. I have
also
also resoldered some connections and don't believe cold solder joint to be
one to blame. Cables are OK. Voltages going to the tuner would seem to be
OK
too, as far as I know.
Strangely, when a channel seems to be near and the noisy sound comes on,
it
may vary in the same pace that the digital clock in the front panel
blinks.

Don't have a repair manual or schematics.

Which one, tuner or modulator, or what else could it be?

Thanks,

EK


I would be leaning towards a bad tuner. It could be a bad antenna input on

the RF Modulator. Is there a cable that goes from the RF Mod to the tuner?
If it's a plug-in type you could unplug it from the tuner & bypass the RF
Mod & plug you antenna straight into the tuner. You'll need to rig some kind
of an adapter for that. (I've never heard of that make & model so I can't be
of much help I'm afraid.)

 

[EK]

Yes, there is a such cable, and it has connectors looking very similar to
RCA connectors. It's soldered but it will open quite easily, I think. Err...
I thought that the cable is OUTPUT of the tuner going to the modulator??!
Well, I must be mistaken. Nevertheless, I actually was wondering, if it's
safe and makes sense to connect that directly... Could you tell me where
might the output of the tuner be then?
I'll try what you said, but later, because I'm couple of days elsewhere off
the computer.

Thanks,

EK

 

[Patch]

"EK" <kuka@kukaNOSPAM.fi> wrote in message
news:btc608$1pmp$1@bowmore.utu.fi...

Yes, there is a such cable, and it has connectors looking very similar to
RCA connectors. It's soldered but it will open quite easily, I think.
Err...
I thought that the cable is OUTPUT of the tuner going to the modulator??!
Well, I must be mistaken. Nevertheless, I actually was wondering, if it's
safe and makes sense to connect that directly... Could you tell me where
might the output of the tuner be then?
I'll try what you said, but later, because I'm couple of days elsewhere
off
the computer.

Thanks,

EK

That cable is the tuner input. The output is on the pins where it mounts on
to the chassis.

 

[Jerry Greenberg]

The tuner module may need changing. Use a scope on its output at the
end of the complete front end at the video detector output, to see if
the video is correct. If it is good at that point, the problem may be
in the modulator.

If the tuner or modulator is defective, these are changed as a
complete module.

Jerry Greenberg
http://www.zoom-one.com

--


"Rommel" <eknuutil@turkuamk.fi> wrote in message news:<btc0p9$1nme$1@bowmore.utu.fi>...

An old Roxy SV-115 VCR (not too common type, is it?), playback fine but
doesn't tune in any channel. Sound and a weak picture with much of noise and
usually diagonal lines, waves and stuff can be found after a hard work.
Same with TV connected to the AV- outputs. Nevertheless, TV can be watched
through RF modulator box (don't know for sure, if this is to be mentioned,
because I'm not so familiar with these things).
Not visual damage in modulator neither tuner, I've opened both. I have also
also resoldered some connections and don't believe cold solder joint to be
one to blame. Cables are OK. Voltages going to the tuner would seem to be OK
too, as far as I know.
Strangely, when a channel seems to be near and the noisy sound comes on, it
may vary in the same pace that the digital clock in the front panel blinks.

Don't have a repair manual or schematics.

Which one, tuner or modulator, or what else could it be?

Thanks,

EK

 

[EK]

Now I have plugged out the cable going to the tuner and connected tuner
directly to it. No effect, almost the same. I guess the tuner must be bad
then?

EK