Quote:
Originally Posted by stonehopper
I'm not sure what is meant by 'glue' - literally, or is that a reference to solder. If as I suspect the latter, I have noticed a track with a gap in it. It runs between a resistor R30, and the OC81 TR6. Yet as the voltage readings have already been taken it would seem this has no effect - or might it!
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The transformers are probably OK, and it would get into the realms of being totally uneconomic unless you can pick up a free one from a scrap set. The money would be better spent on a newer better Robert's and keep this as an ornament.
The break in the track looks like someone may have tried to improve the treble by taking out the tone correction R30/C33 BUT what is more interesting is the solder splutter around this break, which would cause a problem if it was shorting out the transformer. This needs to be cleaned up, a link can be soldered over the break as the tone correction components are not likely to be faulty.
Thanks for posting the circuit. It is a bit of an unusual output transformer.
Other things worth a try, as Steve suggested, the speaker could be disconnected with the OC's refitted and the battery current monitored, if it is more than 10 to 20 milliamp it should be switched off straight away.
The volume control if it went open wouldn't have any direct effect on the output as the driver transformer isolates this stage from the driver transistor for DC.
You are not doing to bad if you hand copied that diagram, one of the base connections in the lower output OC81 base is missing though
Geof