If that test fails (I or V not changing) check the drive V to Q1.
If that is changing but the I does not (or the V across the R), suspect Q1.
Mark
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Ruben -
Probably the easiest check is to see if the voltage across the?
resistor changes with frequency.? Somewhere in the service manual,?
they should give you the ma/Hz number for this circuit.? If that works?
out correctly, the YIG drive is OK.? If the current is different than?
specified, the problem is with the YIG drive circuit.? Also, be sure?
you are measuring the main YIG drive and not the FM coil.? Bu be sure?
to check the current in the FM cil as it also can cause problems?
(usually less frequently).
Cheers!
Quoting RubenRubio <rubenrb2019@...>:
> Reading the schematics, I bring you some ideas, correct me if i'm wrong:
>
> - I must measure the voltage drop across R1 (one of the power?
> resistors in the plugin) and that will reveal the current sent to?
> the YO coil, isn't it?
>
> - The black heatsink on A9 board it's always hot. I think it is?
> hotter than it should be, should check Q1 too? Maybe the transistor?
> is shorted and it doesn't send sufficient current to drive the YO.?
> What you think?
>
> Regards,
> Ruben
>
>
>
