VOX AD60VT tuner not operational , and else..

[jean-marc]

Hello all
With your help I did repair my pot Drive for pedals on my blue face Vox.AD60VT , fine for this; But now I realise that when i pressed the Tuner function , it comes in (small hyphen) and even the muting works, but there in no tuning operation at all, no indication of note pitch on any channels leds, all off...I did perform many times the Reset procedure, no change.. Also ,but maybe it is not related, when i pressed the channel 3 in Banks, the channel 3 led rarely comes on, but sometimes yes...All others are Ok ; I have to admit I am not too familiar with the operations of this type of modeling amp , but I am studying the manual and trying...; So if some of you have some ideas about my tuner and other problems, I would appreciated. Many Thanks.

[jean-marc]

Maybe to be more precise :
Let s pretend the tuner circuitry could be defective (+5V or comparator or Q12 or..else ) Would it be the ONLY function defective or it will be associated with another function ; I am trying to pinpoint the problem of the tuner but have no clue ; Is there a way to isolate the tuner function , Meaning : How can I troubleshoot this tuner problem ? Thanks , JM

[g1]

Please post the schematic you are working from.

[Enzo]

Maybe this will help:

Look at the input circuits on main board.. Signal comes in through IC6, IC10. (and then into the ADC) Note IC6 pin 7 also branches down to IC2b. From there to J2-4 G_BUFF OUT That is the line to the tuner. J2-4 sends signal to FRONT board CON17. Once on the front board, see CON17 top edge toward the right. Signal is now buffered by IC11, and through Q12 (used as a level shifter I think) And finally from collector Q12 down to a port on LSI IC07. Name of the port? TUNER.

So stuff a signal into the regular input and see if it shows up leaving IC2, leaving the board at J2-4, leaving IC11 on the front board, and leaving Q12 collector.

[jean-marc]

Thanks to all , I will check this out ...

[jean-marc]

Hello All , sorry for the long delay...sickness... Now ok;
I was about to dismantle my AD60VT for a tuner repair; Just a question before : When i select Tuner fonction (-) in display, is it normal that the settings stay On and that the sound output is the one that was selected ;
ie : should it go in a certain flat no-effects mode for a sound to ease the tuning procedure or not ? Thanks

[eschertron]

the tuner is before any processing, IIRC.

[jean-marc]

Ok fine , So in my case it means that the Tuner fonction is not coming On at all ?