Variax 500 will not work on batteries only

[murwin]

I am trying to resolve a problem with my Variax 500.

 

It works perfectly when powered via the footswitch using a TRS cable, however it refuses to work when battery-powered and connected to my amp via a 1/4" mono cable - absolutely no sound comes through at all. (When I first acquired the guitar it worked fine on batteries.)

 

I am attempting to track down what the problem is. I don't think it's the jack connector on the guitar because if a stereo cable works fine, then I don't see why a mono cable shouldn't. I am wondering whether there is a problem with the battery holder or the connecting power lead from the holder to the internal PCB - I will try replacing these soon. Or could it be that it's a firmware problem (I did update it a while back and ever since battery power seems to have been a problem - although this could be just coincidental?). Or perhaps the PCB is on the blink, but then why does it work perfectly when on mains power?

 

If anyone can suggest other areas I could look into, in order to try and get my guitar working on batteries again, I would love to hear them.

 

Thanks for any help offered.

Mark.

[Charlie_Watt]

Check the diode at the power input.  Even a momentary connection of the battery backwards (easy to do!) will blow that diode.  Make sure your batteries are good.  Measure the battery voltage.  It needs to be > 7Volts.

[murwin]

Thanks for this info Charlie. It's important to know that the battery power must be greater than 7 Volts. I have done a check and the battery voltage is over 8 volts, plus I have checked the continuity on the diode that you mention, and it beeped OK on my multimeter.

 

However I think that I have found the problem in the process of checking these.

One of the pins appears to be broken in the PCB power socket itself. So If I can find this part to purchase, and brush up my soldering, I may be able to get the batteries working again. Fingers crossed!