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Viper trouble

Started by Dante, October 17, 2016, 08:28:19 AM

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Kim

The Viper used to be mine; it's Stan's now.  There's a chance we may take a look into it again this weekend.

MarshallJMP

Kim, let me know if I can assist in any way.

StanSki

Quote from: MarshallJMP on October 19, 2016, 07:46:06 AM
Well my first guess is the buffer behind the red channel.It's also causing problems in the classic so...
Now in the viper there are 2 buffers,almost identical to each other (some different resistor values).One for the clean channel (Q5 + R32,42,44) and the red channel (Q8 and R59,60,61).The viper is different from the preamp because the clean signal is tapped after the first tube and also goes to the red channel.We know that the clean works so you could measure some voltages on both buffers and compare them to each other.They will be a bit different but not much.Maybe you could start there Kim?
Let me know if you need some assistance.

Found Q8, R59, 60, & 61. Now if I only knew what voltages to look for. I'm an advanced newb at this stuff but trying to learn as fast as I can. Always been more of a "yeah, it's burnt, just replace it" kinda guy. See a part physically toasted to know it's bad and needs replacing. This sneaky "looks good but gotta test it 'cause that could be the problem" stuff is not yet common to me regarding values and voltages etc. I'm watching tons of D-Lab, Guitarologist, and other U-Boob electronics gurus to get a clue, but I'm still flailing. I can read the bands on the resistors to get their values so that's a start, which will lead me to their voltages. But Q8 is a transistor so I'm outta my depth on that.
They say the eyes are the windows of the soul. I beg to differ. It's the ears , man. The ears.

MarshallJMP

A transistor can be tested with a multimeter that has a diode check. Look around on the net on how to do this. It's fairly easy. Now this only works for transistors ,not fet's or mosfet's.