bhuskins
Super Member
I'm going through a Spec 2 amp that came to me in protection when initially tested. Powers up, all the lights work including the protection one 
Upon inspection, 1 of the amp boards had a less than impressive tech hack at it at some point. Black tape holding the STV-3 diode together, odd ball transistors and the such...even a bare wire jumped off one of the transistors...you get the idea. a complete overhaul was in order.
First for those that have worked on a Spec 2 before, I want to understand what behavior I should expect. With both amp modules removed if the unit is powered up the protection light does not come on when powered on. Maybe that's a good thing for the rest of the amp (which appears to be original based on initial observations.) Is that what the amp should do upon power up without the amps installed? No protection light at all or should it come on then go off once the protection circuit gives the all clear?
Only one of the amp boards had been hacked at and the other board only had the STV-3 repaired (and not very well...black tape again)
I opted to completely rebuild the 1st amp board and went through everything. All new transistors, all new variable resistors, all new caps, new relay, new 34v (17v*2) zener diode, new 100 ohm resistors as all 4 read OK but looked a bit charred. New STV-3 installed. The STV-4 is in good shape. I also pulled all the output transistor and all 6 tested good, so I installed new insulators and grease and reinstalled the OTs. All other resistors and diodes tested out OK and are still original.
To see if I was getting somewhere, I hooked up the freshly rebuilt amp module and upon power up it immediately goes into protection. This occurs regardless of which side I plug it into. No other symptoms, etc.
Do both modules have to be installed for it to come out of protection once 1 is hooked up? Understanding what the normal behavior for the amp is would be helpful in addition to suggestions on what I should look at next.
Upon inspection, 1 of the amp boards had a less than impressive tech hack at it at some point. Black tape holding the STV-3 diode together, odd ball transistors and the such...even a bare wire jumped off one of the transistors...you get the idea. a complete overhaul was in order.First for those that have worked on a Spec 2 before, I want to understand what behavior I should expect. With both amp modules removed if the unit is powered up the protection light does not come on when powered on. Maybe that's a good thing for the rest of the amp (which appears to be original based on initial observations.) Is that what the amp should do upon power up without the amps installed? No protection light at all or should it come on then go off once the protection circuit gives the all clear?
Only one of the amp boards had been hacked at and the other board only had the STV-3 repaired (and not very well...black tape again)
I opted to completely rebuild the 1st amp board and went through everything. All new transistors, all new variable resistors, all new caps, new relay, new 34v (17v*2) zener diode, new 100 ohm resistors as all 4 read OK but looked a bit charred. New STV-3 installed. The STV-4 is in good shape. I also pulled all the output transistor and all 6 tested good, so I installed new insulators and grease and reinstalled the OTs. All other resistors and diodes tested out OK and are still original.
To see if I was getting somewhere, I hooked up the freshly rebuilt amp module and upon power up it immediately goes into protection. This occurs regardless of which side I plug it into. No other symptoms, etc.
Do both modules have to be installed for it to come out of protection once 1 is hooked up? Understanding what the normal behavior for the amp is would be helpful in addition to suggestions on what I should look at next.
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