I got one of theese amps in for repair.. After looking at it i dont really wanna work on it so i was gonna send it in to get fixed..
I called around a few places yesterday..
1 place i called asked what the amp was doing and i told him that it powers up and idles perfect just no sound..
I checked it and there no rail to rail oscillation..
He told me that the driverboard is bad. I then told him that the driverboard is brand new never used..
So then he told me that if the 33 ohm gate resistors for the outputs do not read exactly 33 ohm the amp will not oscillate..
He said if they measure 33.5 ohms 32.5 ohm ect and not measure exactly 33 ohms the amp will never work..
Just wondering if anyone knows if there is any truth to this??
I called around a few places yesterday..
1 place i called asked what the amp was doing and i told him that it powers up and idles perfect just no sound..
I checked it and there no rail to rail oscillation..
He told me that the driverboard is bad. I then told him that the driverboard is brand new never used..
So then he told me that if the 33 ohm gate resistors for the outputs do not read exactly 33 ohm the amp will not oscillate..
He said if they measure 33.5 ohms 32.5 ohm ect and not measure exactly 33 ohms the amp will never work..
Just wondering if anyone knows if there is any truth to this??
apart of calling DD and getting a quote on how much would it cost...
Start with basics, chech if there is short on input, if not, chech if there is one on remote. I will assume for now, that there isn't one. Next start with gates of supply, check with scope, if there is square wave on them, if not, trace the circuit back to driver board, see where you can find such signal. If there is not one, even when you are on driver board (I think main ic SG or TL is on there), check if that is gets supply voltage, and all other pins have right voltage on them (do not assume driver board is ok, even if brand new (I don't know where you got if from))
Btw, if there is PWM (square wave) on power supply gates (on each one) check is supply is making high voltage (you will run amp without heatsink by then, so don't load it with any loads...)
post anything here, and will go from there on
Start with basics, chech if there is short on input, if not, chech if there is one on remote. I will assume for now, that there isn't one. Next start with gates of supply, check with scope, if there is square wave on them, if not, trace the circuit back to driver board, see where you can find such signal. If there is not one, even when you are on driver board (I think main ic SG or TL is on there), check if that is gets supply voltage, and all other pins have right voltage on them (do not assume driver board is ok, even if brand new (I don't know where you got if from))
Btw, if there is PWM (square wave) on power supply gates (on each one) check is supply is making high voltage (you will run amp without heatsink by then, so don't load it with any loads...)
post anything here, and will go from there on
Ok i talked to another repair place and they said they also fixed alot of Z2's and the resistors have nothing to do with it..
I forgot to ask them the other thing i was wondering..
I noticed that all of the outputs in this amp DO NOT have the same date codes on them..
Would that cause the amp not to oscillate ???
Just wondering i know for long term i need to get all the outputs replaced but as far as testing goes wondering if the outputs dont have all the same date code if that may cause problems?
I forgot to ask them the other thing i was wondering..
I noticed that all of the outputs in this amp DO NOT have the same date codes on them..
Would that cause the amp not to oscillate ???
Just wondering i know for long term i need to get all the outputs replaced but as far as testing goes wondering if the outputs dont have all the same date code if that may cause problems?
hmm interesting question...why so, well if gates of audio fets are pulled low (fets can't turn on by themself) then yes you can... you can find that out, if gates of fets have resistor between gate and source (could also be one resistor for several gates)
My bad 
, I keep forgetting he repairs amps for other people. If it was my personal amp all of the resistors would be replaced with the tightest tolerance regardless and being new they would be more likely undamaged. I'm now curious to find out what the issue ends up being. Either way, a date code wouldn't matter in any amp class if the builder tested the transistors individually to better match their tolerances or to make sure they are in spec. Who knows if this company goes that far though. Made in Korea so you never know.
, I keep forgetting he repairs amps for other people. If it was my personal amp all of the resistors would be replaced with the tightest tolerance regardless and being new they would be more likely undamaged. I'm now curious to find out what the issue ends up being. Either way, a date code wouldn't matter in any amp class if the builder tested the transistors individually to better match their tolerances or to make sure they are in spec. Who knows if this company goes that far though. Made in Korea so you never know.
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