Kate--Lyle's 700 Ser 1 is back..

Gepetto said:
Now you know why I provide the shorty screws in my Backplane Kit Lee...exactly for that reason.
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I left those screws out of my WOPL400 upgrade- too much chance of piercing a wire, especially the AC line to the thermal protect switch.
 
Joe, I've got a problem with the low negative voltage regulator on a quasi comp Rev C board. I'm getting -30 volts DC with rail voltage of 76. I'm getting + 20 on the other side. I had hi DC offset which took me to the regulator...
 
The negative TL 431 is acting funny on the diode test, like shorted..(imagine that) the positive tests well on both jct's...


These regulators do test like a bi-polar correct??
 
Changed out the TL-431 negative regulator, regulated voltage is now - 20.72, and + 20.64 Offset went from 48MV to 10 mv...
 
laatsch55 said:
Changed out the TL-431 negative regulator, regulated voltage is now - 20.72, and + 20.64 Offset went from 48MV to 10 mv...
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I like how you worded the MV to mv. Glad to see you found the problem straight away.
 
Thanks Navo, I get a pretty sinewave through it but I'm not happy with it.My Q10's are running what I think are a little warm. Bias won't go below 330mv either. There is still a problem. I have an out of tolerance resistor someplace...
 
laatsch55 said:
The negative TL 431 is acting funny on the diode test, like shorted..(imagine that) the positive tests well on both jct's...


These regulators do test like a bi-polar correct??
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No they do not Lee, they are an integrated circuit, not anything like a normal transistor.
 
laatsch55 said:
Well, they can show a short.....
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You were seeing 30V because the fail safe diodes kicked (D80, D81) in to protect the rest of the circuitry. Those 2 diodes do nothing in normal operation. They protect in the event of the VR1 and VR2 regulators failing to do their job.
 
laatsch55 said:
????????
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Failure Mode Effects Analysis. You see what will happen in the event of a component failure and try your best to mitigate the failure and keep it from propagating into a cascading failure event. This is SOP for us in HA design.
 
SOP where I come from as well. DFMEA and PFMEA are used for all items we design and manufacture.
 
Gepetto said:
Failure Mode Effects Analysis. You see what will happen in the event of a component failure and try your best to mitigate the failure and keep it from propagating into a cascading failure event. This is SOP for us in HA design.
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Further evidence that I have the best amplifier on earth.

What a brilliant person you are!
 
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