Great, my VT52 is shot.

Jon Elson elson at
Wed Apr 22 10:52:04 CDT 2020

On 04/21/2020 10:09 PM, Brent Hilpert via cctalk wrote:
> On 2020-Apr-21, at 5:27 PM, Chris Zach via cctalk wrote:
>> Meantime reading the manual I found an interesting test: If you short emitter to base on Q4 (easiest way is to jumper diode D10) the voltage on the -12v supply goes to .4 volts. They're saying it's E2, R15,R17,R14.
>> Is there a way I can test the op-amp in circuit? Maybe it's dead.
Well, if the circuit **IS** regulating, then the voltage on 
the two inputs will be identical.
But, since it might not be regulating, then these voltages 
would not be equal.
But, if you can see that the + input is more positive than 
the - input, yet the output
is pegged negative, for instance, then you know either the 
op-amp is bad, or another circuit is overloading
the output and forcing it that way.


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