[volt-nuts] Replace neons with LEDs in Fluke 845AB

[Dallas Smith]

Hi Lou,

I believe that the transistors are good. If they do not run to hot to 
hold on to.
Yes CR105 feeds the negative supply. Did you check CR104 and CR105?
Q203 and Q204 should also be check since they could shunt the transformer.
Is transformer T202 and T203 hot. The high voltage windings on T202 
could be leaky.
Try taking out C119, did rails go to approximately 15 volts?
Time to start isolating the supplies to various circuits to find the 
culprit by removing one leg of various resistors.
You can deal with the carbon resistor accuracies later.
I had all many issues with my meter, after all their very old.

Dallas

On 6/7/2016 11:09 PM, Lou Amadio wrote:
> Hi Dallas
> I set my DMM on Diode Check mode:
> Q201, PNP, no part number: EB/BE=0.23/Hi, CB/BC=0.21/Hi, EC/CE=Hi/Hi
> Q202, PNP, no part number: EB/BE=0.22/Hi, CB/BC=0.20/Hi, EC/CE=Hi/Hi
> Q111, NPN, 2N1304: EB/BE=Hi/0.28, CB/BC=Hi/0.26, EC/CE=Hi/Hi
> Q112, PNP, 2N1305: EB/BE=0.26/Hi, CB/BC=0.25/Hi, EC/CE=Hi/Hi
>
> The two 15v rails are down to about 5v each. The oscillator is working but
> fluctuating badly on frequency.
> Replaced all the electro caps. Have not replaced the resistors or diodes.
> Will check these next.
>
> CR105 feeds the neg 15v supply cap??
> Regards
> Lou
>