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

[David]

On Tue, 7 Jun 2016 13:06:47 -0400, you wrote:

>Hi David,
>
>That's just what I was thinking.  As well I couldn't find any data on the GA2817's.
>Do you think the transistors are actually bad?

It is not real clear from the description what is going on.  Lou
wrote:

>My 845AB 15v supplies are currently down and I suspect the germanium transistors around T202 may be leaky?

and 

>The +/-15v is really low so I need to do something.

Assuming that +/- 15 volts is in fact missing completely, I think one
or both Q201 and Q202 are the most likely fault.

It would take an awful lot of leakage to cause the inverter to fail
and if that happened, the transistors would self destruct anyway so if
they were leaky once, they are not anymore; they are shorted or open
instead.

There is no short circuit current limiting so the various rectifiers
should be checked also.

The transistors I mentioned are inexpensive and readily available.

>What is the status of the new modern chopper design talked about in earlier post?
>Is there a PCB design now for it?
>
>Dallas

You would know more than I.  I mostly lurk here. :)

The described replacement of the neon bulbs with LEDs looks easy and
reliable but I would try to fix the original circuit first.  Either
way, the inverter has to be repaired.