5441 Storage Scope Loss of +30VDC, -15V

p mc
 

Tim,

I've changed the subject for this post.

So maybe the 30V will be an easy "fix". tbd.

Someone reported fixing a dead +15V rail in a 5440 with a new MJE800, so apparently they aren't invincible.

https://groups.io/g/TekScopes/message/126094

Dunno that one event counts as a ding against reliability.

pmc

On Sat, Feb 1, 2020 at 02:02 PM, Tim Phillips wrote:


From Tim P (UK)

I have a manual, thanks - in fact, after perusing the schematic, I realised
that my +38 V on the +30V test point is the UNREG voltage.
So, maybe the erstwhile +30V is not being regulated at all. I will check
around the +30V circuitry. Are the Darlington pass transistors (MJE800)
reliable with age ?

Tim


On Sat, 1 Feb 2020 at 21:06, p mc <pmc@...> wrote:

Tim,

TekWiki has a complete 5441 manual. http://w140.com/tekwiki/wiki/5441
It doesn't have "voltage and waveform" data but has the schematic, board
layout, adjustment & Theory of Operation info.

Do you have that?

pmc

On Fri, Jan 31, 2020 at 10:14 AM, Tim Phillips wrote:


from Tim P (UK)
re the 5111 - what was the problem with the -30V ?
I have a 5441 with a low -15V (11V) and a high +30V (+38V)
The LVPS in the 5000-series seem to be very similar. I would be
interested
in your investigations and cure
regards
Tim

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