Help troubleshooting HP 400H VTVM (Constant meter deflection)

[Blue Jinn]

Hi,

Powered up and there is a constant minor deflection (it rests at zero when off, so I don't think it's mechanical):

It otherwise appears to measure a 1kHz sine wave OK, with this constant deflection:

On the 1 volt scale:

Measuring a nominal 9v on the 100v scale, looks to read about that constant deflection higher. Tried this out for a 146v that also reads higher, as if the meter was mechanically set high. But it does rest at zero when off.  However,  at a lower frequency, (about 100Hz) it flutters high:

This is the .317v signal on the 1v scale.

Here is the schematic:

https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxibHVlamlubmF1ZGlvfGd4OjI5YWQzYmRmZjgwYjBjMjk

I read that this could be caused by C32-34 leaking. Any ideas appreciated.

 

[PRR]

> C32-34 leaking

It's a place to start.

 

[CJ]

works better as a mic preamp,

never could get that thing to give the same readings at different frequencies,

but the 200 CD generator is still on the bench,

 

[Blue Jinn]

Well, now it's reading off altogether, so something else has failed. ... There are some initial troubleshooting steps in the manual to start with....

 

[CJ]

sadly we had to swallow hard and chuck the  ol HP in the nearest trash receptacle,

after a complete rebuild that is,  :

https://groupdiy.com/index.php?topic=35567.msg436560#msg436560

easier to pick up a Fluke on evilbay , you save a lot of time and money, however, if you are a vintage freak, the HP stuff is killer, even the huge scopes with the chrome frame and castors,