Heathkit vtvm IM-11 voltage readings needed

[jimthegreek]

I am working on repairing a Heathkit IM-11 vtvm. I am having some problems with the dc calibration and setting the ohms adjust.
Does anyone have some voltage readings for this? I have the schematic and the complete manual. Thanks.

[floobydust]

I've never seen the voltages posted (other than Heathkit's two for the PSU) and there are a few high impedance nodes, typical multimeter loading would upset some voltage readings around the tube's grids.

One challenge is the power supply secondary is not using input(-)/chassis as common.
Instead, it is sorta middle-referenced by the AC BAL pot R5, to give +50 to +70VDC at C1(+) and -60 to -85VDC at C1(-).
As a start, check you have around 110-150VDC across the filter cap C1 (and it should be a newer part).
Then, between common (ground) and each end of C1 for around +50VDC and -60V, to make sure balance can be in the ballpark.
With power off you can also check resistors etc. there are many 22MEG parts that can age.
I would get DCV working first. You can measure tube voltages on 1.5VDC range and post here, to help figure out what is going on. Or tell us about what it is doing.

hi-res scan https://www.byan-roper.org/steve/manuals/Heathkit/IM-11-VTVM.pdf
other threads:
https://www.eevblog.com/forum/testgear/heathkit-im-11-vtvm
https://antiqueradios.com/forums/viewtopic.php?t=269163
https://www.eevblog.com/forum/repair/repair-heathkit-im-11-vtvm