Author Topic: Heathkit VTVM restoration  (Read 2844 times)

Offline darrylo

Heathkit VTVM restoration
« on: November 05, 2012, 02:35:15 PM »
Hey all.

Since I have this interest in all things audio and old, I needed to setup a workbench to keep my little projects going. I decided to start looking out for some vintage test kit to keep the theme going.

I managed to get my hands on this nice little unit from a swap with another forum member. It's a Heathkit IM-13 Vacuum tube volt meter.  A little research on the subject revealed alot of interest and information about these devices. It seems the analogue meter has is place on the work bench when working with old valve amps.

This unit happens to be 110v version so I currently have it hooked up to a bench top autotransformer. On first power up the unit seem to work but the results and readings where far off the mark and very inconsistent. The good news is the movement was working so it was a viable project.

Before I go on Ill post some Pics later today showing the strip down and clean and test results.
Always Looking for Heathkit, AVO and Leak
"I refuse to prove that my cables will make your system sound better", says the snake oil vendor, "for proof denies faith, and without faith, you will hear nothing."

Offline darrylo

Re: Heathkit VTVM restoration
« Reply #1 on: November 05, 2012, 05:03:59 PM »
Ok so here she is



And inside







Ad the 1st thing to replace
Always Looking for Heathkit, AVO and Leak
"I refuse to prove that my cables will make your system sound better", says the snake oil vendor, "for proof denies faith, and without faith, you will hear nothing."

Offline fdlsys

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Re: Heathkit VTVM restoration
« Reply #2 on: November 05, 2012, 05:28:11 PM »
On this note; I still have that almost-vintage bench power supply for you. By the time you take possession of it, it might become a true vintage! :point:
The four building blocks of the universe are fire, water, gravel and vinyl. Dave Barry
Come back when you’ve lived a little. Miles Davis

Offline darrylo

Re: Heathkit VTVM restoration
« Reply #3 on: November 05, 2012, 05:31:03 PM »
On this note; I still have that almost-vintage bench power supply for you. By the time you take possession of it, it might become a true vintage! :point:

 :BWAHAHAH: Yes it has been a while. It will probably need to be restored too.
Always Looking for Heathkit, AVO and Leak
"I refuse to prove that my cables will make your system sound better", says the snake oil vendor, "for proof denies faith, and without faith, you will hear nothing."

Offline bluesman

Re: Heathkit VTVM restoration
« Reply #4 on: November 05, 2012, 06:00:57 PM »
I think the VTVM is junk. You should allow me to remove it for you as I once had one of these, lost to a mentally ill ex-wife. Feel for a poor maligned ***phile, please!
Always and never are dngerous words

Offline darrylo

Re: Heathkit VTVM restoration
« Reply #5 on: November 05, 2012, 06:30:20 PM »
OK. here is the results of a little testing after some liberal application of contact cleaner.

I've only tried to calibrate the DC and -DC.

I 0'd the scale with power off
Powered it on on DC+ and let it settle for a few minutes
I then connected a single aaa cell that I tested at 1.5v and set the calibration screw
I then flipped through the scales and read 1.5v on the different scales.

If I reverse the polarity of the cell and switch to -DC scale. It under reads by about .5v on the lowest scale. but on the rest it reads 1.5v

I need to take a closer look at the switches and test the individual resistors and caps.

could The valve be suspect ?
Always Looking for Heathkit, AVO and Leak
"I refuse to prove that my cables will make your system sound better", says the snake oil vendor, "for proof denies faith, and without faith, you will hear nothing."

Offline alternativeroute

Re: Heathkit VTVM restoration
« Reply #6 on: November 05, 2012, 08:55:33 PM »
mmmm, I might be wrong but often a new AAA battery can read up to 1.7v


The past, the present and the future walk into a bar. It was tense.  :nutter:

Offline darrylo

Re: Heathkit VTVM restoration
« Reply #7 on: November 05, 2012, 08:56:24 PM »
mmmm, I might be wrong but often a new AAA battery can read up to 1.7v

I did check it with my DMM for reference  :thumbs:
Always Looking for Heathkit, AVO and Leak
"I refuse to prove that my cables will make your system sound better", says the snake oil vendor, "for proof denies faith, and without faith, you will hear nothing."