Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Heathkit VTVM
#1

Hi everyone hope this is the right place for this.
I was hoping someone could help me troubleshoot my Heathkit Im-28 VTVM. When I put the dial to DC+ the meter moves all the way over to the right then after a few seconds it goes back to the left which from what I understand is normal in either DC+ or DC- positions. Now, when it moves back to the left My zero adjust doesn't do anything, it wont move the meter at all. If I move the selector to DC- the meter then stays to the right and doesn't move back to the left. The troubleshooting page suggests to check capacitor c6 and resistors R35, 37 and 38 but they are good. I even changed C6 to 22uf 450v to be sure it was good. I did notice that with the variac set to 110volts coming in I have 123 volts ac coming out of the transformer and across c6, and if you measure DC at the + side of c6 I get 108 volts instead of 50 to 70 volts and on the - lead I get 42 volts which should be 60 to 85 volts. I have attached the schematic, I am hoping someone has an idea of what might be going on here. Thanks anyone for any time on this matter, I don't really want to buy another vtvm so I am hoping I can find the problem here. Warren

[Image: http://i1348.photobucket.com/albums/p721...84cbb8.jpg]


Messages In This Thread
Heathkit VTVM - by Warren - 07-13-2014, 12:16 AM
RE: Heathkit VTVM - by morzh - 07-13-2014, 12:19 AM
RE: Heathkit VTVM - by Warren - 07-13-2014, 12:21 AM
RE: Heathkit VTVM - by Radioroslyn - 07-13-2014, 06:49 AM
RE: Heathkit VTVM - by tab10672 - 07-13-2014, 09:04 AM
RE: Heathkit VTVM - by codefox1 - 07-13-2014, 12:42 PM
RE: Heathkit VTVM - by Warren - 07-13-2014, 04:33 PM
RE: Heathkit VTVM - by gregb - 07-13-2014, 06:09 PM
RE: Heathkit VTVM - by Phlogiston - 07-13-2014, 08:38 PM
RE: Heathkit VTVM - by Warren - 07-13-2014, 09:15 PM
RE: Heathkit VTVM - by Radioroslyn - 07-14-2014, 05:49 AM
RE: Heathkit VTVM - by TA Forbes - 07-14-2014, 10:28 PM
RE: Heathkit VTVM - by Warren - 07-15-2014, 12:20 AM
RE: Heathkit VTVM - by TA Forbes - 07-15-2014, 09:08 AM
RE: Heathkit VTVM - by Warren - 07-15-2014, 03:55 PM
RE: Heathkit VTVM - by codefox1 - 07-15-2014, 09:34 PM
RE: Heathkit VTVM - by David - 07-15-2014, 09:41 PM
RE: Heathkit VTVM - by Warren - 07-15-2014, 10:21 PM
RE: Heathkit VTVM - by Phlogiston - 07-16-2014, 12:37 AM
RE: Heathkit VTVM - by Bradley Rush - 07-22-2014, 12:40 AM
RE: Heathkit VTVM - by Warren - 07-22-2014, 05:26 PM
RE: Heathkit VTVM - by codefox1 - 07-24-2014, 10:03 PM
RE: Heathkit VTVM - by codefox1 - 07-24-2014, 10:07 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Another amp build - here I go again!
Sweet! I actually have a Dyba Mark 4 that I had been running with 6L6s with no mods. seemed to my 14-year-old head a...MrFixr55 — 12:57 AM
PT-6 finished!!
Hi Gang, Tube heaters are not "Ohmic" devices (that maintain specified resistance over wide temperature, c...MrFixr55 — 12:03 AM
Electrolytic restuffing/internals
Look here: Philco-F676-124 Vlad95 — 08:02 PM
PT-6 finished!!
Well the 35Z3 doesn't have a tap on the tube heater for a pilot light, so in this set they have the dial lamp paralleled...Arran — 06:21 PM
Electrolytic restuffing/internals
Thanks. I think I try to cut this as suggested. I don’t have a lathe, but I do have a tap and die set. I am going to see...bridkarl — 04:46 PM
Another amp build - here I go again!
Hey all! Well, I guess that with what I learned from my last build, it's time to move up the ladder another rung and tak...TV MAN — 04:38 PM
Electrolytic restuffing/internals
There are various ways to handle this, one is to cut near just above that rolled in area is near the bottom, using the r...Arran — 04:36 PM
philco predicta
If you have a television signal generator (a must-have for TV repair) and an oscilloscope (the same), then this problem ...RadioSvit — 04:23 PM
HiFi (Chifi) tube amp build - but my own design.
Thanks Rod for the offer but I don't think those would work. There's some differences in the sizing and mounting holes b...TV MAN — 03:13 PM
philco predicta
Bob Anderson (Bandersontv) on Youtube would be the go-to guy on these. Lots of good videos. I don't know what model you ...TV MAN — 03:02 PM

[-]
Who's Online
There are currently no members online.

>