Heathkit IM-5228 VTVM on the fritz

View previous topic View next topic Go down

Heathkit IM-5228 VTVM on the fritz

Post by Wildcat445 on Sun Sep 07, 2014 7:25 pm

This thing will not work at all. The pilot light comes on and the tubes light. No function works. I have the assembly and owners manuals, but there is precious little in the way of diagnostics. This is a kitbuilt unit that my elmer gave me before he passed. I don't know who built it. It is in pristine condition physically. Any ideas where to start?

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by jerryhawthorne on Sun Sep 07, 2014 7:28 pm

WC, the power supply voltages would be a start.
Jerry

jerryhawthorne
Member
Member

Number of posts : 732
Age : 72
Registration date : 2012-10-13

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by Ragwire on Mon Sep 08, 2014 11:41 am

With the VTVM unplugged, I usually take a 1.5 volt battery in series with a 10K ohm resistor and just brush the terminals of the meter movement itself to see if there is any needle jump. Sometimes I have to reduce the resistor value in series with the battery, depending on the meter. Minding the meter and battery polarity, of course.
avatar
Ragwire
Member
Member

Number of posts : 526
Registration date : 2013-05-20

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by Wildcat445 on Mon Sep 08, 2014 3:49 pm

I'm going to investigate a little further and get back to you guys. Thanks for your suggestions.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by Wildcat445 on Mon Sep 08, 2014 6:50 pm

I may have accidentally fixed this thing. Now I really feel foolish! Rolling Eyes

This VTVM has been bolted to a shelf on my bench for eons, probably over ten years. It was given to me by a friend, who has since passed. It did not work, and I probably would have tossed it, if Lloyd hadn't given it to me. He said it did not work, and was sick of fooling with it. So he gave it to me "to fool with if you want to." He was right. It did not work. When I would turn it on, the needle just sat there. All the way to the left end of the scale. It refused to move.

Until today. I am in the process of "Fall cleaning" and getting rid of debris and junk off the top of my bench. I had removed the probe from this instrument, so when I turned it on today, the meter moved over to the right side, just like it should. I let it warm up for a bit, then zeroed the meter. It worked just fine. So I plugged in the probe. The meter went to the left end of the scale and sat there. Hmmmmm. The probe comes apart in three pieces. The wire that goes from the probe to the VTVM is shielded. I got out the instruction/assembly manual and found that whomever had assembled the probe has simply cut the shield wire out, instead of soldering it to the probe. They had left a piece of shield (which is used as a common or ground) dangling and it would intermittently touch the hot lead, making the meter move all the way to the left, just like when you "zero ohms" your meter. I cut the wire off, connected it properly, and, viola!, it worked on DC and AC. The ohms part still did not work. Wonder if there is a battery in there somewhere? Yep, sure was. An old Ray-O-Vac that had been there maybe 30 years. It had the old logo with the cat jumping thru the "O". I replaced that C cell with a new one. Now the ohms setting works. I guess I need to start a regular maintenance program on my test equipment. I run this stuff until it quits, then I am annoyed. I should have paid more attention to this thing. I might have tossed a perfectly good meter.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by jerryhawthorne on Mon Sep 08, 2014 7:11 pm

Happy you got it working WC, generally it is the simple stuff we never look at.
Jerry

jerryhawthorne
Member
Member

Number of posts : 732
Age : 72
Registration date : 2012-10-13

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by Ragwire on Thu Sep 11, 2014 9:19 pm

Cool!
Most of us are guilty of letting maintenance ride until something quits. I've been trying to get better about inspection and checking calibration.
avatar
Ragwire
Member
Member

Number of posts : 526
Registration date : 2013-05-20

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by Ragwire on Mon Apr 13, 2015 8:12 am

Well, guess what? I picked up one of these IM-5228 meters recently and its meter movement is definintely bad. It is othewise clean and in almost perfect condition so I'd like to fix it.

WC, do you know if it is a 200 microamp movement? I need to start looking around...

avatar
Ragwire
Member
Member

Number of posts : 526
Registration date : 2013-05-20

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by Bill Cahill on Mon Apr 13, 2015 11:24 am

There is a battery for the resistance inside the meter.

_________________
Please also join us here;  http://videokarma.org/index.php
avatar
Bill Cahill
Admin
Admin

Number of posts : 4530
Age : 66
Registration date : 2008-03-12

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by Wildcat445 on Mon Apr 13, 2015 9:09 pm

I'm not doubting your diagnosis, but Heathkit meters were fairly robust. Like Bill said, check your battery. I will look for you tomorrow and see if I can get some information on the meter you asked for. I have the assembly manual, so maybe that will help? Good luck. Mine turned out to be a nice instrument after I took the time to look at it.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by Ragwire on Tue Apr 14, 2015 8:13 pm

The meter movement itself was not linear. The springs were somehow messed up because it wasn't the weights or debris in the mechanism. I believe someone was in there messing with it at some point, and I finally gave up on trying to put it right. I did get the manual now, and hopefully the new meter I also got ordered will be a good donor.
Usually, if a meter movement moves and doesn't stick, it is good all the way. I have never seen one that was just plain wrong in its readings before. (And wrong by alot.) Measuring the DC current proved that it was the movement and not the meter's circuitry.
Thanks guys.
avatar
Ragwire
Member
Member

Number of posts : 526
Registration date : 2013-05-20

Back to top Go down

Re: Heathkit IM-5228 VTVM on the fritz

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum