[Heathkit] [Heathkit-Radios] IM-5228 VTVM - Problem Solved

[k5jwkgary at gmail.com]

Thanks Bill.  I removed the troublesome pot and carefully took it apart, cleaned the inside, put it back together, and tested it with alligator wires.  Problem solved.  Remounted the pot, soldered the wires, and did a test.  Worked like it is supposed to work.  Put it back in the cabinet and calibrated it.  ALL IS WELL.

 

Many thanks again Bill.

 

Best 73,

 

Gary H. Harmon Jr. / K5JWK

6003 Archwood

San Antonio, TX 78239-1504

(210) 657-1549 home

(210) 884-6926 cell

 <mailto:gharmon at idworld.net> gharmon at idworld.net

k5jwkgary at gmail.com

 

From: Bill Green <bgreen3940 at yahoo.com> 
Sent: Tuesday, June 13, 2023 5:51 PM
To: k5jwkgary at gmail.com
Subject: Re: [Heathkit] [Heathkit-Radios] IM-5228 VTVM

One thing that happens are tin whiskers. I repaired a Heathkit VTVM where one of the cal pot's was ‘infected’ with tin whiskers. Took while to find, about 2 minutes to fix. 

You can’t spray them away. Neither could I use a magnet to remove them. I had to use some painters tape, using the adhesive to capture the whiskers. This worked on both the outside case and carefully the inside.

I could finally see them by placing the VTVM on the workbench. Then with a flashlight, flash the beam so that it’s parallel to the workbench across the pots. This casts shadows, but a light 

that is directed parallel to your eyes will hide the whiskers. With a magnetized screwdriver wave it close to but not touching the pot. If you see movement your seeing the whiskers.

Hope this helps.

Bill

 

 

On Tuesday, June 13, 2023 at 05:21:24 PM EDT, <k5jwkgary at gmail.com <mailto:k5jwkgary at gmail.com> > wrote: 

 

 

The issue seems to be the AC CAL pot.  When I turn it off and leave it off

for a while and then turn it on, the DC minus pegs to the right and the DC

plus and OHMS peg to the left.  When I lightly bank on the rear of the AC

BALANCE adjustment everything returns to normal.  I have sprayed all the

controls and run them through the rotation cycles.

 

The AC BALANCE pot is not easy to get to.

 

The voltage cap has been replaced but not the diode.

 

It's always something weird.

 

Thoughts?

 

Best 73,

 

Gary H. Harmon Jr. / K5JWK

6003 Archwood

San Antonio, TX 78239-1504

(210) 657-1549 home

(210) 884-6926 cell

gharmon at idworld.net <mailto:gharmon at idworld.net> 

 

 

-----Original Message-----

From: n2lxm at juno.com <mailto:n2lxm at juno.com>  <n2lxm at juno.com <mailto:n2lxm at juno.com> > 

Sent: Monday, June 12, 2023 4:13 PM

To: k5jwkgary at gmail.com <mailto:k5jwkgary at gmail.com> 

Cc: Heathkit-Radios at groups.io <mailto:Heathkit-Radios at groups.io> ; Heathkit at mailman.qth.net <mailto:Heathkit at mailman.qth.net> 

Subject: Re: [Heathkit] [Heathkit-Radios] IM-5228 VTVM

 

Good Afternoon Gary,

 

        I have the same model. Check the filter cap and diode rectifier.

Mine was doing something like yours. Once a replaced the cap and diode,

cleaned the cal pots and switches. It works like new.

 

 

                                                    Jeff N2LXM

                                          Amateur Radio Operator

                                                      American

                                                        Patriot

                                    Proud Father of Two US Marines

 

 

______________________________________________________________

Heathkit mailing list

Home: http://mailman.qth.net/mailman/listinfo/heathkit

Help: http://mailman.qth.net/mmfaq.htm

Post: mailto:Heathkit at mailman.qth.net

 

List Administrator: Gary Harmon, K5JWK

** For Assistance: gharmon at idworld.net <mailto:gharmon at idworld.net>  **

 

 

This list hosted by: http://www.qsl.net

Please help support this email list: http://www.qsl.net/donate.html