32V-2 no grid current - how to troubleshoot

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Todd, KA1KAQ:
It sounds like you may not be equipped to repair this beast, Frank - which is fine, the 32V series transmitters are not what you'd call 'easy to service'. The design was probably more on par with the Globe King, size-wise, then re-engineered to fit into a smaller, desk-top cabinet. Ease of access is sacrificed - there are very few areas of this transmitter you can fix easily. Even if it's a simple case of a single component.

I've had mine apart numerous times, actually had a friend fix it once because I couldn't figure it out. Turned out to be the tuning linkage - it had slipped and gone out of sync, so to speak.

There's also an oil-filled cap in back that goes bad. Am trying to remember if loss of grid drive is a symptom. I roached two of them in the span of a couple months, but both times they blew up in use and left an easy trail of oil to follow. One was kind enough to spew its guts out after removing its lid.

As Phil says - don't tackle it until your head is clear and you can focus entirely on the mess ahead of you. Probably true for any piece of gear, but especially so for the maze inside the 32V. I can take several sessions just to disassemble, repair, then reassemble the unit.

If you decide not to pursue it, go with plan B: sell it as-is. You'll get more that way, and have far fewer headaches than trying to strip and sell parts. The few desirable bits would get snapped up first, then you'd be left with the rest.

NQ5V:
Frank, check some of the voltages on the buffer and multiplier stages before making any drastic decisions.  These can be checked (CAREFULLY) when the unit is out of the case - the HV interlock will be open but you don't need HV on for these checks.

I have a 32V3 that had identical issues a few years ago.  The rig had been working fine but after a short break I came back and there was zero grid drive.  Everything looked normal, but there was a faint plastic smell in the air.  I opened the RF compartment (on a v3 that is a big job) and visually checked everything but could see no burned or strained components.  However, the 1st multiplier plate voltage was very low.  Schematic shows 1st and 2nd Mult's to have 1K 1W plate resistors but I couldn't find these anywhere. I finally figured out that these resistors are inside the gang-tuned multiplier coil metal cans.  Don't try to open them - its a pain to re-coordinate the gang tuning and almost impossible to drop the RF deck open to remove the coils.  You don't need to - the equivalent end points of the resistor come outside the cans to other components (a choke and a capacitor) and you can connect the replacement across these points.  Still tight, but doable.  Don't try to remove the bad resistor in the can.  If its gone up in value high enough to shut down the stage, it won't have a lot of effect on the new 1K 1W you will install.  By the way, I think the same situation holds true for all the RF stages - there can be a 1K 1W in the plate can of any of the multipliers or buffer.

After doing the above, my grid current rating was closer to spec than it had been for many years.  That resistor must have been drifting high for some time.

WZ1M:
The 32V series of transmitters had very poor low voltage transformers. I know, I have wound several of these beauties.
Regards,
Gary

WD5JKO:


A useful reference with these rigs:

http://www.qsl.net/wa5bxo/32v3/


Jim
Wd5JKO

W7NGA:
I've worked on my 32V-3 extensively .. and found that many of the drive problems are usually traced to the tube socket pins and the occasional cold-solder joint. If you can, try wiggling the tubes in the driver/multiplier section and watch for changes. If you should find a problem, needle-nose pliers can be used to reform the pin connection.

W7NGA  dan
Seaside, Oregon

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