Re: {Collins} Collins 32S-3 Restoration

I have run into a few situations where either the incorrect line cord was plugged in, or, when the center pin of the 11-pin connector is broken, the correct plug was inserted but "off".  What usually happens is that a number of the heaters ("filaments") in various tubes are burned out.  Sometimes, and sometimes not, the wiring is also "fried".

Of course, there are other things that could happen as well.  As for the "pinched" wire:  Could have happened at the factory.  However, most likely due to a later happening.

Glen, K9STH


--- On Fri, 7/22/11, kenwood950@xxxxxxxxxxxxxx <kenwood950@xxxxxxxxxxxxxx> wrote:

Hello All,  I have a recently aquired 32S-3 that I am restoring.  The prior owner (an estate broker) said it was plugged into a 75S-3 power cord instead of the correct 516F-2.  He claimed that the radio would not power up following that event but was supposed to have worked prior to the error in using the receiver's 110 volt ac power cable.  Before trying it on my 516F-2, I looked over the schematics for both radios and I don't see how the receiver power cord would have damaged the transmitter.  The only place 110 AC would appear in the transmitter is on the +800VDC line.  It does have .001 bypass caps to ground, but the impedance wouldn't let enough current to flow to hurt them (I believe).  I would be surprised if the engineers at Collins didn't forsee the possibility of this happening and designing a fail safe arrangement givin the fact they chose the same plug for both transmitter, receiver and even the KWM-2.
The plot thickens.  I removed the transmitter from the cabinet and had a look inside.  The only obvious problem I found was the 6.3 volt fuse was blown.....???  No possible connection to the RX power cord there.  Further investigation revealed a filament power wire (going to pin 5 of V2 6U8) pinched underneath the metal shield and some black smoke (about 1/8 inch in diameter) on the chassis in the same area.  The damage isn't bad, and it appears more like low voltage arcing.  Were it somehow 110 volts AC that caused this, I think the insulation would be toast, but instead, its just fine except where it was pinched.  What surprises me is there appears to be no mods or monkeying around of any kind inside.  I have a feeling that the pinched filament wire was done at the factory as the screw heads attaching the shield looked mint and the two components (that route thru grommets in the shield) had perfect factory looking solder joints.
I wonder, does anyone on the reflector have experience with plugging a receiver power cord in a transmitter and if so, what happens??  If the power cord incident is not an issue, I will proceed with standard troubleshooting measures.

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