Philharmonic BOL Deluxe Selectivity Control

[Kent King]

If anyone can look at the underside of a red-band Philharmonic Deluxe, I need to know where the switches and the variable capacitors should be at each end of the rotation. After recapping, I realized this set has been played with and I do not believe the shaft is properly aligned with the control. Any assistance would be appreciated!

BTW - this is not the same as a pointer dial set - the Deluxe has an extra wafer switch on the shaft - so hopefully someone has another Deluxe BOL to examine. 

Thanks!

Kent

[Scott Seickel]

I have seen different colored coil forms as shown in your picture quite a few times.  I don't know why some are different, but there is no way all these transformers were replaced in the various sets that I have.  I would not worry about a couple of loose windings as long as they are not broken, just leave them or use a little wax to get them to stay in place. 

I personally would not replace that transformer until proven defective.  I would follow Norman's advice and address grounds and shielding first. 

[Norman S Braithwaite]

Interesting.  When you remove the 2nd IF, you might find a serial number scratched under the bottom plate.  If so and if not matching the receiver chassis, it was replaced.  The only IF transformer that is electrically different is the first IF with only three banks of coil on its primary.

Norman

[Kent King]

when doing alignment... Just realized the 2nd IF appears to be different than the others. Also, some windings are loose on the 3rd IF coil. So, I have enough parts sets, I think I'm going to swap out both the of them and try again. Not of work but not too bad.

[Norman S Braithwaite]

A ground problem is a good possibility.  The IF is going into oscillation which may be caused by ineffective shielding or a bad or missing ground connection.  Loosen and tighten all screws holding the IF can and the nuts holding the tube shield bases.  When you indicate that the volume gets louder when the output meter gets lower, is that when aligning or listening to a broadcast station?

[Kent King]

I had some time yesterday and went over it carefully. It doesn't completely match the schematic for either the 1939 Deluxe or the AM part of the FM Philly - it is a bit of both. For example - the 1st and 2nd IF tubes, the cathodes are grounded (1939 diagram shows a typical R/C connection)...but - I am very suspicious of the 2nd IF. When I try to tune it, even approaching the adjustments with an IF tool cause it to deviate, and tuning the secondary sounds like a Theremin. And the 1st IF adjustments scarcely change the meter (although I can hear a slight variation in the signal). The 3rd and 4th IF adjustments work reasonably well.  So...I must be missing something in the 2nd IF - maybe a bad ground somewhere? Any ideas? All voltages good, tubes tested. Oh, one last thing, the sound gets louder but the meter declines when adjusting the 2nd IF. I might just swap the whole unit from a parts chassis, but that's a lot of work...

Kent

[Kent King]

Thanks everyone! I may not get back to it for a few days - work is annoyingly busy right now. I've got plenty of things to check - and Norman's suggestion just tells me it's been too long since I've done serious troubleshooting. I should have thought to work back through the stages. Scott suggestion will be checked too - the set is a hot mess. 

Kent

[Scott Seickel]

Seeing as thought the selectivity trimmers were moved on this set, I would check to see if the resonant frequency was moved out of range of adjustment.  The selectivity control works by detuning the stages a bit to broaden their response.  Try moving the signal generator up a bit and then seeing if you have some adjustment on  the non-responsive IF's then do the same moving it down again.  Keep the input signal as low as you can to get a response on the meter. 

I will email you a copy of the 9 knob schematic redraw.  A lot easier to work off of it when you are troubleshooting. 

[Norman S Braithwaite]

Make sure the filament of the 3rd IF tube is illuminated.  If so, inspect the 3rd IF for shorts or a miswire.

 Norman 

[Kent King]

OK...next puzzle: I verified my uA is working, and I was on the "wrong side" of the capacitor, so I got all that set up and now I've got a nice clean reading, 10 mV in is giving me around 25 uA...yay!

The problem: only the last (4th) IF adjustment appears to change anything. It behaves normally, clear peak, etc. but the other IF controls do absolutely nothing. I have the AVC clamped. I verified all plate and screen voltages are good...any ideas?

Kent

[Norman S Braithwaite]

A 100uA meter should be sufficient.  If you are only getting a uA or two, the IF is out of alignment.  I use a 50uA meter and have to turn down the signal generator to keep the current below 30uA while aligning.  You may have to reduce the selectivity (not full sharp) to start the alignment and chase the selectivity down while improving the IF alignment.  If you have no meter response at all, make sure the output meter is on the far side of the capacitor attached to the high end of the volume control.

Norman 

Oh, and verify that your 100uA meter is good with a battery and appropriately large value resistor in series.