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New member with 37-650 Questions
#31

Thanks, the bakelite blocks were gutted. I put those safety caps on the outside as they could not fit inside. The old caps were removed inside.
Across the full R58 I'm reading 137ohms. Thanks for the tip with numbering the circuit and all your help
#32

Ok now what is the voltage across all of R58 while operating. Same place you measured 137 ohms. 
If I understand correctly this is the item in question. It should not be 120v. 

If this resistor is good the rectifier tube can not deliver enough current to drive it to 120v.

If there is still 120v here the resistor or something with it is bad.

!!!!!!!!!!!!!!!!!!!RESISTANCE IS FUTILE!!!!!!!!!!!!!!!!!!!!!!  
                           /\/\/\/\/\/\/\/\/\
                                                     
                                 [Image: http://philcoradio.com/phorum/images/smi...on_eek.gif]  Chris
#33

I'm not picking up any volts across R58


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#34

Just a follow up...I took some readings on the rectifier socket mostly to see if the transformer is working properly. I'm getting the proper voltage on the rectifier plates but not the rectifier filament pins. I'm getting little over 1 volt and the print wants 5v. I was looking at the blue wire that feeds the +C59A and as I moved the wired the volts jump to 5v then drops and repeats. At one point, I heard crackling coming from the speaker which I haven't heard any sound from the radio yet. I'm thinking short inside the transformer. I would like to just replace this transformer but I haven't seen any available for sale. Im also thinking to just open up the transformer and see if these wires can be replaced. I'm not sure if this solves my original issue of C59 exploding though but was happy to hear sound from the speaker.
#35

Resolder those connections around there. Use some flux. I think that's what's loose. C59a

!!!!!!!!!!!!!!!!!!!RESISTANCE IS FUTILE!!!!!!!!!!!!!!!!!!!!!!  
                           /\/\/\/\/\/\/\/\/\
                                                     
                                 [Image: http://philcoradio.com/phorum/images/smi...on_eek.gif]  Chris
#36

I looked at your picture of the voltmeter and it looks like it’s set to AC volts. The ~symbol on the display shows this. Shouldn’t you be measuring DC volts there?

Tony

“People may not remember how fast you did a job, but they will remember how well you did it”
#37

Yes Did you push the little select button? I been tripped up by that more times than I want to admit.

!!!!!!!!!!!!!!!!!!!RESISTANCE IS FUTILE!!!!!!!!!!!!!!!!!!!!!!  
                           /\/\/\/\/\/\/\/\/\
                                                     
                                 [Image: http://philcoradio.com/phorum/images/smi...on_eek.gif]  Chris
#38

From my point of view, we need to step back and check the power supply and associated voltages, or back to the basics. If you think of it in simple terms, a car won't start with a weak or dead battery. A radio will not work if its power supply is not behaving for some reason. Attached is the voltage chart for all to look at with us.

A few things come to mind based on comments made.

First, make sure that you know what parts of the circuit are AC volts, and what parts are DC Volts. I think you understand this already, so please don't take my comment the wrong way.

I suggest measuring the resistance between the chassis and the HV center tap. Id expect to see 128 ohms. Also using an ohm meter, measure resistance between HV center tap, the - terminals of C59A, C57, and the + of C59. they should all read 0 ohms or whatever you meter reads with its test leads shorted, usually a little more than 0 ohms because of lead resistance. Occasionally when old filter caps are removed from the circuit, mis-wiring occurs to the various leads that were connected to the capacitor terminals. Double check that nothing was missed. Also check the resistance across 59a to chassis, and 57 to chassis to make sure there are no shorts.
All ohm meter tests are done with no power applied. Resistance test without power can really find issues and keep caps from blowing and potential transformer damage.

It appears that all DC voltages are measured to chassis as well. The one exception is the first filter cap 59A which Philco gives you 2 voltages to check. One across the cap and one from + to Chassis. This reading shows that there is 15VDC difference between Chassis and 59A negative. The 15 VDC is what you should see across R58 and is the bias for the 6F6 tubes.

You mentioned that voltages around the rectifier tube are off. You must have approximately 5 volts AC across the filament pins, not pin to chassis. Also, per the attached chart, you should see 350 V AC from the center tap to each of the plate pins, or approximately 700 VAC across the plate pins. I suggest measuring the voltages at the rectifier tube socket. You should use caution in the socket area as its mounted on top of the power transformer. Quite often the old wiring/insulation under the socket degrade over time. This may not be happening, as it seems your power transformer is not overheating, but it is worth being aware of this.

Besides measuring the DC voltage across C59A (315VDC to chassis), there should be 265 VDC from C57 + to chassis. This calculates out to approximately 50 VDC across the field coil with a current of 108 Ma.

R58 should have 15 VDC across it with C59 + to chassis.

If the readings are very high, I'd would really look for mis-wiring, or simply a lead that was missed. I also see what look like cold solder joints. I suggest cleaning up the old solder from any of the terminals you worked on and flowing in fresh solder for a nice shiny connection.

Let us know what you find.


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Tony

“People may not remember how fast you did a job, but they will remember how well you did it”
#39

After cleaning up soldier joints, DC voltage across R58 reads 0.3 mV


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#40

No voltage means no current flowing in the audio tubes for sure. What are the other voltages I asked for? Have you checked the resistance readings? Is the speaker plugged in? Does the output transformer check good with an ohmmeter?

This is pointing to a miss wire somewhere, especially since you said you were getting static in the speaker when you poked around.

Sorry to ask a lot of questions, but this is really basic troubleshooting that will help us help you.

Tony

“People may not remember how fast you did a job, but they will remember how well you did it”
#41

Thank you Tony for all the suggestions. I didnt see your response from earlier asking for the values. No worries on the questions too, I appreciate any help or suggestions. Everyone in this forum has been extremely helpful. The only resistance I measured at this point was across R58 at 137ohms. I will probably respond back tomorrow or so with the values your asking. Also, the speaker is plugged in when I'm taking these readings.

Thank you again for your time and suggestions.
#42

Going back to the rectifier tube with only 1 volt on the filament. Does this mean filament is not heating up? yes-no

Either way there must be a bad connection somewhere. Tube socket or maybe solder connections. 

This must be fixed first before any other troubleshooting can be done.

There should 5v ac to light up the filament on the rectifier.

And at the same time see some 300+ volts dc Filament to the xformer center tap at R58. Be careful here.

The filament of the rectifier has both 5vac and 300+vdc at the same time.

!!!!!!!!!!!!!!!!!!!RESISTANCE IS FUTILE!!!!!!!!!!!!!!!!!!!!!!  
                           /\/\/\/\/\/\/\/\/\
                                                     
                                 [Image: http://philcoradio.com/phorum/images/smi...on_eek.gif]  Chris
#43

Based on the schematic, the rectifier socket is part of the transformer assembly. It will be nearly impossible to measure voltage at the 5Y4 pins. I suppose one could build an adapter so you can get at the pins.
I would think measuring them with the tube out is a good start. Let’s see what info we get before digging that deep.

Tony

“People may not remember how fast you did a job, but they will remember how well you did it”
#44

Checking the socket you should be able to tell just wiggling the tube while looking for voltage.

!!!!!!!!!!!!!!!!!!!RESISTANCE IS FUTILE!!!!!!!!!!!!!!!!!!!!!!  
                           /\/\/\/\/\/\/\/\/\
                                                     
                                 [Image: http://philcoradio.com/phorum/images/smi...on_eek.gif]  Chris
#45

Sorry for the delay with these readings. With the holiday and my wife not feeling well its been a busy few days. So the reads I'm getting are:
- Resistance from HV CT to chassis is 0 ohms
- Resistance from HV CT to -C59A, -C57 is total continuity
- Resistance from HV CT to +C59 is 0 ohms
- Resistance on +C59A 15 ohms, -C59A is 0 ohms
- Resistance on +C57 is 15 ohms, -C57 is 0 ohms
- Voltage across C59A is 500 VDC
- Voltage from +C59A to chassis is 0 VDC
- Voltage from +C57 to chassis is 0 VDC

After taking these readings, I had to disconnect C59 as it has balloned and about to explode. I hope I capture all the request and again truly appreciate everyone's time and help.




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