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Philco Model 66 Repair - Printable Version

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RE: Philco Model 66 Repair - Radioroslyn - 11-27-2012

Measure the resistance of resistor #15 the 32k resistor
Measure the dc voltage from chassis to pin 5 of the 6A7.
Report back.
?????
Terry

RE: Philco Model 66 Repair - radiola - 11-27-2012

My mistake. I forgot to list them. They are:
resistor #15- 32.95
DC Voltage from chassis to pin 5 of the 6A7= 12 volts

RE: Philco Model 66 Repair - Radioroslyn - 11-27-2012

So you didn't notate the resistance #15. 32.95 Ohms?????
Anyway you've got a bad winding on the osc coil. The one that measures 214K. Count the turns while removing the winding. Rewind it with magnet wire anything from 32-40Ga will be fine. Also note the direction of the winding, rewind the new in the same direction. It's probably the outer most winding double check to make sure it is the outer one. If it isn't let me know. Post a pic of of the coil.
Pin 5 voltage is WAY low but this could be caused by the open coil. Fix that first and then remeasure pin 5.
GL
Terry

RE: Philco Model 66 Repair - TA Forbes - 11-27-2012

Good advice, Terry!!! Icon_wink

RE: Philco Model 66 Repair - radiola - 11-28-2012

Coil side of resistor 10 to 800 pf (side connected to pin 4 of 6A7) 214 K

Coil side of resistor 10 to 800 pf that is connected to the coil. 64 ohms

Just making sure we're on the same page. Line one above describes coil side of resistor 10 to 800 pf which is not the coil side, but the reading is picked up at pin 4 of the 6A7.

Line two describes basicly resistance of one oscillator coil lug to the other.

So, is it a proper reading to test the resistor, coil side and pin 4 after it has gone through a mica cap??

Sorry, just want to make sure we're on the same page.
Much appreciated !!

By the way, resistor #15 is 32.95 K, well within spec of 32 k. Sorry.

RE: Philco Model 66 Repair - Radioroslyn - 11-28-2012

Ok So the coil is Ok. Measure the voltage from pin 6 - lead to pin 4 + lead of the 6A7.
Terry

RE: Philco Model 66 Repair - radiola - 11-29-2012

Sorry I don't know what you mean when you say test a positive lead to a negative, but someone on this forum a while back told me that when I test tube voltages, it's in respect to the cathode. In other words, he said, use the black wire on the multimeter and touch the cathode instead of the chassis. So, I tested all the pins with the black test lead on the cathode, pin 6. Hope this helps. Sorry my terminology is not great, but I appreciate you hanging in there with me.

pin 1=3 volts
pin 2=12 volts <--- Plate should be about 260 ??
pin 3 = 85 volts
pin 4 = 212 volts
pin 5 = 10 volts
pin 6 = cathode 7 volts to ground
pin 7 = 3 volts.

Thanks !!!

RE: Philco Model 66 Repair - Radioroslyn - 11-29-2012

Measure the DC voltage from pin 2 of the 78 tube to chassis.
Terry

RE: Philco Model 66 Repair - radiola - 11-30-2012

245 volts

RE: Philco Model 66 Repair - Radioroslyn - 11-30-2012

Seems like the the primary of the 1st IF transformer is open. Check the resistance of the winding, should be 100 ohms or less. If it reads higher than that you'll to remove it and closely inspect the wiring to make sure that nothing is broken. Be careful as the wires are very small in gauge and break easily.
Terry

RE: Philco Model 66 Repair - radiola - 11-30-2012

There are four wires.
1 & 2 = 10 ohms
3 & 4 = 10 ohms
Any other combination resulted in high resistance of 3m. See diagram below. Thanks!
https://picasaweb.google.com/lh/photo/WDBKBwjnzj4afCTHObX6QM6phe6e24_bNKOQO8U9_sA?feat=directlink

RE: Philco Model 66 Repair - Radioroslyn - 12-01-2012

Measure the voltages on all IF transformer connections. Two should have HV on them if the resistances are correct. If you don't find any HV at the IF transformer you may have a missing or broken wire. On the IF transformer the connection that is not connected the pin2 of the 6A7 but shows 10 ohms between it and pin 2 should have 245v on it. If not connect a wire to that connection of the IF transformer and pin 3 of the 42 tube. Make this connection with the set OFF unless you like getting knock on your backside. Don't ask me how I know!!
Terry

RE: Philco Model 66 Repair - radiola - 12-02-2012

Terry, pins one and two yield nothing. Pin 3=252 volts, Pin 4 = 253 volts.
Of course, by design, pin 3 is linked by post to plate of 6A7, and
pin 4 is linked by post to pin 3 grid) of 42. Thanks !! I feel like we're narrowing this down.

RE: Philco Model 66 Repair - Radioroslyn - 12-02-2012

Well seems like you've got a bad connection between the transformer and the plate pin of the tube (PIN 2). Pin 2 must have that 252v on it to make the set work.
Terry

RE: Philco Model 66 Repair - Radioroslyn - 12-04-2012

So guess it's working???
Terry