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GE 107 wont start up - Printable Version

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GE 107 wont start up - Tgace459 - 06-09-2016

Just replaced the power cord and filter caps on a GE 107 and...nada. No Pilot light, no sound nothing.

I did some preliminary voltage testing and the switch is working and I am getting voltage readings on some of the tube pins.

The pilot light works if I jump it from the pins with a 9 volt battery so I know that is good.

I'm strictly a novice at this so I'm looking for some troubleshooting guidance.

Thanks!

RE: GE 107 wont start up - KCMike - 06-09-2016

Hello. Here is the schematic link for anyone wanting to help you. Could be me but I don't see a lamp symbol in the schematic.

http://www.nostalgiaair.org/pagesbymodel/584/M0007584.pdf

RE: GE 107 wont start up - morzh - 06-09-2016

Check all tubes. Make sure the filaments are all good and connect to their respective sockets well.

Also please specify more precisely what "voltage on some of the tube pins" means.

RE: GE 107 wont start up - Tgace459 - 06-10-2016

If this link works..... here is the schematic.

https://drive.google.com/file/d/0B2EZ5GijL7Z1RzFrQVZFOEtxcGs/view?usp=drivesdk

I'll get the exact pin readings ASAP.

Thanks

RE: GE 107 wont start up - Arran - 06-10-2016

 Check the plate load resistor, 470,000 Ohms, on the 12SQ7 tube, if it's open you won't get any stations coming through. Also if the output transformer has an open primary you won't get any audio at all.
Regards
Arran

RE: GE 107 wont start up - Tgace459 - 06-10-2016

Question.

The schematics tell me to measure the pin voltage from B-. Is that just the chassis on this radio or some specific point????

RE: GE 107 wont start up - leftwing25 - 06-10-2016

(06-10-2016, 01:11 PM)Tgace459 Wrote:  Question.

The schematics tell me to measure the pin voltage from B-. Is that just the chassis on this radio or some specific point????

I believe it's from the negative end of the output filter cap.

RE: GE 107 wont start up - klondike98 - 06-10-2016

That is correct. B- is the negative lead on cap C15a and C15b and all points electrically connected to them. If you look at the schematic and scan your eyes left along that neg C15 connection you'll see on the schematic its labeled B- and the line above that is B+.

RE: GE 107 wont start up - Tgace459 - 06-10-2016

Alright. These are the readings I get. I've double checked/triple checked and while the (DC voltage mostly) seems to fluctuate 15-20 volts between some reads this is what they come out to most of the time. Due to the quality of my schematic I cant read/tell if some of the readings were supposed to be DC or #=AC. In those cases I read both.

Interestingly the reads I initially did with the ground as chassis are pretty much the same as the readings I got from that common negative point...


Hmmm..I cant recall if I had the volume control set to minimum as the directions ask...if that's a dealbreaker Ill check again....


[Image: http://i.imgur.com/oNf3yGF.jpg]

RE: GE 107 wont start up - gregb - 06-10-2016

R8 the 150 resistor on pin 8 of the 50l6, check that for value and if its ok the 50L6 may be bad. That tube is the largest load in the radio and those voltages are reading high like there is no load.

Greg

RE: GE 107 wont start up - Arran - 06-11-2016

 If those voltage readings are correct then the output transformer is obviously good, though the proper B- common negative point in most AC/DC sets is the power switch on the back of the volume control. That being said 165 volts (hopefully measured on the DC range) is ridiculously high for the plate and screen grid voltages on the 50L6, as Greg stated if the 150 ohm resistor (R7) isn't open circuit then the tube might be bad, open cathode perhaps. In this set the B- is isolated from the chassis by a .05 uf cap (C20) paralleled with a 470 k Ohm resistor (R11), if you are measuring DC voltages and they are exactly the same between B+ and the chassis as they are between B+ and B- then the .05 uf cap C20 may be shorted.
  The resistor that I mentioned in the last post was labeled R5, it's a 470,000 ohm resistor on pin 6 of the 12SQ7, but given your voltage reading on the plate of that tube I'm wondering if you have your volt meter set on AC volts rather then DC volts since you are also reading 165 volt there when it should read about 40 vdc.
Regards
Arran

RE: GE 107 wont start up - Tgace459 - 06-11-2016

Any reason for the pilot lights failure to work?

RE: GE 107 wont start up - klondike98 - 06-11-2016

re: pilot light. If any of the filaments in the tubes are open then the pilot light will not work. The filaments are all in series. Filaments are easy to check. Pull the tube and check the appropriate pins with your ohm meter for continuity. If all filaments are good then you may have a bad connection in the tube sockets (clean with Deoxit and use a fine sand paper or a nail file on the pins on the tubes). If it still doesn't work, check any solder connection that are in that circuit. After that...I'm out'a ideas.

RE: GE 107 wont start up - Tgace459 - 06-11-2016

You folks are the best! I'll check on your suggestions when I get home. Thanks!

RE: GE 107 wont start up - morzh - 06-11-2016

The simplest check is, put the ohmmeter across the AC plug, while Off. Turn it on. The resistance should be on the order of a few hundred ohms or less . If very high (Kohms, Mohms), your filaments are open or the tube sockets do not make good contact.