GE A-66 new refurbish job

[bandersen]

OK, how about this then ? They all work the same way regardless of the physical position of the transformer. Any chance you could takes some pics so we can see what's going on ?

Anyhoo - if you can determine which of those 3 wires is common to the field coil and transformer, you should have about 1330 ohms between that and one wire (field coil) and 712 ohms on the other (audio transformer). Make sure the set is off and the caps are discharged before you check that. Now that you've got it powering up, there could be 100s of volts across those caps.

Speaking of that, have you tried measuring the voltage going to that speaker's field coil or across the 10MFD cap ?

[leadlike]

Hmmm...if you're getting some white noise static across that speaker, then maybe your B+ is fine. Just power up the radio, and put your finger on the antenna terminal (to be safe, don't grab the chassis at the same time). With your finger on the terminal, the static should get louder, and instantly much more quieter when you remove your finger.

Do a little am radio research for your area. If you don't know what your local stations are, then grab the cheapest radio you have and see what you pick up strongly. You should be able to easily pick them up on your GE with your "finger antenna". If you should tire of making yourself the antenna, just use several feet of any old hookup wire you have laying around.

[de.facto7]

Oh, that it would be so easy....

not a thing...

[de.facto7]

Ya know, it's not really white noise either. it's just a faint hum an a cracking or 2 when I move the knobs. The background noise does rise when I turn up the tone control or the volume. I don't hear any sound changes when I change from one band to another either.

Wishful thinking before... now back to the grind stone.

[leadlike]

Touch your soldering iron to the center terminal on the volume control while the radio is power up...does it produce a hum?

Alternately, you could put your finger on the cap of the 6j7 tube and do the same thing.

[de.facto7]

Thank you very much Sean for the much improved version of the schematic!

First thing I see on it that's different than I could make out is R-17 that is not listed on the parts list but on the schematic is says 300K ohms. I thought it said 500K ohms on the old schematic therefore I put in 500K ohms.

It's across a couple of pins on the angular connecting bar (I have no idea what you call it) near the C-33 cap. Does this make a big difference? If it does, I had better replace it.

[de.facto7]

Funai, we cross posted... I'll try it.

[de.facto7]

Wow... more excitement. Yes there is a slight increase in hum when I put my finger on the cap of the 6j7.

And... there is a very small intermittent arc on pin 2 and/or 3 under the 6f6 socket when I increase the tone control knob (on/off switch as well)

So many things to do. Life is good.

[leadlike]

Tell us more about this arc on the 6f6-this concerns me a bit.

Moving on, your finger test on the 6j7 cap tells us that your amp is working just fine. You should be able to adjust the tone control and volume control and alter the sound of the hum your finger is producing. If you can do that, then all is basically well with the amp section.

[de.facto7]

This is a similar arc that I had with the 5y3 socket recently. It's seems to be coming from between the 2 layers of the wafer. It is not arcing from the pin of the tube itself. It is between the pin holder on the socket and the wafer. It passes sporadically sometimes at pin 2 and sometimes pin 3 and sometimes not at all. If I adjust the tone control upward it increases he incidence. It's probably more of that oily stuff that has made its way between the wafers. I think I will just try replacing it like the other. But if you have any ideas what it may be that is different, please let me know. I can always check that before or while I'm replacing the wafer.

[Reece]

The arcing might be because of naval jelly getting in there, or some other chemical. Wafer sockets are prone to breaking down nastily in there where you can't see anything going on. Once it starts it makes a carbon track so it self perpetuates. Only cure is cleaning and grinding it out or replacement.

[de.facto7]

Thanks Reece! How do you grind it out? The arc is between the wafer layers. 'just take the rivets out, clean/grind the 2 parts and replace the rivets?

[de.facto7]

Here's my nightly update...

The new wafer is in. I found one at a junk store and works great. No arc. The speaker works. The volume control is working. The tone control is working. The finger on the on the 6k7 gives a sharp rise in the speaker volume. All the parts look great and no smoke/smell etc.

There are also no incoming signals detected. There are a great many AM stations around here that should come in strong.

I am now on to the next thing... hearing something radio like.

On this, I will really need some help. I hope you guys aren't too tired of me yet. I'm almost there... I hope.

[bandersen]

Awesome
I don't think anyone is tired of this thread - over 1,000 views
A great way to troubleshoot a radio once you're at this point is to work your way backwards from the speaker. You've already determined that it's OK and the audio amp is OK so keep working back towards the antenna. Check your work, the tubes, the voltages, etc. You're in the homestretch now!

[leadlike]

That's very good! Now we'll be messing more with the radio's front end-the 6A8 and 6K7 in particular. Measure the pin voltages on all of those tubes and tell us what you get (set your meter for AC voltages for the filament tests, DC for all of the rest). We'll assume for now that it is an issue with a dead or a singular circuit error for now.