Fire in the hole.....

9/25/2010 1:48:54 PMCindy

Well, the Airline was working great for over an hour or so. Went back later and all was garbled. Few hours tried it again and it worked for a short time then garbled again and lost most stations. Played with the volume knob to make sure there was good contact and darn thing caught on fire....burned a hole and took off one end of the potentiometer...It was oily looking inside...Not me...
So I tried other pots, at 500,000 per schematic, one on there was a 1 meg. I get nothing but garble once again....
I had to replace alot of caps and resistors and still cannot find what I did wrong. Could someone send me a pic on how to properly wire up the switch. I followed the schematic to a tee, yet I feel something still is not right. Obviouly isn't, doesn't work.
Biggest problem is I painted It a cherry red with creme across the grid with those bullet shaped knobs, It is a beauty....Please help. It is an Airline 64BR-1504B....

9/25/2010 3:46:01 PMEdd

Cindy . . . oh Cindy . . . . . .
I could probably only see that as an old volume controls switch getting ready to fail . . . OR . . .if you had cleaned it, possibly a graphite residue could have ended up draining from the control portion into the adjunct switch contacts area and across them.

It was to then initially break down with the AC voltage and then after an initial arc path had developed, some serious conduction after the molded bakelite also then got involved and fully carbonized.

You then , as I am reading it, have got a different new control and switch in there, and the set is still remaining "garbled" .

Any chance that this "garble" is time related, like it is not being apparent when the set is stone cold and only after a warm up period.

If the latter, I would place the tuning dial off station and measure the DC plate voltages of the 2 AF tubes and log them down with the set stone cold.

Then tune in the set to a station and await for the trouble to onset, then place off station and check on how those voltages have changed when the sound is bad.

Leaning towards a leaky AF coupling cap. . . but probably not since you have changed them already . . . or possibly a def AF output tube , failing after hot.

73's de Edd

:Well, the Airline was working great for over an hour or so. Went back later and all was garbled. Few hours tried it again and it worked for a short time then garbled again and lost most stations. Played with the volume knob to make sure there was good contact and darn thing caught on fire....burned a hole and took off one end of the potentiometer...It was oily looking inside...Not me...
:So I tried other pots, at 500,000 per schematic, one on there was a 1 meg. I get nothing but garble once again....
:I had to replace alot of caps and resistors and still cannot find what I did wrong. Could someone send me a pic on how to properly wire up the switch. I followed the schematic to a tee, yet I feel something still is not right. Obviouly isn't, doesn't work.
:Biggest problem is I painted It a cherry red with creme across the grid with those bullet shaped knobs, It is a beauty....Please help. It is an Airline 64BR-1504B....
:

9/25/2010 4:04:23 PMBill G.

Dear Cindy,
I am with Edd on this.
It is dangerous not to be since he is so good.

It seems your problems are not related. the arcs came from the on/off, the garbeling from something else.

To make sure jumper around the on/off. If it has resistance in it, it can cause the garbeling.

More likely is as Edd suggested, and AF tube. Audio output tubes commonly test good on tube testers. This can really throw you.

I once had an Airline in here with type 42 output tube. It sounded OK, but not as good as it should have. I had a spare 42 and swappped them. It sounded the same.
I sold it on eBay and it arrived with the type 42 cracked, so I sent him the spare. The buyer went out and baught a new one anyway. It arrived first. He plugged it in and the radio sounded great.
When my replacement arrived, he tried it, too. The audio he said was awful. It turns out I had TWO bad type 42 tubes, both tested good on the tube tester.

Beware of audio output tubes that test good!

Best Regards,

Bill

9/25/2010 4:18:17 PMCindy

:Dear Cindy,
:I am with Edd on this.
:It is dangerous not to be since he is so good.
:
:It seems your problems are not related. the arcs came from the on/off, the garbeling from something else.
:
:To make sure jumper around the on/off. If it has resistance in it, it can cause the garbeling.
:
:More likely is as Edd suggested, and AF tube. Audio output tubes commonly test good on tube testers. This can really throw you.
:
:I once had an Airline in here with type 42 output tube. It sounded OK, but not as good as it should have. I had a spare 42 and swappped them. It sounded the same.
:I sold it on eBay and it arrived with the type 42 cracked, so I sent him the spare. The buyer went out and baught a new one anyway. It arrived first. He plugged it in and the radio sounded great.
: When my replacement arrived, he tried it, too. The audio he said was awful. It turns out I had TWO bad type 42 tubes, both tested good on the tube tester.
:
: Beware of audio output tubes that test good!
:
:Best Regards,
:
:Bill
:
As far as the tubes I will try everyone I have and see if there is any change.

9/26/2010 1:15:19 AMPeter G. Balazsy

Don't know about that fire and bad pot... but as for the garbling... It does seem like a bad 50L6

Pin 8 should measure about +5 or +6 vdc as measured across R-11 the 150 ohm cathode bias resistor.

If the tube is going bad you may find that the cathode voltage starts drifting high from +5 up to +10 or so.
If that's the case the 50L6 is bad.
While you're there you can make sure R11 is still at 150 ohms.

9/26/2010 12:11:05 PMCindy to Peter

:Don't know about that fire and bad pot... but as for the garbling... It does seem like a bad 50L6
:
:Pin 8 should measure about +5 or +6 vdc as measured across R-11 the 150 ohm cathode bias resistor.
:
:If the tube is going bad you may find that the cathode voltage starts drifting high from +5 up to +10 or so.
:If that's the case the 50L6 is bad.
:While you're there you can make sure R11 is still at 150 ohms.
:
:
Thanks for all the help. Let you know how it turns out.

9/26/2010 4:11:26 PMVinny

Cindy, hello.
The first radio that I restored had the exact same problem and Dr. Edd gave his diagnosis and the subject lived, an output tube transplant was needed.
See Post below:

http://www.nostalgiaair.org/forums/Messages/672/M0064672.htm

Vinny A.

9/26/2010 6:05:25 PMCindy

:Cindy, hello.
:The first radio that I restored had the exact same problem and Dr. Edd gave his diagnosis and the subject lived, an output tube transplant was needed.
:See Post below:
:
:
:http://www.nostalgiaair.org/forums/Messages/672/M0064672.htm
:
:Vinny A.
:
Thanks for the link. I am going try Edd's diagnosis today. I pray all goes well. Thanks for all the help. You guys are great. Keep up the good work....

9/26/2010 10:48:16 PMcodefox

Ex Navy
it is "Fire in the Hold"

:Well, the Airline was working great for over an hour or so. Went back later and all was garbled. Few hours tried it again and it worked for a short time then garbled again and lost most stations. Played with the volume knob to make sure there was good contact and darn thing caught on fire....burned a hole and took off one end of the potentiometer...It was oily looking inside...Not me...
:So I tried other pots, at 500,000 per schematic, one on there was a 1 meg. I get nothing but garble once again....
:I had to replace alot of caps and resistors and still cannot find what I did wrong. Could someone send me a pic on how to properly wire up the switch. I followed the schematic to a tee, yet I feel something still is not right. Obviouly isn't, doesn't work.
:Biggest problem is I painted It a cherry red with creme across the grid with those bullet shaped knobs, It is a beauty....Please help. It is an Airline 64BR-1504B....
:

9/26/2010 11:54:43 PMCindy to Codefox

:Ex Navy
:it is "Fire in the Hold"

There was no hold on this one. It was in a hole, and it was on fire...Just used it to get attention to my problem. It worked out...Thanks Ex Navy, my ex was a Navy too.
:
::Well, the Airline was working great for over an hour or so. Went back later and all was garbled. Few hours tried it again and it worked for a short time then garbled again and lost most stations. Played with the volume knob to make sure there was good contact and darn thing caught on fire....burned a hole and took off one end of the potentiometer...It was oily looking inside...Not me...
::So I tried other pots, at 500,000 per schematic, one on there was a 1 meg. I get nothing but garble once again....
::I had to replace alot of caps and resistors and still cannot find what I did wrong. Could someone send me a pic on how to properly wire up the switch. I followed the schematic to a tee, yet I feel something still is not right. Obviouly isn't, doesn't work.
::Biggest problem is I painted It a cherry red with creme across the grid with those bullet shaped knobs, It is a beauty....Please help. It is an Airline 64BR-1504B....
::
: