[Joe]

Hello & thanks to all so far who have helped me. I completely aligned all stages of the 90. All stations now track the dial & come in very strong. BUT...It only plays well and consistent after being on about a half hour. Please let me try to explain. When first turn radio on, just get low hum, but volume control works, but no stations as if no antenna connected. After 5 minutes, get this shoooshing sound like listening to the ocean through a seashell, or a far away thunder/lightning storm. When it does this, the volume control does not track. After 15 minutes, get constant seashell sound as if it had to warm up to get to that point. After that, had volume but very very low, even with volume control now tracking. The radio stabilized in this low volume state, & at that point, I touched a grid cap with a screwdriver & it came to life as if it had to be kick started. Had to do this a few times till it stabized in a good working state. It's been playing well now for three hours tracking the dial well, stations strong with shoooshing sound very low. (Stations override the low shoooshing). Have not had to touch any grid capa with screwdriver at this point. Lastly, what seemed to eliminate even the low shoooshing, was disconnecting & reconnecting the antenna lead. Any ideas why all this would happen?
THANKS...Joe

[ipwizard]

There was a video on Youtube from AllAmericanFiveRadio where he was working on a 90 that had a simular issue. When his was cold he turned it on and it wouldn't play, then he would touch a screw driver pretty much anywhere and it would come to life. I believe it was a cold solder joint. Ill see if I can find the video where he explains his problem.

Here you go:

[Video: http://www.youtube.com/watch?v=LBQwcx30b...GbsdJudi5I]

Hope it give you some help.

[codefox1]

I think you may have a bad silver mica capacitor. Either that or one or some small carbon resistors have drifted way up in value. The resistors are easier to change, I would start there, probably a good idea anyway.

Of course it could be a tarnished tube socket or a faulty tube, so see to that as well. Let us know.

[LASJayhawk]

Assuming you have replaced ALL the paper caps..... I vote a bad tube. The cold/bad solder joint would be my 2nd choice, but resweating the joints would be the 1st thing I would do as the cost is $0.

It is not within bounds that you have a broken wire in the set, when it heats up it expands enough to make contact....thats a 1 in 1000 shot but it can happen.

[Joe]

Lots of good advice and things to check from you guys. I checked out the cold solder joint video. Interesting. I am going to test the tubes again with my TV-7DU tube tester, check for cold solder joints, and tighten up anything loose for starters.

Thanks...Joe

[Eliot Ness]

Lots of good ideas here Joe. No harm in testing your tubes, but if you have spares the best test is to swap them out. Also make sure each tube socket connector is clean and tight (small paint gun cleaning brushes work well to clean). Also clean your tube pins, it has probably been years since the contacts or tube pins have been checked/cleaned (if ever), and don't forget the grid caps and connectors on the 24's.

Next I'd reheat and reflow (with a little fresh solder) all the solder joints; they might look OK on the surface, but under that glob of 80 year old solder a cold joint might be lurking...... and remember to check the tuning cap screws as mentioned in that video. A bad ground that looks OK to the eye has been the cause of a lot of strange problems.

That's the easy stuff you want to do first; if that doesn't work it's time to roll up your sleeves and start some serious troubleshooting. Good luck, you can do it!

Here are links to some inexpensive brushes that are great for cleaning in tight spots (just add some of your favorite contact cleaner):

http://www.harborfreight.com/5-piece-air...68155.html
http://www.harborfreight.com/10-piece-tu...95947.html

[Joe]

Making good progress. Tightened all loose trimmer cap screws and anything else I could find loose. Hit every solder connection to try to eliminate cold solder joints. Think I got them all. Tested all tubes on my TV-7D/U tube tester. Tested for shorts, gas, etc. All strong.  The 90 now turns on right away, with good reception unlike first post where I had 15 minutes of rushing thunderstorm sound with almost no reception.  However, even though it is playing ok, now hearing rushing noise every 10 minutes or so. It starts, builds up a bit lasts about 5 seconds and ends with a slight pop, and is gone. This pattern seems to repeat . What is also happening is the volume will drop, but not at the same time as the rushing.  With these things occurring however, I never completely loose reception.  With the volume drop, if i touch any part of the chassis with a screwdriver (could be grid caps, ground point, even turning the station tone knob, the volume comes back for a while. Any further thoughts at this point? Want to mention that the 90 is aligned just about dead on now.

[TA Forbes]

I would look for communists in there. They are everywhere......

[Arran]

I would also check the solder joints on the tube pins and the grid caps, especially the grid caps since they head up every time the set is turned on. I have had this happen numerous times in older sets, the solder joint in the grid cap often goes flakey over time, not to mention the lead connected to it.
Regards
Arran

[Joe]

I resoldered all grid caps and swapped out the 80 and the 27s. Unfortunately, I don't have a spare 47 or 24 as I would try them. But I will try heating up the pins on those tubes.

[codefox1]

Gotta think it is a silver mica problem, if banging around with an old dry chopstick can't find a faulty connection. Knock on the tubes as well, you never know. I like to replace all the small carbon resistors in an old set at the same time as I replace the wax caps, so I can rule them out for such delightful circummstances as you are now experiencing.

[Joe]

Regarding the Silver Micas, are they the 4 trimmer caps on the 4 gang tuner? If so, can I back off the adjustment nuts and take the micas apart and clean them? I was able to align the radio perfectly, so I know they work, and the radio is holding its adjustment (no drift).

P.S....I knocked around every thing possible ( tubes, components, cans sockets, tuner, adjustment caps, etc and can't get the radio to make the rushing shooooosh noise, or have the volume drop. BUT, when it either of these things happens on its own, especially the volume drop, all I have to do is touch a grid, or even a ground point with a screwdriver, and the volume is back and it plays like a champ!

[codefox1]

No, the mica trimmers do not have any silver. If alignment went well, leave them alone.

[Joe]

Hello Codefox 1. Can you tell me what capacitors in the Philco 90 could possibly have Silver Mica Disease? How do I identify what capacitors have silver?

Thanks...Joe