The PHILCO Phorum

Ok I picked up a 80 (on ebay) nice cabinet, but the usual trashed chassis.

it leads to many questions. The layout of the block capacitors is way more like the 81 in riders #3 than the 80... but it's an 80 I'm guessing a later revision chassis?

The output transformer for the audio amp was bad, I subbed in one I had on hand, a small merit A-3025. It's rated at 2500/3.2 ohms, 50ma, 3w. Is that big enough?

The grid lead for the 36 detector/oscillator was missing (as in gone!) I assume it came through the antenna coil can and was tied on to the bottom of the coil?

both 36's test very weak. I know these radios were 'touchy' when new, but would weak 36's keep it from working at all?

after adding a lead for the det/osc grid,the output transformer, and replacing the filter caps I have not much, if i touch the grid of the 2nd det i get some 60 cycle hum but thats about it. My next move is to replace the block caps as they all look like they have run hot, but should I get some 36's on order?

Several service tips I would review. I'm sure Ron will add the many things he knows on these sets. Also perform a Phorum search. Plenty of Model 80 post.

http://www.philcorepairbench.com/tips/svctip43.htm

http://www.philcorepairbench.com/tips/svctip44.htm

http://www.philcorepairbench.com/tips/svctip03.htm

OT should be fine. Replace caps and check resistors particularly 10k and the 1 meg at the detector tube. Would replace the 36's it's bad enough trying to fix one of these with good toobs. Check the feedback coil for the oscillator.
Terry

IT'S ALIVE!!!! sort of.

Replaced the 9K 10K and 1M resistors all were way out of tolerance.
didn't work.

Changed all the caps in the block caps.
didn't work.

played with the regen adjustment and got a few birdies but didn't work.

So in a hail mary move, I swapped the weak 36's.... jackpot!!
It's nowhere near right, and has almost no volume but is gettting about 10 stations on a 6' antenna.

I'll get some new 36's and a 42 then go from there.

Congrats finding the #36 tube problem! Sometimes, something as simple as swapping identical tubes in different sockets on same chassis' reveal weak tube problems indeed. Tube testers can lie also, nomatter how expensive models they are. Even the high dollar Hickok tube testers lie!The best test for any tube is testing in the circuit it is designed to work where correct voltages are applied. About 10 yrs ago I got tired of running across weak tubes and waiting for new ones to arrive. I started ordering 2 extra of most every common type ( I thought) tube I ordered to have extras and save on shipping costs. I have hundreds of nos tubes now and every once in awhile my new backstock has what I need onhand. But I still have to play the waiting game on getting new tubes even though I try to keep most in stock. Frustrating indeed, especially when waiting on nos tubes for customers sets! I need to move my shop next door to AES, or Bob Dobush at findatube so I can walk and get what I need when I need it. (ha!) I don't like Ohio winters!! Frustrating indeed! Out of all the hundreds good tubes I have here, there is always one or two oddballs that I don't have in stock when I need them "now"! Murphys Law? You bet! Ohms Law always works, until Murphy's Law shows up to spoil the party!!

Txrocker. Ain't that the way. I'm lucky that AES is 2 days away ups ground. (better than nothin) but you should have seen me rootin' through NOS tubes. 24A, 24A, 15,15, 12 (what the heck is a 12 anyway?) 27 etc.

the swaping 36's was a wild a$$ guess, but paid big dividends. enough to let me know the chassis is sound and can be fixed, so I can waste my money on stuff like a new dial scale!

A 12 is a old audio output tube for a battery set. Look up 112A. Handy toob to have if you fool with sets that use 01A's
Terry