[murf]

You are correct as usual Morzh.
Traced wires and they are wired with one lead going to the 27 tube, and the other goes to bypass condensor #18.
Guess I will just replace these hacked wires with new.
Direct shot to #27 tube and the bypass condensor.
Thanks again,
murf

[Image: http://i1161.photobucket.com/albums/q509...co90-2.jpg]

[murf]

Here we go.
Electrolitics replaced and open coil repaired and working.
Now I have to deal with the bakelite blocks that were re-capped on the outside of the block instead of installing new caps on the inside.
THis has caused a confusing and hacked up mess, with the wiring and resistors that were mounted to the blocks all removed from the blocks.
How the H*ll am I going to straighten this mess out?
When powered up now I get a very faint amount of audio.
Can hear it is picking up a few stations, but very low volume.
Have swapped some tubes and am now going to check resistors and finally attempt to re-cap the bakelite blocks.
What a mess.
murf

[murf]

Hello again,
Looking at how I am going to move those bakelite caps back inside the blocks where they belong.
Noticed while checking it out that the previous owner had also removed the enclosure for part number 30(condenser)
Should be 2 caps in the enclosure. Schematics says there is a .25 uf and a 1 uf
Is that value of 1 mfd correct or is it supposed to read .1 uf ?
When they removed the enclosure, they just wired in two .33 uf caps and left the enclosure off.
Need to know if the value of that 1 uf is correct, and also need to know which lead goes where for the 2 caps.
Schematics doesn't tell me which of the 2 leads is for the 1 uf. One lead is going to a tube socket and the other goes to a bakelite block.
Can anyone enlighten me?
Thanks guy's,
murf

[morzh]

It says 1uF.

There is a discrepancy between Ron's website version and the Rider's, but the 1uF position is the same.

[Ron Ramirez]

The Rider's schematic is incorrect; mine is correct, I've done the research. Read:
http://www.philcoradio.com/tech/90error.htm

[murf]

Thanks for the info guy's,
Really nails it down.
murf

[murf]

Hello philco members,
Have now replaced the caps in the bakelite blocks and still have very weak audio.
I can barely hear audio.
Seems to be receiving am signals if I go up and down the dial.
Was wondering if it could be a problem with the output transformer of the speaker voice coil?
Not sure how to check these on this radio.
I have replaced the caps and a few resistors.
Thing that also bothers me, is that the electrolitics had been changed years ago.
They also left the original electrolitics wired as they did with a lot of the bakelite blocks.
I can't imagin that the thing ever worked after they butchered it the way they did.
Looking for suggestions here other than the garbage can.
Anyone care to chime in?
murf

[klondike98]

murf, I'm not the best guy to troubleshoot this, haven't worked on a 90 before but just a dumb thought....do you have an antenna attached? 10 feet of wire should work, won't get much without it.  If you do....as Gilda Radner's Rosanne Rosannadanna used to say....nevermind 

[murf]

murf, I'm not the best guy to troubleshoot this, haven't worked on a 90 before but just a dumb thought....do you have an antenna attached? 10 feet of wire should work, won't get much without it.  If you do....as Gilda Radner's Rosanne Rosannadanna used to say....nevermind 

Yeah, and I plugged it in too.

[klondike98]

LOL...yea...I've been there 

[murf]

Here is another possibility.
What if either the ouput tranny or the speaker voice coil were bad.
Would either of these cause the very faint audio?
I remember Morzh stated once that if the OT was  bad there would be no audio at all.
I am getting  slight humm, and I can hear faint audio with a few stations along the dial.
Voice coil?
Is there a simple way to check these?
I did try using my ohmmeter on the output lugs coming out of the OT.
All I got is verification that was continuity.
Just thought I better ask you guy's.
Have re-capped, replaced a few resistors, an checked the tubes again.
Did replace that #7 coil as well.
There are a couple caps that were added at some time that are not on the schematic. I just replaced those with new caps. Tried disconnecting thos 2 as well, with no change.
Stumped again  
murf

[morzh]

Murf

If you have another 90 (with an SE Output) or better yet a 70, you could use its speaker to see if it is the problem.


One more way (used it myself):

1. Make sure the field coil is good (3.2kOhm or so...)
2. unsolder the output transformer secondary and connect it to any PM 4 Ohm or so speaker, and
3. See if your sound improved.
4. While at it, measure acrss the unsoldered voice coil, should be about 0.7 Ohm.

If no help, see if the output transformer is good, replace if necessary.
Have you checked the tubes?

[murf]

Hi Fella's,
Well I parked the 90 for a while and just recently brought it out again.
I had re-capped it earlier and replaced a coil.
Could not get good audio, just very faint audio.
Well, I needed another set of eyes to look at it so I tooki it over to a friend of mine to have him give it a look.
After polking around, he found an open resistor in the audio section.
Thought I checked all of them, but must have missed one.
New resistor and we now have a strong playing radio.
Hooray.
We can now put it back in the cabinet and have that project done.
I was really glad to hear that all the messed up electronics that I started with and replaced, was all done correctly with no issues.
Think I will let him look at my RCA 281 and diagnose it for me.
Later,
murf

[klondike98]

Good success!!!

[morzh]

Is there such thing as bad success?

Congrats!