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Philco 90 with Twin 47 Tubes in PP
#16

Sorry missed that you tried already, try pulling one or two turns off the coil and try resoldering.

Gregb
#17

If while taking the turns off the wire proves brittle, even if you could resolder - don't.
#18

Started unwinding the Primary, Had to remove 65 inches of it to get to good wire. Looks like something maybe the Tape made the wire rot. The Primary has 53 dc ohms the Secondary has 56 dc ohms
Re-soldered to lugs. Got nothing to loose will reinstall and see what I have.

Gary has a bunch of 262 Coils that would trim to 260, just finding one to fit in Original can is the task
sent Gary a Pic of original.

Later
Bob


Attached Files Image(s)
   
#19

I have a replacement IF coming for the 2nd IF
So I went ahead and re-stuffed all the Caps and replaced any bad resistors and a few Mica caps that were flaky when value was checked.

I have a problem with Resistor Item 32 missing. Schematic shows a 499K in the Det Amp circuit .

Other than that just awaiting the 2nd IF

Bob T
#20

It is item 32 and it is present on the chassis drawing.
#21

As long as the primary has continuity now difference of 3 ohms DC resistance should not effect the inductance enough that you can't adjust the IF to 260 kc. In fact they may have been mismatched to begin with, either through accepted margins of error or because they wanted a step up between the primary and the secondary windings. I would try re-using the original IF coil if you can, and save the new one as a spare.
Regards
Arran
#22

Chassis again SINGING STRONG

Thanks Ron for a good schematic

Thanks Mike for the IF Coil and Tom for the 2 110pf caps.

But I did end up putting the missing Item 32 Resistor in AND

Used the Original IF transformer. Had it in and out 4 times
Repaired break in Primary
The Secondary checked good with ohm meter 53 ohms but would not work in radio, Cleaned wire around rivet and soldered it. That did it

Need to do alignment , but it is playing very well . Impressed with the 2 47 Tubes. Also I am running the Console Speaker with it. May not sound as well with the 8" Speaker.

Thanks again for the input from members here. It was helpful and made things easier

Bob T
#23

UPDATE

Powered up to do Alignment, NO RF !!!!!!!!!

Went to check OSC Tube Voltages. Touched my Meter probe to Plate Pin 2
RF returned. So osc was not running

Cleaned tube pins and cleaned pins and socket with contact cleaner.

Came back 2 hours later. Aligned IF , went very well. Peaked nice @ 260KC

Went to to rf alignment , rf disappeared again. Once again touched Pin 2 of OSC and rf came back.

This time I re soldered the connector pin 2 and bent the contact points closed.

Completed rf alignment , again all went well.

If I loose rf again will try another 24A Tube. I do not see any bad connections in the area.

Time will tell

Meanwhile enjoying 40's Hit via my SSTRAN Icon_clap

Bob T
#24

Yes I think a tube (have you checked it BTW?) might have a problem starting oscillating. Could be low gain.
Also remember that #13 and #14 items?
In case another 24 tube does the same you could possibly try to play with those.
#25

24 Tube checked very strong on my TV-7. Item 13 was replaced and 14 is 8.2K as found in it and suggested by Ron.

Been Playing over 2 hours trouble free

Bob T
#26

What the tube checks like is not quite everything especially when it comes to oscillators.
Once it starts though it will oscillate forever without problems - it is the start-up condition that is finicky. This is where the tube might potentially influence the behavior of the whole circuit.

You tester checks for certain parameters, it does not check for the whole performance.
#27

The testers provide a starting point, best tube tester going is the piece of equipment its meant to work in.
Gregb
#28

OK been Playing Flawless.

Now for next fix
Dial Tuning is sloppy. Part shown in Pic is worn out and allows dial to drift.
I need the Part Pictured and marked .

Thank You
Will post in WTB also


Attached Files Image(s)
   
#29

I have both 70 and 90 having zones where it is slipping. Guess it is quite a common problem for this type mechanism. I found out that moving the dial just a little along the axis helps it but you have to make sure it does not rub against the escutcheon.

Another thing, the grease tends to accumulate there and makes for less friction, so those need to be degrease.

Honestly, I do not remember this spring-pulled washer in either my 70 or 90. I wonder if they added that (or it was a home repair remedy) to increase the pressure of that rim onto that groove. I am not sure it is a factory solution - hadn't seen it before.
#30

Mine is not slipping. The part marked has worn egged shape so allows Dial to shift.
I need the part shown and marked as such.
The added spring and washers are the result of last owners attempt at a fix.

Replacing the Part marked with a good one, I believe a 1/4 dia bore will solve my problem




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