Hey all. Just got back to this project after being sidetracked by another (built a motorbike for my brother). Cleaned the chassis up, and assessed the situation. this is a code 121A (any particular reason for the "A" designation?), and the schematics pretty much jibe up with what's in the set, EXCEPT for a couple of anomalies: 1) TRANSFORMERS- calls for 2 smaller ones, and a big one.( I have the correct big one), but calls for a 32-7869 and a 32-7871... I have a 32-7115T between the front large xformer & the rear (which appeared to have a massive meltdown, judging from the amount of resin that oozed from it down to the cabinet. I assume it's fried. The rear is a 32-7671T. Are these compatible? (They seem original...) 2) ELECTROLYTICS (on top of chassis)-- SCH#102 calls for a 2 section (part #30-2201) 8/10 uf- BUT an ugly orange Sprague single 8uf is there in its' place... SCH#98 calls for a single 18uf, but has a double Solar brand 8/8uf there. ... SCH#77 (on the RF chassis on top) calls for a 2 section 4/3uf, but has a double Solar 8/8uf there- would that be considered excessive for that circuit? Under the chassis, SCH#101 .25uf is nowhere to be found, but a single Sprague 8uf is there directly below the oozed transformer, with no ooze on the Sprague, or anywhere under the chassis... So obviously, this drives me up the wall, and I must acquire the correct Philco electrolytic cans and the correct Philco .25mfd cardboard housing, of which I will advertise for on the sale/trade section soon. Surprisingly, save for a couple non-Philco tubes, that appears to be the extent of "repairs". All else appears correct and original. So the question of the day: Does that "A" designation on the 121 code change the electrolytic can configuration, or is it all sheer debauchery? P.S. I transferred my pics to this computer...Just gotta figure out how to show them here...the instruction book is 392 pages long it appears...(ha ha)
>any particular reason for the "A" designation?
Not sure.
> I assume it's fried
Wouldn't condemn it yet. Remove the 5X4 tube and measure the AC voltage from pin 3 to pin 5 at the socket. Should see about 600vac. You can leave it on for 10-15min (again w/o the 5X4 inserted) and feel if the power transformer gets hot. If it makes hv and stays cool I would not replace it just because it's lost some wax.
> The rear is a 32-7671T. Are these compatible?
Don't know don't have a parts catalog.
> but has a double Solar 8/8uf there- would that be considered excessive for that circuit?
Would suspect that these differing capacitor values were what was on hand at the time that it was serviced. Fortunately the values are not particularly critical. Some like 14mfd were not a standard value (8's or 16's mfd were)
> I must acquire the correct Philco electrolytic cans and the correct Philco .25mfd cardboard housing
Not necessarily there are several ways to replace what you have.
>Just gotta figure out how to show them here...
I just use the edit button on the tool bar to resize the image down to 600/325 and attach the image.
GL
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Thanks for the reply!!! I understand I can substitute other components of equal value, but I'm a stickler for originality, and WANT to get the old Philco cans and re-stuff them. Like I say, I just got back to this project, and did the preliminary cleaning and inspection. Still need to make a crude cradle for it to get better access to the undercarriage, and I have compiled a parts list, as per the schematics. The only thing in question I guess ( I can't exactly remember what I used for the 42-400) would be the safety caps... Don't we use those of the 1,000v variety? THANKS!!!
What is that silver rectangular box with the wires coming out of it in the lower right hand corner? It reminds me of an old bathtub cap, but I know it's not. Can't seem to locate it on the schematics... I pulled the cover off somewhat, and it kind of does look like an electrolytic, but i'm not sure I want to mess with it...
Like Mike said probably some bypass caps inside. Trace the wire back to what they are connected to and check them on the diagram to find
their values.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
(This post was last modified: 10-28-2017, 04:17 PM by Radioroslyn.)
A slight variance in the schematics: Schematic # 84 (code 121) shows a .05uf, part # 30-4177. What I have in there is a .002 @ 1000v. Oddly, this condenser (original, as it was buried under a bank of resistors, and looked untouched) is ALSO part # 30-4177(P), as is written on the condenser itself. Question: Since I didn't get a .002 @ 1000v (as there is no .002 on the schematics) when I got my new parts, should I stick the .05uf @ 630v in it, or just put the old .002 back in it- (it lays squarely at .002 on the meter)? NOTE: Out of 25 components I've changed so far, only 2 resistors have been out of tolerance, and only by about 30%. ALL other resistors have been within 10% tolerance... ALL capacitors have been dead on the money so far I feel kind of foolish for "fixin' what aint broke", but I know all these should be changed, for safety's sake.
#84 is part of the negative feedback circuit for the audio amp. I would think if you changed it to a .05 at best it would alter the tonal quality of the sound and at worst it would oscillate uncontrollably.
As mentioned many times before here and on other forums testing old w/p caps is a waste of time. With modern test equipment they can give you an accurate assessment of the capacitance BUT they test at a very low voltage so it doesn't tell you anything about voltage leaking though the cap in question. 9vdc is virtually nothing by comparison to the hundreds of volt applied to it in it's the vacuum tube circuit it came out of. This is a critical factor as when there is leakage it can cause an upset in the bias voltages causing the tube it's associated with to to draw excessive current. Also can be the source hissing and popping sounds in the audio.
Off the soapbox.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Thanks Radioroslyn! Pretty much expected that, as I change out ALL caps ALWAYS (except mica, as needed), but where would the best place to pick up one of those .002@1000v - The guy I got my caps and resistors from I can guarantee does not carry that. Now that I got my components, who will actually sell me one cap?
To answer your question of resent date, grab a couple of .005@630v and wire them it series. That will give you .0025 @1260v.
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
(This post was last modified: 11-08-2017, 10:27 PM by Radioroslyn.)
I pulled the cover off somewhat, and it kind of does look like an electrolytic, but i'm not sure I want to mess with it...
I feel kind of foolish for "fixin' what aint broke", but I know all these should be changed, for safety's sake. 
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