The PHILCO Phorum

While replacing caps, I have been highlighting them on the schematic, indicating they've been replaced. Using the schematic that is posted here on the Phorum, specifically for this model 116PX, I couldn't find the 2nd C56. C56 is a dual .05 block. I also couldn't find R46, a flexible resistor that is across one of C56, and attached to ground. However, they are on the schematic for 116X. They are shown coming off of the 1st IF 78 tube. It seems that my chassis is a mix of the 2 different schematics.

I just started in on a 116X last night. 46 and 56 set the gain for the 1st IF amp, by grounding the cathode it's running the tube pedal to the medal. Looks like the screen grid circuit is the same for both sets which is another way to control the gain (by lowing the sg voltage it will lower the gain). Would think that having 46/56 in the circuit is a better way to go as it would tend to keep the IF stage quieter.
An other difference is the shadow meter has a parallel resistor to limit the current on the coil. On your set an open coil will kill the plate voltage to the mixer and 1st IF.

Last night I worked on the bakelite blocks. I still have a few left, but this one surprised me . I've re-stuffed many Philco blocks on several models, but this is the 1st time I saw brown biscuits instead of paper wrapped film caps inside. This is from the inside of an 8035-DG- twin .00011 (110pf) bakelite block.

I would measure these; if they are good, I'd re-use them.
If know in advance these were micas, they probably should've been left alone.

(07-16-2017, 01:10 PM)morzh Wrote: [ -> ]I would measure these; if they are good, I'd re-use them.
If know in advance these were micas, they probably should've been left alone.

I pulled then out of the garbage, and both measured at 184pF on my digital MM. Should be 110pF. Too out of spec?

Yep. Too much.

Work is slowly progressing. Still working on re-capping the bakelite blocks.  



I had to make a run downtown to the only remaining electronics store in town where I can get some of these parts. I came up short on caps for the bakelite blocks. I also got the rest of the electrolytics I'll need, and while I was there, picked up what I might need for my 116B, once I get around to it....

Oh! I probably should mention: I didn't have any .15uFd caps for a couple of the 6287-DU blocks, so I picked up .22uFd. I thought that would be close enough . Those would be in C82 and C102 on the diagram. My store had some .15uFds, but they were older stock, and huge . They wouldn't have fit in the blocks.

C82 is OK. If C102 (I could barely read the Rider's) is the one across the filter choke, which for some reason says "0.2uF" I would keep it the way it was as it is a hum compensating cap and its value is tailored to the choke's phase shift to compensate the pulsation. Does not have to be 1% but it helps to keep it as close as possible to original value.

I wouldn't even install C102. Leave it out and up the second filter a little.

Steve

Not a bad idea either.
In this case I would specifically use low ESR capacitor after the choke, as the ripple voltage is pretty much the ripple current times the ESR.

I've had a busy Summer, so I'm starting to find time to continue to chip away at this. All the Bakelite Blocks are done, and I've started on the electrolytics. The single 8ufd, and the dual 8ufd-10ufd have been gutted, and re-stuffed. Still working on reconnecting the dual. For the dual, I opted to drill a hole in the bottom of the cap, feed the wires through, and connect to the tabs, rather than trying to do internal connections. The ground wire had to connect to an external tab anyway, for a floating ground.

While in there working on tracing wires and connections, I noted a waxy-like substance on a couple wires coming out of the main transformer. I know enough that I panicked a bit. I thought one of the windings of the main transformer might have heated up and might be bad.  I did find a bad 6A3 when testing tubes.  

So, I took the time at this point to check all the windings of the main transformer. I'm happy to report that all check out fairly close to original specs.   I will, however, be cautious and keep an eye on voltages and temperatures when I power it up.  



I have my annual October radio show listening party coming up on October 21. I'm hoping I can at least have the radio of this beauty up and running for the party.

Wouldn't lose ant sleep over a bit of wax out of the pt. My 116X pt runs pretty warm after it's been on for while. Would think a little wax lost is normal for a 81yr old that was used often.

Well, despite the fact it's been a month since I last posted , I have been chipping away at the restoration of the chassis, and spiffing up the cabinet a bit, in hopes I could have at least the radio running and presentable for my annual Radio Show party, coming up on the 21st.

I left off at the rebuilding of the electrolytics. I got the single and double cap cans done. That left the 4-part can to rebuild. Since all the negs were common, this is what I put together in order to get it inside the original gutted can:



And after attaching the wiring:



It all fit nicely inside the can.