Philco model 87 - Printable Version
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Philco model 87 - flatheadjr - 09-28-2016
So here's an update, I found a model 87 chassis and speaker I checked the audio output and it reads 580 ohms on the 2 connections to the 45s, what should the other transformers read as far as their ohm readings on the a.f. transformers. I'm thinking of using this set to go into the model 96 till I can find a decent output trans for the 77. Anyone have the complete information for this set or will I have to order that up again as well?
RE: Philco model 77 - Radioroslyn - 09-29-2016
As a rough guide any thing under 1000 ohms should be ok. The typically bad winding will be open or a high resistance in the 10's or 100's of 1000's of ohms (10k-100k). That high flunks. This is for audio transformers.
RE: Philco model 77 - flatheadjr - 09-29-2016
Other than the cable being broken on the tuner everything else checks out. Unfortunately some has done some work on this thing, they replaced the electrolytics a long time ago but did it outside the metal box full of capacitors. As soon as I repair the tuner I'll have to see whats happens. I'll have to order the caps for this to repair it right.
RE: Philco model 77 - Arran - 10-01-2016
(09-29-2016, 12:17 PM)flatheadjr Wrote: Other than the cable being broken on the tuner everything else checks out. Unfortunately some has done some work on this thing, they replaced the electrolytics a long time ago but did it outside the metal box full of capacitors. As soon as I repair the tuner I'll have to see whats happens. I'll have to order the caps for this to repair it right.
These sets didn't use electrolytics originally, they used a series of large paper caps and chokes for filtering in the power supply. The original paper caps are inside that can and were probably bypassed by the electrolytics, hopefully because the old caps were open and not shorted. In any event you can use modern polyester film caps as replacements for the paper caps inside the can. Apparently Philco liked to line their condenser cans with fish paper so it isn't too hard to remove the contents if you want to rebuild the can.
Regards
Arran
RE: Philco model 77 - flatheadjr - 10-08-2016
Update on the model 87, good news is after re stringing the dail I did a few checks to see if there were any opens anywhere and couldn't find any so just being daring and plugging it in a power strip for some safety it came to life, first one I've had that still works! The volume control doesn't work well, whats best for that? What's best for cleaning and lubricating these old volume pots? Also I'd like to replace the original cord with an original style cloth covered, are they still available? The only other thing this needs is a re cap and it should be in good shape. So for sure unit doesn't use any electrolytic caps at all?
RE: Philco model 77 - Radioroslyn - 10-08-2016
<for cleaning and lubricating these old volume pots?
Alot of discussion on this, I like wd-40 for carbon pots and Deoxit for switches.
> I'd like to replace the original cord with an original style cloth covered, are they still available?
Try Radiodazes. The new ones are plastic zip cord w/a cloth cover.
> So for sure unit doesn't use any electrolytic caps at all?
Correct.
RE: Philco model 77 - flatheadjr - 10-12-2016
Okay so I used a little WD40 to clean the volume pot it made one change, instead of a changing higher volume now I get just one volume level. I was able to remove the cover off of the rear and could see the contacter running on some type of material that appeared to be loose. Not really sure if it is damaged somehow because I don't know whats inside the volume control.
RE: Philco model 77 - Radioroslyn - 10-12-2016
https://en.wikipedia.org/wiki/Potentiometer
Yours is a dual pot, it has two sections. Can't seem to find the resistance for each section. One section shorts the ant to the chassis at low volume and the other section controls the gain of the rf amp stages.
RE: Philco model 77 - Radioroslyn - 10-17-2016
Did a little research and found that IRC sez to order from Philco. Mallory sez it's 250 / 5000 ohms which is the same value as the early model 70 chassis uses.
RE: Philco model 77 - flatheadjr - 01-04-2017
Not quite sure what these are they look like a resistor, capacitor mix, across the top of them I get 100 ohms or very close to that, the other part is the capacitor that goes to ground.
http://rs32.pbsrc.com/albums/d5/flatheadjr/20170104_193737_zpskin1sc1a.jpg?w=480&h=480&fit=clip
RE: Philco model 77 - Radioroslyn - 01-05-2017
(01-04-2017, 11:08 PM)flatheadjr Wrote: Not quite sure what these are they look like a resistor, capacitor mix, across the top of them I get 100 ohms or very close to that, the other part is the capacitor that goes to ground.
http://rs32.pbsrc.com/albums/d5/flatheadjr/20170104_193737_zpskin1sc1a.jpg?w=480&h=480&fit=clip
Yup your correct!! The resistor is in series w/the HV going to the rf amp tubes and the cap connected to one end of the resistor and to the chassis. The simple way the replace the cap is to cut the ground wire off of the original cap and solder the new cap from the end terminal to the ground terminal. On my model 87 all three of those caps were close to being a dead short so there was very little HV in the set. The resistance value isn't very critical as long as there not open.
http://philcoradio.com/phorum/showthread.php?tid=3490&highlight=model+87
RE: Philco model 77 - flatheadjr - 01-05-2017
I was thinking of just taking and isolating the end that connects to ground with a nylon washer and nylon screw so there's no longer a connection on that end, and then soldering the new capacitor to the terminal that connects to the coil end and the other end to a nearby ground. I'm not concerned with restoring the underside which is closed in and you can't see it anyways. I probably won't re stuff the cap box either, the new capacitors are much smaller and they'll all fit under the chassis as well. This chassis still has the cover as well.
RE: Philco model 77 - Arran - 01-09-2017
(01-05-2017, 09:46 PM)flatheadjr Wrote: I was thinking of just taking and isolating the end that connects to ground with a nylon washer and nylon screw so there's no longer a connection on that end, and then soldering the new capacitor to the terminal that connects to the coil end and the other end to a nearby ground. I'm not concerned with restoring the underside which is closed in and you can't see it anyways. I probably won't re stuff the cap box either, the new capacitors are much smaller and they'll all fit under the chassis as well. This chassis still has the cover as well.
Most will restuff the condenser box because it's not really that hard to do and results in a clean looking restoration job. I believe that the cans are lined with fish paper so a small amount of heat will cause the block to slip out of the can after which the wires can be clipped off at the base. These sets did not originally use electrolytic capacitors for filter caps so they used large value paper caps of about 1 and 2 uf and housed them inside that can along with several bypass capacitors, whilst they may have modern electrolytics of the same electrical size that are much smaller they don't hold up well in that application, so modern plastic film caps are recommended.
Regards
Arran
RE: Philco model 77 - Radioroslyn - 01-09-2017
(01-04-2017, 11:08 PM)flatheadjr Wrote: Not quite sure what these are they look like a resistor, capacitor mix, across the top of them I get 100 ohms or very close to that, the other part is the capacitor that goes to ground.
http://rs32.pbsrc.com/albums/d5/flatheadjr/20170104_193737_zpskin1sc1a.jpg?w=480&h=480&fit=clip
That pic isn't from a 77 chassis it has the wrong tubes in it, it looks to be a 87. According to the schematic the 77 doesn't use those decoupling resistor/capacitor. The pic in the beginning of the thread is a 77.
RE: Philco model 77 - flatheadjr - 01-11-2017
Well the thread started out with a 77, but the field coil was bad on the speaker and so far I have been unsuccessful in finding a replacement. I found an excellent buy on this 87 and it was even still functioning but needed a recap. I'm not interested in restuffing the cap box on this one, I'm just looking for functionality as anything I do won't be seen from above. The model 77 I'll repair when I'm able to either find a speaker or a good field coil transformer.