I am a novice with Philco brands, especially this vintage as my experience has been with Zenith 1950's era.
I had a 40-195 given to me and it was a tube and had some real issues with wires brittle wires. Using the schematics to the best I could, I replaced the capacitors, resistors and wires that were in bad shape.
The unit powers up, tubes light up and get warm but there is no sound. Looking for some help with what to check next with the understand I am a newbie with this brand and model.
I am new to working on Philco's and I am restoring a model 40-195. I have worked on Zenith 1950's vintage, but nothing of this generation. The set was given to me so I figured why not.
I replaced all the paper capacitors, crumbling wires, resistors, 2 electrolytics and the 6J8G tube which was missing. The set lights up, tubes light up and the magnet area of the large speaker gets warm. The issue I am having is there is no sound, no hum, nothing. I am not sure if it worked before I replaced the older parts since, I was told it did not.
Looks like someone worked on it at some point before me and gave up.
I have not tested the tubes, not sure how to on the Hickok 600 tube tester I have as these tubes are unlike others I have tested before.
Update on my progress with the 40-195. Found online a chart for testing the tubes on the Hickok tube tester and found a 42 and 2 37's that were bad and replaced them so I know all the tubes are in good condition.
The speaker wire and connector contains 4 wires and was in bad shape with wires that had separated from the chassis itself. Looking at some online pictures, I think I have them in the right positions but wanted to know if anyone had detailed information to confirm. The schematic is not exactly easy to understand for a novice.
I was just looking at other posts and noticed that there are several regarding the output transformer. Mine has a Philco 32-7981. Is there a way to test it to ensure it is working properly? If not, has anyone replace one with something similar as I cannot find that model.
First off, based on the schematic, this radio should be an excellent performer and worth saving!
Below are some voltage checks. However, a standard warning:
This radio employs high voltages, some as high as 700 -800V AC between the rectifier plate connections. If you are not used to working on high voltage electronics, seek the help of experienced persons. Also note that the noise suppression capacitors marked 89, across the power transformer primary can short and render the chassis to be "hot". Remove these NOW. the radio will work without them. Eventually, they should be replaced with the correct Safety Caps.
Check, doublecheck and triple check the wiring. The ability to read schematics will be very helpful here. Use a du\ocument such as the RCA Receiving Tube Manual for the "Pinouts" for the various tubes, particularly the Rectifier and the 2 '42 Audio Output tubes.
Measuring the resistance of the 3 primary terminals of the power transformer will help identify the correct leads. The 2 leads with the greatest resistance between them (about 700 Ohms) go to the plate connection of each of the 2 '42 tubes. The plate connection is to the left of the 2 largest pins (the filament connections) when looking from the underside. The 3rd wire should measure about 350 Ohm between it and either of the other 2 wires. This wire ties to one side of the field coil and is the connection to B+ for the rest of the radio This joins with positive terminal of Filter Cap 77. The remaining field coil connection is to the junction of C78 and the Cathode of the '80 Rectifier.
Start out your voltage checks by checking between any wire to the Output Transformer and ground. You should get between 230 and 250VDC. If zero V, check your power supply for shorted electrolytics, especially the one labeled 77 in the diagram, the 25uF electrolytic. Remember that these are polarized and will short if polarity is reversed. Shut the unit off before burning out the field and recheck wiring.
If the voltage is there, check the speaker voice coil (you will have to disconnect the transformer secondary from the voice coil connection). If the Voice Coil shows open at the terminals, check the flex cables between the terminals and the cone. The constant flexing is a routine cause of dead speakers. Measuring between the center tap of the HV Section of the power transformer at R77 and chassis ground, expect about -15 and -25VDC. If much more (Say 200 - 300V), the resistor R77 is open, but you would not find the speaker field coil to be warm.
Good luck with this set. If you are successful, this should e a great performer. The Audio Stage consists of '42s in push pull with 2 '37 push pull drivers, a "cathodyne" phase inverter and feedback, and is much more sophisticated than many other Philco and other moderate end radios of the time, and should be truly HiFi if a really good output transformer is used. Once you get this working, add a phono / MP3 jack. This will also be a rather mellow guitar amp.
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
Thank you for the reply MrFixr55, I appreciate it. I agree, this is a system worth saving! I will take a peek at your suggestions with the utmost care since this is a high voltage until.
Maybe this is beyond my experience level and should seek a professional as I hate to ruin it since reading the schematics for this radio is not easy for me. I cannot find the noise suppression capacitor 89 on the schematic or it listed on the parts.
I have done well with replacing capacitors, resistors and electrolytics with the ones that meet the specs. I am careful to do them one at a time to ensure I am not messing it up.
89 doesn't exist he's referring to #85 it's the bakelite block that the line cord is soldered to. Perhaps this pictorial will help you sort the spkr wiring. If the opt is bad it's pretty hard to find one that has a tapped 2ndry and work properly. So using a pot across the winding, adjust for best sound and replace with two fixed resistors.
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: 12-31-2021, 11:46 PM by Radioroslyn.)
OOps, Sorry about that guys, was rushing out to the barber and didn't proofread. Thx Terry for picking up the mistake and replacing about 100 words with a pic worth 1000!!
And a great idea for that trick tapped secondary.
Best Regards and happy New Year
"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
Best Regards,
I traced from the OPT (black and white wires) to each Pin #2 x #42 tubes as expected. I am not sure what the #85 capacitor is based on the schematic so I am going to include some pictures that may help.
This is a time when I wished I had a clear picture of before I replaced parts and after! Lesson learned.
The speaker has a connection as you can see and since they were frayed and cracked, I ran new ones up through the chassis and made connectors on the other side so it would be 'safe'. The yellow, red, black and white wires that are in the shrink wrap are the ones I brought in.
You can see the 2 orange drop capacitors that I used to replace the paper ones. I do have some X2 capacitors I could use if those are the ones that could fail and make the chassis hot.
Ok so ypu set is a little different then I thought. Your spkr only has the voice coil and field coil connections. It's just like the 41-300. Most of the older sets have the output transformer mounted to the spkr frame and are wired as I described.
You've got 2 hv wires that go to the fc and two wire that go to the vc. Pretty easy. Next step is to use your ohmmeter and measure the resistance from the wire with tracer on the opt (goes to pin 3 on the 42) to pin 2 of each 42. Should see a low resistance like several hundred ohms. If much high the opt is bad.
85 on the schematic is near the ac plug and the off/on switch and the big black thing last pic in the center is it!. If you flip it over and it has a black tar bottom then it hasn't been serviced. Should replace caps and x2 are a good choice.
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: 01-01-2022, 10:12 PM by Radioroslyn.)
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