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Repair Help on 1936 Philco Cathedral Radio - Printable Version

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RE: Repair Help on 1936 Philco Cathedral Radio - KB1PKS - 02-02-2022

Dear RonB, Terry, Mike, Bob and Philco lovers,

Here is a YouTube link to the cleaning effort that brought my 1936 Philco Cathedral Model 60B back to life!

 https://youtu.be/nojLDxvmMqE

73's Bill

RE: Repair Help on 1936 Philco Cathedral Radio - Radioroslyn - 02-02-2022

I see that the original filter caps are missing. If you have them you may want to consider: https://www.philcorepairbench.com/rebuilding-aluminum-can-electrolytics/  Looks kinda naked back at the rt rear corner.

RE: Repair Help on 1936 Philco Cathedral Radio - mikethedruid - 02-02-2022

I see you still have the clamps for the original electrolytic condensers, which makes thing a lot easier. You can make pretty decent looking replacements for them fairly easily. I showed the method in my thread on restoring a Philco 38-10...
https://philcoradio.com/phorum/showthread.php?tid=22318
This method works whether you wish to make functional replacement condensers with modern electrolytic condensers inside them, or just empty dummies. It is not expensive, and is a whole lot easier than trying to find originals to replace the missing ones. It doesn't look bad either.

RE: Repair Help on 1936 Philco Cathedral Radio - KB1PKS - 02-03-2022

Dear Terry and Mike,

Yes, about 5 or 6 years ago I replaced the filter caps and like a dummy I just discarded the cans.  I could kick myself of doing this because as you both point out it looks pretty bare without those cans.

However, I really like the idea of using PVC pipe and painting them silver to look like real cans. Thanks for the know how on such an easy dress-up. Most certainly worth doing now that the radio is running well again!

Kind Regards and 73's, Bill

RE: Repair Help on 1936 Philco Cathedral Radio - KB1PKS - 02-22-2022

Dear RonB, Terry, Mike and Bob,

I would like to give you guys a quick up date on my 1936 Phiico model 60. A special thank you goes to Mike (Mikethedruid) for his link {https://philcoradio.com/phorum/showthread.php?tid=22318} on the preparation of replacement "cans" for the filter caps.

If you follow this link https://drive.google.com/file/d/1UDTgPysDGA49jbsDFfwlOoMlPj5RYKFc/view?usp=sharing

you will see the results. Thank you Mike!

Next I will work on the cabinet restoration. I was told by a trusted woodworking friend to carefully start with a 50-50 mixture of double boiled linseed oil and paint thinner.

Bill (KB1PKS)

RE: Repair Help on 1936 Philco Cathedral Radio - KB1PKS - 04-23-2022

Dear Ron B, Terry, Mike, or anybody else who might be able to help,

I just purchased a very nice working signal generator with aim to re-align my 1936 Philco model 60.  As instructed by the Philco Service Bulletin No. 164A, I get a nice tone on the speaker by putting in a 460kc rf signal into the control grid of the 6A7 tube and turning the number 17 compensating cap.  I can hear getting the tone getting louder or softer as I turn the tread on cap 17 one way or the other. However, other that crude, by ear adjustments, I can't peak by ear alone so I put my old analog Radio Shack Micronta Multitester VOM across the speaker leads hoping to see a voltage change while turning the compensating cap. Even on the lowest setting (0.6 volts DC or 6 volts AC) I can barely see the slightest meter needle movement even when the signal generator gain is turned up and the sound from the speaker is blasting!  I know my old VOM is working as designed, is it that the output to the speaker is actually in Milli-volts? I thought the output to the speaker would be in the single digit volt range, am I wrong?  Am I doing something wrong or do I need to buy a new VOM meter that can measure in the Milli-volt range? 

P.S. - If I do need to buy a VOM that can measure in the Milli-volt range, does anyone have any recommendations as to make and model?

RE: Repair Help on 1936 Philco Cathedral Radio - Radioroslyn - 04-23-2022

Would you happen to have a vacuum tube volt meter or a fet input analog meter? These have a much higher input impedance and won't load the circuit down that they are connected to. Something like this could be used to monitor the AVC voltage which would give you a indication of signal level. Like a S meter.

Your VOM is more than likely about 10 or 20K ohms per volt. The VTVM or fet input meter is going to be about 10meg ohms per volt. So the latter is pretty much invisible to the circuit.

The voltage across the voice coil is going to be ac so trying measure it with your meter set on a dc input will not work... Unless you place a diode in series with it.

The other solution is to disconnect the secondly from the voice coil and connect a 2 ohm 5W resistor across the secondly.

RE: Repair Help on 1936 Philco Cathedral Radio - KB1PKS - 04-23-2022

Hi Terry,

Thank you for getting back to me.

I do have an old VTVM but the last time I used it I could not zero the meter on several of the lower range settings. I will give it a try however, because all I need is to see the indicator increase or decrease, the actual value is not really important in this case.

If I can't get my old VTVM to work do you know where I might find a FET analog meter at a "reasonable" price?

Bill

RE: Repair Help on 1936 Philco Cathedral Radio - Radioroslyn - 04-23-2022

I just have an old Heathkit VTVM I use alignments and testing pots. The VTVM were made for long time by comparison to the fet models which had short run before digital models came out. Somewhere around the mid '60s to the early '70s
You can use a digital meter they are high impedance. But they are hard to read cause readings are shifting while you are trying to read them.

RE: Repair Help on 1936 Philco Cathedral Radio - KB1PKS - 04-23-2022

Thanks Terry!

I'm also looking into Sanwa Em7000 Analog Multimeter FET typs and others if my old VTVM fails (Maybe I should just look into buying another VYVM on ebay - it's just taking another chance on ebay that you won't get more junk in your Ham shack)!

Cheers, Bill

RE: Repair Help on 1936 Philco Cathedral Radio - Radioroslyn - 04-23-2022

On your old meter clean the range and mode switches well. Loosen and retighten the connections on the back of the meter. The zeroing pot may be bad (worn out carbon track). Some have standard value pot others not so much.
If you have the manual or can find one online adjust ac,dc,voltage and ohms setting with a good battery in place. Then try the zeroing control.

If you want to give 75mts a try sometime I haven't have the H-W TBS-50 on the a while... Shoot me a pm.

RE: Repair Help on 1936 Philco Cathedral Radio - KB1PKS - 04-24-2022

Terry,

Thanks for the the tips. There are no batteries in my Hewlett Packard Model 400H. There is only one screw on the meter itself to zero the meter. On settings below 10 volts RMS I can no longer zero the meter. I'm hoping I'll see some movement at this setting?

RE: Repair Help on 1936 Philco Cathedral Radio - Radioroslyn - 04-24-2022

I misunderstood the adjustment you were describing. I was thinking electronic and you were thinking mechanical. I found the manual for it: http://www.mcmlv.org/Archive/TestEquipment/HP400.pdf  Seems likely that the issue might may be CR-1 and 2. These are the diodes are connected the meter. After all the yrs they may have developed some leakage causing the needle to favor one side or the other. Might not hurt to replace the two 2mf caps too.

RE: Repair Help on 1936 Philco Cathedral Radio - Mondial - 04-24-2022

Its most likely the 2 uF caps in the meter circuit if they are the original molded paper caps and have never been replaced. I would change them before doing anything else.

I have two HP 400D meters and both had upscale readings due to the meter bridge caps. Replacing with film caps cured the problem.

RE: Repair Help on 1936 Philco Cathedral Radio - KB1PKS - 04-24-2022

Dear Terry and Mondial,

Thank you both for these tips!

Today I tested all the tubes in my Hewlett Packard Model 400H on my Hickok 539C tube tester (recently purchased) and I found V1 Cathode Follower (6CB6) to be bad (3700 mmho, spec is 3900 min), V7 Series Regulator (12BA4) to be bad (5000 mmho, spec is 6000 min) and the V9 (5651) Reference Tube to be completely dead! First I will seek to replace these three tubes and if replacement fails to correct the meter zeroing issues I will seek to replace diodes CR-1 and 2 and /or the 2 uF caps in the meter circuit.

Thanks again for all your help!

Bill