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  restoring capacitor tar block
User Avatar Forum: Philco Electronic Restoration
Posted by: Kestas - 12-28-2017, 01:44 PM - Replies (8)

This is my first time restoring a capacitor tar block on a radio.  This is the metal box with 5 film capacitors, not the bakelite block.  I've got it apart and plan on reusing the original wires that come out.  I don't have circuit board material on hand, but I'm planning on cobbling up some cardboard and perforate holes to secure the capacitors.  What I'd like to know is what different concepts people used to secure the new capacitors in the metal box, maybe better ideas than what I have in mind.  The radio is a Philco Model 60.

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  Scott 16 - Restoration Begun
User Avatar Forum: Other Radios (Non-Philco)
Posted by: rfeenstra - 12-28-2017, 12:48 AM - Replies (7)

Yikes! What have I gotten myself into?!  I decided to start on my E.H. Scott 16.  The Amp/Power supply was the least intimidating so I started there.  Now to check out re-chroming businesses in the Grand Rapids, MI area.



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  Philco 37-620
User Avatar Forum: Philco Electronic Restoration
Posted by: Alan - 12-27-2017, 09:15 PM - Replies (25)

Hello everyone. I'm new here.  I hope you all have a great New Year!!  I've been reading some of the posts and was looking for some advice.  About 20 years ago I bought a Philco 37-620 in good condition. Just needed some cosmetics. I ran a couple of "tandum" wires where I saw questionable wiring on top (and replaced the power cord) the year I bought it.  You can see them in the picture (but left original wires in place). It has worked great for years. Here is the advice I need.  If it works fine...should I change out any components like capacitors for potential fire hazard?

I have it out of the cabinet to repair the speaker cone (mover put a finger through it)  Thank you for your help!

Alan
Burrke, VA



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  Philco chair side radio A801 value
User Avatar Forum: Philco Home Radios
Posted by: June - 12-27-2017, 05:33 PM - Replies (6)

Hello, 
I have a philco chair side radio A-801.  It works although the cord is a bit frayed so we don't use it.  It seems in terrific condition otherwise.  I want to sell it and have no idea how or what value to establish on it.  Does anyone have any ideas?  Thank you in advance.  Admin please delete post if not allowed.

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  Philco 42-380 120 Hz Hum
User Avatar Forum: Philco Electronic Restoration
Posted by: Jason63 - 12-27-2017, 05:31 PM - Replies (10)

This past Summer, I rescued a 42-380 from a neighbor's garage where it had been stored for several decades.  The elements were not kind to the radio, but I thought it would be a fun project.  Not being much for woodwork, I paid a pretty sum to have the woodwork restored and took the radio to a local repairman to restore the radio.  Though I have a decent electronics lab in my basement, I've been busy with work and figured someone with experience repairing these radios would be able to do a better job than I could.

Several months later, the radio was finished.  A quick check sounded fine at the repair store, so I paid the man and took it home.  After setting it up in my living room, I started playing with it.  Sure enough, there was an annoying 120 Hz hum present throughout the AM broadcast band, especially bad on the lower end.  The hum is present with or without a station being tuned, although it is more noticeable when some stations are tuned than others.  I contacted the repairman and he was clueless about the cause.  Given the hassle of transporting the radio back to his repair shop again, I decided I would attempt the repair myself.

The first thing I did was go through the full alignment procedure specified in the Philco 1942 RMS Year Book.  It was clear my repairman had not performed this alignment given how far off some of the controls were.  When I finished, the dial was considerably more accurate and the sensitivity was also noticeably improved, but unfortunately, the 120 Hz sum was still present.

Looking through the schematic, I note the only place where 120 Hz is generated is the rectifier circuit consisting of a 6X5G tube connected as a full-wave bridge rectifier.  The output is low-pass filtered by a PI-filter consisting of C61, L59, and C20A.  C61 was a 475V 18uF electrolytic capacitor.  L59 is the field coil in the speaker.  C20A was a 475V 8uF electrolytic capacitor.  A look inside the radio revealed that the electrolytic capacitors have been replaced as follows:

C61:  22uF at 450V
C20A:  22uF at 450V

I also measured the inductance of the field coil at 10.8 H at 120 Hz with a series resistance of 6.5 kOhms.  The schematic says it should be closer to 1.1 kOhms which means I need to have a closer look at the speaker to see what could explain this large discrepancy.

Closer inspection of C20 and C20A revealed that one of the capacitors was dented due to the overzealous tightening of a retainer clip on the part of my repairman.  I decided to remove all electrolytic capacitors and test them further:

C20:  21.2 uF, ESR of 2.48 Ohms, leakage current of 0.45 mA at 400 Volts.
C20A:  22.1 uF, ESR of 1.96 Ohms, leakage current of 0.55 mA at 400 Volts (this one is dented).
C61:  21.6 uF, ESR of 2.3 Ohms, leakage current of 0.32 mA at 400 Volts.

According to the Nichicon specification, I should have seen leakage currents of under about 0.9 mA, so I guess those values are within specification.  The ESR values seem high to me, though I'm accustomed to lower voltage applications so perhaps they are reasonable given the ~200 Volts they have across them during normal operation.

Next, I did some searching on the forum to see if I could find any other ideas to try.  I found a note about R60 -- a 15-30-146 Ohm compound resistor used for biasing.  Sure enough it had already been replaced by my repair guy and was reading correctly when I checked it.  I spot checked a few other original resistors for correctness and found them to be within 20% of their rated value, drifting high.

The wiring inside the chassis looks very questionable from a modern perspective where we work with fast-changing signals, but I'm assuming outside of avoiding routing the power lines close to any RF input stages, it should be fine.  Some of the original wiring was replaced by my repair guy and I can only assume he routed it in the same manner as he found it.  I'm a bit worried about the placement and wiring of C20 given that it appears to provide additional power supply filtering to the IF stages and is placed next to the power supply filter capacitors.

I'm getting ready to hook up an oscilloscope to the radio and start probing around to see if I can find anything.  I'll use two probes in A-B mode in order to avoid the floating ground issue that would otherwise be a problem.  Meanwhile, I'd certainly appreciate any advice or suggestions anyone here can provide as I've not worked on any electronics of this vintage before and have probably neglected to try many things which would be obvious to those who have.

--
Jason

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  Phonola cathedral radio
User Avatar Forum: Other Radios (Non-Philco)
Posted by: Brad Winder - 12-26-2017, 09:48 PM - Replies (8)

Merry Christmas!

Today I pulled another long-time waiting project from my shelf...a Phonola cathedral, built by Grimes Radio Corporation, which later became Dominion Electrohome Industries. I bought it 16 years ago...where did time go? It is a model #161, built in 1931. 

It uses two 235s, two 224s, a 247, and a 280 tube. 

But...it is missing it's speaker. And the schematics I have don't give any specifications, other than it would have a 1800 ohm voice coil. Would anyone be able to "reverse engineer" from the schematic, and give me an idea of what I should be looking for?



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  Model 39-70 stations there, but dial off
User Avatar Forum: Philco Electronic Restoration
Posted by: NostalgiaRadioTime - 12-26-2017, 12:10 AM - Replies (3)

https://www.tubesandmore.com/sites/defau...pg10-1.png

Haven't gotten to the power supply yet on this. Have been battling a stubborn chassis. Icon_crazy

As mentioned in the thread about adding an A supply to a B power supply, I found the primary of the OSC coil was open. I replaced it with one of the P-70-OSC coils from the Antique Radio Supply but I could not pull in stations. I then found a winding open on the ANT coil as well, so I replaced that with the P-70-A coil from AES. It receives stations now but the bandwidth is quite a bit off. I get 620 AM with the rotor about half way out of the stator on the tuning capacitor, when it should only be out about an 1/4 at most. I tried aligning it but was only able to move the station back a short way before I ran out of screw (the adjusting screw on the tuning cap is backed out all the way). I can get our other strong local station at 1470 and that seems pretty close to where it should be.

Is it just that that replacement OSC coil may not be close enough to the resistance values / number of windings on the original coil to be compatible? Does anyone have any ideas on what I can try doing to move the lower end of the dial back to where it should be?

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  37-630T Volume Control
User Avatar Forum: Philco Electronic Restoration
Posted by: Tucker - 12-25-2017, 10:13 PM - Replies (3)

The schematic shows this radio using a 2 megohm volume control with a 1 meg center tap. I measure the resistance between the two outer lugs and I see 3 megohms on my meter. When I measure between the center and an outer lug I see 1.5 megohms and it goees down to .7 meg with the control all the way clockwise (full volume) position.
is this poteniometer ok ?  While cleaning the track I noticed one spot that appears rough while the remainder is smooth.

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  Arvin 442 cap question
User Avatar Forum: Other Radios (Non-Philco)
Posted by: Foose - 12-25-2017, 12:18 PM - Replies (11)

Hi everyone!

im just getting into radio restoration, and this is the third radio i have attempted repairing. 

the little radio actually still worked when i got it, but it obviously needed recapped and generally gone-over, so i found the schematic and ordered up my caps.

well, like a dummy, i went ahead and ordered one of everything off the parts list, while neglecting to look at the radio itself to see what was actually in there. most everything was correct, except i found wildly different values when it came to the three section electrolytic can cap.

the parts list calls for a 40mfd/150v, a 20mfd/150v, and a 20mfd/25v
the actual can cap in my radio is a 50mfd/150v, 30mfd/150v, and a 100mfd/25v

i know the voltages dont really matter as long as you exceed the working voltage of what was intended to be in there, but im not sure why the capacitances are off by so much. the schematic says that it covers several different models, but it does not specify different can caps for the different models, so that ones got me scratching my head.

i guess the bottom line is i should probably replace the old caps with ones of equal value, regardless of what the schematic says, because the dang thing worked before, therefore it will work again, right?

anyone have any thoughts?

thanks!
Brian

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  Unknown Philco
User Avatar Forum: Philco Home Radios
Posted by: vecher - 12-24-2017, 02:12 PM - Replies (4)

All, Please ID this Philco..I picked this up at Kutztown a couple of years ago from Kirk I think.. Cannot remember the model Number..


It has 11 Tubes..

[Image: https://farm5.staticflickr.com/4599/3855...d11f_b.jpg]

[Image: https://farm5.staticflickr.com/4736/3855...7d89_b.jpg]

[Image: https://farm5.staticflickr.com/4685/3855...cc65_b.jpg]

Thanks

Skip..

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