42-761EZ Chassis Restoration - Printable Version
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RE: 42-761EZ Chassis Restoration - Ron Ramirez - 02-05-2013
The CARE package from Mouser arrived today, so very soon I'll be removing the two Twist-Lock electrolytics, restuffing them, and reinstalling them in the set. I also have a couple power resistors to install...and will remove the 120 volt LED and replace it with an incandescent 1813 (14V) lamp.
Still haven't photographed that tuning mechanism, I need to go do that.
RE: 42-761EZ Chassis Restoration - Ron Ramirez - 02-05-2013
Okay, I had mentioned a problem with the tuning mechanism on this radio.
The tuning shaft goes into the chassis where it terminates in a sort of U-bracket. A matching U-bracket is on the matching end of the tuning drive assembly. Here's a look:
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-05_00002_zps8cdada8b.jpg]
Now, a closeup of where the two U-brackets sort of meet.
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-05_00001_zps62a8caf4.jpg]
It appears that something is missing. A piece of rubber, perhaps, that was once sandwiched between the U-brackets?
The tuning mechanism will not work without whatever piece is missing.
Any suggestions, folks?
RE: 42-761EZ Chassis Restoration - Eliot Ness - 02-05-2013
I suspect, as you do, that there was a rubber piece between the two U brackets. If it isn't too hard to remove one of the shafts it would be easy enough to cut a rubber piece to fit. Use something like a thick chassis washer or whatever you can find in your shop or local hardware store.
If it is hard to remove a shaft, then experiment with different sizes of rubber cut to shape and try wedging a piece in between the brackets; that might require a softer piece of rubber to be pliable enough.
You could try putting a piece of tape part-way around the two U brackets and fill the space with RTV Silicone, but I'm not sure how well it would hold up, I suspect it might not do very well.
RE: 42-761EZ Chassis Restoration - w4rtc - 02-05-2013
Ron
Yes I think rubber would work there very good.
I have a larger coupling like that and one has a rubber spacer and one has a material sorta like fiber spacer. but I think the rubber would give you less backlash if it is cut so that it had to be slightly pinched by the two parts.
Joe
RE: 42-761EZ Chassis Restoration - Chuck Schwark - 02-06-2013
I agree, a medium hard rubber square "dingus".
Grainger or McMaster-Carr may have a rubber product,
or you may have some thick gasket or weatherstrip, or
a leftover piece of auto door edge gasket,etc....
Garage door bottom weather seal. A piece cut from a rubber belt. Just typing out loud . . . .
The Other Guy
RE: 42-761EZ Chassis Restoration - Chuck Schwark - 02-06-2013
Just had a flash....
Slice a "cube" out of a thick rubber chassis
shock mount washer.
http://www.radiodaze.com/category/705.aspx
That Guy again
RE: 42-761EZ Chassis Restoration - Ron Ramirez - 02-06-2013
John, Joe and Chuck - thanks for the great suggestions. Guess I need to visit a hardware store this weekend and see about finding a large rubber washer(s) and cutting it (them) so that it is (they are) held in place by the two U-brackets.
RE: 42-761EZ Chassis Restoration - PhilcoMike - 02-06-2013
I would think a block of rubber would work as well.
Ron,
Thinking out loud, (dangerous activity) I wonder the purpose? Could it be a electrical insulator as well in case grid V or B+ got to the tuner chassis somehow?
Thanks,
Mike
RE: 42-761EZ Chassis Restoration - klondike98 - 02-06-2013
Ron, you might be able to find the right sized plastic tile spacer to do the job (or maybe a couple of them glued together).
[Image: https://dl.dropbox.com/u/54621529/spacer.jpg]
RE: 42-761EZ Chassis Restoration - Electrothaumaturgist - 02-06-2013
That sort-of looks like the "rag link" on the old '66 Lemans. Couples the steering shaft to the steering gear box via a rubber coupler. Cool!
RE: 42-761EZ Chassis Restoration - Ron Ramirez - 02-10-2013
Very productive weekend on the ol' 42-761.
I was in a hardware store yesterday and I saw some of those tile spacers. But I had to buy a bag of 30 or so in order to get one or two, and I decided not to once I found the rubber washers.
I bought three, but as it turned out, I only needed one. As usual, I got busy and did the cutting I needed to do to the washer and installed it before I thought about taking pictures, so let me explain what I did:
The outer portion of the tuning shaft is bolted on to the chassis with two small bolts, and is easily removable. So I removed it and used its U-bracket to determine where I needed to cut four pieces out of the washer, so that the two U-brackets would meet at right angles, if you will. Or if you won't. Anyway, after I finished cutting, it looked sort of like this:
[Image: http://www.philcoradio.com/images/phorum/42-761/washer_zpsba78111e.jpg]
The washers I bought were really a bit large (in diameter) for the job, but it was the only size I found in the store.
Once installed in the radio, here's what it looked like:
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-10_00007_zps20bc7efd.jpg]
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-10_00008_zpsbd6235e2.jpg]
Best news of all: Once installed, the tuning began to work. And it works fine, no backlash, no problems. The washer really should have been half again as thick, but two thicknesses would have been too much. It works well as is, so I'll leave it as is as long as it works.
More to come...
RE: 42-761EZ Chassis Restoration - Ron Ramirez - 02-10-2013
I also installed the new parts I had ordered from Mouser in the Tropic.
First of all, I glued the FP electrolytic insulators back together as best as I could.
Then, I was able to remove the heavy paper sleeves from the FP cans. I cut the tops of the cans off the two FP electrolytics, cleaned the bottoms up, and installed new electrolytics:
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-10_00005_zps3babf4e4.jpg]
The two section electrolytic originally had a 40 uF and a 10 uF unit inside, and there was a 16 uF individual electrolytic mounted under the chassis, connected in parallel with the 40 uF section to equal 56 uF. This was done at the factory.
I could not find a 56 uF electrolytic so I bought a 68 uF instead. It should do fine as a replacement, and eliminates the outboard extra electrolytic.
Anyway, once these were installed on the repaired insulators, I wired them into the circuit, then covered them with the original heavy paper sleeves:
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-10_00006_zps756ec5ac.jpg]
Now, they look just like they did before I removed them.
RE: 42-761EZ Chassis Restoration - Ron Ramirez - 02-10-2013
And, I also installed two chassis mount power resistors (see the left side of the picture below):
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-10_00009_zpsc69216e7.jpg]
These replace the original Candohm, one section of which was open.
One is 68 ohms, and the other is 1000 ohms. The 68 ohm resistor replaces the original 20 ohm section which served as a dropping resistor for the filament string. As you may recall, I increased the value of this one to 68 ohms to compensate for today's higher line voltage.
The 1000 ohm resistor has an additional 100 ohm, 5 watt resistor in series with it. You can see it in the lower left corner of the photo above.
I also installed a 14 volt type 1813 lamp in place of the 120 volt LED I had tried previously. Here's the results:
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-10_00001_zps351ee72f.jpg]
As before, my camera compensated for the low light conditions, so this bulb looks dimmer than the LED in this photo. But the next three show that the incandescent 1813 is clearly superior:
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-10_00002_zpse448b3b4.jpg]
AM (Broadcast) band
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-10_00003_zps67cdc99d.jpg]
Band 2 (lower SW)
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-10_00004_zps7529439a.jpg]
Band 5 (25 meters)
We're in the home stretch. I need to install the 1st IF transformer, install a new wiring harness for the speaker, find a 25L6GT tube, and then this thing should be ready for its first test.
RE: 42-761EZ Chassis Restoration - Electrothaumaturgist - 02-11-2013
That lil "raglink" is GROOVY! Also, the Face of that 761 is pretty "far out"! And I'm not surprised at all that good ol' incandescent illumination is still far superior. ( I edited my own tangent, here).
RE: 42-761EZ Chassis Restoration - Ron Ramirez - 02-17-2013
Progress report:
It's alive - sort of.
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-17_00001_zps43b9f0ed.jpg]
After finding four weak, gassy and/or marginal tubes and replacing them, it is playing very well on band 2 (SW 1 - 2.3 to 7 mc). Notice also that in a normally illuminated room, that band 2 is illuminated fairly well with the 14V incandescent lamp which I will leave in place.
On the 31M band, it is picking up a little bit up to 9.5 mc where it sounds like the oscillator drops out.
Nothing on the AM band, as it appears the oscillator is dead on AM.
I'm currently using a test speaker. I had forgotten that the cone on the original speaker is shot:
[Image: http://www.philcoradio.com/images/phorum/42-761/2013-02-17_00002_zpsdba0e006.jpg]