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 Post subject: RCA 2us7 restoration new issues
PostPosted: Jun Fri 09, 2017 4:24 am 
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Location: South Bend Indiana
Just off the power supply before going into the selenium rectifier are two resistors. One is a 5 watt 66 ohm and the other is a 96 ohm at 36 degrees Celsius. Both resistors test low and will need replaced but I don't know what kind the second one is. It doesn't look like a regular resistor, and I don't know the wattage. In the schematic the resistor in question is resistor 23.
All of their resistors are referred to as fixed half watt or 1 watt resistors. Any ideas?


Last edited by Eforrester on Dec Sat 09, 2017 4:55 pm, edited 3 times in total.

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 Post subject: Re: RCA 2us7 resistor question
PostPosted: Jun Fri 09, 2017 4:29 am 
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Sounds to be a thermistor with a rating like that. Most likely is still okay.


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 Post subject: Re: RCA 2us7 resistor question
PostPosted: Jun Sat 10, 2017 2:35 am 
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Location: Tucson, Arizona U.S.A.
5 watt resistors are usually wire wound and seldom fail. When they do fail, they usually go open. Are you testing these out of the circuit (i.e. disconnected)? Are you sure your meter is operating properly?

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 Post subject: Re: RCA 2us7 resistor question
PostPosted: Jun Sun 11, 2017 2:01 am 
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They were not removed from circuit but the capacitor that was connected to them was clipped. My meter seems to be reading other things ok


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 Post subject: Re: RCA 2us7 resistor question
PostPosted: Jun Sun 11, 2017 3:32 pm 
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Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
Resistor R23 will read differently depending on the temperature. Nostalgia Air's schematic stops short of saying "& 13.5Ω @104° C." as is in SAMS 182-8. Agree the 5 watt unlikely bad, usually tolerance is marked on part. Just what does it read?
Bill J.


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 Post subject: Re: RCA 2us7 resistor question
PostPosted: Jun Sun 11, 2017 6:42 pm 
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The schematic calls for a 66 ohm the one in there says 75 ohm and it reads at 55 ohms


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 Post subject: Re: RCA 2us7 resistor question
PostPosted: Jun Mon 12, 2017 2:20 am 
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Here's the schematic: http://www.nostalgiaair.org/pagesbymodel/893/M0014893.pdf
These parts are in a parallel circuit and will read low if tested in circuit. R23 can be isolated by removing one of the dial lamps but R22 has other stuff in parallel and should be disconnected for a valid test.

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 Post subject: Re: RCA 2us7 resistor question
PostPosted: Jun Mon 12, 2017 2:18 pm 
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Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
Another untraceable change? But when you replace the selenium you can square away the resistor's value.
Bill J.


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 Post subject: Re: RCA 2us7 restoration
PostPosted: Jun Thu 22, 2017 11:15 pm 
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Well I took it out of circuit and it tested fine so I put back in. The chassis is now finished and I am waiting on some parts for the record player to come in to finish it.


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 Post subject: Re: RCA 2us7 restoration
PostPosted: Jun Thu 22, 2017 11:24 pm 
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Here is a before and after. Notice how black that chassis is! Most of the resistors were charcoal. Gave it a good cleaning, and replaced the needed parts. Figuring out the new set up for the electorokytics was fun. Hope the phono parts come soon so I can finish it. It was quite the piece in its day and sold for $129.95 back in 1952. I think it was one of the first rca all speed players.


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 Post subject: Re: RCA 2us7 restoration
PostPosted: Jun Thu 22, 2017 11:28 pm 
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I was also amazed how burnt it was considering how nice it looked on the outside. I bought it for $25 on eBay.


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 Post subject: Re: RCA 2us7 restoration finished scroll down!
PostPosted: Dec Sat 09, 2017 4:52 pm 
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Lately there have been some new issues with this record player. Up till now it’s been playing great. Then it started having issues on 78 a few weeks ago, originally I cleaned the turrets really well and they were doing fine. I thought it was slipping and got a replacement 78 turret, but it didn’t make any difference. Now it doesn’t want to complete the cycle for 33’s. It has new rubber mounts and new grommets for the shift linkage. 78s now come to a complete hault.


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 Post subject: Re: RCA 2us7 restoration new issues
PostPosted: Dec Sun 10, 2017 1:27 am 
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Location: 77001
Was the motor re-built and bearings well-cleaned ?

Show us a photo of motor and the record changer with
platter off.
H


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 Post subject: Re: RCA 2us7 restoration new issues
PostPosted: Dec Sun 10, 2017 2:00 am 
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The motor was not rebuilt just cleaned on the outside. It’s a GI motor , I will post a pic


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 Post subject: Re: RCA 2us7 restoration new issues
PostPosted: Dec Sun 10, 2017 2:06 am 
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Gi motor


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 Post subject: Re: RCA 2us7 restoration new issues
PostPosted: Dec Sun 10, 2017 4:15 am 
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Location: 77001
You can try this:
1. I presume the record changer is a Voice of Music ?
Maybe a 930 or 950 model series.

2. With platter off, does the motor spin freely
when turned on, and spin for some seconds
after powered off ?
There should be a "N" position (neutral) on the
speed selector. This would keep the motor
from engaging the speed turrets.

3. Have you cleaned the inside rim of the platter ?

I recommend you remove motor from motor board.

With heat generated by the rotor, old oil can be wicked
up by the rotor from oil reservoirs. May firm up causing slowing, or
may loosen and fly onto turrets, idler, or inside rim platter,
causing slipping, and thus slowing.

Take photos during process and orient each part exactly
as it was prior to dis-assemble.
You do not have to dis-assemble the motor board, but
you have to move the speed selector pivot on motor board to access
the top of the three long mounting screws for the GI motor.
One screw will have a spacer it goes through.

Remove motor.
Then, bottom motor bearing housing and top bearing with rotor
can be soaked x 24 hrs in solvent to loosen/flush out old
oil. I use 91 % isopropyl alcohol.
Rotor is not to be removed from top bearing housing.
It is pressed on and permanently mounted.

You can use compressed air to blow out the solvent
and old oil.
There are oiling point holes in the top and bottom
pieces of the bearing housings.
Use turbine oil such as Zoom-spout in the oiling points,
after the cleaning.

Hotwax


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 Post subject: Re: RCA 2us7 restoration new issues
PostPosted: Dec Sun 10, 2017 2:21 pm 
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The platter was cleaned, thank you for the directions for cleaning the motor. The mirror does spin freely in the neutral position.


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 Post subject: Re: RCA 2us7 restoration new issues
PostPosted: Dec Sun 10, 2017 7:17 pm 
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Location: Little Rock, Arkansas
The motor needs totally dismantled, top and bottom bushings soaked in lacquer thinner for several hours, re-oiled with turbine oil and reassembled. The turret holding plates need to be thoroughly cleaned of dirt, old oil and grease. New motor mounts need installed. New speed change grommets should be installed on each end of the speed change rod. The turrets themselves need cleaned inside with Q-tips dipped in lacquer thinner. If the idler looks rounded or has flat spots on it, then it needs replaced too.


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 Post subject: Re: RCA 2us7 restoration new issues
PostPosted: Dec Tue 12, 2017 11:25 pm 
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I have anoth 950 changer that I am working on and thought I would finish first before pulling out the gi motor again. This motor is an alliance motor. I have followed the steps for cleaning using 91%isopropyl alcohol for 24 hours, cleaning, drying and oiling. This motor makes a scratchy sound like the bottom of the rotor is scratching the bottom bearing plate. What would cause this?


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 Post subject: Re: RCA 2us7 restoration new issues
PostPosted: Dec Wed 13, 2017 2:06 am 
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Location: Tucson, Arizona U.S.A.
Quote:
This motor makes a scratchy sound like the bottom of the rotor is scratching the bottom bearing plate. What would cause this?

Perhaps it is. Examine it carefully while holding it in it's normal position (shaft up); the rotor should be centered in the laminations, perhaps SLIGHTLY below them, but certainly not above. And there should be clearance between the rotor and the bearings. There are usually some spacers on the shaft to get it in the right position. Did you reassemble these in the same place they were originally? If there were spacers on the bolts that hold the whole thing together, did those get put back properly?

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