Phonograph motor fried?? - Printable Version
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+--- Thread: Phonograph motor fried?? (/showthread.php?tid=12363)
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RE: Phonograph motor fried?? - morzh - 06-03-2015
Well as someone once said back in the old country, troubleshooting eletronics deals with only two problems:
1. A contact where there shouldn't be any, and
2. No contact where there should be one.
A very true statement.
RE: Phonograph motor fried?? - jerryhawthorne - 06-03-2015
I get easily confused but if we are still trying to figure out if the phono motor is good, unplug the radio, take one wire off one side of the motor where it is most convenient and measure the motor's resistance. It should be quite low. If so, take a cut off A/C cord from some other appliance, we all save them, strip it and again with the radio unplugged, attach its leads to to the motor. Does it spin? Motor good? If so, time as Mike said to do some further "checking" of the A/C line trying to get there through switches.
Mike's statement may not be quite clear:
It is as simple as this: if the voltage does not get to the motor it drops on something else.
Perhaps better would be "if the voltage does not get to the motor it is stopped somewhere". A fairly easy testing with your meter once you figure out if there is power to the motor.
Best, Jerry
RE: Phonograph motor fried?? - morzh - 06-03-2015
Jerry
He in fact said before he took the motor and plugged it in a different unit, and it spun.
RE: Phonograph motor fried?? - jerryhawthorne - 06-03-2015
I guess I missed that Mike and sorry. I guess the title of the thread should be changed. The motor is not fried, it just needs to get power. As you indicated, that should be easy.
Best, Jerry
RE: Phonograph motor fried?? - sam - 06-03-2015
Terry
Come on tell him where to look
Your the expert on trouble shooting
Sam
RE: Phonograph motor fried?? - ODPILOT - 06-03-2015
OK people - I've figured it out - but first and most important want to thank everyone for you invaluable input in this case and other issues I've had restoring these things in the past. As has been the case in the past - MORZH has nailed it but everyone elses input was much appreciated.
To refresh your memories - this 53-1750 I'm restoring had no power going to the phonograph motor. When I go this model to restore, someone had directly wired the phonograph motor wires directly into the AC cord. By the way the electric tape looked, this must have been 20 + years ago. I was able to run the motor successfully by hooking into a previous restoration. All on/off switches both for the main power and the phonograph motor board switch AND the Am/Phono selector switch seemed to be in great shape. All caps, any questionable resistors and tubes were replaced. Still no power to the phono motor (radio worked fine with a slight hum). One of the "sayings" MORZH wrote was exactly on the money: "no contact where there should be one". See photos attached: In the previously restored radio, I took a picture of this before I started working on it (one of the few smart things I've done in restoring these things) the AC power line is connected to the input terminal (left side of photo) (see brown AC cord) on the back of the main power switch AND on the other terminal - right side of photo (which becomes hot when the radio is turned on) it has a wire connected to the terminal that supplies one of the power wires for the phono motor. You can see this connection in the photo - it's a very short bare wire. That terminal on the 10 terminal buss assembly is also connected to the terminal next to it with both a capacitor & resistor in parallel - that second terminal is grounded to the chassis with a rivet. On the new restoration radio/phono - this short bare wire is missing (see 2nd photo).
You only see the top terminal on the back of the switch in the photo. But you can see the new yellow .04uF capacitor connected to that terminal on the left along with the original resistor, which is 150K ohm and reads 148K ohms. It seemed to me this had to be the missing piece of this no phono power problem. I was a bit nervous about doing this, but I told my wife and kids and dog I loved them, and then I carefully took a jumper wire with alligator clips and connected the bottom terminal on the back of the switch to the the power terminal where the yellow capacitor, resistor and phono power wire is connected - just like the prior restoration. To my amazement and surprise, not only did the phono motor immediately power up - but I also didn't short out the entire house, nothing blew up and I 'm still here to tell you about it !! There was a slight hum in the radio as well and when I restored this missing connection - the hum disappeared as well.
WTF??? Why would this connection have been missing, I have no idea. With the exception of a 20uF electrolytic cap to replace that big one on side with tubes, nothing looks like it was touched in this thing since 1953 . In any case, the motor works fine, I've rebuilt it and cleaned out and relubed the bearings. Thanks again to all of you. Cheers !
RE: Phonograph motor fried?? - sam - 06-04-2015
congrats on finding problem
sam