5/28/15 Hey Folks. I am the process of restoring my third 53-1750 radio/phonograph. Interestingly (and sadly) someone along the line had cut the power wires to the phonograph motor and spliced the phonograph motor directly into the AC power cord . I did a complete recap, replaced a couple of resistors. Three of the original tubes were bad and they were replaced as well (all tubes now test ok). I plugged in the set last night and it came to life - the dial light coming on, all tubes came on and it was receiving radio stations no problems. However, when I flip the selector switch to phonograph, the motor does not run. I checked the resistance across the phonograph motor wire leads and get around 48 ohms. I don't know if this is normal or if it means the motor is cooked. I connected a voltmeter to the phonograph power wire leads coming from the set and my voltmeter reads ZERO (perhaps i'm not checking the voltage properly ?). The radio/phonograph selector switch seems to work (or atleast it switches to the am radio ok). All connections from tube sockets to the am radio/phonograph switch seem to be ok - so I'm not sure if it is most likely that the phonograph motor is cooked OR the selector switch is fried OR somehow, no voltage getting out to the motor. Obviously, someone - way back when - saw fit to splice the phonograph motor wires directly into the AC cord - so at some point, the phonograph motor had stopped working. Any ideas? Thanks.
It is usually ac going to the motor,if you are using your meter on ac volts and not getting any power then it sounds like for some reason your not getting power to the motor. Also, if someone wired it directly to ac then it kind of tells you they had the problem too. I would find out why your not getting ac to the motor... check the schematics and find out where your losing power.
(This post was last modified: 05-28-2015, 02:14 PM by Warren.)
Thanks guys for your input. It's a bit weird. I don't think the motor is burned out. I have another one of these motors from a parts radio/phonograph that I have, both motors read around 26 ohms. I tried connecting the extra motor, same thing - doesn't work. I tested the radio/phono switch - it seems to work and I tested the onboard switch on the turntable that permits power to go to the phonograph motor when the phonograph knob is turned on and it works. I tested the continuity of the ground wire from the phonograph into the radio ground and there is continuity. I tested the continuity from where the positive power wire lead for the phonograph is connected into the radio to the radio/phonograph knob/switch and there is continuity, so the wires are ok - so it would seem that there's no power getting into the power positive wire from where it is soldered in to the radio. Maybe some cracked solder joints?? I'll have to look into it further but it is a tight little wiring mess - hard to see things well without de-soldering some components. Thanks,
ODPILOT it seems you with help have figured out where the problem exists. Indeed if the motor was wired direct someone had a problem with the selector switch. I suspect the motor is just dandy and directing A/C directly to it , it will run. Time to look at the switch. Posting a schematic would help.
Best, Jerry
(05-30-2015, 01:37 PM)jerryhawthorne Wrote: ODPILOT it seems you with help have figured out where the problem exists. Indeed if the motor was wired direct someone had a problem with the selector switch. I suspect the motor is just dandy and directing A/C directly to it , it will run. Time to look at the switch. Posting a schematic would help.
Best, Jerry
OK - this thing is driving me crazy !! I was able to hook up the phono motor to a previously restored 53-1750 (same exact model) and the motor powers up and runs fine. So it's def not the motor. The radio/phono selector switch tests as good as does the switch on the phonograph motor board. So it's not the switches. Anyway, I've tried bypassing the switches/seletors - doesn't help. On the formerly restored 53-1750, I get 118 Volts coming into the phonograph motor. On the new one I am restoring, voltmeter reads 1.5Volts coming into the switch - something seriously wrong. The positive wire for the motor is soldered into one of the pins for the 50y7gt (rectifier) tube. This pin also supplies power for the dial light bulb - which works fine after the radio powers up. So I'm thinking it can't be the power coming from that pin or the bulb wouldn't work?? The grounding wire for the phono motor is connected into a bus terminal and that particular terminal is connected with a .04uf capacitor to the ground AC power cord wire (another connection on the bus terminal) AND this same ground terminal also has resistor which goes to a ground rivit in the chassis. The ground rivet seems to have good continuity and is not loose or corroded. I've replaced the capacitor with a new one (I've recapped the entire radio) although I did not replace the resistor since it reads correctly (r-17 - reads 148 K ohms, supposed to be 150 K ohms.). The insulation on all the connecting wires are good and the wires have good continuity. So where is the problem - no freakin idea !!
(This post was last modified: 06-01-2015, 10:54 AM by ODPILOT.)
First there is no positive or negative. The motor is AC.
Second. Simply buzz the wires. Cannot be simpler than that. Unplug and start with ohmmmeter all the way from cord to chassis. As long as you methodically do it piece by piece I guarantee you will find it within 10 minutes.
One more thing: you have hot chassis radio, so the chassis is connected through the switch which could be dirty. It could be enough for the radio to work but the motor requires more current and might not work.
So, check the power switch and see if it is a true short of say tens of ohms.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
(This post was last modified: 06-01-2015, 11:00 AM by morzh.)
On the formerly restored 53-1750, I get 118 Volts coming into the phonograph motor. On the new one I am restoring, voltmeter reads 1.5Volts coming into the switch
so check before switch. you have one to check against
Some day, and that day may never come, I will call upon you to do a service for me. But until that day, accept this justice as a gift
mafiamen2
(06-02-2015, 03:14 AM)sam Wrote: odpilot
you checked and answered you own question
On the formerly restored 53-1750, I get 118 Volts coming into the phonograph motor. On the new one I am restoring, voltmeter reads 1.5Volts coming into the switch
so check before switch. you have one to check against
I did buzz around with my ohmmeter and can find no shorts. The on/off power switch and the am/phono selector switch all test just fine. I used a jumper wire to bypass the on/off switch and the am/phono selector switches, and still no power going to motor. I need to look at this better a little later, but in the old restored 53-1750 there seems to be an extra wire that is coming from somewhere, connected to the terminal that has one of the phonograph power wires connected. This wire seems to be missing from the new radio I am working on. I'm not sure why this would be. With the exception of a 20uF electrolytic capacitor that was replaced (looks like it's from the 1960's), nothing else was touched in this radio.( I replaced this capacitor as well along with all the others.) Hmmm - gonna have to look more closely at this and see where this extra wire is coming from and why it doesn't exist in the restoration radio.
mike look at schematic
maybe current is wrong way to say it lets say path
start at plug
1 side goes to ground
other side goes to connection where c16 and m5 meet. goes through m5 to switch on motor board (turn table)
through motor then to ground
so he should check m5 which should be radio/phono switch. since radio plays and m5 and c16 where they connect
he said
The radio/phono selector switch tests as good as does the switch on the phonograph motor board. So it's not the switches. Anyway, I've tried bypassing the switches/seletors - doesn't help.
ken and jerry under stand
sam
Some day, and that day may never come, I will call upon you to do a service for me. But until that day, accept this justice as a gift
mafiamen2
. I did a complete recap, replaced a couple of resistors. Three of the original tubes were bad and they were replaced as well (all tubes now test ok). I plugged in the set last night and it came to life - the dial light coming on, all tubes came on and it was receiving radio stations no problems. However, when I flip the selector switch to phonograph, the motor does not run. I checked the resistance across the phonograph motor wire leads and get around 48 ohms. I don't know if this is normal or if it means the motor is cooked. I connected a voltmeter to the phonograph power wire leads coming from the set and my voltmeter reads ZERO (perhaps i'm not checking the voltage properly ?). The radio/phonograph selector switch seems to work (or atleast it switches to the am radio ok). All connections from tube sockets to the am radio/phonograph switch seem to be ok - so I'm not sure if it is most likely that the phonograph motor is cooked OR the selector switch is fried OR somehow, no voltage getting out to the motor. Obviously, someone - way back when - saw fit to splice the phonograph motor wires directly into the AC cord - so at some point, the phonograph motor had stopped working. Any ideas? Thanks.
EE `s 
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