Old Symphonic Record Player

[spartadrive_in]

Just doing some looking in here to make this maybe work. Was wondering if you could tell me what this is?(see pic) Some sort of inductor? Seems like it had something around it, since its crusting off. Should I replace it? and if so, what is it???

[Enzo]

That is a resistor. A wirewound power resistor, the kind that these days would be rectangular and made of cement. Can you read that number printed on it?

Yes it ought to be replaced.

However, your little record player amp has what we call a hot chassis - there is no power transformer. The mains are directly rectified to make the B+. And the tube heaters are high voltage and wired in series. I bet those two tubes are a 35W4 and a 50C5. How did I do? In the recrod player the hot chassis is no big deal, but as a guitar amp - if that is where you are headed - you really ought to add an isolation transformer.

35 and 50 only add up to 85 volts. A lot of the time there would be a couple more 12v tubes. But in any case, the excess voltage left from the 120v mains has to be dissipated in a resistor. The resistor is in series with those heaters and the whole mess is across the mains.

ANd I belive that is what you are looking at.

[spartadrive_in]

Wow you got it dead on Enzo. Those are the correct tubes. I did not know that the first 2 numbers on them meant the voltage (35, 50).

So then a large cement power resistor is the way to go to dissipate that excess heat? Only thing I can read of that thing is 77 (in the pic).

I am not going to make it into a guitar amp or anything. I just want it to work. To play records.

Anything else? All info is helpful as I hate to blow those tubes. I just bought new ones since one had a crack in it.

[Mars Amp Repair]

Also must have been right before the selenium rectifier was put into use...if you've ever experienced one burning up...you'll never forget how that smell...glen

[spartadrive_in]

Also must have been right before the selenium rectifier was put into use...if you've ever experienced one burning up...you'll never forget how that smell...glen

So when do you think this player was produced?

[Enzo]

Indeed, NOTHING in my humble existence smellls like a burnt selenium rectifier. A sort of burnt rotten cabbage sort of stink. You will never forget it once smelled.

So measure the resistor now. What does it read?

Looking at the photo again, your 77 - actually more like 077 right? - looks to me more like upside down 220. And that could be 220 ohms or something like 1220 ohms or 2220 ohms or whatever. I am not in the shop with my tube book, but the current through the two tubes will be the same, so we have to make up the rest of the voltage with a resistor conducting that current. Basic ohms law arithmetic exercise.

WE got about 35v to drop at whatever current a 35W4 or 50C 5 draws. Look that up and plug in the number. then calculate the wattage and double it for the resistor rating. Well, double it or even triple it.

[Enzo]

1950s, maybe very early 1960s.

Give us the numnbers on the controls and on the transformer.

[spartadrive_in]

Think you can make sense of it using this schematic that is pasted inside?

[spartadrive_in]

1950s, maybe very early 1960s.

Give us the numnbers on the controls and on the transformer.

Transformer reads TR-109 798 727
That is the little one in the amp. or is that the driver transformer?

[Mars Amp Repair]

Turntable

As an aside, I had the exact turntable in an Admiral console at one time as a kid, tho it most likely is some form of a VM for that era...I'd guess also late 50's early 60's.
Can't help you on the value of the dropping resistor, tho...looks like Enzo is hot on the path...my guess would be in the 220 ohm range...I just remember as a kid getting burned by them
It looks like you can see the windings on the exposed portion of the resistor...possibly you could try to chip off & measure what's left & get an idea from that ie; in the hundreds or thousands range...glen

[spartadrive_in]

As an aside, I had the exact turntable in an Admiral console at one time as a kid, tho it most likely is some form of a VM for that era...I'd guess also late 50's early 60's.
Can't help you on the value of the dropping resistor, tho...looks like Enzo is hot on the path...my guess would be in the 220 ohm range...I just remember as a kid getting burned by them
It looks like you can see the windings on the exposed portion of the resistor...possibly you could try to chip off & measure what's left & get an idea from that ie; in the hundreds or thousands range...glen

What is a VM?

I was chasing around the schemn last night and my guess is also 220. I measured it (in circuit) and it was giving me a reading of about 180ish.Hopefully I did that right. Do you know what the wattage rating for that would be? I'm assuming it is the 220 OHM 5W resistor near the bottom middle.
Another question is what does that symbol mean next to that 220 resisitor. The little 4-3-4-3 sawtooth with the tube names on top? This is where that wire wound resistor is.( After following the circuit). Is that the symbol for it?


THANKS A MILLION!

[Mars Amp Repair]

Hello,
yes, the resistor you found on the schematic is the series dropping resistor for the filiaments, so there is your answer 220 ohms @ 5watts.

The slanted lines with the 4-3, 4-3 is the schematic symbol for the tube filiaments. the 4-3 are the pin numbers on the tube for the filiament..they've just broken the filiament circuit away from the tube symbols for simplicity...glen

[spartadrive_in]

So then does that mean that pins 4 and 3 need to be connected?
And just to make sure, when counting pins, it is in a clockwise motion correct?

As for the resisitor I need. Is it's modern equalavent those cement block ones we see in modern amps today? Or at least in that 70s peavey I was working on last month.

[Mars Amp Repair]

No,
Pin 3 & 4 are connected by virtue of the tubes being plugged in their respective sockets.

Just cut the existing resistor out, leaving some lead length to bend over & solder your new resistor to. It's easier than trying to get the old resistor leads off of the terminal strips. Also if you're not very experienced, you can easily break off the end of a terminal strip thereby causing much more work for yourself.

The newer style cement resistors you speak of should be an exact replacement...they might not dissipate their heat as well having less surface space, but five watts is 5 watts.

glen

[spartadrive_in]

Ok that's good to know. I will go out tomorrow and find that resistor and put it in. Anything else I should look out for? I don't want to blow out those tubes.

Finding a second opinion here:
On the schem it has a tube placement diagram. It shows that the 35W4 is in the middle next to the filter. EXCEPT I've been following the circuit around to the socket pins and it appears that the 50C5 is in the middle. So those two tubes should be switched in that diagram. Could I be wrong? Why would they print out the diagram like that??? Maybe I'm wrong??

thanks.