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 Post subject: RCA Victor 63E Short
PostPosted: May Sat 23, 2020 5:08 am 
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I have an RCA 63e record player/phonograph that didn't work when I bought it. After all the tubes tested good, I downloaded some schematics for it, replaced capacitors and resistors that didn't match what they were supposed to be and tried it again and it still didn't work. I tried replacing the cartridge which didn't fix anything either. So I started testing different points with my oscilloscope (the cartridge was outputting a signal but it wasn't reaching the speaker) when I got to the volume knob all the lights went out. :shock:

I quickly disconnected the oscilloscope and turned the power back on. nothing happened until I lifted the tone arm then all the lights went out again. I decided to test all the tubes again and they were all great. Any advice on how to repair the unit? :?:


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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Sat 23, 2020 6:03 am 
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This is a nice simple record player with a 3-tube amplifier, so not too hard to fix.

Safety first! Since this unit does not have a power transformer to isolate its circuitry from the AC line, it is dangerous to connect any test equipment to it unless you power it through an isolation transformer. That may be why your lights went out when you connected your scope to it (unless it is a handheld battery operated modern "scope").

Schematic available here: https://www.radiomuseum.org/r/rca_63e_6 ... s_127.html .

Did you replace all the electrolytic capacitors? There is an 80 uF and a 30 uF, both of which should be replaced with modern electrolytic capacitors rated at 160 V or greater. If the originals are still in place, they can short out and cause damage.

Did you replace all the paper capacitors? There are 5 paper capacitors to replace. It's wise to replace them all, since they have a very high failure rate due to leakage current through the paper dielectric.

Since it sounds like you might be new at this, can you post a picture of the bottom of the chassis so we can take a look at your wiring?

If simply plug it in and turn it on at this point, without any scope connected, does it still blow the breaker? If so, stop for now and let's take a look at your wiring on the bottom of the chassis. Maybe a few pictures from a few different angles so we can check everything for you.

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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Sat 23, 2020 6:52 am 
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Will get pictures by Monday.

It still flips the breaker with the scope disconnected.
I replaces most of the capacitors, the 30/50 2-in-one electrolytic was not available anywhere I could see so I used a 30-30 and a 20.


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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Sat 23, 2020 7:25 am 
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Given that you're still blowing the breaker, I'd suggest two actions:

1. Build yourself a "dim bulb tester." You can find more about this with a search on this site. Basically, you power the unit with a 100 watt bulb in series. If the bulb glows brightly, you've still got a serious short, but this is a far gentler and safer way to know that. Next time you're ready to power it up, do so with the dim bulb tester.

2. Use an ohmmeter to start tracking down the short. Since you're blowing the breaker, if you measure the resistance between the two prongs of the plug on the power cord of this unit, you'll find that the resistance is very low (probably below 10 ohms) when the switch is turned on. Pretty much the only way to have a resistance that low between the two sides of the power cord in a unit like this is to have a dead short (a direct connection) between the two. See if you can find it by inspection; if you can't find it by inspection, start disconnecting things one at a time from the power cord connection. When you disconnect the item causing the short, the resistance will increase.

It's easier to work with the side of the cord that does not go to the switch, since it has only three things connected to it directly. I'd start by removing the turntable motor connection. Then measure resistance again and see if it went up to a much higher value (more like 100 ohms). If that's not it, then there are only two more things connected to that side of the cord -- pin 5 of the 35Z5 rectifier tube (the anode) and pin 7 of the same tube (the filament). If you disconnect all three, the resistance will go to infinity (open circuit). Which of the three connections is causing the resistance to go to zero or close to it? Or is there a solder blob or an errant wire touching something it shouldn't?

You're probably already aware, but just in case not -- lifting the tone arm is what turns on the power switch in this unit.

Pictures may help those of us observing remotely help you find your short.

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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Sat 23, 2020 11:02 am 
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How about the motor? If it is frozen up due to dried grease, it will draw excessive current.

There are very few things that can cause this set to blow fuses. A frozen motor is one. Other options include a short on the B+ line---or maybe an electrolytic installed backwards, and a defective power switch.

First, disconnect the motor. If there is still an issue, then remove the rectifier tube. If there is still an issue, all that's left is the power switch.

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-Mark
"Even if you don't understand Ohm's Law, you are still required to obey it."


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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Sat 23, 2020 5:00 pm 
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If the motor is stalled, Mark is correct that the current feeding the motor will increase. However, the increase is nowhere near large enough to blow the breaker. A stalled turntable motor won't even overheat to a level that is noticeable (these are very low current shaded-pole motors). It also sounds like this motor was working OK, since he mentioned that the signal from the cartridge seemed fine before he started blowing the breaker.

So I would focus on looking for a direct short, given that the breaker is blowing.

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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 4:53 am 
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Image

Images

50/30 capacitor replaced by 30/30 and a 20 - Blue lines
New capacitors - Red lines
Old capacitors - Purple lines


Last edited by Tadfafty on May Tue 26, 2020 6:52 am, edited 3 times in total.

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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 5:21 am 
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The schematic I have from Radiomuseum shows a 80-30 uF filter cap rather than 50-30, but for now we don't need to worry about that. I also see what appears to be three original paper caps still in the chassis, and those should be replaced. However, those caps can't be causing the short circuit that we're focused on right now, so they can wait.

It's not easy to see much in those pictures in terms of individual wire connections.

Let's see if we can track down the short. First, with the unit unplugged, measure the resistance between the two prongs of the power plug. With the tone arm down, it should read infinite (sometimes shown as "overload" or "Ol" on a digital multimeter screen. Is that what you see? Now lift the tone arm, and measure the resistance again. You might see a very low value -- perhaps less than 10 ohms. Is that what you see?

It appears that the power cord goes to the turntable/motor area first, and there is a switch activated by lifting the tone arm there. Then other wires carry the power to the amplifier. Does that look correct to you?

By the way, if you can reduce the size of pictures to no more than 800 pixels wide before uploading them, everything is easier to read since the screen doesn't get so wide. If you're able to reduce the width of the ones you already posted, go back to that post and edit it, delete the pictures, and upload again after you've reduced their width in photo editing program of your choice.

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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 7:01 am 
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Put the ohmmeter across the power cord. Infinite ohms. then I pressed the button it reads 31 ohms for about 1 seconds then went to infinite again. (this is with motor disconnected) Then with motor connected, it goes to about 35 ohms and stays there. The motor did turn correctly before the short appeared.


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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 7:22 am 
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Attachment:
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RCA63e.png [ 84.08 KiB | Viewed 66 times ]


DM


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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 7:50 am 
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I've got a paper with it with the schematic and some "service hints" (disassembly instructions, what oil to use.)


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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 12:03 pm 
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Is the CB a GFCI? The schematic is showing B- / Neutral floating above the chassis, C6 should be an "approved" line cap. Make sure "Common Ground" is and something other than C6, is not miswired to chassis. Then the obscure question what is the chassis sitting on wood, metal?

Marc


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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 4:41 pm 
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35 ohms across the power line is unexpected, so there's a clue there about what is wrong. First of all, however, 35 ohms is too high to blow your circuit breaker, so either this resistance goes down a lot when you actually apply power, or you have an intermittent short (perhaps from moving things around) that is not there right now.

With the motor disconnected, the resistance should be higher than 120 ohms, which is the resistor in series with the tube filament string. With the motor connected, 35 ohms might be about right, but my guess is that the resistance of the motor is actually higher than that.

What I'm suspecting is that the 35 ohms is caused by the switch contacts right now, and when you apply power, it drops to zero. The switch was likely very severely overstressed when you blew the breaker. I'm surprised that it survived at all, since it take 15+ amps to blow the breaker, most likely.

If there ever was a case calling out for a dim bulb tester, this is it. Don't plug it in again until you have a dim bulb tester to use with it. A dim bulb tester is nothing more than putting a 100 watt incandescent light bulb (60 or 75 watts will also do, but 100 watts is better) in series with the power you apply. In other words, break one of the AC line wires going into the unit and connect a bulb across the break. Most people would do this by modifying a short extension cord, rather than breaking into the power cord of the device itself. This will protect the unit, and prevent blowing the breaker. If you plug it in and turn it on, and the bulb glows full brightness, there is a catastrophic short in the unit that needs to be tracked down.

To find the short: Follow your AC power cord wires into the unit. One wire goes to the switch that is activated by the tone arm. Ignore that one for now. The other should connect to exactly three things:

1.) the motor
2.) pin 5 of the 35Z5 tube (anode)
3.) pin 7 of the 35Z5 tube (filament)

Can you confirm that this is what you see? It's very important that it not connect to anything else. If it is, can you tell us what else is connected there?

Here's one way you can tell whether you've found all the connections to the AC line: Disconnect the motor, and pull out the 35Z5 tube. Then you should see infinite resistance between the prongs of the plug. If you see a resistance lower than infinity ("overload" on a digital meter), then there is most definitely something connected that you haven't found yet.

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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 6:20 pm 
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Only connects to the two prongs on the tube and to the motor, other side does just go to switch. It is currently sitting on cardboard, phonograph is baekelite.

Will get the dim bulb tester built.


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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 6:37 pm 
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Pull out the 35Z5 and disconnect the motor. What is the resistance across the power plug now?

Should be infinite resistance; if not there is another short circuit path that has not been found yet.

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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 9:26 pm 
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Infinite resistance, yes.


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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 9:38 pm 
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Can you measure the resistance directly across the two motor leads?

Also measure from the switch (circuitry side, not the power cord side) to all 8 pins of the 35Z5 socket. Any that are less than 100 ohms, please report what you find.

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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 10:16 pm 
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37.7 ohms across the motor.

Just one pin, .1 ohms, one that's not connected to anything. (must somehow be grounded?)


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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 10:30 pm 
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Interesting. Which pin is that? Count clockwise from the keyway (little slot in the hole through the socket).

I see the schematic shows the expected motor resistance as 35 ohms, so the motor appears to be fine.

Just to make sure I've got this straight, with the motor unplugged, but with the tube plugged in, you're seeing 30-35 ohms? And then with the tube out, but motor connected, you also see about the same? And with both the tube in place and the motor connected, still about 30-35 ohms? (shouldn't be possible... but let's wait to hear what your answer is)

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 Post subject: Re: RCA Victor 63E Short
PostPosted: May Tue 26, 2020 10:56 pm 
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Tube in, but motor disconnected, it shows 80 ohms for 1 second, then goes to infinite. Pin 8 if counted from top of socket, pin 1 if counted from bottom of tube.


Last edited by Tadfafty on May Tue 26, 2020 10:59 pm, edited 1 time in total.

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