Need help with Beltron 2972-E

[Aperna1985]

Hey guys I wanted a Beltron for a long time and I finally picked one up. When I bought it I didn't realize that the cable had been cut up. I'm wondering if there's a schematic out there or if someone just knows what I have to do to fix it. It looks like the previous owner tried to add a more modern tube socket to it, and just have to everything up in the process.

I noticed the resolution of all the pictures was fairly degraded after shrinking them to fit on here. So I also uploaded them to my Google Drive here is the link to the folder

https://drive.google.com/drive/folde...e3rk1vDqsKzAq4

[sean]

It looks like the wires are pretty much all there going into each socket. It looks like the harness that came with mine. They just spliced the wires together going out to the sockets. I had posted a schematic I made up of the 2972E a few years ago here:

http://videokarma.org/showpost.php?p...2&postcount=20

The wire colors and connections on the 12-pin B&W socket and 14-pin Color socket are in the upper left corner of the schematic.

[Aperna1985]

Originally Posted by sean

It looks like the wires are pretty much all there going into each socket. It looks like the harness that came with mine. They just spliced the wires together going out to the sockets. I had posted a schematic I made up of the 2972E a few years ago here:

http://videokarma.org/showpost.php?p...2&postcount=20

The wire colors and connections on the 12-pin B&W socket and 14-pin Color socket are in the upper left corner of the schematic.

I was looking at your schematic. I just want to make sure I am understanding it correctly. So Pin 2 of the octal base connector which would be a violet wire would connect to pin 1 of the black and white plug which would be the heater?

It seems like all the yellow wires are disconnected on mine. The drawing that you have doesn't mention any yellow wires. I have three yellow wires coming out of the 14 pin color connector and two yellow wires coming out of the 14 pin black and white.

There's also a white wire coming from the Octal plug that isn't attached to anything.

[sean]

Originally Posted by Aperna1985

So Pin 2 of the octal base connector which would be a violet wire would connect to pin 1 of the black and white plug which would be the heater?

That is correct.

Originally Posted by Aperna1985

The drawing that you have doesn't mention any yellow wires. I have three yellow wires coming out of the 14 pin color connector and two yellow wires coming out of the 14 pin black and white.

It does. Pin 8 of the octal plug has the yellow wire connected. This connects to pin 11 of the 12-pin B&W connector and pins 4, 5, and 13 of the 14-pin color connector. These are the cathodes.

Originally Posted by Aperna1985

There's also a white wire coming from the Octal plug that isn't attached to anything.

Check which pin this white wire connects to in the octal plug. If it isn't connected to any of the pins used then it won't be used.

[Aperna1985]

Thank you I'll take a look tomorrow

[Aperna1985]

I took a look. I was able to get most of it back together. But I'm running into trouble with the small color adapter apparently whoever owned it ripped a lot of wires out of it. By any chance do you have a picture of yours? I'm trying to see where the wires went in the actual plug. They appear to be in a different order than the big color plug

[sean]

Here's the wires on the small 14-pin color socket:

1 Brown (Heater)
2 Yellow/Red (Red Cathode)
3 Red (Red G1)
4 n/c
5 n/c
6 Yellow/Green (Green Cathode)
7 Green (Green G1)
9 n/c
11 Yellow/Blue (Blue Cathode)
12 Blue (Blue G1)
13 nc
14 Brown (Heater)

Pins 8 and 10 do not exist on this socket.

My harness also has a small 8-pin B&W socket:

1 Violet (Heater)
2 Green (G1)
3 n/c
4 n/c
5 n/c
6 n/c
7 Yellow (Cathode)
8 Orange (Heater)

My harness does not have the socket shown in your last photo.

[Aperna1985]

I finally got around to messing with the Beltron again. I gave up on the small color adapter it's too hacked up. Atleast I can use the other 2 sockets. The next problem is, when I plug it in thebshorts light is constantly flickering, and the heater voltage is pinned at 15 volts, the rheostat has no effect. I assumed because of age the caps might be going out. I opened it up and whoever worked on it was a savage. They replaced one of the caps, and fried the associated traces and jumped them with wire. I replaced both 150uf caps and re soldered as many joints as I could. Then I noticed one of the light bulb sockets was broken. I tried to solder it back together but when when I turned it on the light started flickering and sizzling, one of the ceramic resistors started to smoke. I quickly unplugged it. I let it cool and checked the resistors the good news is they're 1000 ohm resistors and they all track at about 998. The next thing I did was check the voltage coming out of the caps one is 167 volts the other is 365 I think, I have to recheck it. The next thing I did was try to check the diodes. I checked the two rectifier diodes but I didn't remove them from the circuit board, one tested like a diode should the other one seemed open. Then I checked the diode that goes to the very first gauge that one also tested as if it was open. I'm wondering if this would be causing all my trouble. Does anyone have a schematic for this? The only thing I was able to find was a hand drawn one and I'm not sure how accurate it is. According to the drawing the main power diodes are 1N4005, I happen to have some 1N4007's on the bench Can I use them to replace them? I haven't been able to read the one on the gauge I'm going to desolder it and check, but it looks much heavier Duty than the two for the power rectifying. I did check and clean the wire wound pot, it actually reads very well between two ohms and 24 ohms so I don't believe that's the problem. I also dug through my spare parts and found a socket that looks just like the original and replaced it so at least the light socket is no longer a problem

[sean]

The filament control is wired as a rheostat. Unless you have a load connected, you will have full voltage indicated on the meter. I always turn the filament control fully CCW before connecting to a CRT. Then I advance the control CW until I get the proper filament voltage reading on the meter.

1N4007 diodes will work just fine to replace 1N4005. Both are rated 1A. 1N4005 is rated 600V PIV. 1N4007 is rated 1000V PIV.

The power supply is a half-wave voltage doubler. The voltage output will be about twice the peak voltage of your AC line voltage.

The schematic you are referring to is probably the one I drew up for my unit. Judging from the build I would not be surprised if there are differences between units.

[Aperna1985]

Originally Posted by sean

The filament control is wired as a rheostat. Unless you have a load connected, you will have full voltage indicated on the meter. I always turn the filament control fully CCW before connecting to a CRT. Then I advance the control CW until I get the proper filament voltage reading on the meter.

1N4007 diodes will work just fine to replace 1N4005. Both are rated 1A. 1N4005 is rated 600V PIV. 1N4007 is rated 1000V PIV.

The power supply is a half-wave voltage doubler. The voltage output will be about twice the peak voltage of your AC line voltage.

The schematic you are referring to is probably the one I drew up for my unit. Judging from the build I would not be surprised if there are differences between units.

By any chance was your unit wired point to point or was it on a circuit board? Mine follows your diagram perfectly except it has a 10ohm ceramic resistor between the negative of the 150uf 150v cap and the feed for the resistors. It looks like someone added it but I'm not 100% sure. My unit has a circuit board inside, and I notice there isn't a trace to and from the resistor but it was soldered in to the other traces. Could it be a last minute revision? Like I said previously someone was definitely in there before, he burnt a few traces that I fixed, and he wired the rejuvenate bulbs in series instead of parallel like it shows in the drawing. I went around and checked for AC and DC on pins 3 4 and 5 of the cleaning terminals, and the testing terminals and got nothing. Pins 3,4,and 5 of the restore connection all had 335v on them. The interesting part is I hooked it up to my TV which is a black and white set and I got a reading on the green gun only, the meter went about a quarter of the way up for emissions. I was able to control the heater voltage without any trouble once I hooked it up to the TV. I tried it in the cleaning position but none of the lights lit, and then I tried it in restore and the blue lights flickered for a second and that was it. Also my shorts light is always on.

I hooked up my BK 465 and the emissions were the same as before trying the Beltron so it didn't do anything.

[sean]

It has been a while since I looked at the underside of my unit and it is much nicer than I remember. Here's a Google album with a couple photos of my unit.

Beltron 2972E Google Photos

Is that 10 ohm resistor in your unit mounted on the trace side of the board? I didn't remove the board when I took these photos but I would have when I drew the schematic. I would think I would have put it on the schematic if that resistor was in my unit.

As to the shorts light, that's something that isn't mentioned in the instructions pasted to the document pouch in the lid. My unit came with all of the paperwork including the "Beltron Promotional Kit" which contains some better instructions. The shorts light will remain on as long as the tube does not have a heater to cathode short. I'll try to get these instructions scanned or typed up into a document and post them.

[Aperna1985]

Hi Sean, yours doesn't have it. I was looking at a schematic for the other version of the beltron and that one uses a 10 ohm resistor. I think they were trying to convert mine into the different version. I think it's an 8080. Here's a link to the picture of my circuit board if you look where the green wires are just below the capacitor you'll see that 10 ohm resistor.

https://photos.app.goo.gl/97WfapvY3T8W46fZA


By the way this pic is from before I worked on it.

[sean]

I don't know what the difference is between the 2972 and the 8080. There are a couple photos on Radio Museum that show an 8080-A where a new nameplate was installed over the original 2972-E printing.

https://www.radiomuseum.org/r/applew...em_2972_e.html

I typed up the instruction sheets that came with my unit and have attached them as a PDF.