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Old 02-02-2017, 01:22 AM
Crist Rigott Crist Rigott is offline
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Rca 621TS

I picked up this TV this evening. Drove to Houston, sealed the deal and drove back. Got in about 11pm.

Overall the set looks nice. It is an older s/n like C 0003445. Pretty clean inside and no rust except on the surface of the transformer. Here are a few pics of it:









I tested the 7DP4 picture tube with my BK 467 CRT tester. Here is the result:


And the LIFE TEST:


The HV lead was disconnected and in faint letters the word BAD was written on the top of the CRT:


What gives? The tube looks to be in excellent condition.

Very pleased with the purchase.

But wait, there's more!
I also got this from the same seller:





Last edited by Crist Rigott; 04-12-2017 at 11:44 PM.
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Old 02-02-2017, 02:45 AM
EdKozk2 EdKozk2 is offline
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Crist,
Glad you were able to buy the 721 with a good CRT, and that Philco. They will keep you busy for awhile.
Ed
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Old 02-02-2017, 09:39 AM
Crist Rigott Crist Rigott is offline
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Thanks Ed. They will.
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Old 02-02-2017, 09:43 AM
Crist Rigott Crist Rigott is offline
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I rechecked the CRT this morning. Yup, it checked that good and no shorts or anything like that. No rattles either. This CRT looks brand new and is a genuine RCA 7DP4 CRT. No evidence of being rebuilt either. I'm not sure those could be rebuilt anyway.

Also the TV does not have a back. So, if anyone has one let me know. I'm going to see if I can find a good picture of a back and see it one can be made without too much difficulty too.

Next up, I'll pull the chassis. Stay tuned.
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Old 02-02-2017, 10:48 AM
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bandersen bandersen is offline
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Yes, they could be rebuilt. Scotty at Hawkeye was doing them before he shutdown a few years ago. Pretty much the same gun as any other early B&W CRT. Only difference being the electrostatic focus.
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Old 02-02-2017, 10:54 AM
Crist Rigott Crist Rigott is offline
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Bob,
OK, I didn't think they were re-buildable. Good to know. Why I think this tube is not rebuilt is that the neck is straight with no evidence of an extension being fused on.
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Old 02-02-2017, 10:58 AM
Crist Rigott Crist Rigott is offline
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OK, pulled the chassis. There very minor rust spots on the chassis but no big deal. The bottom line is it looks like somebody did a partial resto on it. I should have noticed the fuse holder as my first clue. This one will be a good one that's for sure. Seeing it has been partially restored, should I take the chance and power it up using a variac?










Last edited by Crist Rigott; 03-07-2017 at 07:14 PM.
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Old 02-02-2017, 11:27 AM
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Kevin Kuehn Kevin Kuehn is offline
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Well that sure is a nice clean chassis. Apparently the previous restorer didn't have the perseverance and/or resources to complete the project. Some folks very quickly jump to the conclusion that the big bulb must be at fault. At any rate this should be a very educational project.

[edit] Forgot to ask - is there any indication that the electrolytic cans have been restored?

Last edited by Kevin Kuehn; 02-02-2017 at 11:31 AM.
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Old 02-02-2017, 11:48 AM
Crist Rigott Crist Rigott is offline
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Quote:
Originally Posted by Kevin Kuehn View Post
Well that sure is a nice clean chassis. Apparently the previous restorer didn't have the perseverance and/or resources to complete the project. Some folks very quickly jump to the conclusion that the big bulb must be at fault. At any rate this should be a very educational project.

[edit] Forgot to ask - is there any indication that the electrolytic cans have been restored?
Thanks Kevin.

Looks like the E-Caps have been re-stuffed. I looked closely and I might just power this thing up.
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Old 02-02-2017, 11:50 AM
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Eric H Eric H is offline
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That circle on the base of the CRT with a date code seems to indicate it's a replacement tube, either new or rebuilt, I know they used that style at least as late as 1960.
What are the numbers?
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Old 02-02-2017, 11:52 AM
Crist Rigott Crist Rigott is offline
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Quote:
Originally Posted by eric h View Post
that circle on the base of the crt with a date code seems to indicate it's a replacement tube, either new or rebuilt, i know they used that style at least as late as 1960.
What are the numbers?
3
---
48
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  #12  
Old 02-02-2017, 01:13 PM
Crist Rigott Crist Rigott is offline
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I powered the set up.
First with the low voltage rectifier removed. All the tubes lit up. Then with the low voltage rectifier in but the H output tube plate cap removed. I measured 263 volts! Riders says 265 volts. I received good audio from a local OTA broadcast! Then on goes the H output tube cap connection. No raster. Bummer. Then I remembered the ION trap. Moved it around a little. Nice bright raster!

Hooked up my converter box and now the audio isn't so good on channel 4. But I got a picture! Horizontal sync needs lots of help. I'll bet its a mica cap. All-in-all, this set looks like it'll do good.

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Old 02-02-2017, 02:12 PM
dieseljeep dieseljeep is offline
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It looks like someone eliminated the PM ion trap and used the resistor in its place.
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Old 02-02-2017, 02:53 PM
Crist Rigott Crist Rigott is offline
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Quote:
Originally Posted by dieseljeep View Post
It looks like someone eliminated the PM ion trap and used the resistor in its place.
I think he eliminated the electro-magnet, installed a resistor in its place, and installed a permanent magnet ION trap.
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Old 02-03-2017, 12:26 AM
Crist Rigott Crist Rigott is offline
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BTW, I'm making a list of all the resistors and capacitors used in this set.

I'll do my usual practice of going up in wattage on the resistors.

I'll use the yellow tubular film caps from Sal or Just radios all rated at 630V.

All micas will be at least 5% 500V rated.

The E-Caps will be 450V or 500V except for the few odd values and much lower voltages. Those will still get at least 250V simply because the leads are thicker and less prone to breakage.

I know there is a door knob cap rated at 500pf but no voltage is given. I'm guessing at least 10K?

Are there any other caps that are rated at a higher voltage? I see C141 a 56pf cap in the yoke. Would this be like a 1KV or higher?
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