1950 RCA 6t65 Highland console

[jbivy]

Do you know where i can download the schematics for this?

[jr_tech]

Originally Posted by jbivy

Do you know where i can download the schematics for this?

ETF has the Sams (113-7):

http://earlytelevision.org/tv_schema...grams_rca.html

jr

[Eric H]

This set's had a lot of repairs done to it, or some past repairman just replaced a bunch of caps trying to fix a problem. All those colorful plastic caps are from a later period though probably still sometime in the 50's.

I have no idea about the octal plug, perhaps it was used to run a Norelco Protelgram projection unit at some time?

[Tubejunke]

Originally Posted by jbivy

Well this has the 16gp4 crt in it. I have access to a crt tester, but its missing some of the plug adapters, so I will have to find out if i can test this.

When I opened the back, the missing power cord was wrapped around the crt. As well as a strange alligator clip that was clipped to the copper piece that goes between the HV cage and tube. Clipped to the chassis. Perhaps this set died, someone attempted a repair and gave up.

Your last sentence is what you find a lot of. A lot of sets came out of defunct TV repair shop's hoards. That was where I got a lot of my stuff in the 80s as a high school kid taking first year electronics. A lot of our classroom's hoard of donation sets were 50s and 60s. The bulk was that and the rest 70s. That's just what was being replaced, repaired or just upgraded at that time. And I use the term hoard as electronics and the people who work with it tend to form crazy amounts of things buried in piles doing absolutely no good. I am guilty of it myself. I am crazy enough to do my electronics work and hoard in the house. I have my mini bench in a redheads kitchen! Yeah! I am lucky to be alive! Luckily we both collect different things, so maybe she cuts me some slack on the kitchen deal.

Anyway, that alligator clip you mention sounds like it was clipped to the rigid wire that presses against the side of the CRT to discharge the high voltage from the CRT during service. That bare wire is actually part of the HV circuit as much as any other wire. There is conductive paint on the CRT called agadag (spelling?) and the sprung wire must touch the CRT surface to complete the circuit. Always make sure that is touching the rougher aquadag surface and not just glass where a hole has formed.

I have similar RCAs, but a bit older. Mine are 8T-243 and TC-127. Only the 127 I have gotten back to playable. I replaced all the electrolytic and paper/foil capacitors and a few resistors. I have vertical shrinking at the top, but the set is very stable with a really sharp picture. That vintage RCA was known for really good picture quality from all I have read or seen.

My experiences with the two I have compels me to say that you MUST replace the power supply electroytic capacitors before bothering with anything else besides checking that CRT. My 243 was frying 5U4 rectifiers in a New York minute. I had to buy a replacement power transformer for the 127 and my belief is that someone at some point was determined to get life out of the set and simply fried the tranny by leaving it on for a while. You don't want to replace that power transformer! On top of that; your power supply is the heart and soul of the set. You want and need stability there so you can safely see what else is going on.

Slow starting never hurts, and if done right can allow you to reform many capacitors after you stabilize your power supply. Even if you have already applied full AC wall current to the set for a bit, you can go back and let the set 'simmer' at say 50v for a few hours and work your way up in maybe 15v increments. Even after DC or B+ kicks in and you end up finally seeing what the set will or wont do, you will find that the longer you let it work the better it performs. The old caps can take a long time to do what they need to do. Just carefully feel the caps and make sure nothing is getting hot. If it gets hot; replace it.

And does the octal plug have anything to do with sound? I can't remember how my speaker plugged in. I would say a normal speaker plug...

[jr_tech]

Originally Posted by Tubejunke

Anyway, that alligator clip you mention sounds like it was clipped to the rigid wire that presses against the side of the CRT to discharge the high voltage from the CRT during service. That bare wire is actually part of the HV circuit as much as any other wire. There is conductive paint on the CRT called agadag (spelling?) and the sprung wire must touch the CRT surface to complete the circuit. Always make sure that is touching the rougher aquadag surface and not just glass where a hole has formed.

In this case however, the CRT is a 16GP4, which is a METAL CONE CRT. The *whole* cone is connected to the HV, and a "doorknob" capacitor (mounted on the front of the HV cage) is used for filtering. I suspect that the clip-lead was left there for convenient grounding of the metal cone while servicing the set.

jr

[Tubejunke]

Originally Posted by jr_tech

In this case however, the CRT is a 16GP4, which is a METAL CONE CRT.

Oops! That's exactly what my Sylvania tube data book says. I had a DuMont once with a 19AP4 metal/glass CRT. Neat engineering concept bonding metal and glass like that, but the shock hazard is incredibly high. Mine had a rubber boot around the bell of the tube and a big warning label. The boot of course lent some comfort and protection, but I just made it a point to stay away from that tube; especially powered up!

[jbivy]

Im at a bit of an impasse, we dont have the adapter to test this crt. Most of the adapter plugs arent there... I tested the tubes, only a few are low and the 5u4 is dead.

as for the oddball octal socket under the chassis that connects to nothing, i havent a clue. This set has two octal sockets on the top of the chassis, one plugs into the HV cage, the other to the speaker. The one under the chassis, i dont know where or what it was supposed to be.