New '60s Philco Roundie - Page 2 - Videokarma.org TV - Video

DaveWM · #1 10-03-2016, 09:41 AM

Quote:

Originally Posted by Hagstar

I may go with a simplified start up procedure as I strongly suspect the recycle store already powered this up, can't even be sure they used a variac.

Thanks again, will report.

Right that's a good point, its often already been started cold full power. Sometimes you will find one with a badly disintegrated plug that clearly not been used in years.

Findm-Keepm · #2 10-03-2016, 09:49 AM

Quote:

Originally Posted by DaveWM

you can get test sockets for checking HO current, plug the socket in, the tube into the socked. It has test leads coming out that you hook the meter up to.

Pomona 2712, 2712A and EBY Cath-2 (interrupts pin 2) will work.

I don't have a GC/Walsco catalog that shows the one for the 6JS6/6KD6, but they probably made one.

DaveWM · #3 10-03-2016, 09:59 AM

ok now I remember, the HV is controlled by a horz bias pot which directly bias's the Horz out. So you adj the HV to about 25kv with that pot. The regulation takes place from feedback from the fly. The problem I ran into was the excessive heat (to the point of severe wax melting and even smoke) so adj the bias down to get the heat down resulted in under scanning of the crt. That was resolved with a HV disc cap across the yoke horz windings. Pretty mickey mouse fix that maybe was not the right thing to do. Perhaps it needed a new fly.. whatever just don't leave the set alone (good idea for any 50 year old color tube set). I think I adj to about 23kv

DavGoodlin · #4 10-03-2016, 11:00 AM

Quote:

Originally Posted by DaveWM

ok now I remember, the HV is controlled by a horz bias pot which directly bias's the Horz out. So you adj the HV to about 25kv with that pot. The regulation takes place from feedback from the fly. The problem I ran into was the excessive heat (to the point of severe wax melting and even smoke) so adj the bias down to get the heat down resulted in under scanning of the crt. That was resolved with a HV disc cap across the yoke horz windings. Pretty mickey mouse fix that maybe was not the right thing to do. Perhaps it needed a new fly.. whatever just don't leave the set alone (good idea for any 50 year old color tube set). I think I adj to about 23kv

Sylvania used feedback from the fly to regulate pulse amplitude to the HOT grid on this on their later tube and hybrid chassis. Didn't Motorola do it also?

Ill make sure to copy these notes into my "Philco Color TV service manual" a Tab book by Robert L Goodman. I have a 19" chassis version of this set and its fly runs hot.

Few color TVs had a tuning meter or tuning eye tube. The OP's model might have the tuning eye tube. Only GE had a tuning device on their 1967-68 color sets and Westinghouse had that on-screen bar graphic on that one-shot chassis before they quit making Tvs. otherwise, I never saw visual tuning devices on an RCA, Zenith, Mag etc

Electronic M · #5 10-03-2016, 09:20 AM

Sometimes H out tube current test points are there but not indicated on the schematic.
If not present I like to add one as well as protection by placing an above chassis fuse holder in series with the H out cathode...The right fuse will protect it, and I can pull the fuse and replace it with a current meter to check current whenever I feel like it without need to pull the chassis to check.

Electronic M · #6 10-03-2016, 03:33 PM

Probably is the jumper (some continuity tests/circuit tracing should tell you for sure)...The picture is blurry enough that bigfoot ought to be in it.

Electronic M · #7 10-07-2016, 06:37 AM

A good place to start is by measuring base voltages on the H output tube. If the osc. is dead or malfunctioning(manifested in grid voltage), the screen bias network is damaged, or the cathode ground wire is open, then the output tube will not drive the fly properly. I'd change the HV rect and try to get the H out tube workin right. HV has a funny way of re-welding closed or bypassing small opens, and you might get lucky.
I'd be more concerned if it failed a ring test (granted you need the HV winding to ring it IIRC), or windings other than the HV were open.

rob Cashin · #8 10-10-2016, 06:45 AM

How did you make out on powering the set up?

Hagstar · #9 10-10-2016, 08:33 AM

Quote:

Originally Posted by rob Cashin

How did you make out on powering the set up?

The flyback has been cooked to open, see previous posts. Waiting for tubes for more testing.

John H.

miniman82 · #10 10-10-2016, 09:38 AM

Take the tire off and see if the break is near the surface, if it is you might be able to repair it. If not, like you said you can always do the tripler mod.

Hagstar · #11 11-07-2016, 02:40 PM

I have the answer- massive arc-over of the high voltage insulating cup under the high voltage rectifier. Ordered a new one.

Electronic M · #12 11-07-2016, 04:19 PM

Quote:

Originally Posted by Hagstar

I have the answer- massive arc-over of the high voltage insulating cup under the high voltage rectifier. Ordered a new one.

Sometimes that can be fixed. I had a zenith color port set that arced through the bottom of the cup. My solution was to drill out the carbon arcing path then use Permatex gray silicone to fill in the hole...It worked well and was almost a free repair.

Findm-Keepm · #13 11-09-2016, 11:17 AM

Quote:

Originally Posted by Electronic M

Sometimes that can be fixed. I had a zenith color port set that arced through the bottom of the cup. My solution was to drill out the carbon arcing path then use Permatex gray silicone to fill in the hole...It worked well and was almost a free repair.

+1 - works every time. The Silicone Rubber has a higher volts/mil rating than the plastic in the cup - the cup will go before the patch!

RTV3145 is the best for HV applications - it's electronic grade, self wets, and cures in 6 hours or less. Navy avionics owes it's success to RTV3145 - it solved many arcing problems in F-14 (AWG9) radar power supplies, sealed chaff buckets, and I used it to cure arcing in a Conrac monitor used in the CATIIID bench that troubleshot modules. Great stuff.

DavGoodlin · #14 11-09-2016, 01:05 PM

Quote:

Originally Posted by Findm-Keepm

+1 - works every time. The Silicone Rubber has a higher volts/mil rating than the plastic in the cup - the cup will go before the patch!

+2 a similar repair is still holding in a 16" Zenith color portable.

There was a full metal cap behind the HV rect cup, drilled out the pinhole the arc made and plugged and coated the cup bottom with black RTV.

Hagstar · #15 11-22-2016, 04:53 PM

Fixed high voltage issues. Just rough convergence so far but finally an okay picture

My next puzzle is that the AGC doesn't work though the pot seems to measure and function normally. Only just the right fairly weak signal makes an image, it overloads at the drop of a hat.

https://www.youtube.com/watch?v=Uj-wk-OtwzE

John H.