Westinghouse 17TV7C

[Electronic M]

IMHO the best way to kill the HV on a set with a power transformer if to pull the horizontal output tube (on series heater sets either remove the plate lead or get creative...) . I would not run the set with both the HO tube and a gassy rectifier in place. If HV goes to that gassy HV rect. arcing may occur inside it and could cause other issues that ya probably don't want to deal with.

[N2IXK]

Yes, pulling the 6BG6 will prevent the HV from coming up.

I wouldn't suggest just disconnecting the plate cap on one, though. That leaves the screen grid voltage on the tube, and screen voltage without plate voltage applied can result in excessive screen dissipation, damaging the tube or burning the screen resistor.

[MIPS]

I don't have a 6BG6. I do however have a 6BQ6 if that is what you meant.

For paranoia sake I'll bring the set up in steps. In phono mode only the amplifier works, in AM there's the amp and the radio. Finally in TV mode you get the amp and the TV. More results later.

[MIPS]

Well it seems one of my two spare 1B3GT's went bad in storage (did anyone catch me calling it an IB3GT for a while? ). Thankfully my second one was okay.



I also had two spare 6BE6's. The first one had good emissions and life but the grid leakage test swung the needle everywhere. The second tube tested perfectly fine.
Once everything was reinstalled it was attached to the variac and a DMM to measure current and slowly woken up.



No smoke. No nasty noises, no explosions. Current draw also seems to be pretty low. Cycling through the modes all the tubes lit and everything seems okay. We'll let it sit for a while to cook and see if anything happens and then I think it's about time to see if we can get a picture.

[MIPS]

Last thing for the day.

I reinstalled the last two tubes, took off the HV cage and brought up the power.


No arcs, hissing, ozone or smoke and my young ears can hear the coil whine from the flyback. An IR thermometer was used to make sure nothing was overheating and then after five minutes I removed power and grounded the anode cap to the chassis. I do not own a high voltage probe so I can't tell what the voltage is but at least we know we should be ready for the CRT to be reinstalled.

[MIPS]

CRT went in. Only iffy part is the ion trap because of previously stated wiping my alignment mark off but I had an older photo indicating a rough location.




Also spent an hour dismantling and cleaning the five pots that were completely frozen up. Looks like the grease wasn't all that happy long term with the brass. One was so badly gummed up I had to use two pliers and the vice. After that was done they slid nicely and didn't seem to be too badly worn. We'll find out later.


Finally the set was powered up. HV charged and something appeared.

The picture deceives. There is a tiny amount of vertical deflection (it will stretch and shrink) but otherwise there's obviously a problem. There's also a terrible screech that changes in tone depending on the horizontal hold (Or something. NONE of the knobs are labled except for PICTURE and on/off/vol so I'm trying to determine them form the schematics) so for now I have that turned down. There's also an alignment issue. Turn the set off and the dot sits up in the corner. Probably a mix of the ion trap and the yoke being slightly out of adjustment.

[Jon F]

Did you replace the multi-can electrolytics and the plastic molded caps? If not, replacing those will make a big difference.

Also nice pictures, high quality.

[MIPS]

Not yet. That will take another month or so at least, again because the shop is a seven hour round trip.

We've also lost the picture completely. When I put the chassis on its side to find what the knobs did (height and vertical linearity are on the back and the horizontal and vertical hold is on the front but the central of the three front knobs is still a mystery) I powered the set back up and while I still get the squeaking effects there's nothing on the screen at all even though we have high voltage and the neck is lit.

Edited: Nope. It's still there. I guess the high voltage has been pulled down now or something as we've lost the brightness. Also, we've gone from the lack of vertical to pulsing between none and...something. Sure. I'll work on those caps....and that damn lightbulb which I forgot to buy last time I was there.

[Jon F]

Check out justradios.com, easy to order from and very reasonable.

[MIPS]

Main Electronics has an online order system but for that last tiny batch of caps I didn't make the $25 minimum order. IF now I'm buying at least 15 more caps I should be able to make an order. I'll have to inquire.

[MIPS]

Just to confirm...




Left pin is semicircle, top is square and right is triangle?

[nasadowsk]

Yep

[wa2ise]

That capacitor is one month older than I am. Replace it

[MIPS]

Was able to restuff and seal two of the cans before I ran into space issues with the third and finally after 20 years my Weller's tip gave out. I'll get a new tip tomorrow.









I've decided to hold onto the old empty can in case some time in the future we can source smaller caps and can properly restuff it. Three caps jammed into the old retainer looks kind of ugly.

[MIPS]

Well that's another 16 capacitors replaced.



The results were...interesting. The picture control is basically a gray screen for the first third of the knob being turned, then the picture snaps in and it seems to work although the bottom of the picture is an inch above the bottom edge of the tube. Vertical hold works....kinda. Brightness seems to behave. Horizontal hold seems to work on the low side but once you crank it up high enough the high voltage squeals angrily. Vertical linearity seems to work okay? Height control is extremely sensitive. Either you have a picture or the vertical collapses.




Probably a few resistors which drifted out of value?

The good news however is that I attached a speaker and fed an audio signal in from my PC and we had good clear sound and when switched to TV we had white noise. ( >Youtube Link< )