Stabilizing a TS-18

[Zenith26kc20]

My first antique repair (around 20+ years ago) was on a TS-4 which was headed to the garbage can. I used ceramic disc types as that was all I could find at the time. They worked fine for many years. Within the last couple of years I replaced them with the ASC tubulars. My first TS-4 still works fine except it does take the CRT a bit to warm up. By the time the chassis stabilizes the tube is fine. I also installed the dc restoration and blanking from the other threads.
This TS-18 has a better picture without any additions. Once it is back in it's cabinet I want to try the test CRT in my first TS-4.
I'll get pictures tonight.

[bandersen]

Is this the dc restoration circuit you used ? I had no idea such a mod existed.

http://ankythera.com/Projects/video_clamper.htm

[compucat]

I was going to add retrace line suppression to mine but now that there is no more analog reception I find I no longer need it. With the converter box I don't get retrace lines like I used to.

[Zenith26kc20]

Yes, that is the DC Restoration mod. It works quite well. Somewhere else on this sight is the blanking mod. It works well also. The only thing I found when I did the mod is to be careful as the diode dies easy. I killed the first one somehow. Once I replaced it the circuit worked great.
Last night I hooked up a speaker and with just a touch up of the ratio detector the sound is great.
Now comes looking for knobs! Remember, this was a true basket case that almost became a parts donor
One other thing, the later 12SN7GTA have higher plate voltage ratings and if I remember correctly have controlled warmup (11 seconds). This may help more stabilization. Since the vertical circuit has all new parts it seems very stable. Horizontal jumps out one time after 15 minutes and once readjusted is fine.

[wa2ise]

I suppose a damper diode would work for the solid state diode here. Damper diodes have high heater to cathode voltage ratings, but are rather big...

Anyway, not sure what R85 and C82 here do. One would have to take care that the sync seperator circuit doesn't lose input when the clamp is working hard.

[Geist]

Hi All;
What Size are the two Peaking coils ?? And where would one get them from ?? Or could they be Wound by ourselves ??
THANK YOU Marty

[bandersen]

The peaking coils are already in the set. Only the parts that have *New next to them have to be added

[Eric H]

Originally Posted by Zenith26kc20

That one came from the bakelite TS-18 that is really nasty. Someone put some green plastic to hold the CRT in place and it melted everywhere. It took me an hour to scrape the bell and face clean. It's a Philco tube and it is in great shape!

I would bet it's the melted gasket from the Motorola, they are famous for that.
Plain old water will wash it off.

[Zenith26kc20]

I wish it was the grey colored goo but it was bright green where the easy melt was. The nasty part was where it turned black and rock like.
Anyway, the Colonial/Sivertone has the bench before that one so I have plenty of time to scrape and watch TV while I'm not replacing the million capacitors in the Colonial.
By the way, here's the picture of the chassis playing about two minutes after turn on!
Love the little electrostatic critters!

[Zenith26kc20]

I was playing with the TS-18 last night and I remembered something. I never replaced the selenium rectifiers. I checked the B++ and at 120 volts it has 247 volts. It stabilizes in about one minute. I checked my TS-4J at work today. I jumped the seleniums decades ago with silicons and it has been very unstable. I removed the silicons and just turned it on. It came on in sync and B++ is a bit low at 230 volts. No problems anywhere right now. Good width, good vertical size and the slow contrast warmup is gone. I'm going to let it play and watch the B++. I'll also hope that the "pop, pop and a disagreeable odor" as described in the service manual doesn't happen.
One other thing, the amperite does not light up as bright on turn on. I can't see the inside of the metal ballast on the TS-18 that good on turn-on but I use a variac on that set to protect the ballast.

[Zenith26kc20]

Seems B++ on the TS-4 got a bit lower and I got worried. It takes 47 ohms in series with each silicon to bring the voltage to schematic levels. So, I guess no "pop pop" from the seleniums will be in my TS-4's future....

[Phil Nelson]

Originally Posted by Zenith26kc20

I jumped the seleniums decades ago with silicons

Do you mean that you wired the silicon in parallel with the selenium, rather than taking the selenium out of circuit?

Phil Nelson

[compucat]

Originally Posted by Phil Nelson

Do you mean that you wired the silicon in parallel with the selenium, rather than taking the selenium out of circuit?

Phil Nelson

That is what someone did on the RCA I am restoring right now.

[old_coot88]

Originally Posted by compucat

That is what someone did on the RCA I am restoring right now.

Krikeys. That doesn't help with the problem of reverse leakage in the seleniums.

[Zenith26kc20]

I did it years ago. It is just a single tie point now. One of the leads is no longer connected. Once the appropriate resistors come in I'll hide them and the silicon under the selenium. I hate to completely remove them as they do serve a visual purpose. I've never had one short to it's mounting screw that's why they are a single mounting tab now.
I'll check reverse leakage on the seleniums later today when I get a chance to sneak away from work.