An old friend on his last chance repairs: Meet Troy

[leadlike]

Well the yoke arrived yesterday! As it turns out, the only difference in the part numbers is that the one I got comes with a bonus wiring harness. I fired up the tv twice: once before the yoke was installed and once after. HV did not fire up either time. Therefore, no raster, no HV high pitched sound, etc. I am just totally disgusted with this thing. All the low voltage measurements I made before are the same. Swapped tubes, no change, etc. Any ideas on where trouble may lie now?

[bgadow]

If you still have decent voltages I think I would move to the HO tube and damper. If you haven't swapped them yet, good time to do it. Still no audio?

Veg tried very hard to talk me into that set! No room at the inn, or it would be me trying to get that thing running!

[KentTeffeteller]

Hi,

I think ye have a bad HO tube and damper issues here. Both can load things down. Good luck and Karma. Olympic sets of the era are hard to find working. This would be a nice restoration for sure and one which is uncommon.

[Old1625]

No sweep whistle, check the HOT to make sure its plate isn't turning red, which would indicate horizontal oscillator or drive failure. G2 voltage reading will be down also if the HOT is not getting drive. It is possible that something in the horizontal drive circuitry is not quite right, and is letting go. New capacitors can be defective.....

If the person who restored the set pulled a B+ boner such as mentioned in your first posting there may be other bizarre stuff you need to search for.

[Chad Hauris]

What I would do is...
1. remove the plate cap lead from the horizontal output tube. Hook the disconnected lead up with an alligator clip lead to the voltmeter and measure the voltage (since the HO tube is not in the circuit you won't generate HV AC)
You should read about the B+ voltage. With this you can see if supply voltage is getting to the HO tube. This will also check if the damper is working because the B+ has to go through the damper before it gets to the flyback.

2. check negative grid voltage at HO tube grid with the flyback connected back in the circuit. Should likely be more than -30 volts. If the neg. grid voltage is low there is likely low drive from the oscillator.

Sometimes the audio detector stage runs off the boost voltage and if the HO Circuit isn't working right this can cause no audio.

Another possiblilty is if there is low grid drive to the HO tube it got destroyed from the overload. Had this happen on an RCA CTC-16...once I fixed the oscillator circuit and replaced the HO tube it was fine. (there was a lack of plate voltage to the oscillator)

[leadlike]

Wow! Remember this one? Well, there is news-we have a square raster! I bought still another yoke, and this time was finally rewarded with a nice, full screen! This has allowed me to find still more bonehead repairs on this thing, most shamefully the video detector diode was backwards, once that was swapped, I now get a very nice picture! Now for the current problems:

The picture STILL blooms if the brightness is adjusted at all: Turning up brightness really screws up the picture size, as well as creating as 'black hole' type of blooming in the center of the picture. Contrast adjustment is also finicky-throwing off vertical and horizontal holds.

Speaking of which, the vert and horizontal holds are really touchy-and they interact with eachother a lot. It is nearly impossible to get a stable picture for more than a few seconds. Working with the Horizontal drive and oscillator adjustments helped a little, as well as fooling with the vert lin and size.

Just wanted to give some update on this set-I haven't given up yet! If anyone has any suggestions, of course feel free to toss them out. I have one question though-the horizontal section uses two 'ladyfinger modules'-larger versions of couplates where about a dozen components are in a single unit. Are these fairly stable components? Or should they be held suspect as well? Sorry no pics, but I can't get a steady enough picture to run to the front of the set to snag one!

[Bill Cahill]

Any digital camera should be able to pick up a still picture.
Those couplates are known for going bad.
Blooming means hv is low, or, being over loaded.
Have you even re capped thisset yet?
New electrolytics?
Checked any resistors?
If these steps haven't even been performed yet, do so.
Leaky caps, and, bad electrolytics don't help matters any.
Bill Cahill

[leadlike]

This set has been recapped: new electrolytics and all paper caps are replaced as well. There are quite a few original ceramic caps left in this set. I did some resistance checks and did replace any that were out of tolerance. I have several sets of nos HV tubes for this set (damper, output and rectifier) and none of these are really changing the set's performance. Right now I'm planning on redoing most of the sweep sections, but I'd hate to ditch those ladyfinger modules as there really isn't much room under the chassis for a new replacement.

[leadlike]

I found still another wiring mistake! An entire capacitor had been clipped out of the sync separator's grid input! This basically means that entire system was not in circuit. No wonder I wasn't getting vertical or horizontal sync! I haven't hooked it all up yet, but I am getting close now-I have rebuilt the entire brightness/contrast circuits as well as the vertical section.

[gadget73]

Gotta love finding gremlins like that. I've been lucky in that most of my sets have been mostly virginal underneath so I haven't been forced to track down bad past repairs.

[Reece]

Sounds like Mad Man Muntz was in there before you!

Reece