View Full Version : CTC-5 issue


bigaudioal
10-18-2016, 11:53 AM
Last night I was watching my CTC-5 for about two hours. Had been operating fine the past few weeks. I then saw something strange and lost raster.

I noticed what looked like twinkling stars or starbursts inside and on the face of the CRT. Saw this maybe two or three times within the minutes leading up to losing raster. I had gotten up to investigate and turn off the set when all went black. I did not hear anything unusual at all associate with this. No smells, not pops, nothing.

Yesterday morning I got into a car accident with my brand new 2017 Ford Explorer, was rear-ended by a woman not paying attention or she was texting. So I was in no mood to investigate at all. So just turned it off and went to bed. Anyone seen this condition before and might have a clue as to what to look at?

Thanks.

DavGoodlin
10-18-2016, 12:24 PM
Sorry to hear about the accident Al. I hated driving around the DC area when I lived there 30 years ago, I guess not much changes.

The first thing you need to do is test the CRT just to make sure there is no gas problem. Next check the HV and my guess (and hope) is you lost the 3A3. I recall the
3DJ3 failing in our Zenith when I was 10, and it did this effect with a load buzz-pop IIRC.

bigaudioal
10-18-2016, 12:28 PM
My first step was to test that CRT and PRAY it still tests good. Hoping it is NOT that. That's the rebuilt 21AXP22 you found, Dave.

Here's hoping the 3A3 went. :)

Electronic M
10-18-2016, 01:03 PM
It is possible the damper or H out went or had a socket intermittent.
Good luck.

There are clusters of bad drivers nation wide....Our 02 Honda CRV got totaled back around 2011 in much the same fashion....That car would have been gifted to me by now had that not happened...

bigaudioal
10-18-2016, 01:30 PM
It is possible the damper or H out went or had a socket intermittent.
Good luck.

There are clusters of bad drivers nation wide....Our 02 Honda CRV got totaled back around 2011 in much the same fashion....That car would have been gifted to me by now had that not happened...

The poor driving is totally related to distracted drivers. I did not see her, but guarantee she was texting or looking at her phone and just did not see traffic stop ahead of her. She did not apply brakes until she hit me. Could totally tell by the force of the impact. There should be a device that disables texting and email functions on phones when that device is within 10 feet of a running automobile. Allows the phone function to still operate but not texting or email. If someone could invent that, there's a billion dollar idea.


Anyhow, I hope to get to testing a bit tonight. Will start with CRT and then move to HV rectifier tube, horiz output tube, damper tube, etc. Kinda bummed. It had been working so good since the recap. I guess I should also check the horizontal sweep output fuse.

DaveWM
10-18-2016, 02:18 PM
This is why auto makers are trying to make smart cars that brake for you or auto pilot like features, so folks can tap out messages, nice.

how about put the freaking phone away when driving, is that really asking too much (I know it is, device addiction is rampant).

I drive a 40 yr old car that is dumb as a rock and I like it that way. have to shift gears, crank up windows, manually lock doors you stay engaged with traffic the way you should.

agree with the others check the HV stuff 1st and hope for the best.

Electronic M
10-18-2016, 03:58 PM
Some of it is phone based, some isn't. In Fl smart phones were not a thing yet, and the people intentionally blew lights and did other dumb things. The CRV died from traffic suddenly stopping over a hill on the interstate and the old lady following mom panicking and mashing the gas instead of the break...

This is why auto makers are trying to make smart cars that brake for you or auto pilot like features, so folks can tap out messages, nice.

how about put the freaking phone away when driving, is that really asking too much (I know it is, device addiction is rampant).

I drive a 40 yr old car that is dumb as a rock and I like it that way. have to shift gears, crank up windows, manually lock doors you stay engaged with traffic the way you should.

agree with the others check the HV stuff 1st and hope for the best.

I can't stand smart cars....Hell a tesla auto pilot got the 'driver' killed from a 'malfunction'...Some stupid maker has put in rear collision avoidance that 'will move your car into the oncoming lane where traffic permits'...How many serious accidents is that going to cause?

My car is much like yours...Only it is a luxury make with automatic trans and power everything. I much prefer my car to issue no warnings and control none of my driving, and to instead focus at the wheel.

Once the government mandates these nanny state features in cars I'm either going to stop using any modern vehicles, or learn how to hack those features out of existence.

SpaceAge
10-18-2016, 05:03 PM
[deleted]

Tom9589
10-18-2016, 05:31 PM
I worked for 20 years in the cellular telephone industry. Right now they have the sensors and the capability to detect anytime the phone is in motion. Just make the phones so that you can't send or receive a message when moving.

I still remember when you hunted for a phone booth so you could keep your conversation private!

Hagstar
10-18-2016, 08:59 PM
My CTC4 did a similar thing and it was a flaky CRT ground strap. I still can't get the OEM one to work reliably and so have a jumper lead as a backup for now.

reeferman
10-19-2016, 12:39 AM
I doubt it is the CRT.
From my experience in the trade, I would suspect something other than the CRT. I agree with the others, start with the HV section. It's most likely the culprit.
Good luck.

bigaudioal
10-19-2016, 02:01 PM
Well CRT is fine.

Started there to cover my bases.

Next check was the horiz sweep circuit fuse. BLOWN! So put a new one in. Took off HV cover and fired up the set. Raster came back. Something has to be blowing that fuse. Think I found it. Shunt regulator tube (6BK4) was flickering blue inside and I noticed a very faint clicking sound (arcing). Standing a few feet from the set, the sounds is unnoticeable. But getting close - can see and hear it. Also found a crack in the plate cap for the same tube. So will replace that tube and plate cap and fire it up and see if that fixes it.

Hope it does.

bigaudioal
10-19-2016, 02:04 PM
My CTC4 did a similar thing and it was a flaky CRT ground strap. I still can't get the OEM one to work reliably and so have a jumper lead as a backup for now.

Good to know. Will check my ground strap too. Thanks!

benman94
10-19-2016, 02:14 PM
Al, I think you have a typo.
The shunt reg is a type 6BK4/6EL4. 6BK8 is equivalent to type EF86.
My Hoffman had a screwy 6BK4, acting similar to yours. Replaced it with the last revision (6EL4A maybe?) and that fixed my problem.
Good luck.

bigaudioal
10-19-2016, 02:17 PM
Sure makes a nice picture!

bigaudioal
10-19-2016, 02:17 PM
Al, I think you have a typo.
The shunt reg is a type 6BK4/6EL4. 6BK8 is equivalent to type EF86.
My Hoffman had a screwy 6BK4, acting similar to yours. Replaced it with the last revision (6EL4A maybe?) and that fixed my problem.
Good luck.

Ah crap, you are right. TYPO! 6BK4. Fixed it. Thanks.

bigaudioal
10-19-2016, 02:26 PM
Anyone know of a good source that might carry plate caps? Want to replace the cracked one on my 6BK4. I don't have any in my current parts stash. Thanks!

Zenith26kc20
10-19-2016, 04:09 PM
Very interesting! When my 25MC233 had a 6BK4 failure high voltage went thru the roof! What is the high voltage on your CTC5? If I remember right they are not capable of ridiculous levels like my 25MC33 (close to 32 KV when the tube died). Sounds like yours went gassy.

bigaudioal
10-19-2016, 05:23 PM
Very interesting! When my 25MC233 had a 6BK4 failure high voltage went thru the roof! What is the high voltage on your CTC5? If I remember right they are not capable of ridiculous levels like my 25MC33 (close to 32 KV when the tube died). Sounds like yours went gassy.

The CTC-5 HV is around 20kV at best. One of the complaints everyone has about it. Whereas most of the other vintage color sets are around 25kV.

Hagstar
10-21-2016, 08:30 PM
My CTC4 topped out at 22 kV before the flyback fried, with the tripler in place though I now get around 24.

John H.