1960s vintage 9" GE B & W Portable TV has no Picture - Page 2 - Videokarma.org TV - Video

***Eric H*** · #16 07-06-2015, 01:04 AM

Short of testing the tube the only way to find out if it works is to get the chassis working and see if it makes a picture.

First step would be to check for high voltage, since you have audio we can assume the basic power supply is working.

You can still check for HV at the 1V2 using the screwdriver method, you just have to hold it near the connection at the base of the 1V2 where the output of the Flyback connects.

Captainclock · #17 07-06-2015, 05:51 AM

Quote:

Originally Posted by Eric H

Short of testing the tube the only way to find out if it works is to get the chassis working and see if it makes a picture.

First step would be to check for high voltage, since you have audio we can assume the basic power supply is working.

You can still check for HV at the 1V2 using the screwdriver method, you just have to hold it near the connection at the base of the 1V2 where the output of the Flyback connects.

it seems that's my only option right now, which is to check for H-V.
but the fact that the TV has no picture at all period and someone else on here told me that if the picture tube was "dead" it would still have a faint picture which mine doesn't even have a picture period leads me to think that the picture tube is more than likely still good yet (albeit not 100% after 60+ years) but just that the TV set has either a Low B+ issue or a Low or no High voltage issue.

Gregb · #18 07-06-2015, 08:06 AM

I was just working on a very similar Hotpoint set that uses the same CRT as yours. I have a CT tester and my tube tested good so I went ahead and recapped the set and on first power up I had the same issue. Totally dark screen no matter what and I had good high voltage. All that was wrong was the ion trap needed to be adjusted.

Gregb

dieseljeep · #19 07-06-2015, 09:34 AM

Quote:

Originally Posted by Gregb

I was just working on a very similar Hotpoint set that uses the same CRT as yours. I have a CT tester and my tube tested good so I went ahead and recapped the set and on first power up I had the same issue. Totally dark screen no matter what and I had good high voltage. All that was wrong was the ion trap needed to be adjusted.

Gregb

The set has a low B+ circuit. There is a large value input electrolytic cap that is probably dried out and lost value. As a result, the set won't produce HV and do much of anything, but hum. A cap pulled from a scrap solid state color set would be close.
The CRT is a blown glass bulb, similar to the 7JP4. As a result, rebuilts were never available. The CRT is probably OK.
The tubes are rather odd-ball type with 300ma heaters. Some types, seemed to only be used in that particular set.

***Eric H*** · #20 07-06-2015, 04:02 PM

That he said the sound was good made me think the B+ is okay, or at least ballpark.
It could still have horizontal oscillator problems keeping it from getting any high voltage, that's why I suggest checking that first. If it has HV and a dark screen then the Ion trap may be misadjusted, the CRT may be bad or it could have video problems.

The 9QP4 was a disaster, GE replaced a ton of them under warranty, the replacements may not have been much better. My own experience with these sets is not good as far as CRT's go, I've had to buy several junkers to get good tubes to fix my better sets.

There is some information on repairing these sets here: http://antiqueradios.com/forums/view...hp?f=3&t=91582

And some info on the Tube here: http://www.videokarma.org/archive/in...p/t-52670.html

They are so simple you can replace all the paper tube caps in an hour or so, a little more for the Electrolytics.

I've had to replace the Horizontal AFC Diodes on the ones I've done, they are Selenium and don't hold up.

Captainclock · #21 07-06-2015, 05:24 PM

Well I removed the 1V2 HV Rectifier Tube tested it (along with the rest of the tubes on the set) and everything tested perfectly, and so I put the tubes back in and plugged the tv set in and powered it on and sure enough after about 2 minutes I had a picture and it was a pretty decent picture at that (so I'm guessing the picture tube is still good), the only issue I saw was that the the height was not correct (it was too short the picture was relative to the actual picture tube size) and I tried adjusting the height adjustments and what not but the picture wouldn't fill the whole screen for some reason, which I'm wondering if the vertical Amp tube is about shot in this case.

Any ideas?

Like I said when I finally got picture it was pretty bright and seemed like it had plenty of life in it yet (the filaments were glowing nice and bright yet) just the height was out of wack and couldn't be made right with the adjuster on the back.

EDIT: The TV is now back to stage one where I had no picture (well actually it has picture but its barely visible) and it started doing this when I put the cover back on, but when the cover was off it was working just fine (minus the height being off) so I wonder if the 1V2 tube has a short in it that didn't show up on my tube tester, either that or the tube is actually just about shot but my tube tester for some reason thought it was still good.

Olorin67 · #22 07-06-2015, 07:08 PM

sounds like if you got a picture at all, the main systems of the set are all functional, but maybe some portions are out of whack due to old caps and maybe other parts like resistors that havnt aged well. Re-capping any electrolyitcs and paper caps would be a good place to start. The set is working enough that you may be able to see gradual improvment as you replace suspect parts. If you read through the other threads mentioned above, that will give you ideas of parts that frequently require replacement in this set. Check the controls, too, a dirty brightness or contrast pot can make troubleshooting interesting... and the more aging parts you replace, the more reliable the set will be in use, hopefully.

Captainclock · #23 07-06-2015, 07:27 PM

Quote:

Originally Posted by Olorin67

sounds like if you got a picture at all, the main systems of the set are all functional, but maybe some portions are out of whack due to old caps and maybe other parts like resistors that havnt aged well. Re-capping any electrolyitcs and paper caps would be a good place to start. The set is working enough that you may be able to see gradual improvment as you replace suspect parts. If you read through the other threads mentioned above, that will give you ideas of parts that frequently require replacement in this set. Check the controls, too, a dirty brightness or contrast pot can make troubleshooting interesting... and the more aging parts you replace, the more reliable the set will be in use, hopefully.

That's what I was just thinking, probably bad electrolytics and paper caps and some bad resistors as well, which should be pretty easy to replace in this set since it has PCBs instead of actual metal chassises to work with, I also noticed that in one of the bottom vent holes I saw a pretty large selenium rectifier that could also be causing some issues...

Olorin67 · #24 07-06-2015, 07:33 PM

Yes, doesn't sound like there's much wrong with the set apart from aged components. Start with the more likely offenders, and measure resistors as you go.

Captainclock · #25 07-06-2015, 07:41 PM

Quote:

Originally Posted by Olorin67

Yes, doesn't sound like there's much wrong with the set apart from aged components. Start with the more likely offenders, and measure resistors as you go.

That's probably what I will do, the large Can caps will be tricky to take care of because they're sitting in funky locations in the cabinet as for the paper caps (which are plastic cased "good-all" caps which are notorious for going bad due to age) are going to be easier to replace and should be easily replaceable with mylar or polyester caps. the resistors should also be easily replaceable as I have a large stash of 1/4 and 1/2 watt resistors which appear to be what's mostly inside the TV. I don't have a service manual for the TV so maybe someone could dig one up for me and send me a copy. :-)

rca2000 · #26 07-06-2015, 08:09 PM

What # H-out and damper tubes does this set use?

zeno · #27 07-06-2015, 08:38 PM

Works then dont....... Do some light tapping around.
Probably a bad tube or PC connection. It would be better
to get it somewhat running 1st. That way you can test
as you go when recapping. Two big advantages:
If you make a mistake there isnt much to check. Also if
you change a cap & it makes a big change for the good
you file it in your mind for future use.

73 Zeno

dieseljeep · #28 07-06-2015, 09:36 PM

Quote:

Originally Posted by rca2000

What # H-out and damper tubes does this set use?

Horiz out is a 18A5 octal base and the damper is a 17H3, IIRC, a 9 pin miniuture The 18A5 is similar to a 25AV5.
It seems that this is the only set, that used these tubes. Two other strange tubes are 10C8 and 12CT8.
Leave it to GE, as they owned their own tube plant.

Gregb · #29 07-06-2015, 09:40 PM

By the sounds of it that set and my Hotpoint are one in the same. Those are the tubes my Hotpoint uses as well. I just have a few finishing touches and mine will be done.

Gregb

Captainclock · #30 07-06-2015, 10:02 PM

Quote:

Originally Posted by dieseljeep

Horiz out is a 18A5 octal base and the damper is a 17H3, IIRC, a 9 pin miniuture The 18A5 is similar to a 25AV5.
It seems that this is the only set, that used these tubes. Two other strange tubes are 10C8 and 12CT8.
Leave it to GE, as they owned their own tube plant.

Yeah and I tested all of the tubes in the unit except for a couple of the tubes and they all tested excellent on my emissions tube tester which means that the tubes apparently have low hours on them. All of the tubes inside this TV set are all the original GE Tubes (except for the 1V2 rectifier tube which i swapped out for a NOS Motorola 1V2 tube I had laying around in my tube stash.)