10HE Portacolor problem - Videokarma.org TV - Video

legenbass77 · #1 01-01-2014, 10:10 PM

Well I got ready to watch a movie on my Portacolor, but unfortunately the picture never came up. I did hear the high voltage come up, have sound, but no raster at all. Static on the screen felt normal, but don't have a high voltage probe to confirm. All tubes filaments are lit including the crt. I can hear the vertical circuit running, because I can hear it change when I turn the V-hold through it's range. I thought maybe I turned the brightness down while dusting, but that did nothing. Wiggling the tubes did nothing. No strange smells, or burning smells. Set worked great last time I used it about a month ago, and didn't even do the color change problem. Seems like something went open. I don't have a schematic. Any help would sure be appreciated.
Thanks!

Electronic M · #2 01-02-2014, 03:29 AM

A way to test for HV is to try and draw an arc off the HV line at an exposed point(HV rect socket in HV, cage or unplugged suction cup). Depending on the set 1/4" to 1.5" should indicate decent HV.

If there are any TV repair shops in your area that service CRT sets you might be able to talk them in to letting you borrow their probe or having them measure the HV.

I have a portacolor and a copy of the sam's so I'll try to get you the CRT voltages tomorrow afternoon.

***Kamakiri*** · #3 01-02-2014, 06:49 AM

I never felt comfortable doing that, myself. I picked up a neon bulb from Radio Shack, clipped the leads short, and taped the leads to the body of a bic pen, with the refill and guts removed. Put the neon bulb near the flyback or HV anode, and if there is HV, the bulb will light.

Electronic M · #4 01-02-2014, 01:56 PM

On the HC chassis HV should be 15-18KV with 16 reccomended. Cathodes should be at 220V, grids at 175V, Screen grids 530-600V (though from the wiring it looks like they can be set between 270-670V). The focus is listed as DO NOT MEASURE and is connected to either ground, 270V, or the 670V boost.

The neon test is great if you don't have the nerve for the arc test or if your set has a fairly low HV, but I like the arc length better as I can get a quantitative measure of voltage based on arc length VS arc length of a known votage...My HV meter is DC only so I can(and had need to) guage an AC high voltage by arcing a known DC voltage and comparing arc length.

Good luck getting it going.

legenbass77 · #5 01-02-2014, 06:23 PM

Ok so I pulled the cap off the hv rectifier tube, and got a pretty healthy arc. Not much room to move the cap in that little cage, but I could get a good half inch arc moving the cap away from the tube before it would start arcing all over the place. Now on measuring the cathodes, grids, and screen grids. Which color wire corresponds to each tube component to be measured? I sure don't want to mistakenly try to measure the focus wire. I did use the neon bulb test too. The neon lit up in the hv cage area, but not outside leading up to the anode cup. It barely lit up when I touched it to the tripler. Could the tripler have failed? Thanks for the tips so far.

DaveWM · #6 01-02-2014, 06:52 PM

neon will not light up around the anode, needs the AC not the DC. It may flash but will not stay lit. It could be a bad HV rectifier tube. I would just pop for a HV probe, if you are going to own vintage TV's you need to learn how to work on them and the tools to diagnose problems. If the HV is not there and you have a good arc at the plate cap of the HV rec tube then a good chance the problem is the HV rec tube.

There is no tripler used on tube portacolors, maybe a focus divider if you have the high voltage focus set. should not lite up around that either, again DC.

neon should lite up around the horz out tube, the top of the HV rec tube and anywhere near the fly.

If HV is there, I would look at the CRT pin voltages as mentioned for where to look next.

Not sure about this, but on reg color sets you need the focus voltage or the raster goes away. With the high focus voltage PC's maybe the same in which case you will need to confirm there is focus voltage at the CRT pin (if the other CRT pin voltages look good). I use a simpson 260 5000vdc to check focus voltages. you can also use the HV prob as well for focus, just not as good resolution as the simpson.

IF focus voltage has gone away, then I would look at that divider off the HV anode.

zeno · #7 01-02-2014, 07:09 PM

The black block with red & green wires sure looks like
a focus divider. Newer PC did have a high focus jug.
So I would be suspect about the focus voltage from Sams.
Hows about putting up the model # may be more than one version.

73 Zeno

legenbass77 · #8 01-02-2014, 07:28 PM

Model number is WAHE5223RW! The lack of voltage around it up to the anode sure caught my attention. Is this a fairly common failure mode for the focus divider to be working with no symptoms of imminent failure to be dead next time the tv is powered up?

andy · #9 01-03-2014, 11:12 AM

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legenbass77 · #10 01-06-2014, 02:28 PM

Ok back on the 10he with some voltage updates. I found, and bought the sams! Now the voltages I have checked: 665v boost off pin 3 of the flyback. I'm getting 7.4 ohms across pins 3-6. Checking voltages on the blue, green, red triple pot test point "1" B+ on the sams I have 273v. On test point "42" boost I have .02 volts, so looks like my boost is disappearing. I cut the .1 mfd @ 1000v out of the circuit, and subbed a new one with no change in operation. I also checked voltages on the 11bt11 according to the sams pin 2 should be 80v, I have 89v. Pin 11 -5v, I have -205. Pin 10 125v, I have 145v. I have the tv in direct sunlight, and can see tin whiskers around the pots. I guess taking them apart, and cleaning may help?

DaveWM · #11 01-06-2014, 02:44 PM

I would suggest you do some continuity checks from the output from the fly to the boost side of the pot. look for continuity from thru the circuit and look for shorts to ground. something does not make since since 0v at point 42 would tend to indicate a short which should kill the boost a the fly (assuming you have continuity from the 0v test point back to the 670v boost point.

legenbass77 · #12 05-26-2014, 08:28 PM

I decided to finally get back on the Portacolor this week. I replaced the .039mfd @125v capacitor with a safety capacitor, which I believe now to be the original failure. I did see where the smoke was let out. Also the .1mfd @ 1000v, and the .047mfd @ 630v. Still no go, now no high voltage at all, and the horizontal output tube was red plating. Finally I noticed the high voltage adjustment pot was laying down on the chassis, so gently stood it back up, powered on once more and it actually came back to life! Must have bumped into the pot while checking voltages earlier in the year. I've been running it for about 3 hours, and it's settling down nicely!

user181 · #13 05-31-2014, 12:07 AM

Quote:

Originally Posted by legenbass77

I decided to finally get back on the Portacolor this week. I replaced the .039mfd @125v capacitor with a safety capacitor, which I believe now to be the original failure. I did see where the smoke was let out. Also the .1mfd @ 1000v, and the .047mfd @ 630v. Still no go, now no high voltage at all, and the horizontal output tube was red plating. Finally I noticed the high voltage adjustment pot was laying down on the chassis, so gently stood it back up, powered on once more and it actually came back to life! Must have bumped into the pot while checking voltages earlier in the year. I've been running it for about 3 hours, and it's settling down nicely!

I'm glad to hear your good news. My PortaColor has almost the identical problem. What are the reference designators of the capacitors you replaced? Did you have to replace anything else, or was the cure just those caps?

legenbass77 · #14 05-31-2014, 04:27 PM

Quote:

Originally Posted by user181

I'm glad to hear your good news. My PortaColor has almost the identical problem. What are the reference designators of the capacitors you replaced? Did you have to replace anything else, or was the cure just those caps?

Thanks! I'm happy to have this going again. The .039 @125 volt cap on the power supply board was burned open. I'm positive that was my original problem. The three replaced were C401 .039mfd@ 600 volts according to the Sams, while the set had .039 mfd@125 volt. I replaced with a safety cap .047mfd @275 volt, closest value I could find and it's working fine. C212 .047 mfd@ 400volt, and I replaced with a .047mfd @630volt. C268 .1mfd @ 1000volt, and I replaced with exactly the same value. The set in the Sams is laid out a bit different than my set, like it shows C268 down by the flyback, mine is under the power supply board on a terminal strip. My second problem was the high voltage pot (R273) shorting on the chassis. I must have bumped into it, and laid it down while checking voltage on the flyback back when the failure occurred around the first of the year. I walked away from it for a few months, and finally decided to give it another try. So the three caps, and bending the high voltage pot upright got mine going, nothing else had to be done! I got the caps from Just Radios while I was ordering for my Admiral 19A11.

user181 · #15 05-31-2014, 09:05 PM

Thanks for the information, and especially the annotated photos! My set has an H4 chassis and I believe predates the HE. There are some board and component layout differences, so perhaps the later chassis made some improvements. I still like to know the details of your repair, and can compare it to mine.

Until my set failed this past November, it was in regular use, decked out with a DTV converter, DVD, VHS, and a Roku.