My Dad's main living room tv, a Zenith B27A11 BPC set, made in 2000, he's getting vertical foldover issues that fade after about 20 minutes of warmup. I told him about recapping, and he asked me to give it a try-recap the vertical section, and see if it works. The problem is, I can't ID what the vertical section looks like on this set. I gather it is an IC? Can anyone steer me in the right direction on this board?

If I remember right, the vertical IC should be up front right side as viewed from the rear. Change the caps around it.
Don't use the set until it is fixed as the vertical IC will fail from the caps drying out.
If the chassis is the newer, the vertical IC is directly in the middle rear. If the speakers connect in the rear it is the first chassis I mentioned.
Post a picture if you can.

speakers connect in the rear, so we are on the same page now. The yoke hooks up on the right side, so that makes sense that vert sweep would be nearby.

In the previous posting for the '95 Zenith, I saw a mention of resoldering the vert IC pins. Is that something worthwhile to do with this model? The boards look somewhat similar, although mine looks quite a bit cheaper (less shielding/heatsinking).

It's a good idea to resolder the vertical IC pins on any TV. On many brands, I've encountered poor solder connections on the vertical IC that led to intermittent problems and possible failure of the IC. They are not soldered very well to begin with and after years of heating and cooling, the solder cracks and the connection becomes intermittent.

okay, I have the board with me now. In the area where we believe the vertical IC is, here is what is in that area:

The front right has the power supply/relay circuit, and just behind that sits a large transistor on a heatsink-D2499. After that is the flyback, and we are at the back of the board. Is the D2499 used for vert output?

Another possible suspect is to the left of the fly, to the right of the audio output section, along the back of the board-a single row six pin affair mounted to a heatsink, it has about a half dozen caps associated with it, while the former D2499 has only about 3 caps in the neighborhood. Which should I go for?

The D2499 is the horizontal output transistor. The only other things that are on heatsinks are the power supply regulator IC (STR53041), the audio output IC, and the vertical IC (probably an LA78xx).

Alright, then I am after that six pin deal-I can't read the IC numbers, as the chip is held to the heatsink with a steel clip that obscures the ID number. I'll just pull those caps and get some 105 degree Nichis in their place.

The vertical IC should be 13 pins if it is the one in the right front area, viewed from the rear of the chassis. The big 6 pin sounds like a regulator in the power supply

I count 11 now-I didn't see the fully vertical pins. The IC heatsinked in the upper right- a 5 pin STR 53041. Given it's proximity to the filters, power resistors and AC hookup, I'd gather this is a regulator.

Is this vertical IC mounted nearly in the middle of the rear of the chassis?
Does it have staggered pins?

yup, it is as you described. I ordered parts yesterday.

Oh the gawd STR53041. Either it is fiery hot or get clobbered again. CRT did it. But I wondered how this happened this way. I know many other makes TVs with SMPS didn't blow up simply because the CRT is leaking too much current. How come?

Cheers, Wizard

The only thing I can come up with is that the power supplies in these sets were designed to run at the maximum operating limits. Any overload, such as a shorted CRT, will cause an excessive current draw and burn out the power supply.

When the Zenith dealer was still in business, I was getting these sets from their garbage when these sets were only a few years old. I could replace the power supply parts and the set might work for a few minutes, few hours, day, week, or month; but, the CRT would arc or short and that would be the end of it. In some of the late '90's sets, a shorted CRT would result in components in the video output circuit being damaged. I finally got to the point where I won't even take these sets in because they are so unreliable and I don't need something coming back to bite me in the butt.

I fixed the vertical issues, and hooked it up back at my Dad's last night. I had run it for several hours, cycling the power several times, before bringing it back.

My Dad called a few hours after getting it back, saying there was a purple splotch on the screen-which was not there when I powered it on for him earlier after reinstalling it for him. He cycled the power a couple times to energize the degauss coil, and the screen discolored purple and green all around the edge of the screen. I guess the degauss coil or thermistor is screwed up. Any thoughts?

I'm considering just unplugging the sets coil and doing a screen wipe with my own coil. Will the set still play with the coil unplugged?

I fixed the vertical issues, and hooked it up back at my Dad's last night. I had run it for several hours, cycling the power several times, before bringing it back.

My Dad called a few hours after getting it back, saying there was a purple splotch on the screen-which was not there when I powered it on for him earlier after reinstalling it for him. He cycled the power a couple times to energize the degauss coil, and the screen discolored purple and green all around the edge of the screen. I guess the degauss coil or thermistor is screwed up. Any thoughts?

I'm considering just unplugging the sets coil and doing a screen wipe with my own coil. Will the set still play with the coil unplugged?

It will work with the coil disconnected. The most likely problems are loose solder connections on the thermistor and/or the degaussing relay or a defective thermistor.

I'll touch up the soldering on the board before taking the coil out of circuit. Thanks for the tips.

Those thermistors were always failing in Zeniths, and we stocked them pretty deep. 63-10710 or 63-10710A, depending on chassis. (or in Zenith parts speak:063-10710). LG still stocks them, and some distributors are still stocked pretty well with them, so they aren't terribly hard to find.

Cheers,

Yup, got it open, and the thermistor had just disintegrated. I unplugged the coil, put the set back together, and wiped the screen with my degauss coil. The only thermistors I have are some CL-90s, so I'll see if I can hunt the OEM part down.