Toshiba CZ32V51 - vertical hold issue

[The Robman]

I have a 32" Toshiba CZ32V51 TV that dates from around 2000 or so (I forget exactly when I bought it). The vertical hold has started to have intermittent problems, sometimes the screen will reduce to just a horizontal line and sometimes it will go completely black. Whenever this happens, we will turn the set off, wait a few seconds, then turn it back on and all is fine again.

Obviously I'm concerned that one day it will just die completely.

So the question is, is this something that I can fix myself (and if so, how) or will it require the services of a TV repair guy?

[jimdunn]

If you've already googled the problem, you may well have found this:
http://www.fixya.com/support/t180135-to ... deflection

Usually the solder joints on the vertical output IC crack and the little pico-fuse opens. Resoldering the IC and replacing the pico fuse should bring the picture back. If you have never heard of these parts before and have no idea how to find them, then allow a qualified tech to handle it for you.

Probably of limited help, since it's not quite the same model number, and absent a schematic doesn't tell you where to look for the vertical output IC or the fuse.

But it sounded similar enough to your problem to be worth a mention.

[zaphod7501]

ditto "jimdunn". Vertical output ICs coming unsoldered is almost a universal occurrence. I have not seen any fuse failures myself but that could happen, however most sets just used current limiting resistors rather than fuses.

If it is still coming and going, then there are probably no components needed. The chip is pretty easy to ID. It's going to be a 7-10 pin inline chip mounted on a heat sink near the connector going up to the yoke on the neck of the picture tube.. There will probably 2 that meet this description. The other is the audio output IC.

Toshiba does have a unique vertical failure problem when the picture "folds over" at the top or has reduced height. This is a capacitor failure and (on Toshiba Only) it is caused by two or three capacitors that can be identified by their color. They are brown or red-ish rather than gray. One is located by the video processor chip and the other(s) are near the vertical output IC.

[The Robman]

I finally got around to pulling the TV out and am ready to start working on it. Here's what the circuit board looks like (click to enlarge):



I'm guessing that the heat sink in question is the one in the lower right corner (though I haven't looked to see what's under it yet). Does that sound right?

[zaphod7501]

Looking at the picture as oriented, and saying that the high voltage transformer is in the lower right corner, the heat sink closet to it (to the left) is the horizontal output transistor. The heat sink next to it (further to the left) is probably the power converter IC. (inside the section screened off, the board possibly labeled "Hot")

The vertical output is probably almost dead centered on the board, where the IC cannot be seen in the picture because it is facing away.

The green and yellow wires on the connector going up to the yoke are the Vertical leads, the red and blue are the horizontal; so you can look at the copper traces on the bottom of the board also to see where they go to.

[The Robman]

Here's a couple more shots, one from the other angle and another from on top.




and here's the screened off area (under the twisted colored wires):

[The Robman]

I just a closer look at the center of the PCB and the one chip that I circled in red above is most definitely loose, so I will try re-soldering that one tomorrow.

[zaphod7501]

Vertical output ICs are usually mounted on good sized heat sinks.
The poor solder connections are often not visible without magnification.
I'll check and see if I or a friend has a manual for this model as soon as I can.

It is always possible that the set uses a pair of vertical output transistors instead of an IC but that would be unusual.

[The Robman]

This chip that I found that is loose, has 3 pins and a wider leg (that I assume is just there for physical stability). There's no question that this chip is loose as it wobbles and I can clearly see the solder is bad without a magnifying glass.

However, that doesn't mean that there isn't also an issue with another IC.

[zaphod7501]

In order to track down a service manual, I need the chassis number. My friend referred to a "TAC" number. Their manuals were issued by chassis rather than model numbers, making locating the right one difficult.

[The Robman]

Where should I look for it, and any idea how it would be labeled? (ie, TAC, number, chassis number, etc)

[The Robman]

Here are the only numbers that I could find (the obscured number is 18139218129):

[The Robman]

I've soldered the transistor that was loose and I think I spotted the IC that Steve was talking about right next to it (it's a Toshiba TA8427K) so I re-soldered that one too, and so far so good, it looks like it's working.

[zaphod7501]

I'm really not sure where the chassis number is located. My friend is the Toshiba specialist. He worked for a large service company that shut down a few years ago and he retained a lot of manuals. He now works on the office build-outs around my office complex.

That IC is a vertical output chip.

[The Robman]

So that is the chip that you were talking about. I'm going to leave the set downstairs for a bit so I can see if the problem starts up again, but so far so good. As always Steve, thanks a lot for all your help.