Zenith B09A02X


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Zenith B09A02X

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bowdre
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Jan 17, 2003, 5:31 AM

Post #1 of 4 (3436 views)
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Zenith B09A02X	Can't Post

Hi, I have a Zenith B09A02X 9" color TV that seems to have a problem in it's horizontal circuit. I am not extremely familiar with TV repair, although I do know a thing or two about monitor repair. In any event, the TV receives audio, but there is no video, as the CRT does not power up. I assume that the TV power supply works based on the TV LED coming on (and from hearing audio); the measured TV power supply is 12V. I don't meausre any B+ going to the neck board. The fuse is intact, and the HOT looks good. I am sure that the horizontal circuit never activates because I don't hear a high pitched squeal, nor do I see that the flyback powers up. This is a fairly lightly used TV, plus it was manufactured in 1998 (not even any dust on the chassis board), so I'm wondering if maybe this is a common problem. I don't have a schematic for the TV either. Thanks in advance for your help!

Alan
TV Repair Authority

Jan 17, 2003, 8:19 PM

Post #2 of 4 (3426 views)
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Re: [bowdre] Zenith B09A02X [In reply to]	Can't Post

Bowdre
I am not familiar with that TV, but I do have the schematic for a 9" Emerson, so they are probably similiar.
The audio ccts would not require more than 12V.
Have you measured the VCC to the HOT and horz driver? The HOT should be around 130VDC and the horiz driver around 50VDC. Have you checked the HOT for proper resistance with a diode checker?
When you say that the CRT is not powered up, I assume you mean that the filaments are not lit?
I am going to the library tomorrow and will see if the Zenith schematic is there. If the Zenith is like the Emerson, it uses a scan-derived PS, but the 130V should be on the HOT whether the horiz section is working or not.
Alan

bowdre
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Jan 18, 2003, 3:12 AM

Post #3 of 4 (3421 views)
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Re: [Alan] Zenith B09A02X [In reply to]	Can't Post

Thanks for your reply. Here's what i've found in regards to the HOT. It does not test shorted. Since I don't have the schematic, I'm not sure which lead is base, emitter, collector, but on one of the leads, I read 3V, one is 0V, and one is 2V. Obviously this is not right, so perhaps there is a problem with the horizontal driver. I actually just recently had a monitor which was not getting sufficient voltage to the startup pin of the horizontal IC, so I'm wondering if maybe this is a similar problem. That monitor had a shorted diode and an open resistor which was directly in line with the startup voltage pin, but it was easier to find because I had a schematic, so if you find one, let me know which components I should pay attention to. Also to clarify, the CRT filaments are not lighting up, plus I hear no high-pitched squeal that you should hear when the horizontal circuit activates. Thanks again for your help.

Alan
TV Repair Authority

Jan 19, 2003, 12:45 AM

Post #4 of 4 (3414 views)
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Re: [bowdre] Zenith B09A02X [In reply to]	Can't Post

Bowdre
I was unable to find the schematic at the library.
You can probably get the HOT data sheet from:
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm
If it's not there, post it and I can probably get the data sheet.
It is possible that the HOT is shorted C-B or E, and took out the B+ supply (a common problem). I would test the HOT out of the circuit. In- circuit, there should be short (or near short) between the E and B as they are connected to the horiz driver transformer secondary. C-E should read like a normal diode as there is usually a damper diode built-in to the HOT.
You should be able to trace the collector lead to the flyback xfmr.
Alan

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