Riddled TV Repair Forum

hmmm strange · Joined: 29 Jul 2008 Posts: 4

10 year old Zenith a27b33w TV has worked perfectly until this morning. Pressed power and relay clicked on then off instantaneously. Subsequent power button presses would repeat same cycle. Unplugged the TV and power button would not create a click within the first few seconds then same thing, relay on then off immediately.

Removed back cover and removed the layer of dust. No obvious blown components. A few discolorations on the PCB from prolonged heat. Nothing stood out, no burnt smell. Checked the bottom of the board, all traces, solder joints fine. Tested a few resistors and tested the 3 caps (500pf) across from the HOT all fine.

Plugged it back in and still same symptoms. Pressed the power button a dozen times and it came on. Perfect picture everything seems fine. Can turn it off and it will turn on the first time no problems. If I unplug it, the symptoms return. Will turn on with 30 seconds of waiting after you plug it in and a few power button presses.

Any suggestions? Anyone have the schematic for the Zenith A27B33W or similar model?

Thanks Aaron

Google

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

Aaron,
I think you may have a set that is Older than 10 years. Maybe closer to 15 Years Old. That being said, it would be very helpful, due to the age and the service bullitons available, to have you give me the part numbers of the boards in the set, mostly the deflection and the signal boards. Most of the bullitons were cataloged in this way. The part numbers are usually on a white sticker on the boards and should be in the format of X-XXX-XX Sample = 9-253-04.

Thanks

Jesse

hmmm strange · Joined: 29 Jul 2008 Posts: 4

Jesse,

Thanks for your response.
There are no white stickers on the main board. Silk screened on the board is 49-98 which could be the week/year date, as the tube has Nov 98 on it. There is also 204-3310-03 and 6CSID and GEMSTAR silk screened.

On the chassis diagram is 101-8776-01.

On a chip heat sink is
9-1999
EIA 343
9015M5 12 654

On a transformer is
9901 95-4515
EIA 343 MEX13

On the sweep transformer is
8501 FEC 25
EIA 343 MEXICO
95-4511

The CRT board doesn't seem to have a number on it. It has 3 TO220 transistors and a few discrete components.

Update: It is becoming increasing harder to get it to power up.

Thanks,
Aaron

hmmm strange · Joined: 29 Jul 2008 Posts: 4

Just want to clarify the speed of which the relay clicks on then off. Just estimating that when i first press the power button it will click on then is ~20ms it will turn off. It now takes 30 or so presses to get it to power up. As it gets closer to powering up the relay delay from clicking on to clicking off will gradually increase to ~300ms.

Aaron

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

You are right about the age, do a good visual for expanded electrolytic capacitors. Your symptom is that of a bad cap.

Jesse

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hmmm strange · Joined: 29 Jul 2008 Posts: 4

Update,

Its fixed.

Culprit was cx3416 100uf 25v cap. Tested fine with my dmm which only tests at 3v. Benched it with 20v and it was shot, a rare true leaky cap. I replaced it with a 35v cap which i would recommend.

Earlier on the repair journey, i found CX3233 47uf 160v cap with a slight bulge, and when i say slight, i mean slight. Turned out to be completely open. Replace it and now i don't have to have the brightness turned completely up.

I was up to over 150 power button pushes to get it to fire up. Makes you realize how important the TV is. I'm sure i would have pushed it 1000 times.

Aaron

GSGregg · Joined: 27 Jul 2016 Posts: 1 Location: Pasadena CA, USA

Hello! Hope I won't be banned for massaging an eight-year-old topic, but I have the same set, mfd April '98, doing the same thing (and for good measure, my SF2799Y2, mfd August '89, likewise). When the power got sluggish responding to the remote, I began unplugging when I anticipated no need for TV, but eventually the time required for firing up got so long that when it did grab, I decided to leave it on full time. That worked---for about three weeks, but now there is no sound of the relay or anything else.

As this is surely a common problem, my question isn't so much whether it can BE fixed, but rather who in the world (or, Southern California, anyway) might still bother stocking the parts. A few years ago, Pasadena's Dow Radio closed up and after a few members of a new family took turns floundering, they closed down and now serve a more limited clientele from their main store in Orange County about an hour's drive away. Oh, for the good ole days.....

If anyone can handle these, I'll get whatever help I need to get the Zeniths to the worksite Mr. Green

Thanks for reading;

Gregg