32" Citizen CRT TV Cuts Out and Won't Come On

[canadaboy25]

Hey guys, I have a Citizen 32" CRT TV which is causing me some trouble. The model number is JCTV3210 and the chassis number is C-251. The date of manufacture is 1989. The TV used to come on and work fine for a while but then it would turn of and come back on while sounding sort of fizzy. Now it wont come back on at all but you can hear the main power relay clicking when you press the power button. Nothing looks seriously wrong inside except for some slight discoloration on one part of the board. Percussive maintenance doesn't seem to have any effect. I have looked but been unable to find any schematic or service manual for this TV.

I have uploaded a short video to my Google drive of the issue in action --> https://drive.google.com/file/d/0B6X...ew?usp=sharing You can see that at some point in the video the STEREO and SAP indicator lights are flickering and flashing on and off at random which doesn't seem very good. My apologies for the excess background noise. The moment I finally caught the fault on camera, the lawn mower pulls up behind me

[dick_barton]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

You need to post good photo's of the circuit boards. I would suspect that your capacitors have dried up on the power supply with the set being that old. Perhaps some of the solder joints on the PSU would also require touching up.

[R_J]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

Yes check the caps in the power supply, a lot of times its the small ones that give problems, between 1 and 47 uf usually around 50 volts or less and they usually don't bulge or look bad. also one to replace is the one around the horzontal drive transformer (it could be around 1-4.7 uf maybe around 100v or more)

[canadaboy25]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

Here are pictures of the boards. Where would the horizontal drive be? Sorry I have no experience with CRT's.

[canadaboy25]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

Well I replaced the 3 smaller capacitors on the left of the power board (3rd picture) because I had them on hand and still nothing.

[Andrew F. Ali]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

See if you have B+ to the FBT. Test the Horizontal Drive transistor. See if you are getting voltage at the Collector and 0.3Vdc on the Base of this transistor. Yes as the previous posts say....check or replace those e-caps on the Primary Power Supply.

[R_J]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

Just checked my old records, I repaired one jctv3210 back in 1995 Do I remember what I did to it... Noooo

[canadaboy25]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

I tested all of the pins on the flyback transformer and the pins of what I'm assuming is the horizontal output transistor?? I've attached pictures of the board and a list of the pins and their voltages. The transistor I tested has the collector tied to pin one of the flyback transformer. Is this the right one?

HV-147v
AFC-0v
123v-143v
16.5v-0v
ABL-23v
25v-0v
175v-0v
heater-0v

E-0v
C-147v
B-0v

[Andrew F. Ali]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

It would seem you don't have Horiz Oscillation from the Main IC to the Base of the Horiz Oscillator Driver Transistor (may be a small transistor 2SC-XXXX) The Collector voltage may be around 120Vdc.

[canadaboy25]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

It would seem you don't have Horiz Oscillation from the Main IC to the Base of the Horiz Oscillator Driver Transistor (may be a small transistor 2SC-XXXX) The Collector voltage may be around 120Vdc.

The horizontal oscillator driver transistor is oscillating and the signal is reaching the small transformer that drives the horizontal output transistor. (Not sure of the name) I have verified this with an oscilloscope. The small transformer is receiving 150v and oscillation on one winding. This winding measures 0.2 ohms. The other winding is connected to ground on one pin and the base of the horizontal output transistor through an inductor on the other pin along with a small ceramic cap. Strangely that winding has from 400k to 500k ohms of resistance. I took the same transformer out of another TV that I have and the winding measured 25 ohms. I removed the horizontal output transistor and powered the TV up and still no signal was getting through the transformer. 500k ohms is much to high for the winding on that transformer isn't it? If that transformer is indeed bad, why would the TV work for a few seconds once in a while? Or am I completely off base and that is the correct resistance for that transformer?

[Andrew F. Ali]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

OK...So then You have B+ on the Collector of the Horiz Output Transistor, and to the Flyback Transformer. You also do have Horiz Oscillation and you determined that the Regulated Primary power supply is good (all E-caps tested OK). I would check any low Ohms resistors and Diodes stemming from the Flyback Transformer secondary pins and if those are good I will say the Flyback Transformer is BAD.

[canadaboy25]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

OK...So then You have B+ on the Collector of the Horiz Output Transistor, and to the Flyback Transformer. You also do have Horiz Oscillation and you determined that the Regulated Primary power supply is good (all E-caps tested OK). I would check any low Ohms resistors and Diodes stemming from the Flyback Transformer secondary pins and if those are good I will say the Flyback Transformer is BAD.

I'm a little bit confused. Why would a bad flyback transformer cause no signal to reach the horizontal output transistor. I've attached a picture of a horizontal output circuit with my values drawn on. I also removed the horizontal output transistor and turned the TV on to make sure that the transistor wasn't somehow pulling the signal down. Even with no transistor the output of the horizontal drive transformer was absolutely nothing. Shouldn't I get a signal to the horizontal output transistor even if the flyback is bad?

[Andrew F. Ali]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

No you wouldn't 'see' any thing there, just yet. Make sure you are seeing approx. 0.3-0.5Vdc on the Base of the Horiz Driver Transistor. Also, the X-ray Protect cct may be keeping the set down if it is faulty or really seeing a problem. If you do have 0.3-0.5Vdc on the Base of the Horiz Driver Transistor, the pin off the Main Chip would have a 10uF 50V e-cap to Ground that is fauty. Try a TEMPORARY connection to ground on the X-ray Protect pin and see if the set turns ON. If it does shutdown the set immediately and trouble shoot that cct. If not get a new Flyback transformer.

[R_J]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

I just checked a Horz. drive transfomer I have and the primary dc res. is about 6 ohms, the secondary reads less than 1 ohm. If your drive transformer reads what you posted then the secondary is open.
I checked an older Sony chassis and the drive transfomer is P: 100 ohms S: 2.5 ohms

[R_J]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

I just checked a Horz. drive transfomer I have and the primary dc res. is about 6 ohms, the secondary reads less than 1 ohm. If your drive transformer reads what you posted then the secondary is open.
Is tha a round transformer or a square one? sometimes they have holes for mounting either one, find a junk chassis and see if it has one similar you can try.
Replace that C2 as it is common to go open.

[canadaboy25]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

My x-ray protection isn't activating the voltage is at 0 and shorting to ground does nothing. I am 100% sure that that is the correct reading on the transformer because I took it off of the board and measured it several times. It is one of those little round transformers where you can see the windings on the outside.

EDIT EDIT EDIT: Sorry guys stupid mistake!! I say that I'm 100% sure and then I realize that I'm wrong... The primary winding is the one that is open not the secondary. I don't think this is too big of a mistake because neither winding should be open. I was looking from the top of the board and got it backwards in my head.

I've attached 3 waveforms saved from my scope. The first one is the base of the horizontal oscillator transistor. The second is the input to the primary winding on the horizontal drive transformer. The third is the output on the secondary winding of the horizontal drive transformer. It is pretty clear that the transformer isn't passing the signal through because it has 150V and the oscillation on the primary winding but nothing on the secondary.

Sorry for the mistake!

[canadaboy25]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

Well here's a picture of the suspect. The glue on the side of it looks discolored due to heat. Is it possible that it failed due to overheating? This makes me hesitant of trying another transformer because the only other one I have is from a working TV and I don't want to blow the ass out of it. I'm tempted to just unwind the thing and see if the wire is broke.

[R_J]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

Thoese where a peace of shit, I replaced a few of them. The fact the primary is open and the secodary is still ok is good, as when the secondary goes open the horz. output transistor usually shorts. If you have access to some other tv boards you might be able to find one, does the pc board have the other holes to mount the square type transformer, some had both sets of holes.

[canadaboy25]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

Well I decided to go for broke and bodged in the transformer from my other working tv set and it fired right up. The color is a little wonky on the edge and the picture is a bit smeared but at least I found my fault. The board does have 5 holes but they didn't line up at all with the other transformer so I had to use wires. Now to find a replacement transformer. I'm assuming that is not the type of thing you can go buy a replacement for.

[canadaboy25]

Re: 32" Citizen CRT TV Cuts Out and Won't Come On

Well I did a very dodgy repair. I unwound the primary winding on the transformer, all 51 turns of it, and took the wire off. I then peeled back the isolation tape and while I was doing that the base cracked in half and the core fell off. I found the ends of the secondary winding and the one going to the inside was very very short. I tinned the wires and sure enough there was 68 ohms of resistance. I then Krazy glued all three pieces and took a small strand of copper, attached one end to the post and painstakingly soldered the other end to the winding. For the other end I just unwarpped one turn and soldered it to the post.

I used some scotch tape as an insulator and started winding the primary. When I was done I was worried that it was too loose. I put it in the tv anyways and it seemed to work because I could hear the high pitched whine but there was no picture. I took the transformer off, unwound the primary, and then rewound it much tighter and in a more uniform fashion. I put it back in and surprisingly enough, it worked! All the colors were back to normal as well. I don't imagine this repair will last for very long but at least it works while I find a replacement.

Thanks for all the help in tracking down the issue to everyone!