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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
Zenith SR2549S flyback problem

 
 


007dust
New User


Apr 18, 2007, 6:31 AM

Post #1 of 5 (1981 views)
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Zenith SR2549S flyback problem Can't Post
OK, I did a basic search and found nothing on this matter so...
Product:
Zenith model # SR2549S (1996 model, 25")
When I power up I only have a thin vertical line (still colored). I pulled the cover to check things out. Naturally, the first thing I did was immediatly try to discharge the flyback. Nothing, no voltage.
Common sense puts 2 + 2 = "Here's your problem". The question I'm presenting is, is this likely the only problem or is it likely something else went with it or caused it to go? I found a new replacement (part# 95-4430-01) for like $16.95 + shipping, so the investement would be minimal. But I don't want to waste my time on this aging TV for nothing when I can pick up something new for a resonable price.
I don't really have anything to test with and I'm not taking it to a shop. So if I can't do it myself, cheaply, then I'm not going to bother.
Any input is very much appreciated!!
Thanks,
Lug
Money can't buy happiness -- but somehow it's more comfortable to cry in a Porsche than a Kia.



rrobor
Veteran

Apr 18, 2007, 8:49 AM

Post #2 of 5 (1975 views)
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Re: [007dust] Zenith SR2549S flyback problem [In reply to] Can't Post
Sorry you are not talking common sense, you are talking you dont know. First vertical is top to bottom, I know this sounds condescending, it is not, as I cant see I have to be sure you know the difference and as Im going to talk about horizontal scan issues it becomes somewhat confusing. You have no horizontal scan but you have EHT. Forget about discharging the flyback, there was no voltage there its on the cap on the centre of the tube, dont remove that and all is OK. You have a very simple fault, 99% its a bad connection. Look at the coils on the tube neck, there is a lead from that with 4 wires, go gown to the board and check the socket that plugs in to. Next there are large capacitors, check they are OK. But do not get the part you think, it aint that.


shadetree
Veteran

Apr 18, 2007, 2:43 PM

Post #3 of 5 (1969 views)
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Re: [007dust] Zenith SR2549S flyback problem [In reply to] Can't Post
resolder the pins on the vertical output ic


mel
Veteran

Apr 18, 2007, 6:36 PM

Post #4 of 5 (1964 views)
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Re: [007dust] Zenith SR2549S flyback problem [In reply to] Can't Post
I have found that it is common for the fusible resistor feeding B+ to the vertical IC to randomly open. I don't have a schematic for that specific model but it is probably a 1/2 ohm resistor off of pin 9 of the flyback. Check to see if you have 23 volts on pin 10 of the IC (assuming that it is a TDA8174). If not, trace the circuit back to the IC and see where the open circuit lies. Also, check the IC to make sure that it is not shorted causing the resistor to blow.


007dust
New User


Apr 19, 2007, 10:10 AM

Post #5 of 5 (1958 views)
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Re: [mel] Zenith SR2549S flyback problem [In reply to] Can't Post
Great advice, thanks, even to the ever so charming rrobor. The tube neck coil connections are all fine and clean. I found no problems there. I coudn't find any capacitor issues visually either. However I did look around and found 2 badly burned and completly lose resistor solder joints on the tube PCB. The resistors appear to be ok, but I didn't pull them (I know, I should have). I cleaned everything up and resoldered them. Of course this didn't work, but I'm figuring it may have led to or contributed to the problem. I've included 2 pix of the bad spot, you can see the discoloration of the board from the heat. I'll checkout the ideas from the other posts and see what I can come up with on the rogue resistor your talking about.
Thanks again,
Lug
Money can't buy happiness -- but somehow it's more comfortable to cry in a Porsche than a Kia.


(This post was edited by 007dust on Apr 19, 2007, 10:14 AM)
Attachments: Resistor burn.jpg (50.0 KB)
  Resistor burn II.jpg (55.7 KB)

 
 
 


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