Blank TV Screen With Sound

Please direct me in solving this problem. I'm trying to repair a Zenith TV service model sm3457rk8 made in 1999 I have to say that I haven't found any information on that model what I did find was model sm2789bt8 which is almost identical, because there are two separate boards in the set; sweep and main. The fuse that blows is on the sweep board fx3403 the set has sound but not a picture and only picks up the local PBS station with cable connection.Changing channel does nothing.I believe there's a short somewhere but with out necessary equipment I cant pinpoint could you point me in the right direction? Could qx3208 need replacing or IC2100 please help

by replacing the sweep module will most likely repair the problem.although they can get exspensive if its available.does the fuse blow right away when you plug it in.then it would be a shorted horiz out put usually the big transistor on the heat sink.or primary side of power supply. if the fuse blows when you hit the power button then its ussually on the secondary of the power supply(transformerside) maybe bad diode.these boards are very hard to fix even for exp. techs

Thanks for the response. I will have to check to see if it blows before or after.If a heat indication(browned from heat) is evidence of a burned out diode I have that on the horizontal side near the the heat sink where the fuse has blown. Not certain though because its a diode

I have been repairing t.vs for 25 years my first t.v was a tube t.v. I repaired.when components get burnt on the board the best thing to do is replace the board.if you do not have trouble shooting exp.and schematic.and time chances are that its either not repairable or going to take a long time.

Nice you are right there hitting the nail on the head and I appreciate your advice. One thing that has me stumped is on the sweep board Diode CR3409 is the one showing signs of heat only there. (circled in picture) The other question is the heat sink module the arrow points to is that the sweeps module you mentioned? Trust me all this help is greatly appreciated though I know It can seem that its not at times. You are a God among laymen thanks again for your assistance In addition I check the diode and there is no reading on the meter when the positive test lead is on the anode side I feel it should be replaced, agree? have a board from another model for spare parts

yes you should get some kind of reading but depends on the circuit.you can unsolder one side and pull that side up from the board and recheck diode.I use the diode scale on my meter and one side should be around .440 and the other side shold be around 1.30 or higher.not sure on the ohm scale what it should measure but as long as positive side of lead clip is onbar side of diode and it is not shorted it is probably good.byt if you have one by al means re can replace it.if the board is a little brown in spots thats o.k that just means that circuit runs a little hotter.check for loose connections were you see brown spots from heat.good luck