[TechAssist] Re: Zenith SM2727RK - UPDATE

  • From: "C&W Electronics" <c_w_electronics@xxxxxxxxxxx>
  • To: techassist@xxxxxxxxxxxxx
  • Date: Wed, 17 Oct 2001 23:17:51 -0500

Chaz,
Just did one this week. Shorted: ICX3431(STR53041),Q3431(121-1264-1)/ECG194. 
Open RX3434(43 ohm 1w),RX3433(15 ohm 1/2w). High ESR on 
C3432(100uf/25v),C3434(22/63v). Cleaned CRT Guns.




From: "Chaz" <chaz@xxxxxxxxxxx>
Reply-To: techassist@xxxxxxxxxxxxx
To: techassist@xxxxxxxxxxxxx
Subject: [TechAssist] Zenith SM2727RK - UPDATE
Date: Wed, 17 Oct 2001 22:31:38 -0500


For all those following this thread: recently, I did a little more cleaning 
of the
PCB to get a better viewing of previously described burnt parts.  After 
doing
so, discovered that the diodes - CR3431 to CR3434 - weren't, afterall, 
burnt.
Just tarnished badly by the explosion from a TO-92 transistor - Q3431.  My
diode tester says they are bad.

So, what I need is at least a partial schem of the section showing the above
diodes, Q3431, ICX3431, and burnt resistor R3432.  I will attempt a repair
with replacement of these parts, depending on cost/avail. of STR53041,
without CRT connected.  If the board then functions, it gets my other CRT
with it and hopefully returns to service.  If not, this project will be 
dumped.

Thanks to everyone who has offered suggestions so far and/or further
continues to offer help.

Thanks in advance.
Chaz
-------

 >
 > Late yesterday, I recieved a hi-fi Zenith TV that had been hit with 
lightning
 > (SM2727RK).  I checked everything on Tech- Assist, even for close 
numbers,
 > and found nothing.
 >
 > Visual inspection shows blown FX3401 fuse, and what looks like the p.s.
 > bridge of diodes (burnt) close to the ICX3431 (I believe) STR???? 
regulator.  I
 > can't read anything on these diodes nor make out well the PCB location
 > descripts.  I also suspect that the STR4400 (not able to read well 
either) volt-
 > reg is shorted - ohming it says so anyway.  Without knowing what these
 > parts are, and resourcing cost of regulator, I can't do much with it 
right now
 > w/o chancing more part damage.  Customer wants it fixed but also is a 
little
 > short on budget.  Anyone have any ideas, schem, or tips on this.  Part
 > descriptions would be a big help to start with.
 >
 > I'm not sure of the chassis number for this but, the only label I found 
in the
 > unit shows SM2727Rk  EU-593  F49702  (numbers under each other).
 >
 > Customer had said before it got hit with lightning, that the video would 
go out
 > (white screen) and after powering off to cool down, the video would 
appear
 > again.  He said he "just lived with it until this happened".
 >
 > Thanks in advance.
 > Chaz
 > Help make your TechAssist online repair tips
 > database better!  Submit your fixes here:
 > http://www.circuitwork.com/techassist/tip/#tips
 > To unsubscribe write to:
 > techassist-request@xxxxxxxxxxxxx
 > with  unsubscribe  in the subject line.
 >
 >


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