[TechAssist] Re: CTC169BG5 Audio problem additional info

Were the outputs replaced Walter? I had one awhile back that had bad outputs
and the voltage on the supply was doing the same thing. Replacing the
outputs fixed the set. I think the set was shutting off, but I'm not sure.
Al Marquardt
ampm@xxxxxxx
Al Marquardt Electronic Repair
206 W Main
Girardville Pa. 17935
----- Original Message ----- 
From: "walter wood" <wwood_38478@xxxxxxxxx>
To: "Tech Assist" <techassist@xxxxxxxxxxxxx>
Sent: Friday, July 30, 2004 4:51 PM
Subject: [TechAssist] CTC169BG5 Audio problem additional info


> Recap"
> This set has a great picture, but the sound would
> go off in about 5 seconds.
> List members were generous in providing schematics.
> One tech suggested opening up the DC sense line to
> see if that was the problem.
> I unsoldered pin 16 of JS1900.
> The audio stays on longer now, but still shuts off.
> There is a slight thump in the speakers at turn on,
> but nothing unusual at all when the sound
> disappears.
> I got out my trusty Radio Shack audio signal tracer
> and I have sound on pin 7 of U1901 and U1902 at all
> times.
> This can be varied with the sets volume control as
> it should.
> Pins 2 and 4 have the required +17 and -17.
> Pin 3 shows -12.3 on the schematic.
> there is -17 there at plug in.
> That goes to -13 when sound is present, then goes
> to app. -15 when the sound disappers.
> The afore mentioned pin 16 JS1900 is still
> unsoldered.
> This might be a clue.
> When I was testing the voltages the probe slopped
> and I temporally shorted Pin 5 to 3 on U1901, and
> the sound returned briefly.
> I have to admit that I don't understand this
> mute/DC sense circuit.
> Anyone got any clues at this point?
> TIA
> Walter
>
> =====
> Walter Wood
> Future Tech Home Center
> 2786 Hwy. 43 N.
> Lawrenceburg Tn. 38464
> 931-829-3337
> Fax 931-829-4044
> mailto:wwood_38478@xxxxxxxxx
>
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