[TechAssist] Re: RCA F35731MB CTC169JS6 - Shuts off when signal source is connected.

<When it shuts off, I have to unplug the power for at least 5 minutes,
before
my standby voltages will return.>

I have that happen when the SMPS goes into an overvoltage condition or
overcurrent condition....takes time for the SMPS Ic to reset.....when you
unplug the CRT it stops the overcurrent section from activating, and since
you can run the TV WITHOUT signal practically ALL Day....I think it
eliminates the overvoltage condition.....so you are getting overcurrent at
the SMPS, and since you have a GooD Picture...it can't be the CRT as far as
I know.

You've been through this pretty thoroughly......just need to identify the
reason the PICTURE is causing your SMPS to activate overcurrent
circuitry.....how about those resistors on the SMPS output...the emitter to
ground resistors?

I'm having problems believing the X-ray sense is at fault because it DOES
run all day, but it might be triggering....but I would expect you could
unplug it....wait 10 seconds....and it would start. Not 5 minutes.....that 5
minute wait just points to the SMPS overcurrent, plus the part about the
standby voltages not coming up. X-ray won't do that to the standby
obviously....

Damon Brunger
Telrad Electronics
Fort Wayne IN
----- Original Message -----
From: "LeRoy Westlund" <llw@xxxxxxxxxx>
To: "TechAssist" <techassist@xxxxxxxxxxxxx>
Sent: Monday, May 30, 2005 7:40 PM
Subject: [TechAssist] RCA F35731MB CTC169JS6 - Shuts off when signal source
is connected.


> Hi members,
> This set will run all day with raster only. As soon as I hook up a signal
> source (Antenna, or external input), it will shut off after about 10
> seconds. Picture is beautiful, and all voltages from the power supply read
> normal, for that length of time.
> When it shuts off, I have to unplug the power for at least 5 minutes,
before
> my standby voltages will return.
>
> Parts replaced so far, with OEM part numbers :
> Regulater chopper output. (200165)
> Regulator IC (200419)
> Regulator caps. (2.2 @ 100 195691),(15 @ 63 214756),(470 @ 35 190496),(39
@
> 100)
> Horz cap (.48 @ 250 197518), CR4118 (164589), C4703 (47 @ 250).
> B+ cap (470 @ 180 200147).
> Tested luminance buffer Q2906= OK.
>
> Voltage readings:
> B+ = standby = 143.2 (Run = 138.2)(adjusted B+ standby for 140, no help).
> CR4118 = standby = 13.4 ( Run = 12.1)
> Voltage  Q4101-Base = standby = -.19 ( Run = -1.4)
>
> If I pull the CRT socket, set will run OK, and not shut-off.
> Works the same on my 27" test jig in the shop, as it does hooked up in the
> home, to the original Yoke / CRT load combination.
>
> Would it be wise to replace the IFT at this stage of the game ? Customer
> does not want to spend more then $200 for this repair. I may need to
refund
> about $100-165, that I already collected. It worked for about 1/2 hour
when
> I first took it back, but, it went out again after customer already paid
me.
>
> Anymore help on this would be appreciated.
> LLW
>
> LeRoy Westlund
> Westlund TV & Electronics
> 97 North Main                             " I forgot,..to remember,..
> Centerfield, UT 84622-0087           to forget "
> Ph./Fax  435-528-3822
> mailto:LLW@xxxxxxxxxx
>
>
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