[TechAssist] Re: PANASONIC TV / CTK-2790S - HORIZ WIDTH PROB
- From: Gary McCartney <gary@xxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Mon, 18 Nov 2002 15:00:39 -0500
I have sent you some more info on a kit and parts to replace in the
regulator circuit and some other information which will hopefully help.
I had a time with one of these GL7C chassis. Good thing it was my own
set. The regulator kept popping every month or so.
Finally I found a burnt trace between a zener diode and one of the pins
on the regulator IC. I think the diode was the 115V zener if not
mistaken. There is a diode that you need to cut out and leave out. It is
D452. Below is a cut and paste of a message I once sent someone in
regard to my 31" set when I was working on it.
There is a kit available for the power supply. The part # is:
TXANE011SER1.
It is used when the IC801 regulator shorts out. Every time I've had it,
the
main fuse is also blown, so I'm not sure what your problem is if you can
get
the relay to click.
The kit consists of the following parts:
IC801: STR60001F51 regulator
R811: ERQ2CJP1R5
R831: ERQ2CKR33
D816: TVSSR2KN
D805: MA2180A
R821: ERQ12HJ1R8
R825: ERQ14AJ471
Q801: 2SC1384RS
The instructions tell you to remove D452 and leave it out, don't replace
with anything.
Check for an open circuit trace between zener diode D805 and the IC801
regulator. Pin 2 if I remember correctly.
This chassis is very bad for blowing the regulator once every month or
two.
You might find that the regulator heatsink runs very hot. As far as I
know,
there is no known cure. There have been other techs have the same
problems.
My own set lasted for 5 years fine, then trouble started. The first
thing
that went was the vertical IC, then all this problem with the regulator
circuit. I installed the kit and it lasted a month. Then I installed a
new
reg. and some supporting transistors, etc. and it lasted another month.
Then
I tripled the size of the regulator heatsink and added a computer fan to
it.
This time, the heatsink ran cool but it lasted only 3 months. After
replacing the parts, I always measured voltages and waveforms according
to
the kit instructions, and they were all bang-on. Next, I gave up on it
until
recently, when I replaced almost all the electrolytic caps on the main
board, another power supply kit, and a new HOT. I also found the open
trace
between D805 and the reg. This alone might be the clue to the repair,
because I don't know if the trace was blown all those other times or if
it
happened just the last time. After test running the set, I am now ready
to
put the back on it. Do I trust it, NO. If it happens again, I might have
a
nice 31" picture tube for sale.
******* ATTENTION, PLEASE ********
I have a new email address. Please
send all email in the future to:
"Gary McCartney" <gary@xxxxxxxxxxx>
Thanks.
Gary McCartney
McCartney Electronics
7134 Fife Rd, RR 7
Guelph Ontario Canada N1H 6J4
Fax: (519)821-1530
"fremur01@xxxxxxxxx" wrote:
>
> Hello,
>
> I have finally had some time to get this set back
> online. The power supply regulator ic801 was
> originally defective, dead set. It's working now.
>
> However, the horizontal width is inadequate, pic
> coming in on the sides as well as what seems like a
> pincushion circuit problem. I do not have a service
> guide.
>
> Anyone with literature show any case history
> for this model and problem?
>
> Item specs: PANASONIC TV MDL: CTK-2790S FCC ID#:
>
> Thanks Much
>
> Fred
> MTS Electronics
> Fayetteville, NC
> fremur01@xxxxxxxxx
>
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