CK-2690R odd problem

[John Del]

I have this TV in the shop (don't know why the custome wants it....) with an
odd system control problem. The TV will turn on, but show no OSD, nor will it
accept any further commands, including shut off. Unplug it, and it will
restart every time from the buttons and the remote. I initally thought it was
the control IC in the front panel assy, but now think not. I've located the
data lines out of the control panel area where the control IC is, and they
continue to show what appears to be proper data to the main micro even when the
system fails to respond.

I recapped the two smps because of loud squeeling and unstable voltages, which
I thought would also correct the funky sys control. I also disconnected the
power relay, in case the TV was generating noise when it fired up disabling the
sys control, and no change. I located the tuning IC and removed it in case it
was loading down sys control when the TV was on, and no improvement. I don't
know of any other ICs that communicate with the main micro.

I don't have a schematic (no Sams and Mitsu NLA), so I have some questions.
Does this have a separate IC for the OSD that might be bad? Is there a funky
reset on the main micro that needs tripping after the TV starts? Anyone seen
this problem before? Thanks.

John Del
Wolcott, CT

"I'm just trying to get into heaven, I'm not running for Jesus!"
Homer Simpson

(remove S for email reply)

 

[JURB6006]

The SMPS running wild has blown the negative supply to the EEROM (remember
EEROMs ?, it has one)

Hidden by that cloth stuff they used to put around power resistors is one that
is burnt up. It's off a negative supply and feeds a Zener to regulate the "run"
source for the EEROM. The value is 910 ohms, but a 1K will work. You <u>can</u>
do this without a print, I figured it out without a print, and on the first one
the Zener was still good so I simply calculated a resistance that would work, I
think it was 1.5K, later with the print I found out, 910 ohms.

The Zener is a 27 or 30 volt, 1 watt max, but they usually don't fry, the SMPS
output should be about 40V on this leg, but when the cap on the primary side
goes it starts climbing to like 60-65V.

Hang on. . . . . . . . . sorry, I can't seem to get to Repairworld right now.
What I was going to do was search by solution for 910 ohm on that model. I've
done that before, the part is BUBAR and I put in the solution as the circuit
symbol # or value. Saved the cost of a print more than once, one of the cures
would probably include the Zener value or the Mits part #, and then the ECG
book is your friend . . . . .Know what I mean ?

If the Zener is fried, try a 27V.

These components are located near the middle front of the signal board, the
EEROM is a 16 pin DIP and it is near the uProcessor.

Hope this helps, if you need more post back here and I'll have a look at the
print tomorrow, then I can be more specific. Right now I'm working from memory
and my last remaining brain cell is tired.

JURB

 

[John Del]

Subject: Re: CK-2690R odd problem
From: jurb6006@aol.com (JURB6006)
Date: 1/27/04 5:46 PM Pacific Standard Time
Message-id:

Hope this helps, if you need more post back here and I'll have a look at the
print tomorrow, then I can be more specific. Right now I'm working from
memory
and my last remaining brain cell is tired.

Thanks Jeff, I should be fine now. I forgot how these antiques used a negative
supply to the eeprom!

John

 

[Shoreline Electronics]

These are the usual culprits :

D704 18v Zener, R781 270 Ohm, C955 470/25, C3z0 &amp; C952 100/50


==========================
Jeff Stielau
Shoreline Electronics Repair
344 East Main Street
Clinton,CT 06413
860-399-1861
860-664-3535 (fax)
jstielau@snet.net
========================
"If you push something hard enough it will fall over."
Fudd's First Law of Opposition - Sir Sidney Fudd


"John Del" &lt;ohger1s@aol.com&gt; wrote in message
news:20040127185224.22671.00000815@mb-m18.aol.com...

I have this TV in the shop (don't know why the custome wants it....) with
an
odd system control problem. The TV will turn on, but show no OSD, nor
will it
accept any further commands, including shut off. Unplug it, and it will
restart every time from the buttons and the remote. I initally thought it
was
the control IC in the front panel assy, but now think not. I've located
the
data lines out of the control panel area where the control IC is, and they
continue to show what appears to be proper data to the main micro even
when the
system fails to respond.

I recapped the two smps because of loud squeeling and unstable voltages,
which
I thought would also correct the funky sys control. I also disconnected
the
power relay, in case the TV was generating noise when it fired up
disabling the
sys control, and no change. I located the tuning IC and removed it in
case it
was loading down sys control when the TV was on, and no improvement. I
don't
know of any other ICs that communicate with the main micro.

I don't have a schematic (no Sams and Mitsu NLA), so I have some
questions.
Does this have a separate IC for the OSD that might be bad? Is there a
funky
reset on the main micro that needs tripping after the TV starts? Anyone
seen
this problem before? Thanks.

John Del
Wolcott, CT

"I'm just trying to get into heaven, I'm not running for Jesus!"
Homer Simpson

(remove S for email reply)

 

[Ohger1]

Subject: Re: CK-2690R odd problem
From: "Shoreline Electronics" jstielau@snet.net
Date: 1/28/04 6:40 AM Pacific Standard Time
Message-id: &lt;iRPRb.1646$P42.761@newssvr31.news.prodigy.com

These are the usual culprits :

D704 18v Zener, R781 270 Ohm, C955 470/25, C3z0 &amp; C952 100/50

Thanks to both Jeffs. The zener was in fact an 18 volt, and the resistor in
this case was open. Thanks again guys.

John