This 27" TV came in with the HOT (TL035) shorted, fuse OK. Replaced with
230760 (S2055N) and replaced the Flyback (LL005) 262341. The TV now has good
picture and sound. I have three questions:



1) The vertical heatsink is at 67 deg C, and the HOT heatsink is at 52 deg
C. Is this typical of this chassis?

2) I noticed if the menu is displayed on the screen, and the channel is
tuned up or down there is a momentary horz tear in the menu box. Without the
menu displayed the picture is normal when tuned. Is this normal?

3) With the set plugged in but powered off, there is a noise coming from
what seems like the switching transformer (LP003). Sounds more like sizzling
as apposed to a buzz. Should the transformer be replaced?



Thanks


--
Tony Marsillo
Nutmeg Repair
-----------------------------------------------------------------

JURB,
Thanks for the detailed response. The TV has been running for a few hours
now, and I will run it a few more days to make sure.

Thanks
Tony

--
Tony Marsillo
Nutmeg Repair
-----------------------------------------------------------------
wrote in message
ups.com...
In response to:

1) That's around 150F, doesn't seem too unreasonable. Some engineers
will want their semis warm, they get better Vbe and Vce SAT voltages.
This kinda works out in lower voltage situations where leakage is not a
big factor.They do want the HOT cooler though (which it is) because of
Dv/Dt as well as leakage, both of which derate with temperature.
Remember heat sinks work by convection usually and if it's the same
temp as the surrounding air there is no convection. I would say this is
not a cause for concern.

2) With no other problems, the tearing is also probably normal. This is
because the set is switching to a different sync phase and the bitclock
of the OSD generator can't track it perfectly. If the OSD straightens
out quickly when no signal is applied, all is well.

3) If you hear that buzz with the back off, it may be normal especially
if the set runs. Some sets that don't use a seperate standby supply may
run the main SMPS intermittently to be efficient. RCA did this with the
CTC169, and once in a great while you'd get one you could hear. Never
had to take any action though, you could only hear it at a short
distance even with the back off.

Due diligence is a bit rare these days in any field, so it is good that
you are paying attention, but I think you got a fixed unit here. Cook
it for a day, wipe it off, leave it plugged in overnight and if it
works the next morning ship it and get your money :-)

JURB

On 19 Nov 2005 11:43:08 -0800, wrote:

In response to:

1) That's around 150F, doesn't seem too unreasonable. Some engineers
will want their semis warm, they get better Vbe and Vce SAT voltages.
This kinda works out in lower voltage situations where leakage is not a
big factor.They do want the HOT cooler though (which it is) because of
Dv/Dt as well as leakage, both of which derate with temperature.
Remember heat sinks work by convection usually and if it's the same
temp as the surrounding air there is no convection. I would say this is
not a cause for concern.

I really don't like those run HOT. Vertical ICs really don't need to
be running hot since vertical design is dynamic linear regulator
design.

2) With no other problems, the tearing is also probably normal. This is
because the set is switching to a different sync phase and the bitclock
of the OSD generator can't track it perfectly. If the OSD straightens
out quickly when no signal is applied, all is well.

Tearing up stuff is normal on those ITC008. Cheap ITC008 chassis
design.

3) If you hear that buzz with the back off, it may be normal especially
if the set runs. Some sets that don't use a seperate standby supply may
run the main SMPS intermittently to be efficient. RCA did this with the
CTC169, and once in a great while you'd get one you could hear. Never
had to take any action though, you could only hear it at a short
distance even with the back off.

The ITC008 PSU run/standby modes is turned off and on via burst mode
pin on giant micro/jungle IC. When it's in burst mode it is run in
bursts of high freq. newer STR ICs (5) pin types like STRF and later
are burst type for low power standby.

Due diligence is a bit rare these days in any field, so it is good that
you are paying attention, but I think you got a fixed unit here. Cook
it for a day, wipe it off, leave it plugged in overnight and if it
works the next morning ship it and get your money :-)

JURB

Not quite done. If the ITC008 uses dynamic pincushion, the best fix
to prevent shutdowns, leads to eventual HOT failure. Also
intermittent width problems is cut both ends of thick 3 wire BF001 and
BF003 plugs, pull pins out of circuit and solder ends directly in.
Note the pin 1 and 3 is swapped.

Problem is either pins plating is not good for type of frequencies or
current types made connections high resistance or the crimp in those
plugs were loose because of wire gauge too small for type of crimp
size. It is very INTERMITTENT, just wiggle those wires and fault
disappears for days made this a dog for one who is not famillar with
ITC008 chassis.

Cheers, Wizard

Wizard,
See below.

--
Tony Marsillo
Nutmeg Repair
-----------------------------------------------------------------
"Jason D." wrote in message
...
On 19 Nov 2005 11:43:08 -0800, wrote:

In response to:

1) That's around 150F, doesn't seem too unreasonable. Some engineers
will want their semis warm, they get better Vbe and Vce SAT voltages.
This kinda works out in lower voltage situations where leakage is not a
big factor.They do want the HOT cooler though (which it is) because of
Dv/Dt as well as leakage, both of which derate with temperature.
Remember heat sinks work by convection usually and if it's the same
temp as the surrounding air there is no convection. I would say this is
not a cause for concern.

I really don't like those run HOT. Vertical ICs really don't need to
be running hot since vertical design is dynamic linear regulator
design.

I have checked all resistors, diodes and caps in the vertical ckt. The power
supplys are as per the Sams. I did go back and measure the resistance of the
vertical yoke. Sams says 13.5 ohms, I measured 3.5 ohms. Could this be a
misprint, 13.5 seems high, 3.5 a little low.


2) With no other problems, the tearing is also probably normal. This is
because the set is switching to a different sync phase and the bitclock
of the OSD generator can't track it perfectly. If the OSD straightens
out quickly when no signal is applied, all is well.

Tearing up stuff is normal on those ITC008. Cheap ITC008 chassis
design.

3) If you hear that buzz with the back off, it may be normal especially
if the set runs. Some sets that don't use a seperate standby supply may
run the main SMPS intermittently to be efficient. RCA did this with the
CTC169, and once in a great while you'd get one you could hear. Never
had to take any action though, you could only hear it at a short
distance even with the back off.

The ITC008 PSU run/standby modes is turned off and on via burst mode
pin on giant micro/jungle IC. When it's in burst mode it is run in
bursts of high freq. newer STR ICs (5) pin types like STRF and later
are burst type for low power standby.

Due diligence is a bit rare these days in any field, so it is good that
you are paying attention, but I think you got a fixed unit here. Cook
it for a day, wipe it off, leave it plugged in overnight and if it
works the next morning ship it and get your money :-)

JURB

Not quite done. If the ITC008 uses dynamic pincushion, the best fix
to prevent shutdowns, leads to eventual HOT failure. Also
intermittent width problems is cut both ends of thick 3 wire BF001 and
BF003 plugs, pull pins out of circuit and solder ends directly in.
Note the pin 1 and 3 is swapped.

Problem is either pins plating is not good for type of frequencies or
current types made connections high resistance or the crimp in those
plugs were loose because of wire gauge too small for type of crimp
size. It is very INTERMITTENT, just wiggle those wires and fault
disappears for days made this a dog for one who is not famillar with
ITC008 chassis.

This chassis (ITC008FAM) does not have the pincushion daughter board. Data
of manufacture is Aug 2004.


Cheers, Wizard

Thanks
Tony