Have you ever just measured statically what's blown in a given unit, &
after replacing what you think are all the bad parts, & plugged it in &
tried it? Then it blows on plug in? Or do just know so much, it works
every time? For me, this has worked many times, because I have seen
these common faults so many times! How can I scope the SMPS when it
blows up @ plug in? The horizontal output wasn't blown, nor was the
convergence power supply! There are no fluid leaks! How can a cracked
CRT, or bad HV tripler cause this when the unit is in standby when it
self destructs? If you look on this newsgroup, you will see many, many
people who should not even open a T.V., because they obviously know
very little about these units. They could be KILLED!! You can tell by
the questions they ask! Why do you put me down rather than help? I help
many of the people here, with the focus on safety! Sorry I don't sound
"high Tech" like you, but I do this for a living, & do ok at it!

Model # P56812BL, Chassis # CTC195A2, dead with 8-pin SMPS Reg IC
U14101 TDA4605-3 blown apart, Q14101 IRF740 shorted, R14125 badly
burnt, replaced these parts, horizontal output, convergence power
supply, as well as secondary diodes in SMPS, all check fine, no other
static
shorts. Plug in unit, & instantly blows these parts again. Did I miss
something? Thanks, Dani.

Dani wrote:
Have you ever just measured statically what's blown in a given unit, &
after replacing what you think are all the bad parts, & plugged it in &
tried it? Then it blows on plug in? Or do just know so much, it works
every time? For me, this has worked many times, because I have seen
these common faults so many times! How can I scope the SMPS when it
blows up @ plug in? The horizontal output wasn't blown, nor was the
convergence power supply! There are no fluid leaks! How can a cracked
CRT, or bad HV tripler cause this when the unit is in standby when it
self destructs? If you look on this newsgroup, you will see many, many
people who should not even open a T.V., because they obviously know
very little about these units. They could be KILLED!! You can tell by
the questions they ask! Why do you put me down rather than help? I help
many of the people here, with the focus on safety! Sorry I don't sound
"high Tech" like you, but I do this for a living, & do ok at it!

Model # P56812BL, Chassis # CTC195A2, dead with 8-pin SMPS Reg IC
U14101 TDA4605-3 blown apart, Q14101 IRF740 shorted, R14125 badly
burnt, replaced these parts, horizontal output, convergence power
supply, as well as secondary diodes in SMPS, all check fine, no other
static
shorts. Plug in unit, & instantly blows these parts again. Did I miss
something? Thanks, Dani.

The question is, why I NEVER plug a unit in directly after repairing a
massive SMPS or HOT output failure.

It only took one instant failure for me. I ALWAYS use standard SMPS
live troubleshooting with a variac and controlled load. Then move to
the Horizontal output stage and install a current limiting device,
usually a 60W light bulb.

Anyone who repairs tv sets for a living is well aware (typically
learned during the training period under an experienced technician) of
these standard troubleshooting techniques.

David;

What do you know about Pioneers, I got one that is frying just like the
OP said. I've checked all the usuals, changed the opto cause you never
can be sure. The problem is that this SMPS will not start if brought up
slow on a variac, but this may be normal. No print. I am to the point
of going in sideways, and if you don't know what I mean by that, here
it is;

I am considering using substitute Hdrive from a Sencore analyst while
bringing it up on a variac slowly, to check the entire feedback
circuit. This is a PITA, I'll start another thread on it when I got the
model and all that in front of me.

Now to the original poster;

I don't think it was too cool for you to put that whole email address
in the subject line. He doesn't seem to be ****ed so I don't care, just
a word to the wise. Why ? at least make the spammers come in the group
to harvest emails. In the subject line it is right in front of them. I
hate it when an email address get screwed up.

OK, I do not understand why you replaced the convergence PS. The set
will run without it and you will get a picture. You might do well at
service, but let me tell you, when they start considering your billable
hours at over $100 you follow procedure. For TVs, especially
bigscreens, there is a procedure. This procedure is actually not
completely in compliance with Ohio law, but it must be done.

The first and foremost goal is to see a picture. Period. That is the
first thing you do, that tells you if the tubes are good, if there's
any screen burn, and the trained eye can see other problems.

Now you can do what I said earlier, sub the drive but watch the
voltage, but on a 195 that isn't worth ****.

Now you say it is blowing when in standby, that tells me that it is
overvoltage most likely, or something open in the snubber network,
which IIRC isn't much in a 195.

At $100 an hour, I'll tell you what the problem is, because David did
not get ****ed. You have a shorted 130V (or whatever) rectifier. It is
on the secondary side of the SMPS transformer. That would be the first
thing I check when I see a 195 burn down. (that's what I call it when
the chopper fries out)

Whatever switching device they use on the primary side I call the
chopper. I have simplified my thinking. The situation with the 195
chassis is this; It does have short circuit protection. How many times
did you hear one chirp and throw in a 2SC5148 and a 239111 and have the
set work ?

Well I found out why. That circuit can handle a dead short on the
output, if the highspeed rectifier is not shorted. Don't know exactly
why, but a shorted load to a good power supply can be tolerated, but
when there is a shorted rectifier it can't do it. This affects the
feedback in a way that the circuitry cannot handle. When that main 130
V or whatever rectifier is good and the set is running you can almost
take and short the HOT E to C and it will simply start working again
when the short is removed. But the shorted rectifier shunts the
transformer winding in a way the shorted load can not. See what I mean
?

In other words, if the high source (the one that feeds the fly) is
shorted it is still getting negative pulses feedback. I haven't really
studied the circuit enough to fix it or say exactly why, but I know it
is a fact. Like some other sets, ir may just be unable to oscillate at
all and winds up with class A bias. Don't think that just because there
is a heatsink that it would not blow immediately either, there is a
thermal resistance of the die to the case. When you put DC bias on a
transistor with 160V C to E it can burn up so fast the case doesn't
even get hot, and neither does the heatsink. Really, I don't know if
this is the exact failure mode, but I don't care. Get the job done.

Dude, I have not known David to ever put someone down, and that
accusation is probably your perception. If he told you not to mess with
a 195 without training or at least the manual and alot of experience in
the field, he was right. Even the 195 print sucks. Then there are all
these specifics you need to know. Wait until you get a problem in the
signal circuit of a 195, or better yet, you see a CTC211.

If David (and others) on this board told me to get out of something, I
would very much consider their advice. Sometimes there a so many
specifics you need you just can't do it. Even with a print. Not having
read the training manual is a BIG BIG handicap. Now this is coming from
a guy who has almost 30 years experience, makes twice as much an hour
as anyone in the shop (over $20) and gets perks that you wouldn't
believe. I know my ****, but I also know my limitations.

But the 195 is not beyond that. Now, if you are reading a shorted HOT
in circuit, test the thing out of circuit. I bet it ain't shorted, that
is because you are reading the diode that feeds the fly, (that IS a
coil of wire to ground) Read the pad and I bet it is still shorted, but
the transistor ain't.

I give it an 85% chance right. Thats another thing about top techs, the
owner or purchasing agent must tell the tech the price of the parts for
those times when you just can't tell, it is either this or that, and I
can't tell which. Then you learn. Sometimes it is the cheap readily
available part, other times not.

In any case, DO NOT use an ECG type replacement there, use at least a
243636, which I think is an MI-35. ECG probably still says the 580 or
whatever can replace it, but they are full of ****. It is not fast
enough. If you have any real 164589s on the shelf they will work fine
too.

Now that's the kind of **** we get paid for.I don't mean to go on
forever about this, but suffice it to say, we DO earn our money.

JURB

Umm that main diode isn't in the place you expect it, look further. The
main secondary rectifier is a common failure here, and it is a bit
offside to the power supply. There's a good chance of missing it.

JURB