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Mitsubishi cs-2710ra vertical problem

O

Ohmster

Jan 1, 1970
0
Actually an ESR meter will not identify all or even most of the bad
caps in this set. Some will have high esr, most will be physically
leaking electrolyte, and some will be low in capacitance. This
problem may be caused by leaky caps at the vertical output IC and/or
in the 12V supply. Ther will be at least a dozen more that need to be
replaced or more problems will be occurring soon. The circuit traces
that are corroded from the electrolyte leakage will need to be
repaired and all of the residue from the caps will need to be washed
from the board. We fix these all the time and they are a "pay me now
or pay me more later deal." We don't even touch tem if the client
does not want to pay to have all the bad or failing caps changed.
Just fixing the vertical circuit is a sure way to get a recall in a
few weeks or months with an unhappy client.

Leonard

Leonard is right. Old Mitsubishi televisions have a gorgeous picture tube
and last a long time, but after 10 years, the electrolytic caps go bad by
the pound. You have to replace a lot of them, clean up all the crap on the
board around where they leaked, repair the traces of foil where they
corroded, and replace any parts that got wiped by the leakage, if there is
any. But if you do all of that, the television will come out really nice
and you will have a good TV. The only sets really worth this much trouble
are the really big picture tube ones like 35" and larger (They made a super
fantastic 40" CRT set.). A 27" set might not be worth this much trouble
unless you are doing it as a hobby and have plenty of time to kill.
 
O

Ohmster

Jan 1, 1970
0
You can get it from Mitsubishi, but it will likely be a waste of $$$.
It will not tell you how to fix the set.

Leonard

He is right, look for the bad caps. Buy an ESR meter and use it, it will be
well worth the money. I think that MCM has a nice one, get the one with the
analog meter on it, much better than those darned LED ones. I think that
Tenma (Really cheap brand.) has one that is actually pretty good. The only
thing that I don't like about it is that the analog meter is not well
damped, the needle swings too freely if you ask me but this is a personal
preference and does not really render the meter less worthy.

To use an ESR meter, unplug the set and then touch the meter leads across
electrolytic caps. A large swing on the needle means that the cap is
probably good. A small swing of the needle or no swing at all means that
the cap is way dried out or open. Small value electrolytic capacitors
(4.7uF or smaller) will give only a small swing on the needle anyway. Learn
how to use the meter and what to expect by testing it on some new caps. Try
a small one, 1uF, a larger one 10uF, and two larger ones 47uF and 100uF so
that you will know what to expect of the meter.

This meter works in circuit with no power on the set. This test will not
positivly indicate bad capacitors. A shorted capacitor or one with a very
low resistance across it, say a coil or low value resistor, will show up
the cap as being good. Remove cap from circuit to double check anything
suspicious.

Oh, I found the cheap meter for you at MCM electonics, here is a link:
http://tinyurl.com/qa447

It cost $125 and is actually quite good. Buy this meter, it is worth it.
Just to show you, MCM has two other ESR meters prices at $549 and $769 so
for the $125 that they want for this very much working ESR meter, you can
see that it is well worth it and comes with an analog meter. What could be
better? Go for it.
 
L

ladybug

Jan 1, 1970
0
I don't want to buy ESR meter for one time repair. I used to work with
electronics a lot but now I switched to software and don't touch this
anymore. This was my kid's TV and it worked flawlessly for almost 15
years. I desided to give it a shot but don't know if it worth my time.
Do you suggest not to mess with it any longer and get a new set? I can
get 27" tube TV set for under $200
 
O

Ohmster

Jan 1, 1970
0
I don't want to buy ESR meter for one time repair. I used to work with
electronics a lot but now I switched to software and don't touch this
anymore. This was my kid's TV and it worked flawlessly for almost 15
years. I desided to give it a shot but don't know if it worth my time.
Do you suggest not to mess with it any longer and get a new set? I can
get 27" tube TV set for under $200

Oh, sorry. Well, the people in here gave you good advice. You will be
changing a lot of electrolytic capacitors. The only practical way that I
know of to locate them all is with an ESR meter. You could also try
bridging the caps with a similarly sized electrolytic capacitor (Observe
polarity) while the set is running to see if it improves the situation.
This is an "Old Time Practice" that worked. It is not as easy as the ESR
meter and if you have several bad caps, then this method may not work for
you. If you have a meter that measures capacitance, you could take each
capacitor out and measure it, replace any that are not up to par, and move
on. Cleaning and repairing as you go.

No, this is not worth your time if you ask that question. By all means, buy
the new set and be done with it. You have a 15 year old television and even
if you get it fixed perfectly, and this will take many hours of your time,
you will still have a 15 year old television that will not be worth $30 at
a garage sale. If you spend 6 hours on it or more, how much money could you
make in that time? Enough to buy a TV set? Then just buy it and be done
with it. I was under the impression that you wanted to repair this set for
something to do, as a hobby sort of thing. It is in no way worth repairing
from an economic standpoint at all, period.
 
O

Ohmster

Jan 1, 1970
0
Looks like almost all the caps that I have made by rubycon. I'll try to
replace most of them. How can I get off the board leaked acid? Do I
need to replace caps on the tube board? None of tube caps seems to be
leaking. What is the correct part for 1.2 ohm current limiter?

Why are you doing this? It is a 15 year old television and you already
asked if it would be worth your time. Well, is it so far? Not being mean or
a smart ass or anything, just trying to get you to step back a minute and
see the forest for the trees. Best wishes and good luck.

As far as the correct part for a 1.2 Ohm current limiter, any 1/2 watt low
value resistor will work fine, a 1-2.2 ohm will work fine. All it does is
act as a fuse. It burns up if the chip overheats or burns out. Then you
find out what made it burn out, like a shorted chip, replace it, and put in
a new resistor. It is just a fuse.
 
L

Leonard Caillouet

Jan 1, 1970
0
OK, I have said this many times, but I will say it again. The mantra that
you have to have an ESR meter to fix these sets is just WRONG. An ESR meter
will identify some physically leaky caps, and it is very handy for most
repairs, but you can get virtually all of the bad caps in these mitsubishis
with inspection for electrolyte leakage. I have tested hundreds of these
leaky caps and found that low capacitance and high DA are far more likely on
the leaky ones than high ESR. You might miss other problems, but high esr
caps that aren't leaky in these sets are not common. In this case, I would
bet my next paycheck that you could fix it and never test ESR. We do test
caps for ESR but it is almost never the diagnosis that gets the bad ones in
these sets. You could use the techniques below and fix almost all of them
with enough time and enough capacitors. A DMM and a good nose and eyes will
get nearly all of them.

The ways to identify physically leaky caps are:

1. Visual inspection. If there is a spot on the board around the cap or
dark goo on the legs it is leaky.
2. The smell test. Heat the leads and smell for bad tuna.
3. Listen for a sizzle when heating the solder.
4. Look at the solder side. If there is darkening of the trace or a
powdery look to the solder that is less shiny than surrounding solder, it
may be leaky. If the solder is harder to heat than surrounding joints, you
likely have corrosion from electrolyte leakage.

All of the dark traces need to be scraped to bare copper and tinned. The
board neds to be wahsed with a solvent like isopropanol or denatured alcohol
to get off any remaining electrolyte.

When in doubt about a cap that is a black polar electrolytic in a mits of
this vintage...change it.

Leonard
 
L

Leonard Caillouet

Jan 1, 1970
0
Ohmster said:
Why are you doing this? It is a 15 year old television and you already
asked if it would be worth your time. Well, is it so far? Not being mean
or
a smart ass or anything, just trying to get you to step back a minute and
see the forest for the trees. Best wishes and good luck.

As far as the correct part for a 1.2 Ohm current limiter, any 1/2 watt low
value resistor will work fine, a 1-2.2 ohm will work fine. All it does is
act as a fuse. It burns up if the chip overheats or burns out. Then you
find out what made it burn out, like a shorted chip, replace it, and put
in
a new resistor. It is just a fuse.

Is there not value in a DIY project that keeps a product out of the landfill
for a couple more years? Sure the crt is likely aging, but we fix these all
the time and find that the crts are still looking very good. Did one a
couple of weeks ago. Looked great, client was happy. He could have
replaced it with a POS Philips set for tnot much more than the repair, but
chose to fix it. A DIY on these should cost no more than about $25 and some
time and patience. I do things myself all the time that a professional in
some field would not bother with and spend more time than it might be worth,
but there is the sense of satisfaction in completion of such a project.

I find ladybug's tenacity in this repair to be interesting and laudable.

Leonard
 
L

ladybug

Jan 1, 1970
0
I'll try to get it fixed just to keep it out of landfill for a while. I
got something screwed up this time though. I needed to take a list of
all the caps that I need to replace for ordering, and tried to free up
main board as much as possible to see caps values. I unhooked tube
control board and some connectors. After I made a list of caps I
replaced burned 1.2 Ohm resistor with 2 Ohm that I pulled up from old
VCR. After I put everything together I wanted to give it a try but it
didn't come to live. I could hear power relay clicking when I pressed
power button and there was high pitched sound from the fly. I noticed
that there was no light in the end of picture tube. I took tube control
board off again and there were tube pins 1 and 2 ? (2 left pins) bent
together. I got them straighten up and re plug control board back but
still nothing. From what I can say pin 1 is a ground and I shorted pin
2 to the ground when pin got bent inside of the socket. Don't know what
could get damaged. There is no cathode light in the end of picture tube
anymore.
 
C

Chuck

Jan 1, 1970
0
I replaced 5 leaky caps that I found but it didn't change anything. I
suspect that vertical output IC went kaput. After all it died suddenly
without gradual picture srinking. Is it LA7838 chip? Is there a way to
test it with multimeter? What is a good place to get a replacement?


When the caps went bad, the vertical ic probably shorted. You also
will have to replace the resistor off the flyback derived power supply
winding which opens when the ic shorts. I no longer do Mitsubishi
warranty service so I don't have a manual. You'll need one or a pin
out of the LA7838 to trace back the B+ line to the power supply diode
and the open resistor attached to it. Chuck
 
L

ladybug

Jan 1, 1970
0
I got new caps but TV seems to be completely dead now. I don't have
power on the main high voltage transformer so tube gets nothing. No
cathode light, no high voltage... I checked the fuses, no problems
there.. I can hear power relay clicking when I press power button on
the remote, so controls are good. Any ideas?
 
O

Ohmster

Jan 1, 1970
0
I got new caps but TV seems to be completely dead now. I don't have
power on the main high voltage transformer so tube gets nothing. No
cathode light, no high voltage... I checked the fuses, no problems
there.. I can hear power relay clicking when I press power button on
the remote, so controls are good. Any ideas?

Gosh I tried like hell to get you away from this thing, Ladybug. After all
the work you put into it, now this. (And it is STILL just an old 27" TV
set!) ...sigh.

"Any ideas?" ...yeah, pitch the set and be done with it already. But I
assume that is still not an option, yet?

Is horizontal output transistor shorted? This is a large, usually black
transistor (Black plastic, maybe metal back on it, with three legs on it,
attached to a large metal plate of some kind to dissipate the heat.) over
near the flyback transformer. If you put an ohmmeter probe on the collector
(Center leg) and the other probe on the emitter (leg on the left side) does
it read a very high value of ohms or is it shorted (Very low ohms, usually
1 ohm or less.)?

If shorted then you have opened up something in the power supply circuit
that feeds the B+ to the horizontal output circuit, could be a resistor or
fuse (Some fuses look like small resistors, attached with wires to the
board.) and the horizontal output transistor will have to be replaced.
Could also have been caused when you put the CRT board back on with bent
pins on the CRT. Now that they are straightened out, the set might work if
you find out what happened to your B+ for the horizontal output circuit.

Seriously though, if the set is not fixed really soon with just a few last
things to do, consider cutting your losses and running on this. How much
more kicking can your heiny stand on this job?
 
O

Ohmster

Jan 1, 1970
0
Is there not value in a DIY project that keeps a product out of the
landfill for a couple more years?

Of course there is, when it is something that one can manage and is able
to accomplish within reason.
Sure the crt is likely aging, but
we fix these all the time and find that the crts are still looking
very good. Did one a couple of weeks ago. Looked great, client was
happy.

Uh huh. And where is this, at "Emmet's Fix It Shop" over in Mayberry?
Lemmie guess, the Sears catalog is still a big ticket item for bathroom
reading too? It did not "look great" but may have been acceptable for the
time being.
He could have replaced it with a POS Philips set for tnot much
more than the repair, but chose to fix it. A DIY on these should cost
no more than about $25 and some time and patience. I do things myself
all the time that a professional in some field would not bother with
and spend more time than it might be worth, but there is the sense of
satisfaction in completion of such a project.

Agreed, but you have a clue and some obvious experience with television
repair. You can tell by the questions that Ladybug is asking and the
terms being used that this person has no television repair experience at
all. You would recommend a 10+ year old Mitsubishi set with caps bad by
the pound, along with bad solders and everything else that can go wrong
with a 10 year old set to a beginner to cut his eye teeth on? Ladybug
would have been better off with a Radio Shack 150 in One electronic
project kit and I am not being cruel in saying that. At least then
Ladybug could have accomplished something useful like a photosensing
alarm for the front door and would have learned something along the way.

Here, this auction has ended, but the seller still has a 300 in One
Electronic Project Lab Kit for $5.50.
http://tinyurl.com/lsdef
I find Ladybug's tenacity in this repair to be interesting and
laudable.

I am not "down on Ladybug" at all, I simply tried to temper Ladybug's
enthusiasm with some of real life's harsh realities. Like the cost of a
replacement set v.s. the hours that would be spent on trying to fix it
and the fact that after all is said and done, Ladybug would be left with
a 10+ year old television with a picture tube that is fading away, never
to return to it's original brilliance and luster afterwards, possibly
flaring wherever there is green in the picture, you get the idea, and
nothing can be done about it other than to lower the contrast to a very
dim picture, short of replacing the CRT, unless you want to start with a
single winding around the flyback and the necessary resistors to try and
boost the filament voltage of the set, a temporary measure at best.

Oh, make that 15, F-I-F-T-E-E-N years old! Here is what Ladybug had to
say in an earlier post...

I don't want to buy ESR meter for one time repair. I used to work with
electronics a lot but now I switched to software and don't touch this
anymore. This was my kid's TV and it worked flawlessly for almost 15
years. I desided to give it a shot but don't know if it worth my time.
Do you suggest not to mess with it any longer and get a new set? I can
get 27" tube TV set for under $200

Sure it is worth Ladybug's time, as long as Ladybug is accustomed to
earning twenty seven cents an hour. Yes. I suggested not to mess with it
any longer and get a new set and that was pretty darned good advice.
"Been there, done that" sort of thing.

So Leonard, how are you and Ladybug coming along on this DIY project
anyway?
 
L

ladybug

Jan 1, 1970
0
Ohmster said:
"Any ideas?" ...yeah, pitch the set and be done with it already. But I
assume that is still not an option, yet?

Is horizontal output transistor shorted? This is a large, usually black
transistor (Black plastic, maybe metal back on it, with three legs on it,
attached to a large metal plate of some kind to dissipate the heat.) over
near the flyback transformer. If you put an ohmmeter probe on the collector
(Center leg) and the other probe on the emitter (leg on the left side) does
it read a very high value of ohms or is it shorted (Very low ohms, usually
1 ohm or less.)?

If shorted then you have opened up something in the power supply circuit
that feeds the B+ to the horizontal output circuit, could be a resistor or
fuse (Some fuses look like small resistors, attached with wires to the
board.) and the horizontal output transistor will have to be replaced.
Could also have been caused when you put the CRT board back on with bent
pins on the CRT. Now that they are straightened out, the set might work if
you find out what happened to your B+ for the horizontal output circuit.

Seriously though, if the set is not fixed really soon with just a few last
things to do, consider cutting your losses and running on this. How much
more kicking can your heiny stand on this job?

Thanks for you help, Ohmster. Actually I found myself liking to fix
this old TV. Kids have smaller back up TV for now so there is no rush
to get it fixed right away. I got a schematic from the local library
and it proven to be a good reference. I figured out why power was lost.
Firstly a diode D553 ES-1F appears to be bad and reads open in both
directions. I temporary replaced it with a rectifying diode that holds
600v. I found that I have 23V output and other voltages untill pin 8 of
LA7838 gets connected. Once I connect it all voltages from transformer
dissapear, and cathode light goes off. I suspect that I need a new
LA7838... Will try to get a replacement shortly.
 
M

Michael A. Terrell

Jan 1, 1970
0
Ohmster said:
Seriously though, if the set is not fixed really soon with just a few last
things to do, consider cutting your losses and running on this. How much
more kicking can your heiny stand on this job?


Why don't you go create so you can
play there with the other people who are too eager to quit every repair
attempt?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
L

Leonard Caillouet

Jan 1, 1970
0
Ohmster said:
Uh huh. And where is this, at "Emmet's Fix It Shop" over in Mayberry?
Lemmie guess, the Sears catalog is still a big ticket item for bathroom
reading too? It did not "look great" but may have been acceptable for the
time being.

Life is good here in Mayberry, and I think I know the difference between
"looked great" and "acceptable for the time being."

Your condescending attitude toward DIYers doen't seem to be very helpful.
You gave your opinion and it is sound for many people. Apparently Ladybug
chose a different path than you thought wise. No need to be an ass about
different perspectives and diferent values nor to assume that others don't
know what they are talking about.

Leonard
 
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