Mitsubishi TV

I have a ten year old Mitsubishi 45" Tabletop Rear Projection TV Model
#MVS4571. When I turn on the TV the picture rolls and it out of focus for
about 15 minutes until it "warms up". After that the picture is O.K. but
sometimes goes out of focus. Is there anything I can do to adjust the
picture? In the old days we had horizontal hold and vertical hold. Thanks.

Don R.

 

Step #1, ESR every single electrolytic capacitor in the tv set.
Step #2 replace all the capacitors on the PIP circuit board.
Step #3 troubleshoot any remaining failures.

 

Well, almost correct, David, but ESR tests will not get many of the
capacitors that are physically leaking electrolyte, which is the bigger
problem in many of these sets. You have to visually inspect them and/or
heat the leads and smell the results. I have seen many caps that are
leaking electrolyte that pass all tests, including ESR.

Leonard Caillouet

 

"Leonard Caillouet" bravely wrote to "All" (02 Jan 04 20:38:30)
--- on the heady topic of "Re: Mitsubishi TV"

The problem with most esr meters is that they use a rather high
frequency of about 100K Hz to keep the reactance of small electro values
negligible. The problem with this strategy, in my experience, is that
large value electros can test good with the higher frequency because the
outside layers can behave as a perfect small electro and yet indicate
very little esr, since the inner layers are in effect bypassed. Not all
bad large electros behave this way but enough do to make a difference.

As such having a range of about 3 test frequencies would be helpful.
For example 100K Hz is great for electros of 10uF and less to about
0.1uF. 33K Hz is good from about 10uF to about 470uF and 10K Hz for
anything larger than about 470uF up to about 10mF. Then 3.3K Hz for even
larger values, etc.


LC> From: "Leonard Caillouet" <>

LC> Well, almost correct, David, but ESR tests will not get many of the
LC> capacitors that are physically leaking electrolyte, which is the
LC> bigger problem in many of these sets. You have to visually inspect
LC> them and/or heat the leads and smell the results. I have seen many
LC> caps that are leaking electrolyte that pass all tests, including ESR.

LC> Leonard Caillouet


.... Resistance Is Futile! (If < 1 ohm)

 

So do you know of any available testers that have these options? Why don't
you suggest that Bob Parker update his design...

Not that it matters much in this case. The point was that in many of these
sets the problem is due to the electrolyte itself and not the performance of
the cap. I tested one just a few days ago that had one leg mostly corroded
off and it passed all the tests on my Sencore. You can test any way you
want and if you don't LOOK for the obvious problem you won't be successful
in fixing these sets.

Leonard Caillouet

"Leonard Caillouet" bravely wrote to "All" (02 Jan 04 20:38:30)
--- on the heady topic of "Re: Mitsubishi TV"

The problem with most esr meters is that they use a rather high
frequency of about 100K Hz to keep the reactance of small electro values
negligible. The problem with this strategy, in my experience, is that
large value electros can test good with the higher frequency because the
outside layers can behave as a perfect small electro and yet indicate
very little esr, since the inner layers are in effect bypassed. Not all
bad large electros behave this way but enough do to make a difference.

As such having a range of about 3 test frequencies would be helpful.
For example 100K Hz is great for electros of 10uF and less to about
0.1uF. 33K Hz is good from about 10uF to about 470uF and 10K Hz for
anything larger than about 470uF up to about 10mF. Then 3.3K Hz for even
larger values, etc.


LC> From: "Leonard Caillouet" <>

LC> Well, almost correct, David, but ESR tests will not get many of the
LC> capacitors that are physically leaking electrolyte, which is the
LC> bigger problem in many of these sets. You have to visually inspect
LC> them and/or heat the leads and smell the results. I have seen many
LC> caps that are leaking electrolyte that pass all tests, including ESR.

LC> Leonard Caillouet


.... Resistance Is Futile! (If < 1 ohm)

 

You have to visually inspect them and/or

Another thing that can be done is to look at the circuit traces underneath the
mainboard. The leaky electrolyte can seep past the solder joint and can
corrode the coating and the traces, which makes a normally green trace look
dark brown or black. After removing the cap, any and all leaked electrolyte
must be cleaned off as best as possible, including scraping off the electrolyte
stuck on the underside of the board, but being careful not to sever any of the
traces in the process. It will remove the coating that insulates the traces,
though. - Reinhart

P.S. This reminds me of an amusing anecdote involving my Sony SVO-160 with
those Elna LongLife and Duorex II caps. One day, my sister was complaining why
my room was having this strong fishy smell. I went in the room and all I could
say was, "aww, man!" I knew that something in my room that had power had a big
failure involving caps, which turned out to be my VCR. I had to replace every
single LongLife and Duorex capacitor in the VCR as they all had leaked! After
that, no problems.

Crappy Elna caps!

 

Also don't forget to check the circuit boards and CRT assemblies for coolant .
This chassis is notorious(?) for leaks...