Bad caps in Mitsubishi TV's?

[Maxxarcade]

What is with all the bad caps in Mitsubishi TV's? They are always leaking around the leads and smell like fish when heated with a soldering iron

Weird thing is, they are almost always Nichicon VR or Rubycon YX?. Mainly the 47uf and 100uf ~50v value.

I've worked on about 10 different sets, between 27 and 50 inches that have the same leaky caps.

Another odd thing, is the ESR is good on many of the caps even though they are leaking black goo everywhere, and none were bulging.

The symptom is almost always that the set will turn on, then right back off. Soemtimes multiple tries and it will turn on. On some sets the vertical will be collapsed or folded over until it warms up.

It's too bad that they have this problem with leaky caps, because they seem to be one of the best TV's otherwise. Nice optics, all connectors labeled, sturdy cabinets etc. In fact I had a 32" projection set from 1987 that still worked perfectly, but the tubes were burned so bad it was unwatchable. in fact here's a pic of the tubes.

[Tom41]

Re: Bad caps in Mitsubishi TV's?

Oh, so those three large 'lightbulbs' are actually CRTs? I've always wondered how the older video projectors and projection TVs worked (before LCD). I've seen projectors that have red, green and blue tubes to project onto a wall-mounted screen, and I've also looked inside a projection TV and seen them (with a mirror to get the image onto the screen).

Was this out of an arcade machine? I've seen plenty of projection and normal CRTs with INSERT COINS burnt into them - plainly visible during game play!

[kc8adu]

Re: Bad caps in Mitsubishi TV's?

mitsubishi got a bunch of leakers in the 90's
not uncommon to have to replace all the small lytics to fix the set.
and that includes the sm lytics on the pip board which are a very common problem.

[Maxxarcade]

Re: Bad caps in Mitsubishi TV's?

Oh, so those three large 'lightbulbs' are actually CRTs? I've always wondered how the older video projectors and projection TVs worked (before LCD). I've seen projectors that have red, green and blue tubes to project onto a wall-mounted screen, and I've also looked inside a projection TV and seen them (with a mirror to get the image onto the screen).

Was this out of an arcade machine? I've seen plenty of projection and normal CRTs with INSERT COINS burnt into them - plainly visible during game play!

Yep, they are actually just 3 small monochrome tubes, one for each color. They are liquid cooled because they get very hot.

That one was not out of an arcade machine, but I do have some that are. It only takes a few months to burn the phosphors when the exact same image is on the screen 24/7.

My guess about the tubes in the pic, is that someone watched tv all the time, and had the tint adjusted too green. The green tube is in the center and has by far the most wear. The white ring around the outer edge of the tube face is unused phosphor.

If you want to know more about how CRT projectors work, some good info is at http://www.curtpalme.com/CRTPrimer.shtm

The projector in my home theater is a really old Barco Graphics 800, and I'm using it with a 122" screen and a home theater PC.

Regular CRT's can be burned too, it just takes longer. This is how they look after 25 years in the same game...

[Maxxarcade]

Re: Bad caps in Mitsubishi TV's?

mitsubishi got a bunch of leakers in the 90's
not uncommon to have to replace all the small lytics to fix the set.
and that includes the sm lytics on the pip board which are a very common problem.

That was the first thing I heard about when it came to bad caps in Mits TV's. Only recently did I find out about the leaky caps in the rest of the circuits being common too. Just strange that even more than one brand has the same problem, and I don't think it's due to circuit design. Maybe contaminants in electrolyte or other materials that both Nichicon and Rubycon were using at the time? It almost looks like the black goo is the rubber of the bungs breaking down.

[kc8adu]

Re: Bad caps in Mitsubishi TV's?

heres a 27/7 burn in.
i rebuild several of these units a month.

Yep, they are actually just 3 small monochrome tubes, one for each color. They are liquid cooled because they get very hot.

That one was not out of an arcade machine, but I do have some that are. It only takes a few months to burn the phosphors when the exact same image is on the screen 24/7.

My guess about the tubes in the pic, is that someone watched tv all the time, and had the tint adjusted too green. The green tube is in the center and has by far the most wear. The white ring around the outer edge of the tube face is unused phosphor.

If you want to know more about how CRT projectors work, some good info is at http://www.curtpalme.com/CRTPrimer.shtm

The projector in my home theater is a really old Barco Graphics 800, and I'm using it with a 122" screen and a home theater PC.

Regular CRT's can be burned too, it just takes longer. This is how they look after 25 years in the same game...

[Maxxarcade]

Re: Bad caps in Mitsubishi TV's?

I remember seeing that pic in one of my older threads as well. That one is burned in really clear! There must have been pretty good electronics in the monitor not to have any drifting of the picture for that long.

[Maxxarcade]

Re: Bad caps in Mitsubishi TV's?

Got the TV working after replacing a shitload of caps.

The worst part is, the vertical deflection and convergence were not working because of what appears to be a small service switch on the main chassis. Flipped it to center position and got a picture.

Now I just have to put it back together and tweak convergence. The tubes look good for their age.

[tvtech]

Re: Bad caps in Mitsubishi TV's?

That was the first thing I heard about when it came to bad caps in Mits TV's. Only recently did I find out about the leaky caps in the rest of the circuits being common too. Just strange that even more than one brand has the same problem, and I don't think it's due to circuit design. Maybe contaminants in electrolyte or other materials that both Nichicon and Rubycon were using at the time? It almost looks like the black goo is the rubber of the bungs breaking down.

Yep thats what it is,the rubber bung breaks down allowing the electrolyte to leak out ond the cap dries out and loses capacitance and eventually goes open.Nichicon,rubycon and elna capacitors from the early to mid 90's are usually shot today whether they have been installed in a set or are new and never installed.These caps were used in everything from laptops of the time to medical equipment.Mitsubishi and zenith used these caps extensivly Nichicon and matsushita(panasonic) also used the same crappy rubber in their SMD capacitors from the late 80's to late 90's.They used these mainly in older sony and other brands of 8mm camcorders and they are all leaking and have to be replaced which is time consuming and not always sucessful due to the electrolyte eating the traces on the board.At least these capacitors lasted 10-15 years unlike the crap china is making today.Today just replaced the main filters(470mfd 200v capXon's) in the SMPS in 2007 model DLP set,This is just the beginning,I have at least 20 more samsung monitor power supplies with bad caps to rebuld that are less than a year old.

[Logistics]

Re: Bad caps in Mitsubishi TV's?

Any idea what's wrong with my 27" Mitsubishi? When you turn it on, the picture bounces up and down erratically, until the set warms up.

[Krankshaft]

Re: Bad caps in Mitsubishi TV's?

Check the caps in your vertical deflection circuit. They will be around the vertical deflection IC which will be on a heat sink.

You should find at least 3 heatsinks (some TVs have more):

The heatsink near the flyback is the Horizontol Output Transistor (The HOT).

The next two ICs will have smaller heatsinks when compared to the HOT.

Vertical Deflection IC

Dual Channel Audio Amp

The fact that it clears up when the set warms up screams capacitor problem.

When the cap warms up it performs normally but when its cold the circuit goes erratic.

It could also be an erratic vertical deflection IC but its more likely a capacitor.

[Krankshaft]

Re: Bad caps in Mitsubishi TV's?

Oh yeah and I forgot to mention make sure that the jumping is on all channels if not its just a reception or video processing problem.

[Logistics]

Re: Bad caps in Mitsubishi TV's?

Yeah, it's all the time. Even if I'm using a gaming console or some other video input. I was told on a forum specifically for Television repair that it was caps as well. *sigh* I don't mind, I would love to recap it, but TV's are a tad more dangerous than PC PSU's, lol! How do I drain the CRT, again? Tie ground to a screwdriver and stick it under the flyback plug?

[Krankshaft]

Re: Bad caps in Mitsubishi TV's?

The high voltage is low current high voltage so its actually more enbarassing then anything if you get bit.

If you open switching power supplies then a TV is no big deal.

I got bit when I was 15 and didn't know squat about electronics or TVs it wasn't pleasant but I got over it and made sure to discharge that wire from now on.

Most TVs have bleeder resistors that drain the HV considerably within an hour. But as we all know sometimes they fail so your better off being safe then sorry.

Actually if you leave the TV off for a day the HV will be almost completely drained.

To discharge the HV place one screwdriver under the suction cup and touch the HV clip. Take another screwdriver and touch it to the aquadag (the grey metal looking paint on the tube). Then bring the two screwdrivers together if you wait a day there will be no arc if you discharge soon after turning the TV off there may be a little arc between the screwdrivers.

Another discharge procedure uses only one screwdriver. Buy two alligator clips and solder them onto a wire clip one alligator clip onto your screwdriver and clip the other to chassis (tube) ground. Running across the back of the CRT you will see a braided wire that is chassis or (tube) ground (oh so thats why the graphite paint is there and that wire runs over it ) clip your alligator clip to that. Then simply touch the screwdriver under the suction cup.

NEVER discharge to signal ground or you will blow every IC in the TV.

To remove the HV wire to get the mainboard out you simply lift up the suction cup and squeeze the clip with a pair of pliers. The HV wire clips into a little metal cap at the top of the tube.

[Krankshaft]

Re: Bad caps in Mitsubishi TV's?

Oh and another note that problem will get worse. As the cap decays further the time to picture stabilization will take longer and longer. I've seen it happen with other TVs.

Well enough of my rambling.

Good Luck .

[Logistics]

Re: Bad caps in Mitsubishi TV's?

Thanks for replying. It would really make me happy to fix this problem. When I have the TV set for night viewing, so the black is very black and the colors look very crisp and clean, it looks fantastic. I tested it with one of the new Star Wars DVD's and it was amazing. (I used the Avia disc) Even the shop I sent it to last time to have it repaired said they thought the TV looked fantastic.

Umm, instead of crossing the cable to chassis ground, could I just pass it to something like one of the huge water pipes in my garage? Also, just in case, how do I build a little bleeder circuit? Or rather, what sort of resistor could I use to discharge big caps and how long should I have it connected?

[Krankshaft]

Re: Bad caps in Mitsubishi TV's?

Yes a water pipe is fine as long as its bare metal and not painted. In fact thats is what your service box is grounded to all of the neutral and ground wires in the house connect to a bar in the box which connects to the water main via a thick solid cable.

Anyhow here is a site that I used when I was getting started its very informative and should make you feel more comfortable.

http://www.repairfaq.org/sam/tvfaq.htm

Here is a direct link in that guide for the resistive discharge for the High Voltage you were looking for. It also works for the filter capacitors.

http://www.repairfaq.org/sam/tvfaq.htm#tvsafdis

If you short the tube the discharge will be instantaneous but touch the screwdrivers about 4 more times and wait 4 seconds in between just to be safe.

With a resistor in the mix it will take a bit longer since the resistor is slowing the discharge down but at the same time preventing arcing. Read the guide at the link I provided and it will tell you what is needed for this route. You will need a Megaohm resistor good for 30 Kilovolts or more or a string of lower value resistors to get up to this voltage.

Also be sure to install a shorting wire between the anode cap and the metal chassis wire running along the back of the tube. After you remove the anode wire. The tube while discharged can actually charge itself back up. This is because the tube is a capacitor and it can hold voltage deep in the glass which can come out when its discharged. The voltage will not be as high as before the discharge but it is enough to startle you and give you one of those nasty static shocks.

It happened to me once while reconnecting the anode wire.

I can just see some guy carrying a picture tube and his hand just slips a little too far and whoops someone get the broom .

[Logistics]

Re: Bad caps in Mitsubishi TV's?

Thanks again! I would have replied earlier, but I've been fighting off some ridiculous virus. One of those deals where you do a fresh install and then copy your files back over and set everything up; uh oh, the virus is back! It had attached itself to several of the exe's in my saved files. Unbeknownst to me, I was running infected exe's. At least KasperSky let me know which files were infected, and I just deleted them this time. *sigh* (goodbye Cadsoft Eagle)

So, I hear Mitsubishi's have pretty weak power supplies, generally. Should I go ahead and replace the main caps? And if so, do they need some sort of specific type or can I just do the low impedance, high ripple jobber on them? Anything else I can do to help my old Mitz out? It's a CS-2724R

[Krankshaft]

Re: Bad caps in Mitsubishi TV's?

Wow thats ironic I just reformatted a customers HDD because it got this crazy worm that infected tons of files on the drive. After the virus program deleted the infected files Windows ran but it was very limited. Even the system restore partition was infected and wouldn't run . I had to format the whole thing maybe that will teach them to get antivirus software and not to open stupid e-mail attachments .

I'd first open the set up and do a visual inspection for any bulgers.

Low impedance caps will do just fine for the power supply. What I usually do is take the series off of the original caps if I'm not sure and get a datasheet to see if the cap series is low ESR or general purpose.

Also be sure to check the caps around the vertical deflection IC as well.

[Krankshaft]

Re: Bad caps in Mitsubishi TV's?

A good way to test thermally intermittant caps and ICs is with freezing spray.

Simply wait until the rolling settling down then blast the suspected component with the spray.

If the capacitors aren't the culprit.

I would suspect either the vertical deflection IC itself or the vertical sync circuit. The vertical deflection IC is more likely though.

A good way to check if you suspect the IC is to wait until the set warms up and the vertical rolling goes away. Then freeze the IC if the rolling returns thats your problem.

You can go ghetto and turn a spray duster can upside down but I would worry about ICE crystals and condensation shorting things out.

Here is a freezing spray made especially for electronics.

http://www.allelectronics.com/cgi-bi...0_OZ_CAN_.html

If you need ICs for your set go to tritronicsinc.com.