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Discussion Starter #1
Hi Leonard (& all),

I was given a Mitsubishi WS-65909 that has the blinking light problem - they unplugged it to move it and plugged it back in and the problem developed. I've looked at it briefly, but haven't picked it up yet (it's been snowing here).

Doing a little research, it looks like the DM board capacitor problem and it looks like this unit is one that uses seven instead of four caps.

I can find the cap values - 1000uf, 16v, 85 deg, radial, polarized but I haven't ran across the physical dimensions of the caps and I know they gotta fit next to each other and under that metal shield. I actually have some Panasonic caps that are 1000uf, 35v, 105 deg rated and are 12.5mm dia X 25mm long - do you know off hand if those will fit, or do you have a specific recommendation for replacement caps?

Thanks!

Steve
 

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I do not recall the sizes of the caps. Changing values can be problematic, as there are more to caps than just capacitance, voltage, and temp ratings. I would recommend ordering the best quality caps in the size of the ones on the board, paying particular attention to impedance and life ratings.
 

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Discussion Starter #4
Hi Leonard,

Thanks - I'll wait until I get the unit over here and stripped down to see exactly what it has in it and if my current caps will physically fit then.

I'll do a little more research on the caps too - I usually replace things with what came out of them but occasionally with things like convergence ics I run across what others have found to be good upgrades and will vary a bit.

With my limited research it seems with these caps a good upgrade is to move away from the 16v rating (in fact I think I saw a post of yours on another forum where you recommended 25v rated caps) and a move up from the 85 degrees C rating to a 105 degrees C rating. It also seems moving away from the original manufacturer is a good idea, and I thought I saw somewhere where Panasonic caps were good quality - that prompted me to remember I'd worked on a power supply for a cnc router for a friend a while back and still had some caps (the recommendation was to replace them all so I bought a kitted assortment and it turns out I had some caps that I think are close enough, they are Panasonics and of the right value with a little higher voltage rating (35 vs 16 or 25) and the higher temp rating).

When I get it over here I'll see what's in it and if I can dig up a spec sheet on them and see how they compare to what I have.

Well off to do a little more research - as with my other projects, I'll try and take soem pics and do some write ups as the project progresses.

Take care,

Steve
 

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It probably does not hurt to increase the voltage, but if everything else is equal, a cap with a higher voltage rating will usually have higher impedance. In a circuit like this it may be significant. The problem is that things are rarely equal, and caps vary a lot. You will not find good specs for the impedance requirements, so replacement choice is a matter of judgement on the part of the repair professional and many factors have to be considered.

Personally, I like the Panasonic caps and they have a wide variety of caps with different specs for different applications.
 

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Discussion Starter #6
Just picked the thing up . . . is that thing heavy or what???

It looks very nice and I actually like the boxyness of it. This one you could set the cable box and stuff on top of. I think that case is why it's so much heavier than the others I've moved though as the others were half plastic and this one is particle board all the way around.

We stuck some chest handles on either side, centered and about 5" down from the lip where the projection chamber attaches. We also left the back off while moving it so you could grab the lip and help steady it while lifting - between the chest handles and the lip to grab it was a much more comfortable lifting angle and a much more stable move.

I'm hoping to work on it over the weekend and I'll post back more as the project progresses.

/Steve
 

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Discussion Starter #7
Hi Guys,

This weekend was looking a little busy and I had some time tonight so I tore the Mitsubishi down and I took some pics while I did it (pay no attention to the date on the pictures, it never seems to be set right!).

This procedure was done on a WS-65909. Since this model shares a service manual with the WS-55859, WS-65869, WS-55909, and WS-73909 it should also be appropriate for those models also.
 

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Discussion Starter #8
Begin by removing the back panel. There are four black screws on each side of the back panel (note that on the left and right edges of the back panel there are several unused screw holes – I circled the ones that were used with a black magic marker so I didn’t have to sort out which ones to use when I re-assembled the unit), then there are 8 gold screws with integral washers that circle the A/V hookup panel. There are also two of the gold screws on either side of the ac power cord entrance. Remove those and place them in a zip lock bag labeled for the back panel.

Pull out on the bottom of the panel and then down (the panel inserts in a slot at the top so you need to drop it down to get it out of that slot) and then store it out of the way.
 

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Discussion Starter #9
The DM modules sits on the left side of the circuit boards behind a plastic cover, so next we remove the plastic cover. There are three screws on the lower right hand side by the A/V input panel and then two smaller screws – one at the top in the middle and one at the bottom in the middle below the antenna input. Remove those and place them in a zip lock bag labeled for the DM plastic cover.
 

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Discussion Starter #10
Once the screws are out then just lift up slightly on the DM plastic cover and pull straight out. The DM module is actually sitting on it so you need to lift up a bit, and the cover has a guide fin that slides in a slot so there’s a little resistance from that too – just lift slightly and pull straight out and it should come right out. (I’ll take a pic of that fin and slot when I reassemble it)

Here’s what it looks like once the plastic cover is removed.
 

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Discussion Starter #11
Now I know some don’t like to unhook wiring and remove boards, they prefer to leave everything hooked up and solder on the unit while sitting on the floor. I’m not that way, I absolutely detest sitting on the floor trying to get comfortable while trying to get enough light on the subject and trying not to knock the soldering iron over and burning the carpet, or getting solder in the carpet, etc.. Although I’m competent at soldering I don’t feel I do my best work in those adverse conditions so I prefer to just remove the parts and take them to my nice well lit, comfy workbench/kitchen table so I have no idea if you can perform this repair while leaving everything hooked up – I didn’t even care to try.

There are four bundles of wires that come out of the DM module and hook to the circuit board to the right. I took a picture of each bundle and it’s wire routing for reference and then unplugged each one from the circuit board. All of the sockets ran vertical to the back of the unit so as I pulled the plug out I used a Sharpie brand permanent marker and colored the rear edge of the plug so I know the orientation when I reassemble. Then I put a wrap of masking tape around the bundle by the plug and numbered it. Then I used a piece of masking tape and labeled the socket.

Here’s the routing of the first cable bundle I unhooked.
 

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Discussion Starter #17
To open the DM module up remove the four screws and the cover over the wiring bundle entrance. The two screws below on top leave in. There are eight more screws around the perimeter of the lid, remove them and place all the screws and the wiring bundle cover in a zip lock bag and label it DM Lid. Now just pry up on the lid and it will pop off. The sharp edges of the metal are covered with tape where the wiring bundle passes through the lid, but be careful none the less.
 

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Discussion Starter #18
Once you remove the lid you can see the daughter board with the seven caps we need to replace. Beyond the caps there are also two fuses on the board that should probably be checked (mine tested OK).
 

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Discussion Starter #19
The capacitors in this unit are different than the ones I’ve seen detailed for other units. These are 105 degrees C rated whereas the others I’ve seen referenced were 85 degrees C rated. They are still 16v capacitors and the brand, Nichicon, though generally rated well did have some issues with some of their capacitors in the early 2000’s. The caps look OK, no bulging or leaking or anything, but that doesn’t mean they’re not bad so I’ll change them and see if it fixes it.
 

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