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ECP 4101 tube replacement

338 Views 5 Replies 3 Participants Last post by  johnd393
I've got an ECP 4101 with the following tubes:

07MS(B), 07MS(G) & SD187R

Does this indicate that the two 07MS tubes has been replaced and the SD187R is still the original one?

Can I replace the SD187R tube with a 07MS(R) tube or does this require some modification to the neck board (or some other mod)?

Thanks, Henrik
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Not sure what was original on the 4100 series...but something has been replaced. The tubes are completely interchangeable, the only thing needing modification is the focus board. With 187 tubes, the focus resistor was about 45 MOhms and with the 07 is needs to be around 65 (I think that's the right value).

When a mix of tubes are used, a value between the two of 55MOhms is normally used. I bet if you look at the focus module you will see another resistor wired in with the original.

No mods are required to the neck board or any other part of the set.
Yes it looks like it's modded but it's encapsulated in something red so I can't see the value of it. (45, 55 or 65 MOhm).



I probably need to solder one end off to be able to measure the value.

Another question, should it be this sooty on the white components (is it resistors?) saying 1.0K, .22K etc.


BTW the big blue cap on the picture above is the one mentioned in the Bias/Focus board mod right?

(Ps. load the following URL in another window to cache the pictures
http://www.geocities.com/nardjinku/index.html )
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Yes to all your quesitons. That focus resitor looks to have been replaced. The normal 45MOhm unit is a flat, thin, blue item. I have never heard of that red one being an original, but I guess it's not entirely impossible.

It gets pretty dusty inside those units and they are a dust magnet. I wouldn't worry too much about the soot. If it makes you feel better, the board can be cleaned with denatured alcohol...just let it dry at least 30 minutes before you do any soldering or reinstall it into the projector.

Yes, that's the cap to replace with the photo flash unit.
Ops, I forgot to write the question about the soot on the resistors. Is this what a slightly burnt resistor looks like or is it just normal dust?

Another question about the tubes. The PJ does not start, the fuses blows all the time (in power entry and HVPS). Someone told me it can be a tube that is broken. How can I check that? Can I disconnect all of them and start the PJ to see if the the fuses are still blows and if that's ok then add one tube at a time and see what happens.

I know it might also be the HVPS that is broken but I still want to rule out the tubes before I buy a new HVPS which is a big investment.

Thanks for all the help!!

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This idea has been bugging me for a while. Refering to a ECP with (3) SD187's. There must be one color that is always driven the hardest. If the 07MS tubes are a little brighter and sharper than the SD187's, why not replace only the hardest working color with a 07MS?

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