Lexicon LXP15 repair - broken page selector / encoder

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rock soderstrom

Tour de France
Joined
Oct 14, 2009
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Hi folks,

I am doing my favorite passion again  - fixing old fx units. This time it is a Lexicon LXP 15. I have fixed some minor issues, the unit is basicly working, now. The only real problem is the page selector. This guy is broken and was already fixed in the past with hot glue but this is no real solution. The selector looks pretty special and I can not find a spare part. Is there a known source for such a item? Any ideas? Cheers
 

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Looks like a 4 bit gray code encoder. Not that weird. You might be able to find a replacement. You would need to just study it very carefully and look at datasheets for a few hours. How many detents does it have? Something like Grayhill 25LB22-G might be vaguely right. Unfortunately this somewhat depends on the software code that interprets the output of the encoder and that is obviously not something you can fix. But you might get lucky.
 
Looks like electrically the encoder may be ok , the casing  is banjaxed , I can see the metal tabs are no longer able to hold it together ,  a tiny amount of superglue(applied with a pin) to stabilise it ,then small blobs of epoxy on the four tabs , make sure the epoxy is 'gone-off' enough so it doesnt flow into the works.

I never had to fix a Lexicon but I have seen the parts are near impossible to find . 
 
rock soderstrom said:
Actually I guess all 4 bit gray code encoders are going to be 16 detents. So that pretty much nails it. Just look at the truth table for that Grayhill part (or find a 4 bit gray code mechanical encoder with the 5 pins in a line from whatever electronic site you use) and verify that the pinout / dimensions are right. Even if it doesn't match exactly you could probably make it work.
 
Thanks for your help!

After a 3 hour search, it looks like Fender have used similiar encoder in their Super Champ XD amps.

They are Gray Code 4 bit Encoder, 16 pulse and they look pretty similiar. No datasheets though.

What do you think?

https://www.adorama.com/fe0063204000.html

https://ru.aliexpress.com/item/32845183805.html

Or Fender NZ ;D

https://fendershop.co.nz/product/fender-encoder/

 
Maybe. It would be better if you can find a proper supplier that has a well known manufacturer with a datasheet. What's the major supplier in Germany? Farnell? I guess it is a little bit of a weird part. Mouser and Allied in the US both have the Grayhill part.

update: I see two "25LB22-G" on ebay.de.
 
Mouser and rs-online do offer the Grayhill Encoder. The Grayhill encoder is slightly different, no mechanical fixture for the PCB, but they should work. I will check them...

squarewave said:
update: I see two "25LB22-G" on ebay.de.

Strange,  can not find them on ebay.de
 
Yes, I did. The answer was that "the LPX-15 has been discontined for some time and we no longer have parts for this unit."

Cheers
 
Have you checked those grayhill encoders for the lxp15 ?  I just bought a LXP15  and the adjust encoder isn't really going smooth.  Also the pots are rather noisy ...
 
Not a switch solution but these can be midi controlled.  Just as a way to set parameters.  Also there are midi profiles for the unit.  At least they were in older midi profiles in daw’s. so they could be controlled.  The epoxy repair maybe as good as it gets.  I’m assuming you also have the service manual.  It’s been available on the internet for free. 
 
Those encoders seem to be a common failure for this range of lexicon units.

Do you have the service manual?
I'm sure you can also adapt another encoder even if with different size, leg spacing and thread (but with the same electrical characteristics) to work there


have you checked also those Grayhill 25LB22-G?
 
Those encoders seem to be a common failure for this range of lexicon units.

Do you have the service manual?
I'm sure you can also adapt another encoder even if with different size, leg spacing and thread (but with the same electrical characteristics) to work there


have you checked also those Grayhill 25LB22-G?
Hi, just wanted to say that I tried the Grayhill 25LB22-G and it works! They have em on mouser!
 
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