I have a ML ReQuest crossover which allegedly was hit by lightning. A lot of semis on the high voltage sensing board were destroyed. I have replaced these but the board still does not work. It powers up the HT for a while at startup and then cuts off. Feeding signal does not retrigger it like it should. The board is shown only as a block in the crossover schematic. Does anyone have a schematic?. ML tech support is a dead letter box.
Cheers
Mike
Cheers
Mike
Can you post a pic of the board?
Based on the ML museum timeline, it is likely one of the MLPS10x series of boards.
If so, circuit should be very similar to attached.
NOTE: If your Request is an import from a country with 60Hz mains, you may need to bypass the frequency sense portion of the circuit. See post here: ML Aerius import from USA
Based on the ML museum timeline, it is likely one of the MLPS10x series of boards.
If so, circuit should be very similar to attached.
NOTE: If your Request is an import from a country with 60Hz mains, you may need to bypass the frequency sense portion of the circuit. See post here: ML Aerius import from USA
Attachments
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here a pic....of the bias board
Attachments
![reQuest%20tweak%20photo%201[1].jpg](/community/data/attachments/605/605321-3ded19b87c66bfb34276a21ccafc2628.jpg?hash=Pe0ZuHxmv7)
![reQuest%20tweak%20photo%202[1].jpg](/community/data/attachments/605/605323-47d2385405436f49b1b38900ac16e59a.jpg?hash=R9I4VAVDb0)
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Thanks so much - this contained everything I needed to get things ticking again.
Yeee-hah!
Cheers
M
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Once I bypassed the frequency sense circuit, it worked like a bought one.
What a strange bit of engineering - to include something to prevent operation
on 50Hz mains (but allow it on 60Hz).
Thanks for your help.
M
Excellent! 
I just included that note about 50Hz/60hz as an afterthought...glad I did.
I seem to recall reading in Stereophile that ML was included country specific power supplies to help their foreign distributors cope with grey market sales.
I just included that note about 50Hz/60hz as an afterthought...glad I did.
I seem to recall reading in Stereophile that ML was included country specific power supplies to help their foreign distributors cope with grey market sales.