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Luxman M-4000u

VTDave

VTDave

Tech Guy Dave
I've been asked to repair a Luxman amp. (lucky me) The email I received listed it as a M-4000u. I can only find one reference to this model on the web and it is in a sales ad.

Is anyone familiar with this model? How does it differ from the M-4000 or M-4000a?

Thanks, Dave
 
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US version of the M-4000. Probably transformers and power cord and connections for them.
 
only way to find out is to open and inspect - but actually all my luxmans : 1969 sq-507&sq-503 , 1971 sq507x, 1973 l-507 and two 1975 l-100`s one a l-100u and one an European model are all Switchable voltage
 
totem said:
Well we know the M-4000 is not multi-voltage.
Click to expand...

as i am on the lookout for a m-4000 i am quite interested in the subject - but a Little confused by the l-100u example i own that following the logic so far should noy be switchable to 240v but actually is.

so asking for your patience with my ignorance - from where do we know this ? from experience ? it is not mentioned in any manual but neither is the same in any l-100 manual,
please inform me as they are pretty rare beast here in europe and i have at times been tempted to look to the us as they seem to be more obtainable at that side of the Atlantic.

regards paul
 
As a Luxman enthusiast and an owner of a M-2000 I thought I would chime in.

Odd that there is little to no information on the M-4000U. Here's a pic of the back of each one, not sure if it helps

Screen Shot 2018-02-22 at 5.02.43 PM.png

Screen Shot 2018-02-22 at 5.20.43 PM.png

Screen Shot 2018-02-22 at 5.19.29 PM.png
 
Blue Shadow said:
Nope just the US/North American model. My T-110s are T-110U models. Just Luxman's way. Pioneer had different letters for different models too
Click to expand...
I hear (read) that you are the keeper of Luxman knowledge. I have this m-4000 that I am told shuts down after an hour of hard use. I haven't seen it happen yet but I do note the left heatsink is warmer than the right. I've seen bits and pieces of info posted on the bias and offset adjusments but nothing complete. At least not enough for me to move on it yet. Do you know of a procedure I could access? I've downloaded a few manuals but none have had the detail. Not lucky yet, I guess. Thanks.

TH
 
The manual I have shows the offset being tested at the speaker terminals and adjusted by the VR close to the center line of the amp on the PB-1018 driver board, the front board of the two back by the outputs. One board for each channel. The setting here is 0± very few milliVOLTS

The bias is set by measuring current through the fuse on the power board, PB-1019, rearmost board. Replace fuse with meter and set the VR on that same board to 100 milliAMPS through the fuse. This VR is centered on the power board.

Commonly these settings are done with the amp on, no signal, volume all the way down and adjust a couple times after the amp has been on for a few minutes. Check again after 20 minutes. Done.
 
Blue Shadow said:
The manual I have shows the offset being tested at the speaker terminals and adjusted by the VR close to the center line of the amp on the PB-1018 driver board, the front board of the two back by the outputs. One board for each channel. The setting here is 0± very few milliVOLTS

The bias is set by measuring current through the fuse on the power board, PB-1019, rearmost board. Replace fuse with meter and set the VR on that same board to 100 milliAMPS through the fuse. This VR is centered on the power board.

Commonly these settings are done with the amp on, no signal, volume all the way down and adjust a couple times after the amp has been on for a few minutes. Check again after 20 minutes. Done.
Click to expand...

Thank you so much. This should be all I need. The client had this "repaired" elsewhere once before. I hope to make it right this time. And they are in no hurry to get it back so I get to fix it then enjoy it.
 
VTDave said:
I've been asked to repair a Luxman amp. (lucky me) The email I received listed it as a M-4000u. I can only find one reference to this model on the web and it is in a sales ad.

Is anyone familiar with this model? How does it differ from the M-4000 or M-4000a?

Thanks, Dave
Click to expand...
 
Came across this older post regarding the Luxman M-4000u, unless the above poster was referring to a custom modification
he likely was confusing the XLR speaker outputs Luxman changed to in late in production.
This in response to wide spread displeasure with the awkward push terminals.
 
totem said:
Came across this older post regarding the Luxman M-4000u, unless the above poster was referring to a custom modification
he likely was confusing the XLR speaker outputs Luxman changed to in late in production.
This in response to wide spread displeasure with the awkward push terminals.
Click to expand...
 
You are correct! In my haste to post on my phone I wrongly used the word 'inputs' instead of 'outputs'. Thanks for catching that error!
 
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