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Vintage Luxman showdown: MQ60, MQ70, MQ80, SQ38FD, ?

Gooshe said:
Yes, and it is currently being used in Japan, so all good.
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HA! We can cross external power supply off the list!
As of now, sorry to say we are in agreement with relay. Should have kicked in if all OK....
Since you got a warranty, I would limit any additional work without contacting vendor.
If they could offer some easy troubleshooting steps (e.g., check this internal fuse), I might try it. But too many odd things can happen to vintage items during transport. I would rather the vendor did the troubleshooting....
 
mrwood200 said:
HA! We can cross external power supply off the list!
As of now, sorry to say we are in agreement with relay. Should have kicked in if all OK....
Since you got a warranty, I would limit any additional work without contacting vendor.
If they could offer some easy troubleshooting steps (e.g., check this internal fuse), I might try it. But too many odd things can happen to vintage items during transport. I would rather the vendor did the troubleshooting....
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Yep! Agreed. Have already contacted the vendor but since it was a national holiday, I probably won’t get an answer until tomorrow.
Unfortunately this vendor whom I have purchased from in the past will only accept shipping (free for me) back to their store, then they ship it to their independent technician who will do a through checkup and fix any issues free of charge, then ship it back to the vendor and then they ship it to me all free of charge.
Sounds like a lot of shipping and a waste of time, but so far I’ve had good luck with their service/shipping and any repairs they’ve had to do on previous units purchased.
You would think though they would test all their units that come with a warranty before they ship it. I mean i doubt my current issue happened during shipping, so most likely it existed before and now they have to pay for numerous shipping fees to try to fix it since it has a warranty.
Either way, I’m in no hurry and don’t mind shipping it back to them specially since I can request for them to pick it up from me so I don’t have to drop it off. Only thing I have to do is re-pack it.
 
Talked to the vendor and they said they tested the MQ-80 before shipping it and it worked just fine. They claim the the amp took about 30 seconds to kick into Operation mode from Standby and that there was no issue with sound output.

I explained that I have tried everything multiple times, and it’s not my first rodeo (in a nice Japanese way of coarse) and just can’t see how any of it could affect the switch from standby to operation of the amp anyways, unless it is an internal or relay issue. Perhaps something shifted or malfunctioned during the shipping.
I’ve noticed the two 6267 Tubes with the mesh around the plates do not seem like they are lit, in a completely pitch dark room, there is the slightest of a thin line that can be seen but I’m not sure if it’s the reflection of the adjacent tubes.
Since I can’t remove the cage to see the tubes clearly, I’m concerned perhaps those two tubes are not lighting up. Of coarse i checked to see if they get hot after shutting the amp off after 10 minutes and touching them, but still can’t tell the slight warm temperature is from the 6267 tube or the adjacent tubes.
All other tubes do light up and do get hot to touch.
Could the possibility of the two 6267 tubes not lighting up have anything to do with the standby/operation mode issue?

The vendor has offered for me to ship the amp back if can not make it work and they will have their tech check and correct anything necessary but I’m just trying my best to avoid doing that as much as possible.
Wish I could find a manual on this unit to find out what that switch/pot is next to what looks like a relay box to me. It seems like a 2 position pot and not a rotating one but have not touched it yet to find out. Don’t want to mess anything up.
 

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Let's ship this back to the vendor.
I feel you have fulfilled your part of the contract in good faith. You should feel comfortable using the warranty that you purchased. Any additional work is time/money/warranty concerns. Any number of things could have happened during shipment. Could be easy fix, could be tough fix. With a warranty, I am going to let them do the troubleshooting.

(Now if you own it w/no warranty, there has go to be a way to rig the amp to run with cage off. Some tube have readily-identifiable filament glow; other are more hidden. Sight & feel can be useful data points, but you should test circuit performance safety with equipment.)
 
Update….

After shipping the amp back to the vendor for repairs, just got the MQ-80 back today and a bag full of the old parts that were removed and replaced by the Tech.
I think they went overboard and updated the whole thing which makes me super happy that I won’t hopefully have to do anything to this unit for a long time.

Also included with the parts was a description of the work done, labor and materials, which the warranty already took care of.

This amp sounds amazing now. Wow. Very full, detailed and holographic. Not sure what difference in sound all these new parts made but It sure is very pleasing.

The excellent Japanese customer service definitely held its reputation.
 

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So the lyrics were tired and replaced and the gray film caps can have issues after all these years so they got replaced. Guess the rest were also known to need attention after some time. Getting close to time to do my amps, film and multi-cap lyrics, I guess.

Not too bad a wait for a nicely refreshed amp. Should be ready for prime time now.
 
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Gooshe said:
I’ve noticed the two 6267 Tubes with the mesh around the plates do not seem like they are lit, in a completely pitch dark room, there is the slightest of a thin line that can be seen but I’m not sure if it’s the reflection of the adjacent tubes.
Since I can’t remove the cage to see the tubes clearly, I’m concerned perhaps those two tubes are not lighting up. Of coarse i checked to see if they get hot after shutting the amp off after 10 minutes and touching them, but still can’t tell the slight warm temperature is from the 6267 tube or the adjacent tubes.
Click to expand...
That's typical of the NEC 6267. Barely visible even with the lights out, and very little heat.

Jack
 
TriodeLuvr said:
That's typical of the NEC 6267. Barely visible even with the lights out, and very little heat.

Jack
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Thanks for confirming that, Jack.
On the other hand, the 6336-A power tubes get so hot, that they make the power transformer and the chassis near impossible to touch after a couple of hours of operation. I wonder if that’s why there is a safety mechanism that the cage must be ON , or the amp will not operate.
I noticed that today after turning the amp off after being on for 2 hours and then touching the power Transformer. Ouch!
And I know it’s the power tubes frying them because the farther you go away from them, the cooler other parts next to it get.
Might have to run a fan, just don’t like how hot that power transformer gets.
 
Blue Shadow said:
So the lyrics were tired and replaced and the gray film caps can have issues after all these years so they got replaced. Guess the rest were also known to need attention after some time. Getting close to time to do my amps, film and multi-cap lyrics, I guess.

Not too bad a wait for a nicely refreshed amp. Should be ready for prime time now.
Click to expand...
Yes, the wait was definitely worth it specially after finding out how much work was done to it. The Amp had to be shipped to Okinawa from Tokyo and it was shipped by Sea, instead of Air, so safer travels. (That part I don’t understand why it would be safer, once it lands at the port, it will be on a truck and bouncing anyways)
 
Gooshe said:
... power tubes get so hot
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Glad to hear the amp is back after good service!
And yes, as you know, tube amps get hot. Maybe LUX added the cage interlock because your unique tubes get really hot. Not sure.
Did you check the tube bias upon arrival? The repair tech probably did this, but things can shift during transport.
I doubt a cooling fan is required, but may reduce operating temperature & extend life. Some here have added 12V computer fans to cabinets; modern fans can be very quiet.
 
I just bought a serviced SQ38FD. I already have an MQ3600 moded with KT88's. The amp section in the SQ38FD, as I understand, is the same as a MQ60.
Would there be a benefit to use the SQ38FD as a preamp hooked to the MQ3600? sound wise? power?
 
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