Visitors from New Zealand arriving today. So any input I can offer, like measuring the power board voltages on my X11, will be unlikely until the middle of next week.
Although... I will drag a hook through some Japanese restorer blogs and see if any data we can use pops up.
This is the worst affected board in my X1 when it came to the glue.I was checking to see if the board could be removed, by pulling out the PCB, but looks like it is going to be tough, the board can be loosed by removing the screws securing it, but it not come out so easily, i believe the front panel has to be removed to work on this board easily, it is also tough to inspect the board being placed in a vertical manner.
I think these boards will run hot yes. not that I can say from personal experience as I'm still some time off getting my X1 running.I have the same problem with the small mm and mc boards located on the right hand side of the amplifier, the small boards mounted onto eq and mc amp mounting board.
The boards on the F-2772 do run hot on both my X1 and X11.I think these boards will run hot yes. not that I can say from personal experience as I'm still some time off getting my X1 running.
All these phono boards (in the X1 anyway) are setup to use the lid to the phono section as a localised heatsink. All my phono boards have heatsinking compound for where they meet, and screw into that phono section lid.
It needs attention for sure, and since i am running the original transistors , i have to work on the black flags with priority. Now that the transistor hunt being fruitless , it is better to keep the originals in tact.
Remember the possibility of using a 'sacrificial set' of MJ21193 // MJ21194 in place of the original output transistors. I did this with my AU-X1 using just one pair per channel and it worked out well for me. You can set bias from the test points (if you put the sacrificial ones in the right socket locations on the heatsinks), set DC offset, and get audio output. Although I wouldn't recommend any listening tests - just sine wave signal generator tests for channel level comparisons and so on.
Unlikely, much more likely to be something amiss on the respective driver board, also that's a very low test frequency, you ought to use 1Khz for these tests.Will changing the output transistors help with the difference between left and right channel outputs ? The difference with sine wave is around 1 volt, between left and right channels, measured with a 50hz sine.
An AU-X11 restore, with no service manual available, is a daunting prospect for any techie.I was thinking it could be something else,driver board components, but my knowledge is not as good as other techies in the forum.
Will changing the output transistors help with the difference between left and right channel outputs ?
The difference with sine wave is around 1 volt, between left and right channels, measured with a 50hz sine.
I was thinking it could be something else,driver board components, but my knowledge is not as good as other techies in the forum.
Unlikely, much more likely to be something amiss on the respective driver board, also that's a very low test frequency, you ought to use 1Khz for these tests.
An AU-X11 restore, with no service manual available, is a daunting prospect for any techie.
Sounds like aging to me.I did note , that after playing music for 30 minutes or so. and then measure dc offset across speaker terminals, the values are around 30mv for each side, the left side and the right side.
Otherwise when i power on the amplifier, the offset is stable between 0-5mv.
Not sure if this is something to be worried off, i did stop the source from playing, turned down volume knob to zero ( the preamp volume knob with the big dial), but the dc off set was still at 30mv.
The only way i could get rid of it , is to turn off the amplifier wait for some 10 minutes and then turn it on again.
The service manual states for adjusting dc offset let the amp warm up for 10 minutes.
No matter what i do , the DC Off set increases from 0mv to around 30mv after playing music for like 30 to 40 minutes.
On a side note the protector ground in the driver board circuit, in my amp is wired to the copper chassis.
I am not able to look this up, in other photos, as its hard to trace this wire.
Want to know if its the same for the rest of you guys too.
Update :
This time i let the amplifier play for like 30 minutes, and then adjusted the DC Offset to settle at 0mv, and this works fine, but the only issue is that when i first power on the amp the DC offset is around -19mv and then slowly starts increasing to zero.
Not sure whether this is due to aging components, the same applies for DC Bias across test points, it takes a good long 15 to 20 minutes to reach 11mv.
Another Question regarding the driver boards, did you desolder all the wires in the driver boards, say the preamp wires and the power supply wires that go to the driver board for an example.Sounds like aging to me.
I will be adding that info I promised in about 12 hours.
I will refer the above in my measurements.
Sounds pretty normal to me.This time i let the amplifier play for like 30 minutes, and then adjusted the DC Offset to settle at 0mv, and this works fine, but the only issue is that when i first power on the amp the DC offset is around -19mv and then slowly starts increasing to zero.
Not sure whether this is due to aging components, the same applies for DC Bias across test points, it takes a good long 15 to 20 minutes to reach 11mv
On the face of it, it sounds sensible and with many amplifiers I would think this was just about acceptable if there was no other way. However, I wouldn't do this with an AU-X1 (or AU-X11 if I had one). Connectors should be reduced to a minimum, and adding more to these models should be considered an absolute last resort in my humble opinion.To include a bullet connector in the existing wires, this requires splicing the existing wires and a adding a female and male connector to both sides of the wire.
Sounds pretty normal to me.
On the face of it, it sounds sensible and with many amplifiers I would think this was just about acceptable if there was no other way. However, I wouldn't do this with an AU-X1 (or AU-X11 if I had one). Connectors should be reduced to a minimum, and adding more to these models should be considered an absolute last resort in my humble opinion.