oh, I know that is not why the SK-180s failed. They failed due to operator error 100%. I have one dead on each channel. .The remaining most likely not a pair.My guess is that the TJ08 was early production version of the 2SJ14. I don't think the failed K180 replacement attempt is related.
My guess on the failed K180 attempt is that someone didn't fully understand how to set up for the K180's properly and they failed as a consequence ... but that's just a guess on my part.
Thank you Patrice,Hello
On all the B1 I have refixed , I never seen V FET marked TJ08
Here is what every driver boards look like :
View attachment 1096590
OK
What kind of 2SK75 do you have on all your driving boards (green PCB and others) ?
LK15A IDSS 8,00 to 9,00 mA color code RED
LK15B IDSS 9,00 to 10,00 mA color code BLUE
LK15C IDSS 10,00 to 11,00 mA color code ? Did not made any measurements yet
As you can see 1mA difference , very very tight
LJ13A IDSS 2,5 mA to 3,5 mA color code RED
LJ13B IDSS 3,5 mA to 4,5 mA color code YELLOW
LJ13C IDSS 4,5 mA to 5,5 mA color code BLUE
what is the IDSS / color rank for the J24?OK
What kind of 2SK75 do you have on all your driving boards (green PCB and others) ?
LK15A IDSS 8,00 to 9,00 mA color code RED
LK15B IDSS 9,00 to 10,00 mA color code BLUE
LK15C IDSS 10,00 to 11,00 mA color code ? Did not made any measurements yet
As you can see 1mA difference , very very tight
LJ13A IDSS 2,5 mA to 3,5 mA color code RED
LJ13B IDSS 3,5 mA to 4,5 mA color code YELLOW
LJ13C IDSS 4,5 mA to 5,5 mA color code BLUE
I was surprised myself when I saw it. The board was a early revision also.YES this is a part of many mysteries in parts list of service manual
View attachment 1096613
a MPSU60 can't replace a FET or VFET
A FET or VFET can't be replaced by a bipolar transistor
I installed the SK77 yesterday and after adjustments had a good listening. I am using a tube pre and the direct in inputs. To my ears the K180 has a smidgen more extension on the high. All the rest is identical.
The only issue I have is that this B-1 does get very hot. The fact that there is around 30 degrees celsius everyday surely does not help. So after running it for a couple of hours the amp need to cool off before can be turned back on. Is this normal?
Gave it a fresh coat of paint also, installed some better speaker connectors and a IEC power connector.
what is very hot? if the thermo switches are puting the amp in thermal protection, that is not normalI installed the SK77 yesterday and after adjustments had a good listening. I am using a tube pre and the direct in inputs. To my ears the K180 has a smidgen more extension on the high. All the rest is identical.
The only issue I have is that this B-1 does get very hot. The fact that there is around 30 degrees celsius everyday surely does not help. So after running it for a couple of hours the amp need to cool off before can be turned back on. Is this normal?
Here is a close up of the drive boards.
I meant to say, Thank you for the close-ups. I see the fets rank marked with letter.I installed the SK77 yesterday and after adjustments had a good listening. I am using a tube pre and the direct in inputs. To my ears the K180 has a smidgen more extension on the high. All the rest is identical.
The only issue I have is that this B-1 does get very hot. The fact that there is around 30 degrees celsius everyday surely does not help. So after running it for a couple of hours the amp need to cool off before can be turned back on. Is this normal?
Here is a close up of the drive boards.
nice job bringing that bad boy to prime againGave it a fresh coat of paint also, installed some better speaker connectors and a IEC power connector.
Where did you come up with all this stuff?
The K180’s that we’re in before.
And a pic of some unmarked SK75 ‘s
I see an IEC320 socket on the back of the Power Amp. Is there a special tool to cut it out of the sheet?Thanks.Gave it a fresh coat of paint also, installed some better speaker connectors and a IEC power connector.