Tracking a short in an AU-666

[stereofun]

On powercords - since replacing a 999 and Eight powercords, I've noticed that inside the bushing/clamp there is sometimes wear. It might be my imagination but replacing these old, flimsy and sometimes ungodly long powercords does improve sound - and safe operation. It's really easy to do and should imo rank up there with trimmers, another weak spot.

https://www.amazon.com/gp/product/B00MFSESOE

 

[AnalogueBen]

On powercords - since replacing a 999 and Eight powercords, I've noticed that inside the bushing/clamp there is sometimes wear. It might be my imagination but replacing these old, flimsy and sometimes ungodly long powercords does improve sound - and safe operation. It's really easy to do and should imo rank up there with trimmers, another weak spot.

Without a doubt I agree that it does change the sound. I've done it on a couple of units because of need and one to chase performance (666)
On my 666 I tried two different 14 gauge cables, they each had a different impact. Wider sound stage is one, focused highs, just a different tone in general. And after trying out them both I went back to the original, It just sounded the most natural. I don't think I'll change out another cord (plug if necessary) because that's to some degree a part of the transformer and I don't want to alter that part that's been in play all its life. That's just my taking and I'd understand if swaping the cord make all the difference over the stock to some units

 

[TheThreat]

Well I tried to make a table with BBCode but apparently I can't figure it out.

Anywhere here is what I did. All criticism is appreciated.


Part----------------------Original-Part-#-----------Replacement-Part-#
TR801,TR803---------XA495G-------------------KSA992FATA
TR805,TR807---------8002-1---------------------KSC2690AYSTU
TR809-------------------2SC281-------------------Unchanged
TR811-------------------2SC708-------------------KSC2\690AYSTU
TR813-------------------2SA537-------------------KSA1220AYS
C807---------------------47uf 10V Bipolar--------Nichicon-UES1C470MPM1TD-(47uF-16V)
C809---------------------100uF 10V---------------Nichicon-UKA1A101MDD1TD-(100uF-10V)
D801,D803-------------SM-150-1-----------------1N4002RLG-(least-confident-in-this-one)



I also replaced the trimmers but I didn't get the ones I meant to, and they're a royal PITA to adjust. I'll likely swap them out someday. (Un)fortunately I just sold my house and the closing date is only a month away so all projects are currently on hold. I've got a whole box full of other stuff I'm planning to try swapping in and out when I have a workshop again.

 

[AnalogueBen]

For those diodes we typically sub with 1N4148, same as the au999. Without looking at specs I can't tell you if they will work fine, maybe someone already knows??

Looking forward to see the end result

 

[Hyperion]

D801,D803-------------SM-150-1-----------------1N4002RLG-(least-confident-in-this-one)

This looks like a good substitute, personally I wouldn't use a 1N4148 as a sub for this, if the above post is referring to the SM-150-1.

Either replacement will be fine but I think the forward voltage drop will be more closely matched by the 1N4002.

 

[AnalogueBen]

Just did a diode voltage drop test on my meter of the following.

SM-150-1 = 0.560
1N4002 = 0.580
1N4148 = 0.600

It's funny that I keep many pulled parts, guess it's a good thing for future reference.

 

[Hyperion]

Nice one Ben, 20mV

 

[AnalogueBen]

Nice one Ben, 20mV

Just don't ask me which one sounds best!!
Haven't the time for diode rolling

 

[TheThreat]

For those diodes we typically sub with 1N4148, same as the au999. Without looking at specs I can't tell you if they will work fine, maybe someone already knows??

Looking forward to see the end result

I managed to get maybe an hour of listening in on the night it all got back together, but now its on a shelf while I organize the basement to get ready to move! The poor thing will be in storage until November when we get to the new house. I'd even picked up a pair of Dynaco A-25s (from the original owner, no less) that I was going to match it with.

This looks like a good substitute, personally I wouldn't use a 1N4148 as a sub for this, if the above post is referring to the SM-150-1.

Either replacement will be fine but I think the forward voltage drop will be more closely matched by the 1N4002.

I'm not a golden ear so I can't imagine I'd even hear the difference 20 mV would make anyway. When I tested the old SM-150 I got drops of 0.75, 0.79, 0.8, and 0.8V so I'm a long way from there anyway.