BIG problems

This is the sellers reply:

"I use MJ15024 and mj21196 transistors exclusively for Phase products as they have the highest voltage and SOA ratings needed for the Quasi output stage. Using the 024 for the driver transistors is a little over kill(MJ15022 would be good enough)but I buy 500 devices at a time for matching and it is easier to match driver devices also with that quantity; The series II quasi and complementary also used the same transistor in output and driver stage when original devices became obsolete. As for the caps, I would have to look at your order. What value do you have to many of. Let me know, Ed"

Make sense?
 
Michael F said:
A gentlemen from Blackwood NJ, EBay handle Qua-co.
Click to expand...

OK, that is not great advice for the quasi comp. It may work sometimes but is not the proper recommendation as it can lead to oscillation on the lower half signal.

What do you have in the amp for the pre-drivers now? The pre-driver is the bottom TO-3 position on each vertical column. They are usually RCA410 (the best) or SJ2741 or
66546 or the like.

Did you already purchase the transistors or are you just emailing back and forth at this point?
 
Gepetto said:
OK, that is not great advice for the quasi comp. It may work sometimes but is not the proper recommendation as it can lead to oscillation on the lower half signal.

What do you have in the amp for the pre-drivers now? The pre-driver is the bottom TO-3 position on each vertical column. They are usually RCA410 (the best) or SJ2741 or
66546 or the like.

Did you already purchase the transistors or are you just emailing back and forth at this point?
Click to expand...

I already have received the semi`s. I originally had 410 but one is blown.
He also sent 4 small polypro caps to be used "in the event of HF oscillation"

Here are some email exchanges:
Me

Hi again,
Thanks for clearing that up. The caps are little blue poly`s .33, 1kv. They came 4 to a bag with a note stapled to them pertaining to which semi`s are matched. Are these intended for the BC jct of the 40327 and mm4003 pre driver to prevent HF oscillations? If so, is there any harm in installing them regardless?
THX
Mike


Seller

Yes, they are for oscillation problems if you have them, You can install if you do not have a scope to check for oscillation issues. Sometimes you need they, sometimes not. Thanks, Ed
 
Star grounding

I`ll begin this next phase (pardon the pun:) ) with a new grounding scheme. My interpretation of Gepetto`s diagram is as follows:

*Buss bar to center terminal of Left channel backside terminal strip
*Left channel center terminal to center terminal of Right channel backside terminal strip
factory wire from input switch to right channel terminal to be removed

*Buss bar to PL14a Chassis Ground pad
that pad used to get its ground from input/output terminal grounds?

*Buss bar to light board (pad 4?) on WO light board

*Buss bar to Left and Right negative output terminals
input jacks and switch chassis grounded through input/volume pot wire shields to PL14

Does this sound about right?
 
Are you referring to the input switch as the "Direct/Normal" switch on the back??
 
The series II quasi and complementary also used the same transistor in output and driver stage when original devices became obsolete. As for the caps, I would have to look at your order. What value do you have to many of. Let me know, Ed"

Make sense?



I question the validity of that statement.
 
Michael F said:
I`ll begin this next phase (pardon the pun:) ) with a new grounding scheme. My interpretation of Gepetto`s diagram is as follows:

*Buss bar to center terminal of Left channel backside terminal strip
*Left channel center terminal to center terminal of Right channel backside terminal strip
factory wire from input switch to right channel terminal to be removed
Correct, to be removed

*Buss bar to PL14a Chassis Ground pad
that pad used to get its ground from input/output terminal grounds?
Correct, it used to but it should connector to bus bar star point ground.

*Buss bar to light board (pad 4?) on WO light board

*Buss bar to Left and Right negative output terminals
input jacks and switch chassis grounded through input/volume pot wire shields to PL14
Correct except that there is NO ground applied to the switch, that is unnecessary.

The schematic is quite literal, you have correctly interpreted it with all your comments except for the one about the switch ground.
See picture below for a method on how the switch and inputs are handled.

Does this sound about right?
Click to expand...

DSCN0007.jpg
 
laatsch55 said:
The series II quasi and complementary also used the same transistor in output and driver stage when original devices became obsolete. As for the caps, I would have to look at your order. What value do you have to many of. Let me know, Ed"

Make sense?



I question the validity of that statement.
Click to expand...

Ditto
 
C6 mod

I`m replacing C6 with a 470uf/25v and 2 1N4148. With regards to the "back to back" placement of diodes across cap, that would be the 2 in parallel, anode/cathode together on one end and cathode/anode and not the 2 in series i.e. ACCA or CAAC correct?
 
Anoded to cathode onm each end. In other wirds, lay them side by side, reverse polarity to each other, then twist the leads together . Then parallel the leads of C6. In your care package this was already done.
 
laatsch55 said:
Be sure C6 is audio grade...
Click to expand...

How can one tell? It was difficult enough to find a 25 volter, any bigger and the leads would`nt go through the PCB and the cap would take up too much board real estate as well.
The one I bought seems garden variety, should I leave the old one in?
 
On that factory board, I have bent cap leads 180 , then brought them in a little then bent them back down. Post a pic of the cap.
 
Damn I wish my care package had gone thru. It had all the caps you needed for both channels, C3, C11, C6, C15, C16. All Nichicon KZ (Muse) series. In the factory boards, you can drill out the component thru holes. I use a cutting torch cleaning set which is a pin vise with very small drill bits. Those caps I'm not familiar with. Should get you up and running though. Got a cap checker on your meter??
 
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