ZM's 2SK2087C musings, phase two - SissySIT (42) as a cradle

[Rush]

I'm thinking put cap bank and transformers front to back, stand alone caps on sides. See if that gives you more room on sides?

 

[Zen Mod]

mains Donuts must be on opposite side of case against signal xformers

one of the ways - post #908 https://www.diyaudio.com/community/threads/ludef.369990/post-6997306

 

[Dan K]

Re-mounted CLC as in board as possible. Yes I can see your point about interference with trim pots.

Bridges do have thermal paste and lock washers. NTCs in tandem as you suggest. View attachment 1282733

Have the traffos hang over the edge, as far away from the cinemags as possible. Also ditch those std rectifiers and go LT4320 active (IMHO)

 

[Dan K]

Maybe something similar to that, obviously with 2 traffos

 

[Zen Mod]

power wires are so tiny, btw.

 

[Dan K]

Interesting! Silver plated copper, I could double them up

 

[Monk55]

Looks like I have same issue as Rhthatcher..”I had 220R level shift resistors and biased to 1A8 / 0V offset. After cooking for 90 minutes the bias crept up to 2A0x and 1A9x. I coudn't get back down to 1A8 with pot at minimum, so I put in 240R resistors and adjusted them to get 1A8 / 0V offset.”

Will start increasing level shifters…..gonna pop in 240r.

 

[Monk55]

Ok we have heat….level shifter to 232r
Went to 190ma at max P1 setting after 10 min.
I adjust up a tad….

 

[Monk55]

Warming Porn

 

[Zen Mod]

 

[codyt]

Nice looking builds. In the last few I’ve noticed big Ducati film caps attached to final PSU caps – are people getting better results with this extra film capacitance? I like how Monk’s film caps are right at the board too. I’ve never played around with film in PSU, mainly due to lack of space. Might be something to explore if there are measurable and/or sonic improvements.

 

[Monk55]

Codyt….I've only used in tube amps, first time trying with sand. I figure why not. I “ thought” I could tell improvement in the tube gear…..

 

[Monk55]

SissySIT 42 off & running. That ZM can sure make a great amp. Hats off mighty ZM!!

Im letting it run all day on tiny speak….
Final DCV under load 22.66…without load 25.25vdc. Using Antek AS-3218, 18vac secondary’s. CRCc…39k-.1r-39k-80uf. After an hour of running, NTC board 40c, Th51 37c, Moss 35c, & M201 32c.
Indeed put the level shifter on “stilts” so it can be changed! Then just solder in place.
Off to build left channel……

 

[Zen Mod]

I was away of all sorts of e-mail communication for entire evening, but good to see you solved your dilemmas

wasn't there writing on main board, near Daughterboard, something as "Iq CW"



yeah, level shifter resistor is main adjusting tool for cheeky SITs

 

[Monk55]

Darn cheeky SIT’s anyway!!

 

[JKiriakis]

@Zen Mod - what is the purpose of the series of pins that came in the kit? It's the one piece left I can't ascertain. Also, to your point about small power supply wires, they're 16AWG teflon coated also known as 1.5mm

 

[Zen Mod]

see funny holes/pads right at 1R resistors?

 

[JKiriakis]

Okay sports fans, first test of the PS through dim bulb tester, one side at a time via fuse insertion. Measuring 49VDC unloaded

across the Pos and Neg vias on Cap Bank boards. Do I have clearance to wire and test one channel?

 

[Dan K]

Is the mounting tray the right way up?

Will the case still fit together like that?

As is I think the various bolt heads won't allow the lower cover to close.

I'd flip the transformers over, so you can better dress their various wires

Pull out the little red jumpers

 

[Monk55]

Purple tranny shield wires go to same ground point along with green wires. You should twist all tranny wires.