Learnt a lesson today. (Pass power supply.)

[ColinA123]

Upgrading my Pass power supply today to dual transformers and cap / rectifiers.
Fitted crimp, push-on connectors to the transformers. Nothing working!
Traced it to the enamelled wire! Once cleaned up and re-crimped all working fine. 🙂

 

[Zen Mod]

for dual mono, each channel GND is having own NTC to chassis

you have common NTC

crimping - crimp just lightly, then solder it

 

[ColinA123]

Thanks, will sort that.

 

[TungstenAudio]

I that picture, it looks like the purple wires from the transformers are connected to GND through NTC termistors. The purple wires are electrostatic shield connections, and must be connected directly to the chassis. They are not part of the audio ground.

 

[Zen Mod]

I believe that's mid-connected NTC between two 115Vac primaries

Sropshire probably being 230Vac area

 

[ColinA123]

ZenMod is correct again. (As usual.) 🙂
NTC connects white and purple. Transformers made by Block. (Germany)

 

[nicoch58]

HI
are good that block ? remember the model ? tnx

 

[ColinA123]

I have no complaints with those transformers. Ordered from RS components in the UK. as they are easy and fast.
400va 2X18v
https://uk.rs-online.com/web/p/toroidal-transformers/7529393

 

[Allan]

I note your 0v and earth are taken from different points on each PSU board... why?
Reason I ask is I've seen comments where particular PCB GND points make a huge difference, I personally experienced this on AMP PCB ground points where I swapped PSU GND and speaker return. It had a huge impact on a hum problem I once had with my F5

 

[ColinA123]

Allan.
Not sure what you are seeing, the connections are taken from the same pad on the board.
Just two wires to different places.
I was prepared for possible earth loop hum, but everything is silent.
My main impression of the results is better clarity and separation,
but I have made a lot of changes, including new speakers. (Dallas 2 horns with Fostex FE206 en drivers.)

 

[Wang1]

Hi there,

What was your reason for going for such large tx, 400va per chan, i was thinking of using max 250va per chan which is more than enough to cope with a load impedance down to 2ohm at max peak voltage.