Official M2 schematic

Syl20m · 2019-03-24 7:22 pm

An externally hosted image should be here but it was not working when we last tested it.

KevinHeem · 2019-03-24 11:38 pm

@Syl20m

You pictures aren't showing up.

Check to make sure you are using the correct secondary pairs. A pair would have continuity between the two wires.

Syl20m · 2019-03-25 8:14 am

1A0A03EE-6FA7-4E84-87C9-3037C8B85ECC. - Casimages.com

Syl20m · 2019-03-25 8:23 am

Continuity is fine, with about 0.2 ohm on both secondary
Primary is ok also

Syl20m · 2019-03-25 8:28 am

5D36F40E-53EF-4ED4-9C83-32EF2513280A. - Casimages.com

silasmellor · 2019-03-25 8:34 am

I get that it is inconvienient to unsolder but I would take the secondaries out and measure that you get the correct voltage on each pair. Then reconnect and check voltages after rectifiers. And so on going forward.

Syl20m · 2019-03-25 9:02 am

Both secondary are now disconnected !
They don’t give the expected 18vac
Strange for a brand new transformer

Syl20m · 2019-03-25 9:08 am

Transformer does not even show to have a short circuit !
I am using a cl-60 inrush limiter at primary and fuse of 300ma
Could the transformer be broken ?

silasmellor · 2019-03-25 9:43 am

What is the voltage at the secondaries? 300 mA is a small fuse for the M2, did you check that it didn’t pop?

Syl20m · 2019-03-25 10:20 am

Ok, there was neutral not well screwed !
I have 25,3 after both diod bridges, and same after capacitors banks

Syl20m · 2019-03-25 10:22 am

Just tried to play music! It give out something, but very crapp
Lot of noise like saturated and on/off , sound comes out for a short time every seconds on ..off..in..off

Syl20m · 2019-03-25 1:48 pm

Marra · 2019-03-25 2:48 pm

I can't see where your power ground is.

Syl20m · 2019-03-25 3:11 pm

R6 R7 were missingi used 47k... bloody me !!!
Sounds already so great on my crappy test speakers
Offset to set now !
Easy way to do that?
Thanks all

Marra · 2019-03-25 3:17 pm

Glad that you sorted it. The M2 is a great sounding amp imho.

theurbanshaman · 2019-03-25 5:42 pm

It IS great sounding! I just got a hold of a First Watt M2 on Ebay for a nice price. It's not the best match for my Quad ESL63s, but when I pulled out my old trusty Spica TC-50s the speakers disappeared like never before in a deep and wide soundstage!!

Syl20m · 2019-03-25 6:37 pm

Hi all,
I just power up for the first time my M2 clone! And it sounds great.
But I want to move on now with the last needed tuning!
I am not sure about what should be done and how!
-DC offset, what else ?
If someone knows about a good manual, I 'll be pleased to use it!
Thanks in advance!

Zen Mod · 2019-03-25 7:21 pm

nothing else besides DC offset

check DC voltage across source resistors of mosfets (those big ones , 0R47 ) and that's it

yes , write here that voltage

Syl20m · 2019-03-26 7:11 am

Hi zen mod,
For the right channel:
R13: 0.619v
R14: 0.661v
For the left channel :
R13: 0.64v
R14: 0.671v

For info r8 r9 get to about 45degre after 20 minutes
R13 and r14 about 50 degre
Thanks

Zen Mod · 2019-03-26 7:17 am

all good , enjoy

Official M2 schematic

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