Sound advice !

[Cagomat]

Guys .. be gentle ..I’m a mechanical engineer ..🤷 ..and I can build the amp from the drawings but fault finding is the real art ..

I have attached the schematic with some Ac voltages and DC .. please let me know what else you need .. can you make it simple as well 😕

Cheers Brian

the 14V AC on the anode of 300b is way too low. Please control the wiring of your monolit output transformer, and measure the inductance of the primary winding

 

[Brian28]

It looks like the C3Mis amplifying properly.

You have 114VAC at the grid of the 300B.

However you only have 10.4VAC on the plate of the 300B.

You should be approaching clipping with at least 200VAC on the plate.

Something appears to be wrong with the load on the 300B.

Hi , where does the load on the plate come from ? .. OPT ?

 

[Cagomat]

yes the opt primary

 

[AndreK]

Brian,
Are you sure your OPT primary connected to 300B, not secondary?

 

[Cagomat]

Its a little bit confusing, the voltage across the primary winding is 15v the dc resistance of the Monolite opt is 105 ohm. 15V/105 ohm is 146 ma.

 

[Brian28]

Ok ,been in the workshop for a few hours checking everything again .. how about a schoolboy error �� .I seem to have labelled up the pins on the 300b’s incorrectly..
what a knob ��.
I have rewired and fired it up again .. now there seems to be much more volume on the workshop speaker ….I’m going to fire it up again tomorrow and check the voltages again and perhaps try it again on my system ..
I’m hoping that’s the problem ..

 

[Diabolical Artificer]

I seem to have labelled up the pins on the 300b’s incorrectly..
what a knob

Easily done, I've executed some right howlers, away with the faeries, brain only running on one cylinder.


Good your making progress, Andy.