Kitchen workshop - think it looks ok couple of issues with the veneering but nothing major thought I’d leave the panzerholz un-veneered ,well couldn’t be bothered with any more veneering ,stuff was horrible to work with .
One of these, along with swapping the cascode load resistors for a pair of Charcrofts, meant three evenings generally hacking with a soldering iron to redo the power supply and cascode input stage tag boards. And tomorrow we check if it works…
Narrator: it doesn’t. Sound comes out but there is a crackle on the left channel which doesn’t follow the valve and is still there despite reflowing some of the joints, so time to attack more of it again.
Update: fracture in the wire for the left hand cascode connection to the upper grid.
Now sorted, but there is more hum than before so I think earthing needs to be looked at. The cap is there for the first stage, the input RCAs are referenced to the earth the other side of the cap currently rather than the earth for the first stage so I think that may be the first thing to change (tying the two together would seem to be a recipe for a ground loop and the SUT ground isn’t otherwise referenced to signal ground anywhere).
Further update: the hum kicks in about a couple of minutes after switch on. Up until then the output is basically silent.
Seems to imply something thermal, I have swapped out what I would think would be the most likely candidates (first L in the power supply, first power supply C in the phono stage prior to the cascode stage’s LC supply as the C is the new ClarityCap and any open failure there would send the frequency response way out) but still the same.