Techtalk

Yes, the heater goes to ground via the 100r (but you used the holes right after the terminal block, before the 100r resistors ?)
or wait, maybe you did not know you have to wire the heaters like in Drips v1 ?

should look something like this, or better (the silicon cable I used is not good drilled together:


Take the tubes out and measure each heater terminal block input to ground if you actually have 100r. the PCB Billex made for me had a short at one side to ground (I checked the PCB Bernd send me for this, and it was right - but you never know).
[edit: with no power transformer connected of course]

the neon lamp is on the HV rail, if it shines it has more than 65V - that's good.

the best place to measure the HV (High Voltage) is the left side (looking from the front) of R129 or R229.

Hi,
Heater voltage is AC and after a closer look to the solder side of the pcb it seems, that the heaters (H1L, H2L, H1R, H2R) have to be wired by hand. Is that right Volker?
regards
Bernd

Volker, you are too fast

damm, sure now erverything is clear

I hate this undocumented projects

yes volker you are the man

after all my questions this projekt is very well documented


thx

ok...this thing is running and compressing.

gain ratio have to be tuned like volker said (i use sowters) i do it later....

one problem is, that my unit hums a bit. more then it is ok for me

it comes not from the powertransformer, i can move it from side to side and nothing happens.

maybe the ac heaters under the pcb?

i have measured the heater against ground, and i only have around 60 ohms
resistance between ground, but volker said it have to 100R?

maybe this is the fault?

maybe someone has an idea where to look first....

i will try and try

mhm, no hum here.
is it on both channels ?
can you do a photo of your ground pattern ?

yes on both channels, exact the same

in the motherforum someone changed the rectifiers , and then his hum disapeares

...change the retrifiers still hum

all looks good at the photo.
when you disconnect the heaters from one side, is there still hum on the other side ?

waldorfcave hat geschrieben:gain ratio have to be tuned like volker said (i use sowters) i do it later....

one problem is, that my unit hums a bit. more then it is ok for me

how much is "a bit" ? (LA2As are not famous for low noise)
is the hum constant or gain depended ?

hum is to loud, not normal

hum is constant not gain depended.

rewire my ac heaters and check in one minute

Did you mount the 7805 isolated from heatsink and caseground? Doppelkühlung You may have a ground loop. Is hum frequency pre (mains side) or post rectifier (double mains frequency)?

-Harpo

Lars,
did you use shielded wires for pots, output tranny and XLR? The HT wiring is a real pita.
Never mind, Volker
regards
Bernd