LEDs on driver board [resolved]

[Pete]

I'm looking for information regarding the 4 tiny LED's on driver board. There i 2 on the "A-side" and 2 on the "B-side". Currently I have both the A-side lightning and the B-side dark (same driver pcb). The left side and right side channel arre having same behaviour. I have sound in the right chennel but none in the left channel. Sound in right channel seems to be "murky" or "dull".
Any explanation on a) the leds and b) current behaviour?
Regards. Peter

 

[Paul Joppa]

Those LEDs serve as voltage references for the regulator and for the plate load current sources.

To diagnose the prroblem, we'll need your voltages, and a photo or two of the build.

 

[Pete]

Here is some voltages and 2 pics.

all measurements after 2 min warm up time. L and R is left and right hand side of the amp. All measured against *ground

Driver board
POWER
AO/L 450
AO/R 0
IO/L 298
IO/R 0

GLOW (LED)
'A/L. ++
B/L ++
A/R --
B/R. --

POWER

PIN B1 67
PiN C1 67.

32. 354
46. 173
53 66
65. 67

10. 158
14 450
15. 221

GLOW (tubes)
B. +
C. +
A +
D +

I have measure resistance (connection) over and over again and redone soldering, but are unable to get teh right channek uo and running. Hope you can guide me fixing the error(s)

i also attach 2 pictures of diagrams for the driver board connection . I did this to ensure that manual and amp would be the same. fwiiw you may find this of use..


The left channel play well now

Regards. Peter

 

[Paul Birkeland]

On the driver board, these are the voltages of interest:

IA, OA, IB, OB, KregA, and KregB.

 

[Pete]

Right side board (right channel, no sound)

IA, 450v

OA, declimimg to 0v

IB, 352v

OB, 352v

KregA, 2v

KregB.390v



Left side board (left channel, play sound as from black RCA)

IA, 455v

OA, 300v

IB, 294v

OB, 175v

KregA, 2v

KregB. 0


Measuremnt after 2 min warm up, with all 4 tubes inserted. During previous build of the kit all measuremnts were correct before I moved on with the build.

Some of the data above (first posting) point to a voltage splitting issue that has a “dead leg” – problem is I have no idea where to look for and correctiing

Please focus on fixing the “no sound” issue, as this may not ( only) be the C4S board causing this. The tiny leds glow is not an issue in itself

Regards Peter

 

[Paul Birkeland]

OA and IB are connected by wire jumpers (red ones). You have 0V on one of these terminals and 350V on another, so provided these measurements are accurate, the piece of wire that's supposed to be there is either broken or poorly soldered on one end.

 

[Pete]

As per your suggestiona I had anothe look at the backside of the c4s board. I seems to not having seen the black wire thst is attache d to the a-side corner to have broken at the attachment point to the 1-2-3 bridge. After removing a bit of the isolation and resoldering the connectio the Kaiju came to life. I hav benn listening to the amp for a few ours, and i really like

Learnings: Use better light when looking for connection problems (black wire is hard to see). Be carefuld pullimg and pushing the c4s board in and out for inspection. Despite using a Jokari de-isolation tool some damage may have taken plade that has damaged the core wire (don't use a cutter or alike)

Thank to the people abive for input!!!

I only miss toinsert tje DC fiamet improvement - hope for no furter hick uos and even better sound

Regards. Pete