as August said ...
speaking of one channel :
100R trimpots are for buffers , initially upper one (on schematic) set to 0 , confirmed with ohmmeter across R5 , while lower one set to max , confirmed with ohmmeter across R4
2K (1K for Babelfish M25) is for Iq , initially set to 0 , confirmed with ohmmeter , whichever way you find most adequate
10K (or 20K , as sent in last shipments) is for output DC offset , pretty much irrelevant initial setting
I'm finding easiest pre-set of trimpots is while pcbs still aren't mounted on heatsinks
physical position of trimpots on pcb ( screw where arrow on pcb or rotated for 180deg) is pretty much non-important ..... I'm anyway lousy at planning and remembering that orientation thing , always looking at multimeters to decide in which direction to turn them
dunno , most probably years of service work ...... it's easier and faster this way
speaking of one channel :
100R trimpots are for buffers , initially upper one (on schematic) set to 0 , confirmed with ohmmeter across R5 , while lower one set to max , confirmed with ohmmeter across R4
2K (1K for Babelfish M25) is for Iq , initially set to 0 , confirmed with ohmmeter , whichever way you find most adequate
10K (or 20K , as sent in last shipments) is for output DC offset , pretty much irrelevant initial setting
I'm finding easiest pre-set of trimpots is while pcbs still aren't mounted on heatsinks
physical position of trimpots on pcb ( screw where arrow on pcb or rotated for 180deg) is pretty much non-important ..... I'm anyway lousy at planning and remembering that orientation thing , always looking at multimeters to decide in which direction to turn them
dunno , most probably years of service work ...... it's easier and faster this way
My PSUs are almost ready now as well ... 
(Have some Motor Run Caps on order, to be placed at the back of the amp, and to have the Fastons from the PSUs connected to. From there to the amp boards then ...)
2.5 mm^2 wires soldered directly to the solidcore wire on the underside of the PSU boards. Bleeder resistors and some film caps also soldered from underneath.
Have started stuffing the amp boards, but waiting for some more parts from Mouser and Reichelt ...
Best regards,
Claas
(Have some Motor Run Caps on order, to be placed at the back of the amp, and to have the Fastons from the PSUs connected to. From there to the amp boards then ...)
2.5 mm^2 wires soldered directly to the solidcore wire on the underside of the PSU boards. Bleeder resistors and some film caps also soldered from underneath.
Have started stuffing the amp boards, but waiting for some more parts from Mouser and Reichelt ...
Best regards,
Claas
Attachments
I have a place on one of my boards, I thought it was a deformed solder pad, but under magnification it looks like some of the blue mask has come off or is missing?
For some reason, I cant seem to upload pics...never been a problem before, I keep getting the "Aww snap" thing. Tried rebooting, incognito page, original settings etc. but no help..
I will when I can. Is the missing mask a problem?
Russellc
For some reason, I cant seem to upload pics...never been a problem before, I keep getting the "Aww snap" thing. Tried rebooting, incognito page, original settings etc. but no help..
I will when I can. Is the missing mask a problem?
Russellc
![IMG_4712[1].JPG](/community/data/attachments/674/674141-6d4cb9c485300d52921e034f93bbee3c.jpg)
At first I wondered, as continuity showed across the "bald" part....but so do the small pads on the unaffected board.
You are right, will wait for ZM's final say.
Russellc
Yeah ... that was just my usual modular thinking to have the PSUs as building blocks that could be re-used by themselves ...
Haven't tried yet ... boards are still in their frame. Once I'm finished stuffing them, I will remove the heatsink from the case, deburr and smooth the output transistors' mounting area, and drill & tap one more hole for the THF-51S. Then I will be able to report ...
Best regards, Claas