I am repairing a Matrix 6 PSU and have run into an issue.
The initial complaint was it was not turning on at all.
The xfmr was found, by myself, to be physically broken. It did not fail, just cracked at the terminals and was unable to be repaired.
I have replaced the damaged xfmr and DC PCB with a mean well PSU and a small center tapped 9VAC xfmr. Now it turns on,nhas output, and can be controlled with switches, just no VFD. This display was said to be working before.
The display PCB schematic says it needs +5 and a 2x9VAC(J2, 5 and 3)
Issue is with the VFD not being supplied with the necessary -42VDC to operate correctly.
I can only measure -13VDC from the AC/DC circuit that is supplied by the 9VAC.
see pic attached.
I have replaced the 2SA1283, all components in this AC/DC circuit have been removed and tested. I have replaced U6. Removed the VFD (not tested) and not installed, the circuit VDC still reads -13VDC.
I have isolated this little circuit, output not connected to anything, and it still does not read the correct -42VDC, reads -13VDC
The 9VAC xfmr(120V in/dual 9VAC out, center tapped), is switched on with the 120VAC shared with new PSU.
I would like to make sure this -42 is correct before determining the VFD needs replacement.