- Feb 15, 2021
This is regulated -16V rail. If you ever want to use an off-board regulated PSU, you can hook -16V here directly. Otherwise leave unpopulated and unconnected. This also serves as a convenient test point for checking Vreg output voltage.What is the 16vdc molex connection next to T2 on the main board for?
This is a point where you may want to link signal GND with chassis GND. Depending on the particular system this may be not the optimum point, but it's a good starting position. In your situation this is the main and first option. Make a connection there and if you still get any hum, we'll see what's the problem.Thanks, I also noticed in one of your pics you have chassis ground and audio ground jumper-ed
on the main board.
Input transformer is PCB mounted, so there's probably no compatible replacement. If you opt to mount the transformer off-board, any high quality 1:1 line input transformer will do just fine - Sowter, OEP, Lundahl - anything you like.Is there a substitute for the Cinemag CMLI15/15BPC,and CMOQ-2
It’s very difficult to know what’s going on without a scope. Ideally, you should look at the base of switching transistor and see if pulses are there. If they are, the unit should compress. You can try whamming the input with +10 db signal, put a threshold down to minimum and check this point with a frequency counter and see what you get. Don’t forget to set a ratio somewhere not 1:1)))Got it all together and fired it up, passes audio but no compression, I was going to put my scope across the points in the calibration procedure, but my scope's crt just fried out LOL
I do have a freq counter and I am getting around 275khz at D1 cathode, I am going to take a break on this tonight, any ideas how I can trouble shoot would be great, I only have a freq counter, signal generator and a VOM at present.