Prototrak Plus Retrofit with Mesa 7i77 & 5i25 cards

Many thanks Dan! The DRV O & DRV 1 is (TB 5) on 7i77 card. I will look again at page 9. Will post pic soon.

many thanks!

Edit: I have read your load suggestion, this is at the large black transformer, the terminals going to the rectifier and amp, place 110v light bulb to 2 of the 3 leads going between rectifier and transformer. Just need to be clear.

Many thanks andypugh! I recall the rectifier having an post that was odd arrangement, I will be looking close and will post pic if it will help. With the power off and discharged capacitor, I will be testing continuity from the rectifier (post in question) to the terminal output of PSB/capacitor assembly, correct.

many, many thanks! (if correct just don't post)

I can't be sure which terminals are which just from the pic. That is why the light bulb and volt meter. You can be sure you are hooked to a loadable DC output. With a light bulb, if you hook up to anything else, you won't hurt anything. (At least, it is highly unlikely.)

Best, Dan.

Many thanks Andy and Dan! Here are a few pics, use for reference, because it needs to be correct.

this is a diagram of the leads, if you see the rectifier is marked + on the left & - on right. Also the PSB is enlarged in the diagram, with the Brown=Br; White=W; Blue= Bl. I have taken just best guess for the locations in the pic. The other pic is of the amp with the fan assembly rotated for better view.

Many thanks!

It seems fairly clear that white is negative.
But as for which of blue or brown is positive, I can't really tell.
What does the multimeter say? Which connects to the + terminal of the capacitor?

Thank you Andy & Dan! To insure this is tested correctly I place 110v light between 1 & 3 measure voltage; 1 & 2 measure voltage; 2 & 3 measure voltage, changing the light as I go to the next set of leads. Will this also answer Andy's question about 80v. I can pull other capacitor out to see back side of PCB if it is better that way.

many thanks!!