So, my 2020B came in today… Of course the seller packed it extremely well!
Look at the layers and layers of bubble wrap! Of course, you only need bubble wrap on the
top, right?
Unfortunately, despite the
expert packing, it seems the fuse holder was broken in transit.
Not enough to glue it back together. I also shocked the shit out of myself after plugging it in when I went to move it, because I forgot about the exposed fuse. I’ll just replace it with a modern holder.
So, upon turning it on, it does go into overload like the seller stated. I measured 40VDC on the output. Upon checking the back, I noticed there were no straps between the Sense and Output terminals, so I added some wires.
Despite this, it still was outputting 40 volts. I pulled out the current limit knob and a puff of magic smoke came out the top! I opened the bottom cover and the internal fuse was blown. It also appears that R18 is deformed, so I’m thinking that’s what was burning (it smells like it).
So now I’m going to review the schematics and do some tracing. Any recommendations for some things I should check for?
Finally, here’s a nice picture of the entire board. Other than R18, everything else seems in good shape.