This Access Virus Rack was continuously restarting when power was connected. This is apparently a common issue with the Access Virus and is due to a capacitor in the power supply going bad. In this video I replace said capacitor.
I didn’t have to do any real troubleshooting here as there were various references to the problem online. Here is one example:
https://joeyfehrenbach.tumblr.com/post/76338854745/access-virus-b-the-synth-repair-adventure
Hi,
thanks for the video, I want to replace the capacitor in mine as well. But I was wondering, how do you know where the GND side on the PCB is? I reckon it does play a role for an electrolyte capacitor/the circuitry, doesn´t it ?
Kind regards
Paul
The negative (in this case connected to ground) side of the electrolytic cap is indicated by the white stripe with the “-” on it and usually (when the capacitor is new!) one of the legs is shorter to also indicate negative. Just place the new cap in the same orientation (the stripe is on the same side) as the original one and you’ll be OK (see the photos below the video)
I do not have the unit here (as it wasn’t mine) but I would assume the negative side of the cap is connected to a ground plane on the underside of the board in this case. You could have a look at the datasheet for the LM2575T (http://www.ti.com/general/docs/suppproductinfo.tsp?distId=26&gotoUrl=http%3A%2F%2Fwww.ti.com%2Flit%2Fgpn%2Flm2575-n) and on page 1 there you’ll find a typical application. On the top left of that diagram you’ll see a 100uF capacitor (marked Cin) where positive side of the cap is connected to pin 1 and the negative side is connected to ground.
But if you are replacing an existing electrolytic cap; just note the orientation of the cap before desoldering and place the new cap in the same orientation 🙂
And Yes; for electrolytic caps the orientation is important. They might go “pop!” if you orient them the wrong away around 🙂