Today I thought I would practice my soldering skills on a BM1000 that I have that works but is in need of tlc. I thought I would start by changing the two large 2000uf 25v capacitors it has. On removing the old ones I found they have 3 connections not the 2 I was expecting. Also the board doesnt seem to be marked to tell you which is the + or the -. Also on the old capacitor one of the legs has a circle on one has a square and the third has no markings. Can any one tell me how I should replace them and where the + or - is. Please note that this is all a bit hit and miss with me and if I do end up killing the BM1000 im not too bothered as I only got it as a spares unit for the volume knob but it is an early Danish market one so would be quite nice to get it going.

Have you downloaded the service manual? Which type is it?

Its a 2301 white key version. The service manual didnt help me but saying that Im not the most adept at reading things like that. Ive done capacitors in speakers and just thought I could practice on it before maybe doing one of my Beomasters that I dont want to kill! I thought capacitors just had a + and a - but these have 3 connections which stumped me.

The 3rd leg of the capacitor will probably be a tag on the outer capacitor casing to hold it to the board to combat the effects of vibration. You can simply glue the new cap in place before soldering to compensate for this. Boards are usually marked on the solder side with 2 thick lines (within a line showing the track of a capacitor) facing each other, one of which is normally block printed in white - the other being an outline. The block printed side of the symbol is the negative connection.

Chris.