Electrolytic capacitors go bad eventually, Maybe not tomorrow, maybe not next week, but eventually they go bad. If I was a tech fixing this Maxi-Korg on a budget for a kid who just dragged it home from a garage sale I would probably insist on recapping the power supply and replacing the tantalum capacitors, doing some testing and sending her on her way with a $60 repair bill and a few words of encouragement to take care of this neat thing she is now the keeper of.
That is not the situation. I am a guy who likes to do it once and do it right as much as possible. I am going to replace all the capacitors. Top to bottom, inside out – even the couple of tantalum caps tacked onto the back of some of the sliders. And why not there’s only like 60 or so.
Once you have decided to replace all the capacitors in something, you might as well get on with it and put an order together. The easiest way to put your list together is find someone who has done the job before and ask them for their list. This failing, you will have to make your own. My method for making a list is to find the service manual and see if it has a decent parts list. In the case of the Maxi-Korg – sort of.
I ended up spending about an hour and a half looking over print outs of each circuit board and tallying up the caps on them. I have to replace 82 capacitors! I should mention that you replace tantalum capacitors with electrolytics of the same rating. Upping the voltage within reason is fine.
My next move is to review the list and see what sizes I can combine to try and order more in bulk. You can up the voltage of a cap without issue within reason – reason being say 3x or less. For example there are a few 10uf 16v tantalums and several 10uf 25v electrolytics. These call all be replaced by 10uf 25v caps.
Once I have this rationalized list together I go through my capacitor stash and see what I have on hand so I can get started right away and avoid hanging on to capacitors too long. In the case of this rebuild I had the 100uf 50V, 1uf 50V and 220uf 25V capacitors on hand.
I placed my order with Mouser on a Monday and had my box of capacitors on the following Saturday. Some pointers ordering from Mouser: Round up to the next price break if possible – many times you will get twice the number of capacitors for 25% more money and the extras will help you out on a future project. Buy bulk rather than ammo pack or tape reel – the extra time cutting each capacitor from the tape adds up! Think ahead to the next project so you can save on shipping – I ordered all the capacitors I need for a 1968 Fender Bassman 50 I got recently and I don’t think shipping cost me any more.
Up next: probably the control panel, but maybe some cosmetic work on the wood or metal panels.