Ok so first project in the MSX is to recap it… can anyone help me identify these caps? I’ve got the values, I just want to make sure I get the right ones, problem is the product codes have been changed at nichion so googling their codes is pretty useless… Ive got PC(M), PX(M), VS(M) SE(M) can anyone help shed light on which caps I need? and also how much does it mater outside the capacitance, voltage, and temperature?
I always try to go for all the same make capacitor, having done this on a bunch of old stuff. I stick to a single make because either they will all be ok for a long time, or they won’t. Having one or two fail early is nearly as much hassle as replacing them all (in my opinion), plus matching make caps look cool!
I just search my favourite supplier, avoid the likes of ebay. That place can be rife with either fakes, or old used caps that have had new cans put around them (and all sorts of other nightmares). Always go for a slightly higher voltage rating and temperature if possible as JaggedNZ says. Most modern ones will have higher ratings for the same or less physical size anyway.
Watch out for errors in the printing on the board, I know my old ZX48 Spectrum had one error that would have put the cap the wrong way round. So take photos before and after if possible. This stuff you may already know, and I apologise in advance,
The next thing that might be important is ESR (internal resistance), which matters in some locations, and not really in others.
But to do a precise mapping, you need an expert – as in someone who’s spent enough time reading manufacturer’s catalogs to know what exact type maps to what other type, or who can at least make qualified guesses. There’s way too many options out there for any random hobbyist to keep track of all that.
Given that the caps are close to one another I guess it can be more of a challenge to find them to fit size-wise than to find the right capacitance. My 2 ct.
Sorry @Oddball I just spotted this. Yamaha service manual and schematics are out there for most things. When stumped i start with what the supply output should be, list the parts and spec i do know and then guess and adjust the values of the other components using simulation software.
There is no real need to replace them, if they work. Old Capitators can dry out and set on fire or burst. It is pretty simple to messaure them(though they can have shifted a bit, but less of an issue, if they are working, but if they aren’t, you can’t use that for anything) and go after same accurancy there is written on them. I would say it is one those things you take to someone working with those kind of things, rather doing yourself. I mean it is board from Era, where most stuff are big enough to be seen without microscopes, and it is rather easy one, because it seems like they list components and placements, so it was easier to assemble and repair.The only thing I am worried over is the old hot glue around some of them. In some cases it can maybe repair difficult or even impossible. It is a cheap way to isolate or water proofing electronics. Very effective. My dad hates it, because he encounters it too often in his day job as engineer.
Swollen electrolytics call definitely for a change. The chemicals inside a cap isn’t really raspberry parfait …
When replacing and if the cap is in a tight space - pick a 105 C cap.
Also, check other types (paper, ceramics and plastic) in older equipment. Paper caps often distort and may have a increased tgd (tangent(Delta) a bit like ESR) if having soaked up some moisture.
Old ceramics may be microphonic, and if cracked may be successively ruined by moisture.
Have a Soviet synth in my “workshop” where ALL caps are replaced.
Remember that newer capacitors are made withg much tighter tolerances. When I worked for RIFA back in the 80’s, the electrolytics could safely be run at 150% of maximum voltage, due to the processes that guaranteed the numbers printed on the cap.
