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Sun 3/80 - Need replacement capacitor recommendation

T

Thatsmanjear

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Joined
May 9, 2023
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Hi there. I recently acquired a Sun 3/80 and it has a bunch of little yellow rectangle surface mount capacitors with "336" "16" and a "K" stamped on top, and 4mm x 6mm dimension. One of caps is clearly burning (see pic). I need to replace this cap (and perhaps more) but could really use a smart recommendation on what I should use? I've been looking on Mouser and Digi-Key and am getting quickly overwhelmed with choices.

Questions:

1) If I wanted to replace it with exact replica I think it might be Kemet 33 picofarad, 16v, 10% tolerance?
2) Is it smart to replace with same thing, or is there a better choice?
3) Should I just replace the one, or is it a matter of time before they all start to go so should just do them all (there's like 15 on the board).

Really appreciate the help!
 

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Hello 336 is a 33 micro-fard cap and it is 16 volts, for the smd package you will need to find same size
and the line is the plus side, if one burned ot the other may not last as they dry out and short. so you should them both
 
I think you meant to say 33uF (not picofarad) capacitor and yes that is a proper replacement part.

It is better to use a surface mount part like the original. While you can fit other types with leads, if the get bumped or bent over it can pull up the tracks.

To remove it I would recommend adding fresh solder to each side initially, then with two soldering irons, one in each hand, melt the joints on both sides simultaneously, and using the soldering irons, apply a rotational force to remove it, don't pull it upwards away from the pcb as this can lift the tracks. Then remove the residual solder with solder wick and clean up the board with IPA or similar and a cue tip, before fitting the new part.

I would replace the other one too, it probably will short out at some stage in the not too distant future.
 
tantalums don't dry out, they are solid chemistry. they form internal dendrites and short out, which is what makes them burn like this (or else explode).

electrolytics dry out (the electrolyte does), but this makes them fail open circuit, not short.

In the Sun 3/80 these are SMT chip size C or D (IIRC). They are age-failed on every 3/80 I've ever encountered. Just replace them both.
 
Also, this remark might be painfully obvious but worth noting:

Tant capacitors (like electrolytics) are polarized and must be fitted in the correct direction.

Looking at the two them, you will notice they face in reverse directions on the pcb.

The other oddity about Tants, is that the line or dot often printed on them is their + terminal, unlike electros were the line is often the negative terminal.

So, in summary make sure to orient the new replacements correctly, If tants are put in, in reverse, they burn up in short order.
 
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