Capacitor replacement

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By SkalTura

Champion (346)

SkalTura's picture

07-07-2012, 12:04

Hi all,

I'm a repair technician for a big Japanese electronics company, and a standard policy we have for inverters older than 6 years is that all Elco's (not SMD, only trough hole) have to be replaced because these can leak after a few years, causing the value to change.
I searched the internet an found that normally an Elco capacitor had a lifespan between 5 and 10 years.

It is a good idea to also to this for MSX computers, because these are way over 10 years old ?
Or just go with the philosophy: "If it's not broken, don't fix it"...

Thanks in advance for your reply

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By jltursan

Prophet (2557)

jltursan's picture

07-07-2012, 13:42

IMHO if you are good at soldering (I guess you are) it's always a good idea to replace caps with new ones, even with higher voltage as suposedly they're of better quality.

By Miguel_Noe

Champion (465)

Miguel_Noe's picture

07-07-2012, 15:18

Very importantly, seal around the condenser if it is electrolytic.

By SkalTura

Champion (346)

SkalTura's picture

08-07-2012, 10:29

I think most MSX computers only have a single layer PCB, so de-soldering and re-soldering components is not that difficult. As long as you set the temperature of your iron not to high, and don't hold it in the same place to long, or your traces will peal of (some experience is required I guess).

By Repair-Bas

Paragon (1130)

Repair-Bas's picture

08-07-2012, 19:29

Most msx2 computer have a 2 layer and some muli-layer pcb's
Problems with capacitors are vary rare.
Only much problems with external drives.
Cool

By RetroTechie

Paragon (1563)

RetroTechie's picture

09-07-2012, 16:16

In general it's a good idea to replace electrolytic capacitors in old equipment, if that equipment is still used (if only for looking @, no point in replacing elco's).

Of course the "If it's not broken, don't fix it" is strong here. Only a small % of the population is comfortable with a soldering iron, aware of ESD risks etc. So having an 'idiot' try to replace any component, is riskier than leave something in place that's old, but not causing trouble (yet).

What's old for an elco? 5 years? 10 years? 20 years? Also depends a lot on operating temperature, # of hours it has run, function in the circuit, manufacturer / series / perhaps even particular batches, etc, etc. Through hole <-> SMD is irrelevant, but of course there will be technology differences between those (good luck finding SMD elco's in MSX machines, btw LOL! ).

Usually I wait until a machine needs to be opened up for some reason. At that point, the older an elco is, the bigger my suspicion it has negative influence somehow (disturbances on screen etc), the quicker I'd replace it. If <10 years old & not causing trouble, I need a good reason. If >10 years old & suspect somehow, no reason needed.

But it depends on equipment. I have an old (+/- 13 year) CRT here that's still used, which would probably benefit from replacement of electrolytic capacitors inside. Which I don't: because for this old CRT, it's also not worth the expense+effort.

By Sky_hawk

Champion (267)

Sky_hawk's picture

28-07-2012, 20:53

I agree with Bas, I have never seen any capacitor problem in MSX's, maybe they made better ELCO's back then, or they were just not choosing the cheapest crap they could find, like now in most electronics.

Gr,

Jan

By RetroTechie

Paragon (1563)

RetroTechie's picture

30-07-2012, 00:43

In many cases a bad (but not 100% failing) capacitor won't prevent an MSX from booting, just degrade some signal (eg. sound / video output). Those in the power supply would, but these have very wide safety margin, so the machine might still work if a capacitor has 5x the leakage current, and lost 2/3 of its brand new capacity. And the linear power supply you find in most MSX'es is much easier on capacitors than modern switching power supplies.

And most MSX machines will be used only now & then, or stored in boxes most of the time. Unlike TV's, PC's etc which many people leave powered on on all the time (beside routers, modems, network switches, set top boxes etc).

So a combination of factors making that most will last long. But 25 years is respectable age for an electrolytic capacitor. For original MSX machines still in use, I'd expect elco-related problems to increase in the next 5-10 years or so.

By CrazyBoss

Master (209)

CrazyBoss's picture

30-07-2012, 13:57

... and maybe the components used back then are better, and maybe MSX power supplies is not switchmode like todays hardware is ? - Within the last 5-7 years, there was bad capacitors around, which dried out but I only had to replace the big one (400v i thing) in my TURBO-R A1ST. Else i think its not a problem with MSX hardware.

//CB

By sirnak

Supporter (2)

sirnak's picture

31-07-2013, 22:19

I also heard somewhere that these caps have certain life-span that is usually measured in hours and the same cap could last longer with temp of 85C than with 125C. I am not sure but do the dielectric fluid inside the caps get dried-up after the life-span? I was also told that it isn't a good idea to keep capacitors without applying voltage drop across it otherwise oxidization takes place. The caps I have seen do have the manufactured date and with a piece of paper, pen and a calculator; you could easily figure out if it’s time to replace the cap. So in the end, I do agree that it’s better to replace them after certain time.

By ApolloBoy

Expert (96)

ApolloBoy's picture

02-08-2013, 01:59

I've noticed that a lot of Sony MSX2s and MSX2+s tend to have leaky caps, mine had a couple but I've since replaced them. So far I've only recapped a few, including most of the caps for the audio and video circuitry.

I also recapped my old FS-A1, which didn't really need it but I noticed that the 1000 uF cap near the VDP had leaked, so I figured that I'd replace them all while I was at it.

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