Mac Plus turns off after short time

[Timbo]

I just want to say that I have a EU 230v Macintosh Plus and the same thing have happened to that one a year or two ago.The house circuit fuse blows after a few minutes. I've tried it several places and it's the same. I've opened it and the same caps as in Timbo's picture were cracked.

I haven't ordered new caps yet because I'm a little bit unsure on what to replace them with...

I took the analog board out of another Plus today and replaced just the two 4700pF 250v filter caps.

It's been an hour now and it's still running!

Haven't replaced any C1's yet as that order still hasn't arrived.

By the way, I noticed some C1's are 3.9uF and others are 6.8uF. Would it make a difference if I swapped them over?

And, one more- should I bother with a hot glue gun (which I haven't got) to keep the caps I have replaced in one place? Would it really matter if I didn't bother?

Thanks

Tim

 

[nvdeynde]

By the way, I noticed some C1's are 3.9uF and others are 6.8uF. Would it make a difference if I swapped them over?
And, one more- should I bother with a hot glue gun (which I haven't got) to keep the caps I have replaced in one place? Would it really matter if I didn't bother?

Thanks

Tim

It need to be a 3,9Uf High Frequency Bi-Polar capacitor of at least 100 volts.

As far as I know the only alternate on the market is the Panasonic ECW-F2395JA film capacitor.

I used it in my all recaps and works perfect, fitting is just a bit of an issue.

No glue need: I actually remove all the old silicone from the original PCB.

 

[MacDougall]

I'll just stick in my 2c here. I have a 240V mac plus that behaved exactly this way when I first got it. It would boot up and after a short time would trip the residual current device at the fuse box. A quick peek inside revealed the likely culprit, X and Y rated caps in the mains filter were all cracked open. After I recapped the entire board this problem went away but I'm about 95% certain that the RCD trip was caused by these.

I replaced them with these which fit perfectly -

http://uk.farnell.com/jsp/search/productdetail.jsp?CMP=i-ddd7-00001003&sku=1006064

and this -

http://uk.mouser.com/ProductDetail/WIMA/MPX21W3470FK00MYSD/?qs=%2fha2pyFaduj0ApMVe66xmIlWTZwkT1%252btsdp6MlIXDNJF3KG5WmKzuXlIXCj2njBP

This one was a shade bigger than the original due it's rounded case and I had to temporarily remove the transformer to fit it, the pin spacing was not quite perfect either. Otherwise these parts were an exact match for what came out of the european power board in positions C33, C36 and C37.

 

[Schmoburger]

II also have this issue with all three of my Pluses (which never gave issues until now), and recall a similar issue surfacing with one of my 512K's nearly 15 years ago. Never bothered to deal with it back then, but now that ALL my pluses are giving me problems I decided to google the symptoms and lo and behold there is a thread on 68k!

Might pull the analog board out of my original Plus which I partially recapped in around 2003 and see how i go.

 

[Timbo]

Yep. I have replaced these in all my classic compact Macs (not just Plus's) and haven't had a recurrence. It's fairly obvious when they start to crack.

 

[uniserver]

i like when they blow and make clouds of smoke.

 

[mcdermd]

And it stinks. The PSU in my TRS80 Model III made the whole office lobby stink for a few days when it blew two of them.

 

[uniserver]

The funniest thing is the computer still works once these blow.

pop, Bang, Smoke billows out, the computer is still on no problem… haha

 

[techknight]

Those are either X1 or X2 rated safety capacitors, replace them with equivalents of that type.

 

[Schmoburger]

I remember when the big electrolytic caps on one of my Plus A-boards went... big cloud of smoke and they bloody stunk to high heaven. Like burnt peanut butter mixed with flaming M&M's... No I wont go into how I know what they smell like! :lol:

Left a foul stench in my room for a couple of days anyway. :-/