LCs are driving me nuts...

[tjjq44]

Five or six years ago I made preventive recapping on both my LC & LCII before leaking appears... They were still working fine since (Pram battery never did any damage since I always remove them when I get a mac). Two years ago I wanted to try something with my LC... disk span, fan too but no startup sound nor video! I didn't have time to investigate further in the moment.

Today to try to answer Uniserver's question about emulated HD20 from BMOW, I brought up my LC II. It booted normally, even SCSI hard drive was working perfectly. I turned it off for a moment cause I had something else to do. When I turned it back on a while later... same symptoms as LC1, scary!!

I've read somewhere that defective power supplies could be the reason. I brought up my LC475, it works well. I tried its supply in both LC1 and LCII with no results... I tried both LC1 & LC2 power supplies in the LC475, it works!! Supplies don't seem to be faultives...

What can make my LCs die like this :'(

 

[uniserver]

TDK power supplies

 

[uniserver]

if you go to my site www.maccaps.com you will see the 4 caps that leak. change them out and you will be good to go.

 

[uniserver]

if you heat the power supplies up with a hair dryer they will come back on… but…    

 

[tjjq44]

Ok but why does my LC475 boot properly with these 3 supplies?? One of them isn't TDK but a thing like "Dyna Comp, inc."

 

[CompuNurd]

I have seen some of the Nichicon caps leaking as well. I would say it's best to replace every cap, though it is not necessary to replace the line filter cap.

If you want caps, digikey and Mouser are great. I use Mouser because they accept PayPal and are located in Texas, so I usually get stuff quickly.

If you don't want to do it yourself, uniserver can do it.

 

[uniserver]

lol then sound like you have some VOODOO going one there...

Say a few hail marys then all should be fine..

Could have a couple things going on.

maybe wen you re-capped those main board you didn't wash them?

wash them, then blast them off with the air compressor really good, 

sometimes the Vram Simm slot gets filed with dust and stuff too.. if the vram simm is not properly seated or not making a good connection that can cause the machine to not boot up.

Dayna PSU's are pretty solid i' found… so are the Aztec ones too….   in the Aztech's  usually the only cap that goes bad is one 47uf 50volt cap that is right near the HV to LV transfomer.

The TDK psu's are pretty good too…once you replace caps in there.

I have seen a non re-capped TDK psu work in a LC475 and not in a LC1 before… 

where the caps were bad but would run the LC475 but not the LC1… because the LC1 draws more.

But again, that is just luck… after not too long, more goo leaks out and eventually the LC475 won't power up either.

 

[tjjq44]

Ok, I see!

I can't recap them now but I hotted up the TDK PSU and the LCII came back to life Poorly with the same PSU, the LC doesn't work. Surprisingly, after this partial success, the dyna PSU I didn't hotted up fired right up the LCII too but no way with LC1

 

[uniserver]

Ah ha   well now you got the LC-II going… you can experiemnt with that 16 pin ODD floppy like port near the scsi port… and maybe with some help,  get the HD20emu to work with it

Once you get the LC1 going… then you can just attach the HD20emu right to the port near the scsi port and it will just work, like magic

 

[techknight]

 though it is not necessary to replace the line filter cap.

Bad advice. change EVERY capacitor INCLUDING the line filter capacitor! you would be surprised how many of those I find out of tolerance. The worse they get, the harder it is for the power supply to start up. Then they short, and go BANG

 

[Elfen]

Is there is an entire Cap List? Word of caution, the caps comes in different sizes for the same ratings so you could order the caps and they end up being too big to fit into the LC PSU. Both ComuNerd and I fell into this problem though the caps works perfectly when the recap is done.

It would be nice to get a caps list with the cap's physical size with the ratings.

 

[uniserver]

make one elfen, then post.

 

[CompuNurd]

I got these from my latest Mouser order. A few make a tight fit, but there are no issues with getting them in or getting the case on. I would use Panasonic, because they are good and priced well.

Capacitor list for TDK PSU:
(does not include line filter)
 
3x 1000uF 10V 10mm diameter 16mm length
1x 56uF 25V 5mm diameter 15mm length
1x 270uF 10V 6.3mm diameter 11.2mm length
2x 270uF 25V 10mm diameter 12.5mm length
1x 47uF 25V 5mm diameter 11mm length
1x 10uF 50V (replaces C8 at 8.2uF 50V) 5mm diameter 11mm length
 
I will try to get a link to my shopping cart, so you can just click it and buy the needed caps for a PSU.

 

[uniserver]

wait what about all the hv film/ceramic caps?  what about the big 250v cap too.?

 

[CompuNurd]

wait what about all the hv film/ceramic caps?  what about the big 250v cap too.?

Didn't think those were too big a worry yet, since there is no electrolyte to leak out of a film/ceramic cap.

The line filter, I will start replacing in the future.

 

[uniserver]

Sounds Reasonable

 

[techknight]

The only thing I can recall is the silver mica caps can degrade over the years, but that requires 40+ years to happen. And the Ceramic caps get thermally sensitive with age, sometimes to the point of producing static/noise. But again, it takes 40+ years. 

 

[uniserver]

from what i can tell the big round HV cap off the bridge,  when that goes its with a bang… There is a thread on here about someone with a IIsi psu that happened to.