Another LCIII rescue!

[dJOS]

G'day All, long time lurker, 1st time poster!

So I got a lovely little LCIII a while back which had leaking caps and I've decided to restore it. I love these little machines, they remind me of the Centris 610 I had back in the 90's (although that was a 68040). It was actually working but if left any longer it prolly would have succumbed to corrosion damage. 

The Mechanical dirve also died shortly after I bought it and has now been replaced with a SCSI2SD flash based Drive.

I've also dropped in a 68882 FPU and upped the RAM to 36MB ... I also found a 256k VRAM SIMM on eBay for a price I could live with and will install that shortly.

Anyhoo onto the fun part, here's shortly before I removed the caps - the most obvious damage is to the PCB near the battery (caused by the cap, not battery).

Bad Cap! (1 pad completely gone and both traces, not too hard to repair tho)

and the other bad cap! (lucky no real damage tho)

and all dodgy caps gone:

and repair in progress. I haven't fixed the missing pad yet but the other side had trace damage (easy fix) - I suspect the missing track was direct linked to a ground plane but haven't finished checking my theory yet:

Side A:

Side B (a bit neater than side A):

and that's it for now folks, Im just waiting for my new caps to arrive from element14 before I can finish it off.... oh and im going to replace all the caps in the TDK power supply just to be safe.

 

[olePigeon]

Excellent job!

 

[dJOS]

Cheers, I'm just waiting for my caps to finish it off. I've ordered Wurth Electronik aluminum polymer SMD caps rather than tantalum polymer caps so it looks more original.

I've seen a few ppl use thru hole caps too and it just makes me sad. My advice, If you can't do it properly, please find some one who can.

Oh and that applies to removing caps as well, there are plenty of ppl telling others to use side cutters or pliers to remove caps. This is really dangerous especially for caps that have started leaking as you will damage the structural integrity of the pads. Use hot air or hot tweezers and treat your PCB with proper care.

 

[Scott Squires]

Glad to hear you don't use side cutters or pliers to remove caps. I did not know about aluminum polymer caps. These make a lot more sense than rectangular tantalum caps. It appears that you can find them in the correct sizes (I only looked up the ubiquitous 47uF 16v 6.3mm).  It never made sense to me to use caps with the wrong form factor (with leads that may not be the correct spacing).

What are the practical differences between tantalum polymer and aluminum polymer caps?

 

[dJOS]

Glad to hear you don't use side cutters or pliers to remove caps. I did not know about aluminum polymer caps. These make a lot more sense than rectangular tantalum caps. It appears that you can find them in the correct sizes (I only looked up the ubiquitous 47uF 16v 6.3mm).  It never made sense to me to use caps with the wrong form factor (with leads that may not be the correct spacing).

What are the practical differences between tantalum polymer and aluminum polymer caps?

Cheers, I hate seeing butchered HW from using the wrong tools to do the job. 

Aluminium Polymer caps are similar in a lot of ways to Tantalum Polymer, neither of them use liquid like the old electrolytic caps do so they'll never leak. Both also will virtually last for ever and neither of them explode when they fail (unlike the old Tantalum nitride caps). 

Either are suitable for old Mac's but the properties of Aluminium Polymer caps are imo closer to the original specs than Tantalum Polymer (not by much tho).

 

[dJOS]

I was just having a think about how I'm going to repair the other pad for C20 and I just had a realisation - I can probably get rid of the below wire and insert some fine wire into the via's for both pads (the holes that connect the board layers - they are quite hard to see in the pic below but both pads link direct to a via). I'll have to give this a go on the weekend as it'll be much neater if it works!

 

[dJOS]

Finally got around to re-capping my LCIII

This cap was a PITA to fix, I ended up attaching the cap to the via on one side and used a wire, into the other larger via on the other side, to replace the missing pad. 

and she's alive!

and I added some heat-sinks to promote longevity - the 030 and the big VLSI chip get quite toasty without them and the 68882 got one as a bonus.

I need to re-cap the PSU next, I have the caps but havent had the time. She's still not 100% stable (crashes during Monkey Island intro) but seems ok for most other stuff. Im hoping re-capping the PSU will fix this. I may have a short on that 100uF cap still so I need to re-check my work as putting a PRAM battery in yielded no PRAM settings storage, ugh!

 

[Elfen]

This is great work you did here! Very informative! Makes me want to go back to my LC III and 475 and give them another look over as of all the machines I recapped, these two are the only ones that I could not bring back.

Love that you added heatsinks, and even threw in an FPU to that empty socket!

Q: What is holding down the heatsinks?

 

[dJOS]

This is great work you did here! Very informative! Makes me want to go back to my LC III and 475 and give them another look over as of all the machines I recapped, these two are the only ones that I could not bring back.

Love that you added heatsinks, and even threw in an FPU to that empty socket!

Q: What is holding down the heatsinks?

Cheers, I bought heat sinks that came with adhesive thermal pads as they are prefect for retro fit installs. I do the same on my Commodore and Amiga computers.

 

[EvieSigma]

What kind of Amigas? The traditional "keyboard case" ones (A500, A600, A1200) don't exactly have loads of room internally...

 

[Johnnya101]

This thing looks sweet! Always wanted an LC..,. but this wants me make one even more!

 

[dJOS]

What kind of Amigas? The traditional "keyboard case" ones (A500, A600, A1200) don't exactly have loads of room internally...

Yeah wedge cases are my favourite, I never had a big box Amiga so I only have the 3 wedge Amiga's (and a second a500).

 

[dJOS]

This thing looks sweet! Always wanted an LC..,. but this wants me make one even more!

They are great little machines, I just wish still I had an Apple Trinitron 13" CRT like I had in the 90's with my Centris 610'

 

[Johnnya101]

Well theres a few on ebay at the moment...

 

[dJOS]

Well theres a few on ebay at the moment...

Not in Australia there isn't.

 

[Johnnya101]

Oh... I'm in the us that's why

I'm pretty sure they were pretty common. You'll find one eventually!

 

[dJOS]

G'day chaps, I rescued another LCIII today from old cap death but found there is no sound output if I plug in external speakers. Internal sound works completely Normally.

I checked all the new caps in that area and the continuity is all good. Is there anything else to look for that might cause this?

Also has anyone else found that if you drop an FPU in an LCIII monkey island crashes around the title screen? I've found this on 2 now (same FPU which checks out fine in stress testing).

 

[djhaloeight]

How does it run with the SCSI2SD in there? The old 80 meg drive in my LCIII+ is still chuggin away but its definitely the bottleneck of the system, especially when I'm on the web or on Hotline.  It downloads from my cable internet at about 180k sec to the RAM but then the hard drive has to write it and the machine sorta gets stuck until the data is written.

Good to see another LCIII saved though. I had Uni recap my board and PSU awhile back. Had to save it

 

[agent_js03]

How does it run with the SCSI2SD in there? The old 80 meg drive in my LCIII+ is still chuggin away but its definitely the bottleneck of the system, especially when I'm on the web or on Hotline.  It downloads from my cable internet at about 180k sec to the RAM but then the hard drive has to write it and the machine sorta gets stuck until the data is written.

Good to see another LCIII saved though. I had Uni recap my board and PSU awhile back. Had to save it

I have a SCSI2SD in my LC III. I remember it took forever to initialize using the HD setup utility. I think it took like 30+ minutes to initialize a 2gb partition. The first time I did it, I created an image of the resulting volume and moved software onto it from Basilisk, as I didn't have an external CD-ROM and had no way of moving data onto it. I ended up getting some pretty weird disk errors on that one. After re-initializing a couple more times, I think I wore out that SD card since reads/writes were really slow. I ended up getting a new SD card and I initialized it and installed System 7.5 from floppies. I still get weird freezes/crashes from time to time, I realize this could be caused by a number of things, but I am often tempted to blame scsi2sd.