Mint condition IIci was working a few days ago, now isn't

[markfendley]

Good evening,

Apologies if this specific problem has been handled elsewhere. I could not find this exact issue through searching.

On Monday, I took possession of an absolutely mint condition IIci (including boxes, accessory pack, original install floppies etc) with the 13" trinitron monitor. It had even suffered no yellowing due to being kept under a dust cover (which also seems to have contributed to zero dust inside).

I unpacked and connected up my new pride and joy on Monday evening and it booted first time. Ran smoothly for a while whilst I had a play with it then I shut it down.

Over the last week I have periodically booted, used for a few minutes and shut down again. Perhaps a slightly incorrect version of the OS is installed as it does not soft-power-off, instead saying that I may now switch off my Macintosh safely, so I pulled the power cord, and didn't always re-connect it.

Today, having had the power cord connected for about three days (just in case that is pertinent) - I moved the machine from one room to another in order to double-check the condition of its capacitors, in case I need to replace them. As a precaution, I connected everything up after moving it and went to boot.....nothing.

I have tried various combinations of leaving the power cord plugged in for a while before attempting boot, disconnecting it for a while...still nothing.

I even took out the PSU and connected pins 9 and 10 - the PSU started up (although no other pins were connected to the Mac...)

I am guessing capacitor issues.....but is there any reason why it would stop working only a few days after having worked fine?

(tried booting via keyboard and by pressing power switch at the back. Keyboard confirmed to be working as it boots my 7100/66 with no problems).

Many thanks

Mark

 

[unity]

Probably mobo caps, possibly power. I had the same issue with a IIcx. It worked a few times then nothing. I sent it to uniserver for a re-cap and its worked great ever since. I spent a lot of time on the power supply though - but it was never the issue.

At the very least the mobo could use a good cleaning. Sometimes that will help since the cap goo is conductive.

 

[lopaka1998]

The iici only has a couple of electrolytic smd caps in it.  So it's most likely you killed the power supply.  Don't freak out.  If you replace the power's supply caps and the electrolytic caps on the motherboard, everything will probably be fine.  be sure to throughly wash the board.

 

[markfendley]

Brilliant thank you - I've got some isopropyl alcohol on the way (as well as two new 3.6V batteries - one for this, one for the 7100) so will get to work with that and cotton buds around the power area to start with.

Many thanks - I'll keep the thread updated with progress

 

[markfendley]

One question I do have - the 7100 power supply appears a perfect fit (to test with) but has different current ratings on each of the lines - I have heard they are interchangeable but the differing outputs makes me wary...!

 

[uniserver]

https://68kmla.org/forums/index.php?/topic/24837-in-need-of-quadra-700-schematic-rip-quadra-700-1991-2015/

Posted 02 March 2015 - 03:33 PM


Regarding power supplies, the following are pretty much drop in replaceable for each other, although, I think there were some (later?) models which had somewhat higher capacity (wattage).

IIcx, IIci, IIvi, IIvx, Q700, Centris 650, Q650, PM7100.   

Also, on a bench, outside of the computer case one can use a IIsi power supply to test any of the above logic boards.

 

 

[uniserver]

Its like that if you have not changed the caps on your main board yet. One day it will work just fine, and the next day, nope.

www.maccaps.com

 

[olePigeon]

Uniserver beat me to it.  IIci has more than just a couple of caps.  You'll want to get those all replaced.

 

[markfendley]

Thanks all for your kind help and pointers - it is very much appreciated and it is nice to find such a friendly forum!

To update, this evening I took the IIci apart, laid it all out on the table and used some cat-5 cabling (!) to connect up the PSU output pins to the corresponding inputs on the motherboard. I briefly connected up pins 9 and 10.....and the Mac booted up perfectly. Shut down, hotwire again, booted up perfectly, again and again. (By the way, the PSU is a GE not an Astec).

So, I'm guessing still capacitors....?

Many thanks!

 

[unity]

Ya, prob mobo caps on the startup circuit.

 

[markfendley]

Thanks!

Uniserver - I see you are in Michigan.... have you ever had anyone ship you a logic board from the UK.....? ;o)

 

[uniserver]

Sure do, First Class International is very reasonable, as long as it stays under 4 pounds. 

 

[markfendley]

Excellent stuff - I will be in touch!

Many thanks again everyone for your help with diagnosis.