macintosh iici weird power supply behaviour

[bamdad]

hello everyone,

it's been a while. but to my point: i recently received a iici from an seller in my country that was described as 'macintosh for sale working plays music on power up'. i immediately thought that at least it's doing something, and if the chime is the happy mac one, i'm all set.

so i dug around for a cable and some ADB peripherals and indeed, it was asking for a floppy. the SCSI HDD is probably long dead anyway. so i proceeded to disassemble it, do some cleaning before trying some disks. after that i `dd`-d the network install image to a floppy and tried to boot up. it gave me a happy mac and then spat out the floppy. i thought to my self that's weird, must be either some pram problem or a dirty floppy drive. i disassembled the floppy and cleaned and re-lubed that too.

on putting the machine back together, it was stone dead. no light, no screen, no response to either the rear or the keyboard power button.

i thought to myself well that PSU died quickly and without any notice, but put the machine aside and had a night's sleep. but here comes the weird part: today i thought maybe i'll try it again, and it started right up. i thought woohoo it's not dead, maybe some lingering charge went the wrong way or some unpredictable battery thing. but the floppy wasn't ejecting, it only made some weird noises. no problem, i'll take it apart again. then the same thing happened as yesterday. machine is stone dead. i haven't even moved it..

anyone exprerienced something like this before? should i wait another day or so and it will work? should i order a new PSU or is this something completely different altogether? by stone dead i mean even the monitor i plug into it is dead, that's why my primary suspect is the PSU. it's an aztec one and they are rumoured to be unreliable.

anyway, thanks in advance if anyone reads my lengthy story and responds.

cheers,

bamdad

 

[BadGoldEagle]

thought to myself well that PSU died quickly

then the same thing happened as yesterday. machine is stone dead. i haven't even moved it..

Bad PSU. You need to recap it. Astec, Sony, or whatev' they all go bad. 

it gave me a happy mac and then spat out the floppy.

but the floppy wasn't ejecting, it only made some weird noises.

Probably bad caps on the logic board. Remove all the aluminium 'towers', wash the board thoroughly with some hot soapy water and a tooth brush, and then rinse with alcohol for good measure. Dry it thoroughly to prevent any rust. Replace the capacitors with new ones (tantalum, ceramic... as you wish). It should solve many problems. 

And if the floppy still misbehaves after all that... Have you checked the eject mechanism's gears? 

Every single Mac from that era has capacitor related issues. So recapping will definitely help.

 

[bamdad]

Bad PSU. You need to recap it. Astec, Sony, or whatev' they all go bad. 

Probably bad caps on the logic board. Remove all the aluminium 'towers', wash the board thoroughly with some hot soapy water and a tooth brush, and then rinse with alcohol for good measure. Dry it thoroughly to prevent any rust. Replace the capacitors with new ones (tantalum, ceramic... as you wish). It should solve many problems. 

And if the floppy still misbehaves after all that... Have you checked the eject mechanism's gears? 

Every single Mac from that era has capacitor related issues. So recapping will definitely help.

thanks for the reply. sadly, i'm not that good with a soldering iron, so i'll probably get a new (well 'different' to be exact) PSU, but this confirms my suspicions. if this doesn't fix it and i do need to recap the logic board too, i'll try to ask a friend with more experience.

as for the floppy, after the second disassembly, it should work fine. 

one more question: is there a modern PSU out there that can be modded to fit the connection on the motherboard? seems like a better alternative to me than keeping alive the old one, but might be totally unrealistic..

 

[BadGoldEagle]

Humm... I see. Well, it's technically possible to replace the old PSU with a modern unit but I think that would be a lot more difficult than say, replacing the old one's capacitors. If you have a friend handy that's good. To be honest, it's a lot harder for a beginner to replace SMT/SMD capacitors than it is to replace through hole components. What I mean by that is that replacing capacitors on an old PSU is much easier than recapping a logic board. You could theoretically tackle the PSU yourself. Just don't power it for over a week or two and all the dangerous voltages should have gone away.

If you don't feel up to the task (and that's normal, before I started recapping things myself I thought I would cock this up as well), I know someone who does this for a living. He lives in the US so shipping is a little expensive but he does this remarkably well. He's the guy from the link in my last post. If your friend can't do it, then I would recommend going to him for a proper recap. He can do both the PSU and the logic board. I'm definitely not sponsored. There are a lot of alternatives out there, but you don't necessarily know who you're dealing with. Some of them are thieves (it's happened before on this very forum...). Charles isn't one. 

 

[bamdad]

cheers for the suggestion, first i'll try a different PSU, if that doesn't fix it i'll take the PSU and logic board to my mate, and if all else fails i'll contact your guy. shipping to the US and back is definitely not cheap.

 

[BadGoldEagle]

Yeah, I know, that's part of the reason I learned how to solder 

Perhaps someone around here has a recapped one for sale?

 

[just.in.time]

I’ve also had generally good luck with Charles.  That said, I’ve also started learning how to do my own recapping.  It’s a lot cheaper to do your self and is generally a good skill to have

 

[Bolle]

If all else fails I can recap it for you.

Shipping to Germany will be way cheaper.

 

[boitoy1996]

Check your area for places that repair electronics.  they should be able to recap it for you.

 

[bamdad]

hello again,

so i bit the bullet and ordered a USB-C iron from banggood and all the accessories, and i'm proud to say my first soldering job was a success - it's ALIIIVE! the SMD capacitors were a bit hard to replace but i managed to do a fairly nice job in the end. : ) thank you guys for all the helpful links and encouragement.

a bit off-topic, but searching ebay and the trading post here for an accelerator card (i'm looking for a micromac carrera040 in particular) didn't yield any results. anyone know where i could find one?

 

[zezba9000]

Or you can just make a custom new PICO based PSU replacement: Scroll down on page 3.

 

[bamdad]

Or you can just make a custom new PICO based PSU replacement: Scroll down on page 3.

well we're determined that my PSU is not at fault, i've re-capped the board and now everything is fine. but thanks anyway, this might prove useful down the line. : )