Another Half Dead IIci..

[quadra80]

First of all its a pleasure to see such a forum with 68k lovers...i thought we were under extinction! [] ]'>

To the point...

No chime, not powering up.... i replaced all four capacitors with new!

Still no chime throu the speaker but i can hear it (low volume) through the audio out at the back.

Put the motherboard throu a dishwasher cycle... came out shiny and bright but still not powering up!

Psu working it can even start a quadra650.

I found a solution that powers up the IIci but it kinda twisted!

I put the power switch at the back at "server" position doesnt do anything... then i plug an adb cable to the IIci and the other end of the cable to the adb port -momentarily- of an already powered on macintosh . The IIci powers up and works flawlessly but if i want to shut it down i have to disconnect everything (Psu/baterry) leave it to discharge for more than five minutes.

Any ideas? I love this machine and dont want to giveup on it!

Thanks

Nikitas :-/

 

[wally]

If the replacement caps were bad or wired polarity reversed, both power on and power off circuits would be behaving badly, and if the system was jumpstarted then turning it off could be a problem. Not to accuse you of anything, but this might be a good time to remind readers that on aluminum electrolytics, the bar mark is on the negative, and just to be difficult, on tantalums the bar mark is usually on the positive terminal. If the old caps farted on the circuit board and changed some connections, the new circuit could be trying to establish a warp field to an alternate universe. A very thorough visual inspection in good light might reveal something. Verify with a voltmeter that you do indeed have good +5V continuous.

Take a look at the startup schematic for ideas on what next to check-

http://home.earthlink.net/~gamba2/images/macIIcisch.GIF but keep in mind that capacitor goo may have wired something else...

 

[benjgvps]

Could the power supply be bad it seems like that it needed a jump start to get going.

 

[quadra80]

-Tho polarity of the capacitors is correct its quite clear on the caps which is negative.

-As for the electrolytic goo, it would certainly shortcircuit everything around.

-I cleaned it with a solution to clean pcbs and then as nothing happened put the mb in the dish washer (crazy idea but ive seen it on other posts here).

-the psu gives me 4.95v continuous

- im going to go through the motherboard with a magnifying glass and look for oxidations or cold soldering connections

im not good at all with electronics and its hard for me to translate the power circuit but ill give it a try!

- all those t3 caps could thesy suffer from the same leaking like the bog ones?

 

[equill]

Capacitor-failure may produce a variety of defects. You appear to have more than one of them. From your description, the audio output sounds to have been affected. If you found capacitor goo under the PSU, power to the MLB may have been affected. The behaviour of the PSU may indicate either capacitor failure or TRKL circuit failure. The latter is not-at-all uncommon in the PSU that is used in IIcx, IIci and Quadra 700. Have you tried startup immediately after total removal of the PSU from the Mac for 10min. or so? Have you attempted the quick-flick mains-power trick? (Needs a power-board with a mains-rated switch.)

Board-washing may give temporary respite from the loss of capacitor efficiency, but it is not a recovery technique. It is a prelude to complete replacement of aluminium electrolytics with tantalum electrolytics as the only long-term cure. Our very own trag may be able to supply the values and quantities that you need. Even then, the larger electrolytics will need to be replaced with new aluminium electrolytics. You will have to conduct minute inspection of the board traces that were under the capacitor goo, and bridge any that were severed by corrosion.

The PSU may be suffering from leaking or defunct capacitors, but it is as least as likely that it is hobbled by the lack of 5V TRKL supply. This latter is a bias-diode problem, unrelated to capacitor action, and commoner in Astec supplies, but not unknown in the Delta PSUs. See whether you have the following voltages at the PSU connector to the MLB:

IIci-PSU pin-outs:

Pin Signal Description

1 +12V +12 volts

2 +5V +5 volts

3 +5V +5 volts

4 +5V +5 volts

5 GND Ground

6 GND Ground

7 GND Ground

8 -12V -12 volts

9 /PFW Power Fail Warning

10 +5V TRKL Supply voltage for power-on circuit.

TRKL must be 5V for startup, and be able to fall to <1V for software-controlled shutdown, so you will appreciate the centrality of its rôle. Post back as you eliminate/finger the usual suspects.

de

 

[quadra80]

Found the cure!!!! hurray!

replaced the C2 cap and fixed the sound issue....

also replaced tha C10 and fixed the startup issue...

Im sure all the rest capacitors r damaged and i could definitely see some corrosion around those "vomiting" capapacitors but the machine works for now. I will replace all of them some time soon although its not the easiest thing ive done in my life

Thanks for the support

Nikitas