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Apple IIc blinking power light


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Hey guys,

Had an Apple IIc for almost 3 years but it did not came with a power brick.

So I decided to buy a Toshiba charger transformed into a IIc power brick off eBay, the problem is when I'm turning on the computer the green power light is blinking and I'm not getting any startup beep. The disk drive is not running as well.  :'(

 

Any ideas ?

Best regards

Edited by Arths
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  • 1 month later...

How is the Toshiba PSU connected to it?

 

Check your connection and your PSU, I do not think it is strong enough to run a IIc. The IIc needs 12 - 15 volts, you can run off a Lead Gel Battery if in a pinch. It is a Power Hog. Check.this video out: 

 

Includes a pin out for the power port for you to verify.

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  • 2 months later...

Okay guys, sorry for the late response.

I’ve been very busy for the last few months but finally got a my hands on a multimeter :-)

 

Well everything seems to be okay concerning the 15V power pins. I guess there must be something wrong with the internal power converter :-(

Interestingly enough it sometimes seems to be starting up, floppy drive led is solid red and I can hear the speaker cracking a little bit but nothing more..

 

Maybe dead condos ?

Cheers

Edited by Arths
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  • 9 months later...
  • 9 months later...
On 11/10/2018 at 8:35 AM, bibilit said:

have you tried without disk drive ?

 

A short somewhere ?
 

Sorry for the late response :(

Yes I’ve tested without a disk drive and it still won’t boot.

 

What should I check first ?

Is there a place on the board where I can check that the voltages are the ones I shall receive ?

Thanks for your patience

 

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6 hours ago, bibilit said:

Yes. 

 

The 7905 is the negative regulator. 

 

What about the remaining rails ?

 

Here are my results 

 

Capacitors

 

  • C57 shows zero
  • C44 and C43 shows infinite when speaker is unplugged, .845 when it is

 

Rails

 

90506486_Capturedcran2019-09-0217_51_07.thumb.png.1f1d2e6a0a232ba561a53872609f2c4e.png

 

Thanks a lot

Edited by Arths
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  • 2 weeks later...

Hey guys,

 

Turns out it was the LM311N chip which was causing the blinking power light.

Soldered a new one and blinking is gone but it still doesn't want to boot.

 

Hooked the IIc using the composite output and here is what I get..

2019-09-12_17_55_54.2019-09-12_17_57_11.gif.38c213ee021b62e5cf6d37d44c01a8c2.gif

 

Sometimes I get scrolling characters instead like so

2019-09-12_17_55_49.2019-09-12_17_57_42_0.gif.c04f1b9c51d3773dacf5649d9e290eec.gif

 

Holding CONTROL-RESET makes the scrolling stop so I guess the CPU at least understands the keypresses.

Any idea ?

 

Thanks,

Arths

 

 

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  • 4 weeks later...

Hi guys,

 

Just received the chips, tried piggybacking but that doesn’t seem to change anything. :/

 

Maybe there are specific chips I shall try this method on ?

 

If you have any idea, please let me know :'(

Thanks

 

Edit : Piggybacking F18 makes horizontal white bars but that's it

 

Arths

Edited by Arths
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