Apple IIc blinking power light

[Arths]

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

 

[bibilit]

What kind of PSU have you been sold ?

Original item is 12 Vdc at 1.2 A

 

[Arths]

This is the one that I bought

http://www.ebay.com/itm/221294478704

Maybe I'm not using the right cable for the other hand, I'll buy a new one and try again

 

[xboxown]

This is the one that I bought

http://www.ebay.com/itm/221294478704

Maybe I'm not using the right cable for the other hand, I'll buy a new one and try again

What is wrong with the old fashion Apple //c original brick sized power supply?

 

[Juror22]

The two that I could see in the photos were 15V.  I would check the outputs with the a voltmeter.

 

[bibilit]

Or maybe something is faulty on the other side of the PSU.

 

[Elfen]

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.

 

[Arths]

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

 

[Arths]

Well, I’ve replaced the internal power supply as well.. same problem.

I guess the computer is dead  :sad:

 

[bibilit]

Hi,

Keep in mind that the power supply is connected to the internal one :

Not saying this is the issue, but as you have a blinking led some outputs are present...

 

[Arths]

I’ve replaced this one too..

 

[bibilit]

have you tried without disk drive ?

A short somewhere ?
 

 

[Arths]

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

 

[bibilit]

I will run a multimeter, with no power connected, and see if a capacitor is not shorted. 

You have got two just below the psu connector and one above. 

Also a transistor nearby. 

Use the continuity test. 

 

[Arths]

Thanks for your reply,

I will try that as soon as I get home

Already measured the 7905 chip and I’m getting voltage in expected ranges, is it a good sign ?

 

[bibilit]

Yes. 

The 7905 is the negative regulator. 

What about the remaining rails ?

 

[Arths]

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



Thanks a lot

 

[Arths]

Ok, RalfK from Apple Fritter asked me to test FFF and all I get is zero :O

 

[Arths]

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..



Sometimes I get scrolling characters instead like so



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

Any idea ?

Thanks,

Arths