Caple C871i Manual de usuario descargar pdf (Pagina 378)

Apple II Computer Info

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### Created : Sunday, January 14, 1996 Modified: Sunday, January 14, 1996

### File Type: "TEXT" File Creator: "LMAN"

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.cs.su.oz.au!metro!ob1.uws.edu.au!lancelot.st.nepean.uws.edu.au!adrianw

From: [email protected] (Adrian Whichello)

Newsgroups: comp.sys.apple2

Subject: Re: Apple II+ power supply woes

Date: 13 Aug 1994 17:09:31 +1000

Organization: University of Western Sydney

Lines: 40

Message-ID: <[email protected]>

References: <[email protected]>

NNTP-Posting-Host: 137.154.148.15

Keywords: power supply woes

[email protected] (Adrian Whichello) writes:

>Hi Netland

>I have an old 2+ which runs the model railway, among other things.

>Last week it's power supply gave up. I wasn't there at the time,

>I've found that leaving the computer permanently switched on is

>good insurance - the power supplies tend to die between cycles if

>eft off for long periods. Anyway, I opened it up and found that

>an electrolytic had swelled up so much that it had torn it's connections

>out of the circuit board. I replaced it, but all the power supply

>wants to do now is go click click click ie it won't oscillate

>properly. It does this if plugged into the motherboard or not.

>Any suggestions about what else could be wrong. I'm not wild

>about diving into a circuit that is connected directly to the

>house supply without some clues.

>Adrian.

>ps surely this must be a FAQ by now - I have several old supplies

>that are dead for one reason or another.

Hi Netland

had a go at the power supply over the weekend. I was successful, because

I typed this on the Apple. There was nothing wrong with the bridge rectifier

and input side - there was over 300V on the collector of the big transistor.

None of the inductors had burnt out and all the diodes and transistors checked

out OK with a simple multimeter check. In fact nothing looked wrong at all,

physically. There was just hardly any (~0.5VDC) voltage on the output side.

I was getting desperate! I decided to check out the voltage reference section

- I faked 5VDC (from the bench power supply) on the anode of the TL-431C and

up came the power! So then the penny dropped, the capacitor the temporarily

shorts out the 4.7K 1% resistor at power on wasn't doing it's job. I replaced

it and away we went, all systems go. Anyone else found this?

Apple II Computer Technical Information : Apple II Family Hardware Info

ftp://ground.ecn.uiowa.edu/2/apple2/miscinfo/hardware : May 2001 : 378 of 572

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