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Path: utzoo!watmath!clyde!bonnie!akgua!whuxlm!whuxl!whuts!wrc
From: wrc@whuts.UUCP (CLEGG)
Newsgroups: net.micro.cbm
Subject: Re: C64 Problem
Message-ID: <416@whuts.UUCP>
Date: Tue, 3-Dec-85 13:08:19 EST
Article-I.D.: whuts.416
Posted: Tue Dec  3 13:08:19 1985
Date-Received: Fri, 6-Dec-85 06:36:49 EST
References: <571@brl-sem.ARPA>
Distribution: net
Organization: AT&T Bell Laboratories
Lines: 44

> Help!  I have a friend's C64 before me.  Upon power up,
> nothing happens except the drive runs for a few seconds.  The
> pilot light appears to come up to full brightness initially, 
> then suddenly becomes dim.
> 
> I have "heard" that there are chronic C64 problems that appear
> after the machine is one to two years old.  Is this one of
> them?  I'll begin the usual troubleshooting (sans schematics)
> in the meantime, but would appreciate any hints.
> 
> Has anyone seen this or something similar?
> 
> Brint Cooper
> 
> 	 ARPA:  abc@brl.arpa
> 	 UUCP:  ...{seismo,decvax,cbosgd}!brl-tgr!abc
> 
> -- 
> Brint Cooper
> 
> 	 ARPA:  abc@brl.arpa
> 	 UUCP:  ...{seismo,decvax,cbosgd}!brl-tgr!abc

  I had a similar problem with my friend's c64. I found that the 5 volt
regulator that is located in the power supply let loose. The voltage on 
that line varied anywhere between 4.5 up to 9.5 volts. The led on the
computer is tied directly to this line and is the reason that it varies.
The bad news is that this 5 volt line feeds all of the RAM and most of 
the other logic chips and if this voltage goes too high then kiss all
those chips goodbye. Even if thay all didn't go, it will be very
difficult to find the ones that did go. Your best bet in this case is
too get repaired by a dealer. There are some places that replace the 
entire board for $55.00 which isn't bad considering that the price of
some of the individual chips is as much as $30.
	One other thing is that the power supply is not repairable
as it is potted and the components can not be accessed. Befor you go too
far I would recommend that you put a voltmeter on the 5 volts from the
power supply. It should measure almost exactly 5 volts and not vary.




						Good luck
						Bill Clegg