Xref: utzoo comp.sys.mac.misc:1272 comp.sys.mac.hardware:4316
Path: utzoo!attcan!uunet!decwrl!adobe!hawley
From: hawley@adobe.COM (Steve Hawley)
Newsgroups: comp.sys.mac.misc,comp.sys.mac.hardware
Subject: Re: Help!, my analog board is shot
Keywords: analog board, transformer, plus
Message-ID: <3838@adobe.UUCP>
Date: 12 Jul 90 14:37:16 GMT
References: <1990Jul11.194216.1939@cbnewsk.att.com>
Reply-To: hawley@adobe.UUCP (Steve Hawley)
Followup-To: comp.sys.mac.misc
Organization: Adobe Systems Incorporated, Mountain View
Lines: 36

In article <1990Jul11.194216.1939@cbnewsk.att.com> baz@cbnewsk.att.com (Bruce Zenel) writes:
>
>   I need some hardware help.  I turned on my Mac Plus today and all it did
>was click.  No beep, no screen, it just repeatedly clicks.
>   I have a feeling that it is the flyback transformer, which I've read about
>in the past.
>   Is there any way to replace this myself?  Is there a replacement
>transformer that I can buy somewhere?

This clicking is from the speaker and might not be related to the flyback
transformer.

The Mac Plus has some ciciutry in the power supply to check if the power
is at an acceptable level to run the beastie.  Anything out of this range
and the machine will click and not power up.  This is a diagnostic.

To fix/adjust this:

Open up your case, set the mac on something insulated, plug it in and turn it
on.  It will start clicking.  Look at the side of the power supply board
with paper on it.  There should be a label that says "Voltage Adjust" or
something similar that is right by a trim pot.  Get out a screw driver and
turn this until the machine boots (you might want to mark its original
position first).

I had a similar problem when 2 meg was put into my old plus.  The power supply
just couldn't cope because of how much current the memory was drawing (the
machine was being upgraded from a 512K to a plus at the time).  The service
being did exactly the steps above with the exception that he also connected
a fluke volt meter first to measure what the voltage was first  which
was about 4.2 volts in my case -way too low.

Steve Hawley
hawley@adobe.com
-- 
"A blow on the head is... ...worth two in the bush." -Basil Fawlty