Re: C128 parts

From: Terry Raymond <traymond20_at_gmail.com>
Date: Thu, 29 Jun 2017 10:21:25 -0600
Message-ID: <CAEFCF-rnPmxrk0ROgZa188ziC9+Udx1HDf5rkPmOSweVyP86xg@mail.gmail.com>
Already have checked fuse in power source.
At one point the fuse was blowing.
I replaced the Full Wave Bridge Rectifier, fuse quit blowing.

I may have found a very simple problem with the power switch maybe just
an issue with solder joints I'm hoping.

Terry Raymond

On Jun 29, 2017 3:10 AM, "Marko Mäkelä" <msmakela@gmail.com> wrote:

> On Wed, Jun 28, 2017 at 03:17:00PM -0600, Terry Raymond wrote:
>
>> What pins on the power switch can I jumper?
>>
>
> I think that you can use an ohm meter to measure the resistance between
> all pairs of pins, in both the ON and OFF position of the switch. This is
> obviously without any power cable connected. Ignore any readings that are
> above some tens of ohms. If the connection is good, it should be very close
> to zero ohms.
>
> If the switch indeed is a problem (say, there is some dirt or corrosion
> inside), the resistance could vary when you are gently rocking the switch
> in the ON position.
>
> When it comes to the power connector, I think that the only possible
> failure mode should be corrosion or mechanical damage, or a bad soldering
> on the circuit board. You could add some new solder and flux and then
> measure the resistance between the circuit board and the pins on the
> outside. I think it should be more likely that the power cord from the
> power supply is damaged, for example if the cable has been bent heavily.
> Have you checked the power supply with another machine?
>
> I will check all the points you mention Mike.  I did already check U59
>> Regulator it is getting 12V.
>>
>
> Did you measure all voltages on the power connector solder pads on the
> circuit board? Do the voltages remain stable if you gently rock the switch
> in the ON position or if you bend the power cord near the connector or the
> brick?
>
>         Marko
>
>       Message was sent through the cbm-hackers mailing list
>


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Received on 2017-06-29 17:00:03

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