A little more update. The crackly interferance sound was due to a bad
plastic insulator which wasn't doing a very good job keeping a metal screw
from making contact with the metal heatsink on one of the switching
transistors Q2. This also was causing the occasional shocks when I touched
the coin door frame, also the power supply would shutdown when I connected
the ground lead of my oscilloscope to it. So I installed a tightly fitted
plastic screw. Now the power supply is working solid 100%. I'm getting a
nice even +5volts. Note to self, use plastic screws from now on.
I'm still getting a RAM error message C0 W11 at address 2001. I don't
believe it's actually the ram, I believe its further down the data lines.
So I need to trace that bugger out. Once I have that done, I,Robot will be
working 100%
Matt
On Mon, 21 Jul 2008 23:39:46 -0700, Matt Rossiter <matt@rossiters.com>
wrote:
> Here's an update on the I,Robot power supply. I put in the new FEP16CTA
> part and now the power supply works fine. The game and monitor come up
> fine. So if anyone is trying to fix their I,Robot power supply - the
> schematics have that part number wrong. Whoever worked on this before me
> put in the wrong part and probably gave up.
>
> The regulator is regulating at 5.4 volts. Perhaps I need to look at the
> sense line? When I measure from ground to the speakers I'm getting
around
> -36volts. I'm getting alot of crackly hiss through the speakers. Almost
> sounds like radio interference. I'm supposed to be getting around -31.5
> volts so I'm thinking that might be why. I don't think it's just a bad
> volume potentiometer.
>
> Other than that, I'm still waiting for my order of ram chips to come in.
> The screen is all full of dots and is reporting a bad ram.
>
> Almost there! :)
>
> Matt
>
>
> On Fri, 18 Jul 2008 15:17:56 +0000 (GMT+00:00), teeray
> <teeray@earthlink.net> wrote:
>>
>> Check and make sure the grounds for the speakers are not connected
>> to any other ground or metal object.
>> The speaker ground is at -31.5 Volts.
>> Treat it just like it was a power wire.
>> No bare spots, etc.
>>
>> Tim
>>
>>
>>
>> On Jul 17, 2008 2:08 AM, Matt Rossiter
>> Wrote:
>>>
>>>This is just a little update. When I removed L6 the +5v came up just
>> fine
>>>and the regulator didn't shut down.
>>>http://games.rossiters.com/manuals/IR-PS2-1.jpg
>>>So the problem is definitely in the audio section of the board. I'm
>> still
>>>trying to find where the problem is. I've replaced the audio amps and
>> some
>>>of the capacitors. I can't find any bad resistors. There seems to be
>> loose
>>>a ground somewhere because if I touch something metal like the coin door
>>>frame or the power switch I can feel a slight tingle of electricity.
> Not
>> a
>>>huge shock, but enough to be a little uncomfortable. I'm wondering if
>> that
>>>might have something to do with it.
>>>
>>>The boards seem to work fine with the ribbon connectors I made. It's
>>>reporting a bad ram, but I'm not going to keep powering the boards up
>> until
>>>I resolve this loose ground issue.
>>>
>>>Matt
>>>
>>
>
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Received on Fri Jul 25 04:38:38 2008
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