Atari mega ste help

[PhilC]

I'm not familiar with the Mega STe but if you've cleaned that board up then you have at least one broken track between one of the resistors and the keyboard port? (Presuming that's what it is)

Then the 8 pins on the port appear to have dry joints, indicated by the ring of what looks to be flux around most of them.

Resurrecting boards with lots of corrosion is not something I'd recommend to someone with just a meter and a logic probe.

For instance, you need to know if the clock circuit is working, etc.

One thing you can test is this. Find the /halt and /reset pins on the cpu and both should be at 5v if the cpu is running and both should momentarily drop to 0v when the reset is pressed.

If there is no change when you press the reset on at least the /reset pin, then you need to have a good look at the reset circuit. Other than that, I think you'll struggle without an oscilloscope.

[Tomswork]

Hi philc the 8pin port next to the reset switch goes to the rs422 chip I'm guessing apple type port I will check the traces and try a wet solder on the cold solder joints this is the only area like this on the board I looks like something corrosive got in there the switch was almost dust

Tom

[Tomswork]

Got these pictures

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Checked the 7404 pin 11 and found I need a new logic probe or there is no output in mono or rgb

The power supply is putting 5.05vdc under load and 11.90vdc will keep looking and update more tomorrow

Tom

[frank.lukas]

On Pin11 there are simply a low (0V) if a RGB Monitor is connected and high (5V) when a SM124 is connected ...

May be a Battery was leaked ?

[Tomswork]

The mega ste on a rgb crt you can see the difference between no reset and reset pressed also there is 0v at pin 11 with this monitor

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[Tomswork]

This is a picture of the u309 and drive controller area

20191210_142658.jpg

[stephen_usher]

The support for the VME riser looks highly corroded and may have damaged some tracks there from the image.

[Tomswork]

Thank you Stephen sharp eye I will clean and check those it does look like rust a good conductor is across some of the traces and pads

[Tomswork]

I have the vme riser with baking soda paste on then a swab down with isopropyl then a trace test hope for the best

Tom

[Tomswork]

20191210_234924.jpg

Well I get this on a cold boot after the cleaning with baking soda and isopropyl let it warm up and back nothing

Tom