Epson PX-8 won't start. Suggestions please.

[acollins22]

Hello Folks,

I have just taken delivery of my first Epson PX-8. It was sold as not working an is just as described.

When I plug it in and turn on, I see the display darken but there are no characters. Sliding the brightness control darkend or lightes the screen but nothing else.

I did see the "Num lock" LED was lit on one occasion but I don't know what made it light. Pressing "Num lock" or "Caps lock" doesn't show signs of life.


Please can anyone suggest where to start?


Thanks.

Andy.

 

[ldkraemer]

As with anything you work on, you always start by verifying the Power Supply voltages. You might be missing a voltage, or the
Supply could be in Current Limit and has folded back. Once the Power Supplies are within Specifications you look for
the proper voltage on the CPU and a Clock Signal, along with the proper Control Inputs to the CPU so it will go to RUN.

If it has plug in cards, you can remove all of them and see if you get any beeps from the Motherboard. It's possible you could
have a card that is loading the power supply, or a bad Capacitor on the Motherboard, or some other problem with RAM or other
buffer IC's.


https://amaus.net/static/S100/epson/systems/PX8/
582,827 px8-tech-manual.ch1.pdf
1,724,318 px8-tech-manual.ch2.pdf
2,616,299 px8-tech-manual.ch3.pdf
1,520,562 px8-tech-manual.ch4.pdf
1,144,196 px8-tech-manual.ch5.pdf
762,241 px8-tech-manual.ch6.pdf
3,268,608 px8-tech-manual.ch7.pdf


Larry

 

[Oscar]

I have just taken delivery of my first Epson PX-8. It was sold as not working an is just as described.
[..]
Please can anyone suggest where to start?

There's the battery pack and a small internal Nicad - both could be dead by now, but easily replaced. There's also a small 'long term storage' (or something) switch that disables the internal nicad. Lastly, note that the PX-8 does need its own wall wart PS; it's not quite a normal power bricklet.

Also check the tech ref manual , which is pretty good! The PX-8 is a very reliable machine, heavily overengineered in fact.

Regards,

Oscar.

 

[acollins22]

Thank you folks,

I'll check those suggestions and report back.


Cheers,

Andy.

 

[ldkraemer]

acollins,
Yes, if it's a laptop, start with the internal Batteries. Page 15 of ~/px8-tech-manual.ch2.pdf states that you can set SW3 "OPEN", so it just uses the main
Battery. That would be a good first test, assuming you have a good main battery.

Most laptops won't powerup if the internal battery is low or dead. My Compaq V5201 just did this to me. That battery was a CR2032 battery.


Larry