XVI with power on/off issues

[H68k]

My XVI has developed power on/off issues, it was working "ok" for a couple of weeks (it did have slight issues with soft power on/off before) but now it has become a major problem.


The following symptoms are:

When power is applied, it will instantly power on, the Mhz/power light will blink or not. depending on witch position the soft power switch is in. (sometimes it wont blink if the switch is in off position) but it will not power off at all.

Others, it will instantly come on, into stand by when power is supplied, you can press the soft switch and it will power up as normal... but still it will not shut off when the switch is set to the off position.

But on some rare occasions, when the power switch on the PSU is flicked on, it will instantly come on, in stand by. when the soft switch is pressed, it will power up as normal and power off when the soft switch is depressed... it outputs a video signal but the screen is blank. if you press the 'interrupt' button while it's like this, it then displays a generic error message on the screen about it has an 'error' and needs to be reset. if you depress the soft switch, the power light will blink... but it will not power off... if the press the reset button, it will power off after a couple of seconds.


I thought this might be a problem with the I/O board, and replaced 3 suspect capacitors, and removed the battery while I was at it (as it's long since passed it's self life) though replacing them doesn't seam to have fixed the issue...

does anyone have an idea's what's causing this?

[BlueBMW]

Those sound like the classic symptoms of a failing power supply.  Has it been serviced?

[caius]

Hi,
I'd check also the soft-power circuit, this the troubleshooting guide (all credits go to 'master' Lydux):

http://www.gamesx.com/wiki/doku.php?id=x68000:soft_power_switch_troubleshooting_and_repair

[H68k]

Those sound like the classic symptoms of a failing power supply.  Has it been serviced?

No, I replaced it with a PicoPSU and external power brick combo.

It would only run for so long with it's original power supply.. before it would shut off and the power light with be very dim. ( it would come back 'fine' after pulling the plug or flicking the PSU switch off and on again) it seamed it didn't have much trubble with the PicoPSU, for the peroid of time it was working.

I'm currently running it with a ATX power supply while it's on my poor excuse for a make-shift test bench...

Hi,
I'd check also the soft-power circuit, this the troubleshooting guide (all credits go to 'master' Lydux):

Could still be a possibility, if it causing the problem? two of the capacitors I replaced are related to the soft power TTL chips.. problem is though... I don't really know how to test a TTL chip to make sure its working right... (I assume this could be done with a simple multi meter? by probing this or that leg... say, this should be high.. but it's reading is low... etc?)