X68000 XVI shutdown PSU repair SOLVED!!!

[gypsie]

Hello everybody!!!

Once again, i ve got problem with my  X68000 XVI version.

The computer power up well, but the 16 mhz led is blinking and it shutdown 10 secondes after startup. I never opened it, capacitors are originals.

Do you think that is a PSU issue ?  I ve already my X68000 compact ( no adpcm sound) to repair.... I'm very unlucky ....

Is it a known problem on the XVI ?

Thanks so much!

[SuperDeadite]

ALL X68000s MUST BE RECAPPED.
END OF STORY.

[kamiboy]

You are not unlucky, the failure rate of an X68000 that has not been recapped is 100%

[gypsie]

ok ok.

First i will try to finish my Compact with his adpcm issue.

Next, i will recap the XVI.

I spend more time repairing than playing.....

[gypsie]

For info, is there a list of capacitors for the XVI ?

[gypsie]

NEWS 24/09/17

- Removed psu from my XVI and  tested it. Fan spin 5 seconds and the psu shutdown . So The culprit seems to be the psu.
- Opened the psu to check inside. Brown fluid on certain parts!!!!!
- 1 capacitor is curved on top.

[gypsie]

Ho my god!!! Never saw such so bad capacitor!!!!!

[RobIvy64]

Time to change all the caps and clean up that leaked cap juice!

[gypsie]

Hello,

I ve changed all capacitors but now Psu won't power up!!!!!

I ve checked all capacitors, fan, switches ( psu and computer) everything is ok.

I ve tried to shunt "gnd" + "power on" to start the psu without result.

Psu power up well after capacitor replacement... I don't understand the problem...

[JulBS0]

Hi,

The X68000 power supplies are powered up by applying a positive voltage to the Power Control line, unlike modern ATX PSUs.

To test it, connect the Power On line of the PSU to its +5Vsb/Vcc2 line through a resistor (approx. 4.7kOhms is OK). It should power up instantly.
I strongly advise against connecting directly the Power Control line to a +5V source, as it may fry the transistor used to control power.

[gypsie]

Thank for advice.

I ve tested diode zener zd 31. With multimeter i can read 0.06mv in both direction. Diode not desoldered from pcb.

[gypsie]

Hi,

The X68000 power supplies are powered up by applying a positive voltage to the Power Control line, unlike modern ATX PSUs.

To test it, connect the Power On line of the PSU to its +5Vsb/Vcc2 line through a resistor (approx. 4.7kOhms is OK). It should power up instantly.
I strongly advise against connecting directly the Power Control line to a +5V source, as it may fry the transistor used to control power.

Tested with 4,7kohms resistor but psu won't power up.

I will change ZD31.

[gypsie]

Bingo!! ZD31 ( 6,8v 500mw) was dead .