x68000 ACE Soft Power On/Off

[X-Col]

Alright, after recapping the Ace I started to experience PSU problems until the machine finally did not turn on at all.
I decided to make an ATX connector if only to see if the unit was working at all.

Here's were I am,
Connector built using the 2N7000 inverter method.
Red power light goes on, press the front power button and nothing.... (Stays red)
Manually ground the ATX power on wire and the green light flashes on the ACE. It powers on when the power button is pressed (to the on position), and it works!  So at least I know the unit is working (to a fashion)
Press the power button on the front (to the off position) and the green light flashes again and the screen goes blank. I then have to remove the short to the ground wire to turn the ATX PSU off manually (and return the unit to the red light status).

Any ideas why the unit does not fire up the PSU when the button is pressed?   

Cheers...

[eidis]

 Hi X-Col !

Try running this on your X68000 and post the results:

X68k Power Test
http://nfggames.com/X68000/Misc/Diagnostics/SoftPower%20Test%20Program/x68k_pwrtest.zip

More info here:

Soft-Power troubleshooting and repair
http://gamesx.com/wiki/doku.php?id=x68000:soft_power_switch_troubleshooting_and_repair

Keep the scene alive !
Eidis

[X-Col]

RTC Alarm = 0 or 1
Expwon = 1
Ps on = 0

My problem is slightly different however, it won't power up the PSU.
When I manually short the green ATX power on pin with earth, it works. The system goes through the motions of powering down when I turn the front power switch to off, the system shuts down but because the PSU has been manually shorted it does not power down the floppies/HD etc and the green light continually flashes.

Must be something on the IO Daughterboard but what?

To confirm, I connected the following on the 2N7000:-
Source - ground (Black on ATX)
Gate - yellow (x68000 pwr on)
Drain - green (ATX pwr on)

Update: checked voltage of yellow wire and there is nothing in either off or on position. Am I correct in thinking there should be 5v coming through when the front power switch is in the On position?

[costa]

I personally think that a fool prof adaptation should use a 74ls04.
I have tried about three of four times using the 2N7000 without success, not sure what happened.
Once I replaced with the 74LS04 it worked fine... I decided to go always with the 74LS04 because of this.
Since the computer works when you manually activate the power on, I think it is your inverter that is not good.

[X-Col]

I personally think that a fool prof adaptation should use a 74ls04.
I have tried about three of four times using the 2N7000 without success, not sure what happened.
Once I replaced with the 74LS04 it worked fine... I decided to go always with the 74LS04 because of this.
Since the computer works when you manually activate the power on, I think it is your inverter that is not good.

Cheers mate, I'll give the 74LS04 method a try. I went for the 2N7000 because it looked simpler.

[costa]

Yes, it means less soldering, but you will need a small protoboard to solder the pins or they will break with the manipulation.
The 74ls04 is more robust, will hold the wires much better, and you will not need a protoboard to fix it. Just use good layers of isolation (black tape) and it will stay fixed and strong in place longer.

I am no sure exactly why the 2N7000 did not work... I felt it was unstable, behaviour not consistent, and some times did not work at all. I gave up.

I personally think that a fool prof adaptation should use a 74ls04.
I have tried about three of four times using the 2N7000 without success, not sure what happened.
Once I replaced with the 74LS04 it worked fine... I decided to go always with the 74LS04 because of this.
Since the computer works when you manually activate the power on, I think it is your inverter that is not good.

Cheers mate, I'll give the 74LS04 method a try. I went for the 2N7000 because it looked simpler.

[X-Col]

Yeh I did use a proto board to make the connections, so no problem there. I will try the other method but still believe there should be a small voltage coming from the yellow wire (X68000 pwr on) connected to 'Gate', when the front switch is pressed. I think that is what closes the switch on the mosfet 2N7000 and turns on the ATX PSU.

Can someone confirm this? 

Here is a quick video showing the machine with ATX PSU manually powered on by connecting earth to green, then I remove the jumper to work only via the 2N7000 method.
https://www.youtube.com/watch?v=ibdmWMVa578

Update:
checked PIN2 of IC29 and it is 5v when switch in off position and 0v when switched on. There is no change from the yellow wire (no voltage in either on or off). Can anyone advise what needs to be checked between these two as there must be a failure somewhere?

[X-Col]

I have checked transistor Q9 and found the following:
First pin is earth
Middle PIN (output) is connected to the Pwr On output (yellow wire)
3rd PIN (input) is connected to PIN 8 on IC 28

When machine switched off:
Middle and 3rd PIN voltage jumps around

When switched on:
Middle = 38mv (output)
3rd = 54mv (input)
So it is outputting less volts than is input...

I'm positive it should be outputting 5V (Or somewhere near) when the switch is on. Is it a bad transistor?

[eidis]

 Hi X-Col !

I took out my rusty ACE and measured the voltages. Hope that this will help you.

Blue: On: 12v  Off: 0v
Grey: On:-12 Off:0
Orange: On:5.06   Off:5.06
Yellow:  On:1.31 Off: 0.01/0.02

Update: #1

RTC Alarm = 0 or 1
Expwon = 1
Ps on = 0

It looks like the /RTC_ALARM, /EXPWON and /PSON signals are good. This leaves us the /MPWOFF. Try checking IC28 for stuck outputs and desoldering Q9 and testing it out of the circuit.


Keep the scene alive !
Eidis

[X-Col]

Hi Eidis,

At least I know that the yellow should be outputting 1.31v, the other wires are fine.
My yellow is outputting 38mv when switched on (coming from the output of transistor Q9).

Should Q9 be amplifying the output of IC28 PIN8 (54mv) to the required (1.31v), or is the output on IC28 PIN8 too low?

I think I have either a bad Q9 or IC28, but not which...

[eidis]

 Hi X-Col !

Try desoldering Q9 and testing it out of the circuit with a multimeter. If Q9 tests good, replace IC28.

Keep the scene alive !
Eidis

[X-Col]

Hi Eidis,

I have desoldered the C114 transistor.
How do I test it? Do I just look for any shorts between the PIN's like on a mosfet?

Update:
Looks like-
Emitter connected to Earth
Base connected to Yellow wire (output)
Collector connected to Pin 8 of IC 28

I think you test these by testing for any short between emitter and collector.
I measured 18k ohms between them, so am I right in thinking this transistor is knackered?

If so, what is a viable replacement?

[eidis]

 Hi X-Col !

Check your mailbox. There should be a blessing for you.

Keep the scene alive !
Eidis

[X-Col]

Thanks Eidis 

Ok, so I think Q9 is duff. However, I still don't think the output coming from IC28 pin 8 is correct.
Will replacing Q9 increase the voltage from 54mv to 1.31v, I don't think so.

In fact with the transistor configured the way it is, I don't think it is acting as an amplifier.

Can someone with a little more knowledge advise? I am thinking that both parts need replacement?

In the meantime, I've ordered a new DTC114....

[costa]

Have just found this, so sorry about bringing this topic back...

I am sure I did not take care of the static...
Maybe I fried the transistor before even soldering it ?

"BUT: this part *IS* subject to static damage.  Before you handle one, sit
down and touch the nearest metal surface that is grounded (rig, scope
ground lead, etc.)." (http://wa5znu.org/2007/07/2n7000/n6kr-2n7000.txt)

Yes, it means less soldering, but you will need a small protoboard to solder the pins or they will break with the manipulation.
The 74ls04 is more robust, will hold the wires much better, and you will not need a protoboard to fix it. Just use good layers of isolation (black tape) and it will stay fixed and strong in place longer.

I am no sure exactly why the 2N7000 did not work... I felt it was unstable, behaviour not consistent, and some times did not work at all. I gave up.

I personally think that a fool prof adaptation should use a 74ls04.
I have tried about three of four times using the 2N7000 without success, not sure what happened.
Once I replaced with the 74LS04 it worked fine... I decided to go always with the 74LS04 because of this.
Since the computer works when you manually activate the power on, I think it is your inverter that is not good.

Cheers mate, I'll give the 74LS04 method a try. I went for the 2N7000 because it looked simpler.

[X-Col]

Work completed and all is working great!
Thanks for your assistance 

https://www.youtube.com/watch?v=b5D93prLTAk

Thanks Eidis, just to replace the capacitors in the floppies now as they're playing up. That will mean every capacitor has been replaced in the system, including memory and midi boards.
I was going to sell it once finished as I now have a Compact, but I have an emotional attachment to it now, and a great sense of achievement! I might just keep them both... 

The ACE is sexier than the Compact 

[eidis]

 Hi X-Col !

Congratulations on a job well done !

Keep the scene alive !
Eidis

[X-Col]

I've been using this for a while now and everything is working great apart from one quirk,

The unit powers on and off fine, but if you leave the unit in standby for about 5 minutes it takes two presses of the front power button to get the unit to power up. Works fine again until you leave it in standby for 5 mins plus again.

Very strange and it's something I want to address, but no clue where the problem may lie?

74LS08 (IC28), 74LS244 (IC29), DTC114 (Q9) are all new, I'm using a Pico PSU with the 74LS04 inverter mod.

Any suggestions chaps?

Update: Capacitor C64 was bent and resting on top of the nearby chip. Moved the capacitor away from the chip and all seems to be good. Now have a Fully working Ace HD, including both newly recapped floppies!

Thanks again for everyone's help, particularly Eidis 

Now onto the Compact which has developed issues (argh!)