Mini Lenovo PC Dead Power supply (ACbell PCH018)

[sam_sam_sam]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

One other note that if you decide to go that route you might get an error message that says that you have the wrong power supply when you first turn on the computer before you load windows

[Dannyx]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

TBH, I'd just use a single 12v supply that's always on, as this is probably the only way of doing an aftermarket conversion on this PC - Meanwell works "Well" for this task Sure, if it has a fan, then you'll probably need some way to switching the fan on/off. You can do what I did and run the fan off the power connectors for the HDDs/CD, if the supply is always on by nature and the only way to get it to shut off is to kill its mains power. The MB, as far as I can tell, doesn't make use of an on/off signal pin (green) like traditional PCs do, or at least it doesn't use it in the same way, as there is no standby voltage present - I THINK it just toggles the PSU between a low power state and a high power state by adjusting it switching frequency or whatnot to make it "green"...just a theory.

[Cloggy]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

Thanks for the additional tips! I'm eager to continue diagnostics to get full ATX compatability.

One of the things I'm considering is buying a DC-DC converter 5V to 12V to give the board the standby power it wants. However, it would have to do some switching as soon as the 12V line from the PSU comes on otherwise it shorts the +5V standby to 12V line through the HP motherboard.

Any suggestions?

[sam_sam_sam]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

One note on HP switching power supply you can not always get these power supply’s to work with out the the mother board hooked up sometimes it works but not constantly by this method so do not be surprised if you can not get it to work correctly this way for external power supply

[Dannyx]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

I actually just tried what you said and I put the PS_ON from my ATX power supply on the motherboard where the green wire of the PCH018 connects to the motherboard but there is no luck. Basically the PC doesn't start when I press the PWR_BTN.

Yes - makes sense, since there's no power going into the board at that point, so it can't "do" anything to that green wire...

[Cloggy]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

Thanks to your tip I got it to work! It would be ideal if we could actually switch on/off the PSU with the motherboard.

I actually just tried what you said and I put the PS_ON from my ATX power supply on the motherboard where the green wire of the PCH018 connects to the motherboard but there is no luck. Basically the PC doesn't start when I press the PWR_BTN.

[Dannyx]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

You can simply power the PC with just a 12v supply (provided it can deliver enough current) and not bother with the green wire. It worked in my case. I assume if you have a normal ATX supply which requires turning on, you could short the green wire to GND permanently and use the 12v output to power the PC. This would also mean the fan on the PSU runs permanently !

Alternatively, you could probably connect the after-market ATX to the PC "the right way" and make use of the green wire too to switch it on/off, but I haven't tested this to confirm, because it doesn't make sense for this to work as long as there's no STBY voltage - there would be no way for the PC to control the PSU. I imagine what the green wire does is toggle the original PSU between a full power and a low power state to keep power consumption as small as possible, despite the output always being on and fixed at 12v...this makes more sense, since there's no other STBY wire.

[Cloggy]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

I know this thread is almost a year old but I have some questions related to this power supply.

I'd like to replace this PCH018 with an ATX power supply and I'm confused with this green (seemingly) PS_ON wire. There seems to be a little bit conflicting info in this thread. Is it a PS_ON signal or is it a PG signal?

As I measured the PSU on it's own (not connected to the MB) I also found (as Dannyx has) the green line has has 3.3 V on it. Also 12 V is on the yellow lines all the time, by the way. This is without the fan spinning so I'm assuming the PSU is "off".

Before I try something stupid (like short the wrong things) I just wanted to ask how this PSU/PC turns on. Is it just pulling PS_ON to GND? So if I would put in an ATX PSU I'd only have to make an adapter that connects 12V and PS_ON between the motherboard and the new ATX PSU?

[Dannyx]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

For some reason, I read it that you just took 3.3V from the SATA power connector to drive that transistor circuit.

I did that just to test that circuit I concocted, which I then abandoned....since, you know, it's not like I have a bench power supply here, so I have to constantly struggle with all sorts of BS methods to do my job, like using an ATX supply as a multi-rail supply......which IS fairly common, especially in the enthusiast community, but this is supposed to be a top-tier company, so it's only reasonable I expect at least a dumb single-channel 3A supply on my desk....

[momaka]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

^ Oh.... right you did.
For some reason, I read it that you just took 3.3V from the SATA power connector to drive that transistor circuit.
Yeah, NVM then.
Simplicity Level 300 achieved!

[Dannyx]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

While at it, you should just have wired the PSU fan to the 12V rail on the SATA connector. That way, when system comes on and power goes to SATA, it also goes to fan. No transistor circuits needed anymore!

I think I just said this

[momaka]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

That schematic was done mostly to show the layout of the components - as mentioned there, the values were not known at that time. I DID go with lower values for R1 and did the math at the time, but it didn't work

Well, you want HIGHER values for R1 - that is, higher resistance. Lower resistance will only make it worse.

Time scarce and the budget must be kept as low as possible (as always), so there's no reason to push forward - I scrapped the idea and just ran two wires to the SATA power connector for the hard drive, since it comes on and off with the system.

The simplest solutions are always the best, aren't they.

While at it, you should just have wired the PSU fan to the 12V rail on the SATA connector. That way, when system comes on and power goes to SATA, it also goes to fan. No transistor circuits needed anymore!

[Dannyx]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

That schematic was done mostly to show the layout of the components - as mentioned there, the values were not known at that time. I DID go with lower values for R1 and did the math at the time, but it didn't work - pin just can't source the current apparently. It drops to the point where the board actually tries to come on.

Time scarce and the budget must be kept as low as possible (as always), so there's no reason to push forward - I scrapped the idea and just ran two wires to the SATA power connector for the hard drive, since it comes on and off with the system. It's on a separate lead which plugs into the motherboard, so it's switched. The PSU itself has no SATA or Molex connectors at all for that matter - just a standard 4p for the CPU and a 6p, which in reality only uses 5 pins, including that green PS_ON wire which I was going to try and tap into...

[momaka]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

Instead of 10 KOhms for R1, try 100-330 KOhms. Since Q1 only needs to pull about 1.2 mA of current through R2 and knowing that the current gain on these 2n2222 transistors is at least about 100 usually, then the Base current at Q1 could be approximately 100 times smaller - i.e. 10 uA or more should work. Actually, I imagine even less would work, but it would be nice to have a bit of "headroom". If the PS-ON signal still can't source that much current, you might need to go with an op-amp or comparator circuit.

I don't know a lot about FETs as switches, but isn't an N-channel supposed to open when the voltage at the Gate is greater than the source and draw very little current on the G pin ? Assuming my S was GND and I had 3.3v on G....

For N-channel MOSFETs:
When voltage between Gate and Source exceeds the specified Vgs threshold voltage in the datasheet, the MOSFET will conduct between Drain and Source. For good conduction, Vgs > Vd. Otherwise, MOSFET may run in linear/Triode region. Same applies to P-ch MOSFETs, except all voltages should be the negatives of the values specified for N-ch..

[Dannyx]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

Why not use a optic sensor like a 4N25 or something similar to this type of device

I imagine the PS_ON pin can't source the current required to turn on the LED enough to actually close the transistor...

u cant use the ps_on pin of a computer psu as a power source or current source. it wasnt designed for that purpose and it wont work. u have to find somewhere else to source your 3.3v supply. i also tried the same thing before as u and i also couldnt get it to work. the ps_on pin just isnt designed for that.

Well I imagine the pin CAN do some sort of low-current switching action, which allows the PSU to turn on/off - that's how it works after all - though I think it mostly SINKS current, not SOURCE current...it's probably got a high-ish value pull-up resistor to 3.3v on the motherboard, so it's unable to source more than a few mA, if that, that's why I wanted to try a FET, since the gate current should be very small...

[ChaosLegionnaire]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

it worked when I tested the setup on an ordinary ATX supply and powered Q1 from the 3.3v rail and Q2 and the fan from the 12v rail, but once I tried the same setup, but wit the 3.3v signal provided by the PS_ON pin of the Lenovo, it no longer worked.

u cant use the ps_on pin of a computer psu as a power source or current source. it wasnt designed for that purpose and it wont work. u have to find somewhere else to source your 3.3v supply. i also tried the same thing before as u and i also couldnt get it to work. the ps_on pin just isnt designed for that.

[sam_sam_sam]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

Why not use a optic sensor like a 4N25 or something similar to this type of device

[Dannyx]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

Ok, I tried the two-transistor setup in the schematic just for a proof of concept test and it worked......not well enough though: it worked when I tested the setup on an ordinary ATX supply and powered Q1 from the 3.3v rail and Q2 and the fan from the 12v rail, but once I tried the same setup, but wit the 3.3v signal provided by the PS_ON pin of the Lenovo, it no longer worked. The fan turned off alright, as it was supposed to, but also the voltage on the pin itself dropped to nearly 0 and the PC tried firing up as well, which makes sense, since the same thing happens if you ground that pin on a regular ATX....

I think the problem is the pin can't source any current, so any slight load is too much. With this in mind, I tried a FET in place of Q1 and I used whatever I had on hand, which was a FQP6N60C. Same exact setup, except this time I also added a 10k resistor between G and S. It still didn't work: the fan didn't turn off at all this time when I applied 3.3v to the gate of Q1, hinting the D-S junction wasn't closing enough to pull the base of Q2 to GND. It was getting rather late and I was running out of ideas at this stage, so I didn't investigate further. Could be a bad choice of FET or it might be dead and won't open, since I just grabbed it off my desk. It's actually one of the two I used as replacements when trying to fix the PSU in the first place - the one with the "normal" D-S drop when turned on, as opposed to its buddy which has a 1v drop. I don't know a lot about FETs as switches, but isn't an N-channel supposed to open when the voltage at the Gate is greater than the source and draw very little current on the G pin ? Assuming my S was GND and I had 3.3v on G....

[Dannyx]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

I think I'll need something like this to toggle the fan on and off with the PC (with or without temperature control). The 3.3v is the MB's PS_ON pin of the 6P connector which runs to the PSU. Must admit I haven't done any calculations to work out the value of R1 and R2, assuming the two trannies are 2n2222 which I have on hand currently....and what the current draw of the fan is - they may not be able to handle that much current, even though it's a relatively small fan...

[sam_sam_sam]

Re: Mini Lenovo PC Dead Power supply (ACbell PCH018)

If you get one out of an ATX switching power supply some of have a small circuit board that controls the fan and all it requires is 12 volts and the use of the fan that it is hooked to

FSP 300 ( ATX ) switching power supply have a small circuit control board and easy to use

You can also find them on eBay as well