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Thread: Sproggy and Compaq Deskpro

  1. #1
    LDO
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    Sproggy and Compaq Deskpro help

    I am trying to power a Compaq Deskpro 4000 with a Sproggy 2.8+ (Mastero version). All my voltages are correct, but when I attach it to the Compaq, the Sproggy turns on (all voltages correct), but the power on LED does not come on when the power switch is pushed. If I attach a standard AC ATX power supply, then the system boots. There is absolutely nothing attached (not even a CPU in the board!), so it must have enough power to at least turn on the power LED!?

    Jol, I see you mentioned something in one of your earlier posts about your Deskpro using "a sort of ATX power supply". What did you mean by that? Is there someting that I should/shouldn't be doing to get this to work?

    I probably should have a CPU in the board, but I didn't want to chance putting the Sproggy onto my actual machine. I decided to use a spare mainboard I had lying around, but don't have another CPU. Why does a standard ATX power supply turn on the power LED, but the Sproggy does not when the case switch is pushed?

    I was hoping that you could help me jol (or someone that has come across something similar before).

    There does not seem to be much about running a Sproggy on a Deskpro in the forum, so I am hoping that someone has a gem stashed away in their heads........

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    jol
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    Re: Sproggy and Compaq Deskpro

    NOTE: The PS On signal can be configured to be asserted whenever the power supply
    assembly is connected to live AC by setting DIP SW1 position 6 to the “On” (closed or
    grounding) position. This condition overrides all other settings.

    page 137 at this this pdf

    glad to help

  3. #3
    LDO
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    Edit: Sorry for the long post, but I need some serious help here!

    Thanks Jol. I tried changing the switch you pointed me to, but this didn't work. This change will probably help me once I get the sproggy working, as the machine will then turn on when it gets power.

    I don't think I explained myself properly in my first post. Let me try again...

    I cannot get my machine to power on with Sproggy attached. I have checked all the voltages and pinouts, and everything seems correct, but still no go. I am trying to power just the mainboard with CPU attached (no sound card or hard drive).

    When I short pin 14 to ground and test all the voltages on the ATX connector, they are all spot on. Then if I connect the Sproggy to the machine, apply power to sproggy (from a AT power supply), sproggy turn on after about a 2 second delay, CPU fan spins up, but nothing else. No power LEDS, or any boot type activity. The MAX787 and MAX788 are the only ICs that get warm when connected to the machine with sproggy on. I have tried 2 motherboards with the same result (both with CPU clocked down to 166Mhz).

    Let me just say what I have done in case have made a really stupid mistake with getting the wrong components:
    I have the Renco transformer (RL-5533) with pins 7 & 8 reversed (as per earlier posts), the Renco 10 & 47 uH coils (RL-1256-1-10, RL-1256-2-47). I am using the following ICs: MAX788CCK (as IC2 on Sproggy schematic), MAX787ECK (as IC1), and LM2587T-12 (as IC3). I connected all my wiring up to the ATX connector harness as per the connector on the right at this link (ignoring colors though): http://wired.hard.ru/data/pin_atxpower.shtml

    So my ATX connector is wired as follows (looking from the end of the cable that plugs into the motherboard):

    Code:
    		
    __11_________T'''''''''''''''T________20__
    I O I O I O I O I O I O I O I O I O I O I
    -------------------------------------
    I O I O I O I O I O I O I O I O I O I O I 
    __1___________________________________10__
    (Bad ASCI art, I know!Sorry. Do you have any idea how hard it is to do ASCI art in here!) with the little clip between pins 11 & 20, and the "O" representing the actual pins. Duw to my wonderful art skills (not), Pin 10 should actually be at the end of the connector (under pin 20 DUH!). Is this all correct? I have found several sites that give the pinout, but they never tell you which end they are looking at!

    I measured all my voltages according the above link, and they are all correct as per pin number and voltage.

    I am hoping that it is just that I have an incorrect component, but am pretty sure that they are the correct ones. Both motherboards I have tried it on work just fine with a standard AC ATX power supply.

    Any ideas anyone? Mastero? Could it be something to do with the power good signal that the board does not like? I am loosing sleep here! Any ideas appreciated.

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    I thought the Renco had to have pins 1 & 2 switched, not 7 & 8...

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    jol
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    Originally posted by mikeinsanmarcos
    I thought the Renco had to have pins 1 & 2 switched, not 7 & 8...
    I switched the wrong ones too, cant remember wich one now tho.. whats the adress to the thread?

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    arghhh!!! sproggy problem

    So let me get this strait, if pins 1 & 2 are reversed AND pins 5 & 6 are reversed, you could either:

    A.) reverse pins 7 & 8

    or

    B.) reverse pins 1 & 2 and Pins 5 & 6 (which would make it pin compatible with the T6

    Correct?

    Thanks,

    Mike

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    jol
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    reading my very blurry post, i'd go for A.) reverse pins 7 & 8

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    Yah, that would have been the best option but I already soldered it in with pins 1 & 2 switched so rather than switching 1 & 2 back, then switching 7 & 8, I could just switch 5 & 6 and I it should work just right?

    Mike

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    LDO
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    I have just managed to find out the following regarding ATX specification changes - Start Quote:

    "In addition, ATX power supplies provide a "+5V Standby" (+5Vsb) rail which is generally purple. (Note this is not the same as the normal +5V power lead) generated by a solenoid relay which is directly connected to the AC input bypassing the main transformer. This lead is always powered on even if all other rails are off. This allows certain circuits in the motherboard to remain active even when power supply is off. The +5V standby rail is used for software mediated power up of the system. The software power-up may be triggered by activity of the modem or network card or it may be activated at a predetermined time. A green "Power On" lead is used by the motherboard to signal the power supply to turn on.

    Older revision 2.0 ATX power supplies used a 0.01 amp +5Vsb rail. As of late 1997 revision 2.01 ATX power supplies have switched to a 0.750 amp or greater +5Vsb terminal. Mixing power supplies and motherboards with different revisions is a common cause of power-on and power-off problems."

    End Quote.

    Looking at the above, is it possible that the +5vsb on Sproggy is not able to source enough current to initially turn on the mainboard? Maybe this is also the reason why the EPIA mainboards won't power on with Sproggy?

    Anyone care to comment on this? Mastero? Anyone........

    Edit: I just had a look at Mastero's web site again, and he says the 5V standby is capable of supplying 5Amps, but I don't see how this could be when the 78L05 has a peak current rating of 140mA (http://www.national.com/pf/LM/LM78L05.html)!?

  10. #10
    LDO
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    OK, here is what I have done so far:

    I was not happy that the Sproggy 2.8+ was able to source enough on the 5V standby line, so I replaced the LM78L05 with a 1A LM7805. I then tried sproggy on a HP Vectra Pentium II machine, and it works perfectly. The machine boots and loads the OS without any problems. But alas, when I attach it to the Compaq, the same symptoms persist. Still no boot and MAX788 & 787 get hot.

    So, I measured some voltages on the Compaq motherboard to see what the difference is between sproggy, and a regular AC power supply.

    All the voltages were similar except for the following pins which had major differences:

    Pin 8 (with AC PSU) = 1.27V
    Pin 8 (with Sproggy attached) = 4.78V
    Pin 9 (with AC PSU) = 5.11V
    Pin 9 (with Sproggy attached) = 4.15V
    Pin 14 (with AC PSU) = 4.93V
    Pin 14 (with Sproggy attached) = 1.64V

    Before you say it, no the wires are not reversed! I have triple checked them, so no problems there, and as I said, a HP Vectra booted from the same Sproggy supply without a problem.

    There is no way that a Pentium 166MMX CPU, Video card and main board could be trying to draw too much current, so there is obviously something different about these Compaq’s.

    My theory is that whatever is happening here to me with the Compaq could be the same problem that the guys with the EPIA boards are experiencing.

    Any comments/suggestions? Pleeeeeeez

    Oh, and Jol, I am with you on that. I have reversed pins 7 & 8 on the Renco, and all voltages are spot on, so no problems there.

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