A1200 Power Tower switch on & reset issue

[Garnetto]

Firstly, I'd like to say hello to everyone.  I've been visiting this site for years but never got around to registering - until now!!

Ok, down to business.

I bought a Power Tower years and years ago and right from the start I had issues with it not booting first time after switch on, and sometimes after a reboot.  Quite often multiple resets are required before I'll hear the floppy drive click and the machine will boot.

I have tried 2 different motherboards in the tower and several power supplies over the years (AT & ATX) with no change.  Both boards work fine in the A1200 standard case.  All I can think is maybe it's a grounding issue though I'm hardly knowledgeable in this area so I could be talking complete rubbish!!

My current setup is:

A1200 Rev 2B in Power Tower (Rev 1D4 also tried)
Blizzard 1230/IV + 32MB Ram
Mediator 1200 SX + Voodoo 5 5500 64MB
SoundBlaster 128
Fast Ethernet card
Play TV Pro

Idefix buffered IDE interface + IDE to CF adapter + 1GB CF card

This problem remains in any combination of hardware, from bare motherboard to complete setup.  It's more an annoyance than anything but it would be great to find the cause.

[Oldsmobile_Mike]

When you say "it won't boot" you mean no signs of power whatsoever?  I.e., you flip the power switch and nothing happens at all? Does the fan on the power supply spin?

[Garnetto]

There is power - any connected drives will spin up.  The display from the native video output is black but there is a video signal.

[utri007]

There is power - any connected drives will spin up.  The display from the native video output is black but there is a video signal.

Is it so that you A1200 is powered through mediator? Have you really tested it without mediator? I had same problem, it was my Zorro bushboard. One cure was connect floppy power connector from PSU to morherboard. Then I got A1200 mobo's power connector remowed and cables soldered to it. Cables was connected to PSU. That way my A1200 get power two ways from PSU. Seems that powering through bushboard has some problems.

[Garnetto]

Is it so that you A1200 is powered through mediator? Have you really tested it without mediator? I had same problem, it was my Zorro bushboard. One cure was connect floppy power connector from PSU to morherboard. Then I got A1200 mobo's power connector remowed and cables soldered to it. Cables was connected to PSU. That way my A1200 get power two ways from PSU. Seems that powering through bushboard has some problems.

Hi, yes I have tried with and without the Mediator.  I've even had all the hardware setup outside of the tower and it works fine!!  It's only when the motherboard is fixed into the tower that I have this issue.  Very strange :confused:

[Oldsmobile_Mike]

Well then it seems you've eliminated everything else except for the tower itself, correct?  Is there any additional circuitry in there that could be causing the issue besides the power switch itself?

[D00kie]

Do you still get a black screen with the accelerator card removed? I suspect the mediator's adapter is thinner than the edge connector on the A1200 and CPU cards don't sit right on it. I have to put the Apollo in at a very specific angle to work. The fans go and the power seems okay on the accelerator but I think the power to the card is a bit unstable.

In the end I built and fitted a bracket to keep that card in alignment and most times it boots from power-on, but sometimes (if the tower is moved) then the accelerator needs to be re-seated.

I think if you remove the card and boot to the early startup (hold down both mouse buttons at boot) and you get the early startup screen that may be the problem. Black screen usually means the A1200 cannot access the accelerator's CPU.

[utri007]

Hi, yes I have tried with and without the Mediator.  I've even had all the hardware setup outside of the tower and it works fine!!  It's only when the motherboard is fixed into the tower that I have this issue.  Very strange :confused:

OK, I think that you have a same power problem that I had. Connect PSU's floppy power cable to mobo's floppy connector so that mobo get little more juice. If that solves your problems, then mediator doesn't have good enough contact to mobo. Very common problem. I would suggest that you desolder mobo's original power connector and solder cables to it and connect them to PSU. Not stupid move any way.

I could easily understand, that mediator is little bit different position than it is in tower, thats why it worked without tower.

[Garnetto]

 D00ki & utri007, thanks for your input.  I think I will try connecting the PSU's floppy cable to mobo as suggested.  The issues with the accelerator not being seated properly make sense too as even small movement of the tower can cause the card to wobble.  A bracket to sort that is a good idea.
 
 

[Rob]

Do you still get a black screen with the accelerator card removed? I suspect the mediator's adapter is thinner than the edge connector on the A1200 and CPU cards don't sit right on it. I have to put the Apollo in at a very specific angle to work. The fans go and the power seems okay on the accelerator but I think the power to the card is a bit unstable.

I had the same problem with my B1260 although only after I'd removed the Mediator and was connecting the card directly to the motherboard.  I found that it worked fine at it natural resting point when angled towards the right hand side of the case.