GVP HD8+ problems

[motrucker]

Here is the data sheet for the LS74LS244 chip.

http://pdf1.alldatasheet.com/datasheet-pdf/view/46211/SLS/LS244.html

If you search the other number, I am sure you'll find it too.
Could easily be one of the "jelly bean" chips...

[sim085]

at this point i would say disconnect the scsi cable from the hard drive. Then boot up with the hd8 connected.

I disconnected the scsi cable and booted up with the hd8 connected ... still same problem I guess this proves the problem is with the hd8, but does it say anything as to where the problem might be?

[Motormouth]

I had a problem with my GVP HD8+ PSU.  The solder joints on the female IEC plug became loose.  I had to re-solder them.

I would still check the power supply and resoldering IEC plug is about the easily thing in electronics to solder (the solder joints are very large).  I have seen a couple of these power supplies have loose connection.  This loose connection can often cause strange effects.
Only one of the voltages maybe a problem or a ground or even the board may not be getting enough current.

I would get anything from the hard drive not spinning (controller and ram would check out just fine.  Even the hard drive would identify itself with SCSI Mounter)  to a variety of Guru errors.

Remember the A500 HD 8+ and A500 should not co-mingle their power supply, only signals.

improper power to the A5000 HD 8+ will not necessary keep the A500 from coming on

[sim085]

I would still check the power supply and resoldering IEC plug

I replaced the gvp power supply with a PC power supply, checked all voltages on chips and hard drive are correct, but still same problem. Put switch on "Game", remove hard drive (inc. scsi cable), removed all memory sticks, set jumpers on J8 J7 (0 memory), switched on but still same problem. GVP HD8 green lights comes on, fun starts spinning, A500 turns on with blinking LED and screen is black or maybe very dark grey!!

I really can't understand what is wrong.

[sim085]

the hd8 probably does a scan from device 0 to 6, giving each unit time to come up.

What does this mean exactly? What are device 0 to 6?

[psxphill]

What does this mean exactly? What are device 0 to 6?

On scsi everything has a device number, including the controller itself which is normally 7.
 
When the computer turns on the boot rom in the controller will start looking for a hard drive to boot from (which will be in the range 0 to 6).
 
It's possible that without a drive plugged in or if it's unable to communicate with the drive (maybe a bad scsi cable) then the boot rom will sit there for a long time just in case it comes on eventually.
 
The LED is flashing, which would generally indicate a Guru. However if it doesn't stop flashing and reboot and start again (like a Guru would) then it's possible that the boot rom flashes the LED while it's waiting for the drive. However I have never owned a HD8+ so I'm really just guessing.
 
Have you tried a different internal cable?

[sim085]

When the computer turns on the boot rom in the controller will start looking for a hard drive to boot from (which will be in the range 0 to 6).
 
It's possible that without a drive plugged in or if it's unable to communicate with the drive (maybe a bad scsi cable) then the boot rom will sit there for a long time just in case it comes on eventually.

At the moment I do not have an extra scsi cable so I have to wait before I try that as well. However I did discover something else which I do not know if it says anything about where the fault might be...

The hd8 has two LED lights; one green and one yellow with the yellow LED showing hard disk activity. Now, when no scsi cable is connected to the hd8 only the green LED turns on. When I connect the scsi cable to the hd8, but no hard disk, the yellow LED turns on and off repeatedly. When I then connect the hard disk, again only green LED turns on.

Does this mean that the controller is indeed finding the hard disk and the problem might be something that happens afterwards?

I will try a new scsi cable the moment I have one just to make sure I try any option.

[sim085]

I checked the SCSI cable and this seems to be fine as well. Does anyone know what the hd8 tries to do after it confirms that there is a hard disk?

[paul1981]

I checked the SCSI cable and this seems to be fine as well. Does anyone know what the hd8 tries to do after it confirms that there is a hard disk?

How did you check the cable?

[sim085]

How did you check the cable?

With a solderless breadboard + jump wires + led light + 3.7V battery. Did a small circuit with the scsi cable in the middle, tested it for each line on the cable and led light turned on each time.

Is this ok? or that was not the right way to test it? I just tried the first thing that came to mind.

[paul1981]

With a solderless breadboard + jump wires + led light + 3.7V battery. Did a small circuit with the scsi cable in the middle, tested it for each line on the cable and led light turned on each time.

Is this ok? or that was not the right way to test it? I just tried the first thing that came to mind.

That sounds okay, but even so you can never be sure. A good connection depends on good spring force on the little copper connections on the end of the cable onto the pins on the drive/adapter. Poking thick jump wires in the holes could weaken the connections further. So I'd still recommend replacing the cable just incase.
Unless you can test the cable on another computer then you can't be sure it's working correctly at all.