Subject: Re: Two dead AXPpxi33 boards?
To: None <firstname.lastname@example.org>
From: None <email@example.com>
Date: 10/18/2001 18:29:56
On Thu, Oct 18, 2001 at 08:08:56PM +0930, Berndt Josef Wulf wrote:
> Whatever you do, don't test the working CPU in the two apparent dead
> boards as you risk to fry it.
Ah, OK. Thanks for the warning.
> I would first take a multimeter and checkout the power supply
> voltages. Assuming that you've one of the motherboards connected,
> measure the following voltages on J33 in reference to
> Pin 5, 6, 7 or 8 (Power Ground):
> Pin 2 +5V
> Pin 3 +12V
> Pin 4 -12V
> Pin 9 -5
> Pin 10 +5
Will do. If I'd made it through that circuits class I was in I might
be able to use a scope to check the signals out. Alas, it wasn't meant
> The bright shining LED may be due for several reasons, one being that
> you've used an ordinary LED and connected it straight between ground
> and one of the output pins without a serial resistors - they don't
> like to be connected directly to +5V!!! Try an LED with a 470Ohm
> resistor in series.
I assumed that was the case. I also assumed that if the light hadn't
blown instantly then there must be some resistance in the wire or light
> Once you're sure that the power supply is operational, you may want to
> measure the output voltage of the regulator that supplies the CPU. I
> don't know what voltage is expected at the output, but it should be
> substantially lower that +5V (appr. 3V). You may find some information
> on the Internet.
And I would measure this across the two terminals on the backside of
the motherboard where the regulator comes out?
> Perhaps not relevant but for completeness, the reference manunal makes
> mentioning about connecting output ground and the safety ground. But
> if you have mounted the board in a housing using metal screws, this
> should be ok.
The first board didn't work when mounted and properly grounded (well, as
properly grounded as you can get with two-prong 1948 vintage wiring in
your house -- landlords suck). Since then I've been testing without
having a ground go to the spot on the board that is supposed to go to
the case. I'll try connecting it for luck.
> After this place CPU and RAM onto the board. It would be unlikely
> to have two faulty CPU's, but I would spent some time testing the memory.
I have three boards and two processors. One board+processor is
tesseract.neutralgood.org. The other two boards and one processor are
> I assume that the memory you're using is the correct type. If
> available try different memory modules that are known to work.
> Remember, you need a pair of 36 bit wide RAM.
I assume memory from an AlphaStation 200 should work fine.
> Are any cache chips installed? If so, remove them temporarily and see
> if this helps. Also check the Cache Speed Select jumper for correct
> configuration appropriate for the type of cache installed.
> (J17 no jumper = 15ns, with jumper in = 20ns)
J17 is jumpered, if it matters with no cache.
> Check CPU Clock Frequencey jumper J7
> Speed Processor P1-2 P3-4 P5-6
> 66 21068 Out Out Out
> 100 21068A Out Out In
> 166 21066 Out In In
> 233 21066A In Out In
From left to right I have J7 vertically jumpered, jumpered, and not
jumpered. This is the same way my working 166MHz board is jumpered.
> Check SROM select jumpers J28 and J29
> Function Jumper Pin
> Boot from Flash J28 1-3
> Boot with BCache J28 3-5
> Boot without BCache J28 2-4
> Boot from loader floppy J29 1-3
J29 is unjumpered, J28 appears to be jumpered 1-3 (same as my working
> In any case, try to connect a serial console as this will
> be the best way of telling whether or not the system is
> alive. You won't be able to see much activity booting to
> the SRM console.
That's tonight's task. I hope I can use the serial port with just
ground, transmit, and receive wired. I'll get back to it after
dinner and Simpsons.
> Hope this helps
Kevin P. Neal http://www.pobox.com/~kpn/
Seen on bottom of IBM part number 1887724:
DO NOT EXPOSE MOUSE PAD TO DIRECT SUNLIGHT FOR EXTENDED PERIODS OF TIME.