Re: Sys 80 bootup issue
- From: "Dan Beck" <biscuitbecks@*nospam*cableone.net>
- Date: Thu, 9 Oct 2008 07:47:00 -0700
"taylor34" <at93850@xxxxxxxxx> wrote in message
news:46875a6e-21a8-48af-b95d-72ae9f510642@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Oct 8, 1:17 pm, "Dan Beck" <biscuitbecks@*nospam*cableone.net>
wrote:
"taylor34" <at93...@xxxxxxxxx> wrote in message
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On Oct 8, 2:11 am, "PistolPete" <bloc...@xxxxxxxxxxxxx> wrote:
"taylor34" <at93...@xxxxxxxxx> wrote in message
news:f410a2df-9974-4b9f-8ee0-4840c6ab11db@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hello--
Working on a panthera sys 80 machine, have gotten past the power
supply and am now to the cpu board. The board itself is clean, so I
started going through clay's guide. The first part passes, I get 4.5
volts at pin 40 of U1 (I've replaced this chip btw). So I moved to
the 2nd part, trying to get a clock signal on pin 37 of U1. I checked
Z3, and I was getting clock signal on pins 1 to 5--however, pin 6 was
not. As a result, I replaced Z3--no change though in operation. My
next thought was to replace Z2, but before I do that, is there
something else I should be looking at as a culprit? Thanks!
Taylor34
Have you checked the traces, components and timing of the reset circuit
signal? My BH wouldn't boot. going through the normal order of
operation
brought me to the reset circuit. Seemed it fired too quickly on my
board,
before voltage truly stabilized and the CPU was ready. I swapped in a
different value capacitor to get the proper time-to-reset-pulse. and
the
game has worked flawlessly ever since. Stacked tolerances in parts will
mean
failures every so often, even if all the original parts are "within
spec"
when checked individually.
PistolPete
Baltimore, Maryland
** Posted fromhttp://www.teranews.com**
I believe that the reset stuff is working ok at least on my bench
since the board fires up there. Panthera doesn't have the extra reset
card so luckily I don't have to worry about that. I'll try and record
some voltages off of U1 tonight, see if that might shed some light on
what's going on. Z2 and Z3 appear to working even when in the
machine, I get clock signals on them--it appears that U1 isn't
starting for some reason (btw, I replaced the chip and put in a socket
for it, so the chip itself should be ok). Thanks
Taylor34
Hello,
have you investigated/replaced the 12 VDC filter cap and its associated
bridge rectifier, in the cabinet bottom? It may be the case that they
are
tired, and need to be replaced; certainly the cap for sure, if it's
orange!
:-)
I have no experience with the Rottendog power supply; I can't testify
for/against its use. My opinion is a properly rebuilt System 80 power
supply is more than adequate for a System 80 game...
When you have the board powered up on the bench, do you have the pulsing
data/address lines, and the pulsing IRQ lines? Hopefully you own a logic
probe for this... :-)
Regards,
Dan
I have replaced the cap down there, it wasn't orange but it didn't
look good. I would have used the original supply but it was missing
the heatsink and nobody around here had another one unfortunately, so
the rottendog was my only option.
I got some voltages tonight from some pins:
U1 pin 2 - 4.8volts, pin 40 - 4.6 volts, pin 39 4.7 volt, pin 37 4.8
volts, pin 4 0.2 volts.
U4, U5, U6 pin 37 - 4.8 volts
From looking at Clay's document, it looks like my IRQ line isn't
working when my voltage is lower (aka not on my bench). Looks like it
could be anything from a riot chip to z11 to z15, but since it's a
voltage issue that might narrow it down. Anyone have a similar
experience that might point to one or the other? Only one riot chip
on my board has been replaced before, U5, btw. Thanks!
Taylor34
Hello,
well, in all honesty System 80 power supply boards are a dime a dozen on
eBay, but now that you invested in Rottendog you are committed...
Determining functionality of a System 80 control (cpu) board by measuring
ONLY voltages is shaky at best. You really need to be providing logic state
data using a logic probe or an oscilloscope, at least for me to be able to
help you. I know the IRQs should be around 3.0 VDC when pulsing, and the
address/data lines are about 2.4-2.8 VDC, I believe.
My guess is you have at least two sets of problems with your Panthera. The
first may be a feeble output of 12 VDC to the RD power supply; this is
presuming the RD power supply is 100% functional. The second is a control
board with bad 6532s and/or bad switch matrix (Z11-Z15) chips. However,
with the lack of logic state data provided I cannot offer any more guesses.
Regards,
Dan
.
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