Re: Stern Blanking Repair (Harley Davidson)
- From: cfh@xxxxxxxxxxx
- Date: Thu, 25 Sep 2008 03:40:00 -0700 (PDT)
On Sep 25, 2:45 am, "WOLFUS" <timeise...@xxxxxxxxxxxxx> wrote:
I had a similar problem. I called Stern and was given this advice. Touch the
chips any one hotter than another? sure enough that was the one causing the
problem. It was indeed one of the 273's. My question before this was as
yours , which one? I knew that certain coils were firing and the game
locked up not booting but that was the turning point. the chip was very much
hotter than the others.
I'm sure that there may be a deeper issue. Maybe power? I have found that
power issues on DE games and sys 11 Wms are really starting to show the 5v
needs to be rock solid and the smaller caps are the cause on the PS.
Hope this helps someone.
Timathie CARGPB15<c...@xxxxxxxxxxx> wrote in message
news:63c94088-a669-4bb9-9991-5bbe830aa063@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I bought a Stern (Sega) harley davidson from a guy.
Game had an issue at power on, it would blow the main
solenoid fuse F6 on the driver board. This happened because
all the coils would energize at power on for about one second.
This was enough to blow the 5 amp slo-blow coil fuse.
At first i thought it was a problem with U210 on the driver
board. This is the Dallas DS1232 chip (8 pins),
responsible for the blanking signal. The blanking signal
stays low while the game boots. After the CPU is booted
and thinks everything is good, it lets the blanking go high
(which enables all the coils).
I checked one of the resistors R270 (4.7k ohms) connecting
to U210 (dallas chip). It would not measure in circuit,
so i pulled one leg of the resistor from the board and then got
the correct reading. this seemed fishy to me, so i replaced
the U210 dallas chip. But no love, same problem (and R270
still didn't measure right in-circuit.)
R270 connects to the Dallas chip and then to all the
74HCT273 "latches". There are eight of these chips
on the driver board, as they are the TTL drivers
for the FETs (which sink ground for all the coils and lamps).
Using a DMM set to diode function, red lead on ground,
i put the black DMM lead on pin 1 of each of the 74HCT273
driver board chips. Got a reading of .353, which seemed
too low (was expecting .4 to .6). Compared this reading to
a known good driver board, and sure enough, got .5 on the
DMM on a known good board.
This meant one of the reset lines on the 74HCT273 chips was
bad. but which chip? U201, U200, U3, U4, U1, U2, U6 or U18?
So using a set of sharp diag cutters, one at a time, i cut
pin one from each of the 74LS273 chps, and remeasured
with my DMM. Sure enough, after i cut U6 pin 1, the DMM
measurement for pin1 on all of the latch 74HCT273 chips
went up to .5.
I replaced U6 (using a socket) with a new chip, and resoldered
the cut joint on all of the other seven 74HCT273 chips (so
pin 1 was connected to the chip). I remeasured resistor R270
in-circuit and it gave back the correct value. Installed the board
and the game now worked (all the coils did not all fire at power on.)
Powered on and sure enough, the problem was fixed.
The weird thing was this game worked fine,
as long as you turned the game on with the
coin door open. Then after booting, just close
the coin door. All worked fine without issue.
it was just at boot up, the blanking was high
for a second, allowing all the coils to energize
for just a second (blowing the F6 coil fuse).
I tried the heat tip, but that did not net anything.
.
- References:
- Stern Blanking Repair (Harley Davidson)
- From: cfh
- Re: Stern Blanking Repair (Harley Davidson)
- From: WOLFUS
- Stern Blanking Repair (Harley Davidson)
- Prev by Date: Re: Pinbot Restoration Done! Pics
- Next by Date: Re: Seems I have a Stalker
- Previous by thread: Re: Stern Blanking Repair (Harley Davidson)
- Next by thread: Re: Stern Blanking Repair (Harley Davidson)
- Index(es):
Relevant Pages
|
