Steeplechase missing bugle

Lurch666

Lurch666

Active member
Feedback
21 (100%)
Credits
4,166CR
Forcefulfil Kindly offered me a steeplechase cab which I snapped up and have managed to test today.

Tested the PCB and it's working so took all the innards out of the cab to test (the cab wouldn't fit through my front door and there's no power in my garage) to check sound and controls.

It's all working fine except the bugle is missing that is supposed to play when a credit is added.

Fortunately this has full schematics so should be an easy fix which I will document here but just wanted to show this off.
smiley9.gif



Thanks to this having schematics I'm hoping that what I can learn from this PCB will help me to fix my crazy balls PCB which is a similar TTL without CPU type.
 
Lurch666

Lurch666

Active member
Feedback
21 (100%)
Credits
4,166CR

Didn't think it would take long.

steeplechase_bugle.jpg


After finding the bugle trig was operating correctly I found the 9316 at B8 was receiving a signal on pin 2 (1F) but producing no output.

I piggybacked a 74LS161 (equivalent chip) but bent pin 14 up and got a signal on that pin telling me the 9316 was bad.

Removing it from the PCB showed a brown burn mark so it looked like I was on the right track. Fitting a socket and a new 161 I got a tune but it was incorrect and flat.

Since the 9316 at D8 provides the tones for the tune I checked that with my slice and got errors and removing is also showed the same brown burn marks. After replacing it the bugle was back.

This is now fully working-I just have to sort out the monitor in the cab.

A spare came with the cab as the one in the cab doesn't have a chassis but I'm going to have to figure out how to connect it.
 
Lurch666

Lurch666

Active member
Feedback
21 (100%)
Credits
4,166CR
I know what you mean.

Sometimes it difficult to even look at a problem PCB but you know when you finally do you will be going down the repair rabbit hole again.
 
You must log in or register to reply here.
Top