Chips and Boards (mostly not OK!)

 So, after mucking around with the CPU, I'm looking at the power supply. The previous owner of this machine doesn't know how capacitors work.


It turns out, that almost half the values of the capacitors on this power supply were the wrong value. Perhaps that's the source of lots of my problems. I ordered a kit from someone on pinside.com (it's easier than farting around on Digikey), and replaced the capacitors. Someone had been there before me, and pulled up a pad or two. I worked around that by running the leads where the traces weren't.

(The eagle eyed among you might notice that not all the mounting screws are in place. That seems to be a common problem in my machine – not enough connections to ground. I'm ordering a bunch of screws from McMasterCarr to fix this.)

Putting the power supply back in place, and turning on just the power supply has all the test points registering voltages at what I consider "in range". That's good. As I slowly plugged in connectors and powered on the machine, I found that plugging in the playfield solenoids causes the "lazer kicker" to fire. But, that's controlled by the CPU (which is NOT currently powered). Looking at the circuit, it looks like the "lazer kicker" and the "vertical kicker" are CPU controlled, and the vertical kicker isn't firing. I haven't tracked it down too far, but right now I think it might be a PIA chip (they notoriously go bad), or something else between the CPU board and the kicker. Another interesting problem to debug…

What's that sound?

My sound board has been unreliable. It'll play music… sometimes. Also, there's a hum. I figured part was related to the power supply, and part was related to the grounding straps that have been cut between the back cabinet and the playfield cabinet (is there a better word for that part?). Reading online, it looks like sound hums are very common in DataEast/Sega games, and most people have solved their problem by isolating the sound board from the back cabinet's ground plane. A quick trip to my local TrueValue hooked me up with the nylon screws, and testing for continuity on the sound board with ground (and nothing plugged in) tells me my sound board is now floating WRT the ground plane. But, while I had the board out, I took a look at the back of the board, and, "holy not enough solder, Batman."

I've marked some of the joints that don't really have a lot of solder to make me feel comfortable. So, I touched up the board, and connectors. If you look at the all the shiny places in the next picture, you'll see how widespread the lack of solder was:

I'll see how this all works out tonight as I plug away again. I hope the next post will say this is all working, and I'll describe something else I'm 3D modeling, but we'll see…

Comments

Post a Comment

Popular posts from this blog

Twinkle Twinkle Little Star

Image
 The screen my machine came with was busted, and the replacement was the wrong part. I wasn't smart enough to see that when I purchased the machine (but I am now). In any case, I've spent about a month of time (waiting on parts and other things) trying to get my screen working reliably, and with much support from the folks over at ColorDMD , I've finally been able to get it working: The main problem was my ROMs. Maverick has 5 ROMs in it, 1 for the CPU, 2 for the display, and 2 more for the sound. In my case, my CPU and display ROMs were an older version, and the new color display wasn't programmed to support the older pinball software. After much back and forth with the folks at ColorDMD, we decided it was likely that upgrading the ROMs would fix the problem. 27C256 At the junction when you decide you need to upgrade your ROMs, you have 2 choices. You can either order some, or (if you're a nerd like me), you can burn the new code into the old ROMs after erasing the...
Read more

Chips and Boards (mostly OK!)

Image
 I have been debugging lots of problems in the machine. First, some good news, I've gotten the screen working. I've replaced it with a completely new one: I have a few problems with it, but that'll be for another post. Tonight's post is about CPUS. Have Iron, Will Travel Part of debugging the screen has me questioning that the CPU board is in good shape. I'm pretty sure the power supply isn't helping (again, more later), but I decided to take the CPU board out, and see if I could see anything obviously wrong with it. The CPU board was largely in good shape. You will note, there's a battery pack on it. This needs to be removed because, over time, the batteries leak, and put an alkaline all over the board. While this doesn't immediately ruin a board, over time it well. So, that's coming off: Otherwise, as I inspected the board, I didn't see any obvious problems. The capacitors all looked good, the chips all looked good, the transistors all tested w...
Read more

Subscribing to my Blog

Image
Some of you have asked me how to subscribe to my blog. I've added widgets that make it easy to do this. Both are under the terribly designed hamburger menu. Click here: And from there you can find the subscription links:
Read more