Anyone got a used system 7 MPU for sale? Not working is OK.

Mof, it seems to me that problems with drops falling or not usually have to do with the metal leaf "spring" on the back of each drop target which holds each drop target up. If you remove the two screws holding that on you will be able to take it off and bend it slightly. You need to bend it in towards the target for your problem and out away from the target if your drops are not dropping when hit by the ball. If you get that adjustment right you can tighten the bracket again. I think loosening the bracket is usually a quick fix for the drops not dropping but if you get the leaf springs right you shouldn't need to have it loose.

Looking for help with an Alien Poker. Everything is working but the right flippers. They were working as of Sunday evening. Went to play after getting home Monday from work and they do nothing. I've tried reseating all the connectors. I repinned a few connectors. Reflowed solder on all connectors. Had the 40 pin and a few others completely replaced. I've cleaned the switch at the flipper. I know supposedly that the flipper system on this system 6 is supposed to be easy to figure out but I'm at a loss at this point. I'm by no means a pin repair expert though and any help that could be provided for a dummy would be great.

I recently fixed my first flipper issue on HMM, so I will offer my expert advice . Check the wires connected to the flipper coils; I had couple broken solder connections which was causing one issue. Also check that the switch is making contact when the button is pressed. Good luck.

-Do you have 28V or so at the right side coils ? Check pinwiki for best test procedure.
-If not is there a broken wire between one of the coils or EOS switches or bad fuse (I don't have a system 6 right now so don't remember the fuses)
-When you push the right cabinet switch do you get continuity from any right flipper coil lug to the plug at 2J2-1 or 2J2-2 (flipper ground returns)
-If not figure out where the wire is broken. Test flipper to cabinet switch and cabinet switch to 2J2-1 or 2J2-2 (one is for left, one is for right don't remember).

Pretty simple circuit from memory.
-Turn game on and the flipper coil should have power. Check that.
-Start game and the relay engages to connect 2J2-1 and 2J2-2 to solenoid ground on the driver board. So if left flipper works, this should work.
-Press flipper button and flipper ground lug on the coil should connect to 2J2-1 or 2J2-2 and therefore solenoid ground. causing the flipper to fire

Note that the EOS switch is involved so check that is working correctly.

Just repaired a system 6 CPU and thought I'd share the info. This is the same board I repaired about 3 yrs ago for running too fast, see https://pinside.com/pinball/forum/topic/williams-sys-6-cpu-runs-too-fast

This time the game quit running while in attract mode and only G.I. was working on the machine. The diag LEDs indicated it was booting, and pressing the test button locked on the bottom LED reporting bad ram. Of course the ram was not the issue. The board was able to run Andre's test chip and everything passed, but would not run any game ROMs. I compared address line activity with a logic probe on several chips with a working board and found no activity at IC15 pins 10, 11, & 12.
Replacing IC15 - 74LS139 solved the problem.

I read about the controlled lamp upgrade for 3-7 boards, and that there are two options. One is replacing the transistor with a MOSFET and using 2 resistors per line to cut the draw down - the other is easier - replacing the transistor with a TIP-125(or 127) and adding in a 10k 1/4w resistor for the usually burned 27 ohm ones.

I've done it on Sys 6 boards without an issue, but can the same be done to a system 9 board since they're similar design/parts/etc? I see the mosfet option on Pinwiki, but like the TIP-125/127 solution better and would rather give that a go on the board.

I've got a (mostly complete) laserball playfield sitting around. If you can't find anything new and you dont mind used, PM me and I'll take a look for that switch. Chances are I have it..

Id recommend buying the switch blades and contacts from Pinball Resource and either remaking it yourself, or take a regular EOS, transfer it to the larger existing switch body, and add in the new low current pieces. I did this on my Firepower and its worked like a charm

The extra switch on this stack is not a lane change switch, it is to activate the third flipper like on Flash, so these are both high current switches.

Either way - PBR sells both low voltage and high voltage contacts and light/medium/heavy thickness blades. I fix a lot of EM/hugh current ones by taking a switch apart, replacing the contacts, and putting it back together.

Nah, so long as the open one makes solid contact, you'll be fine. Id keep the gap minimal, at least 1/8" but can be a bit more. The smaller the gap, the closer the flippers will flip together. 1/8th is recommended so the switches don't arc across.

Also, its important the closed switch doesn't open till near the end of the flipper stroke, or you'll lose power to soon in the shot.

https://pinside.com/pinball/market/classifieds/ad/104552
Selling untested boards

I stumbled on a badly labeled auction lot for an Algar apron if anyone is looking.

https://dotysauctionservice.hibid.com/lot/82947162/metal-advertisement/

Time for a thread bump. I rearranged my games room to get all my Sys7s together.

20220119_180442 (resized).jpg

I think: D Latch Lock Molex

Not that they're available from GPE right now but this might be them: https://www.greatplainselectronics.com/products.asp?cat=93

might be this: https://www.amazon.com/dp/B074LSHTC6

https://www.pricecheck.co.za/offers/117481409/2-CIRCUITS+.093
Try that

Well, asked Tilt Graphics if their Apollo13 GameBlades would fit in a Space Shuttle and they had no idea.
Anyone know if they would?

bf3ed0_3bc2e5263c224b0988276e4928aec536 (resized).jpg

I would imagine the Apollo 13 playfield probably sits a bit deeper in the cabinet. Thus, you wouldn't see as much of the art blade with them in Space Shuttle. I don't know if that is a big deal or not. This is just a guess though.

It is possible to lower the playfield, but I'm not that ambitious!

I have a project Laser Ball machine that wasn't booting, only GI lights. Some corrision on the mpu and driver boards so I put in a new Kohout set to replace those two and the game now boots into attract mode and I can add credits and start a game but the flippers are the only solenoids that will activate. Also not getting any sound. Apologies for the basic questions but would anyone have any recommendations on what to check next? Thanks!

3-7 combo proto

More info, please!

Prototype sys 3-7 mpu/driver. This is most creative i've gotten so far on a recreation. I put the connectors where they should go and then free formed the rest of it just putting parts where I thought they would route easily at. I changed up a lot of the circuitry to simplify things like using eight bit chips with output disables (way less 7408s) that probably didn't exist in 1978. Test digit with discreet LEDs . There is a spiderweb on the back to fix the all the dumb mistakes I made on the first try, but it works.

I created circuit boards to build a test fixture (lamp tester, switch tester, sol, power distribution, etc) that came in the mail today. I slopped a bunch of polyurethane on a piece of plywood I am going to use to put a test fixture together soon. Dreading doing the wiring.... Anyone have spare wire harness set that goes from the sys 3-6 master display board to each four satellite displays?

Trying to get a System 4 CPU to boot. Anyone have a spare System 3 or 4 CPU board that boots that they would be willing to part with? Thinking it will be easier to analyze side by side and/or part swap.

Have you tried these test ROMs?

https://pincoder.ca

You should be able to get things running there without the need of another board..

I'm running test ROMs and the CPU isn't starting. Reset circuit is only hitting 4V and clock generator wave looks a bit saw-toothy. Processor tested good (popped it into another game). Want to scope out a working board to get a better idea of how everything should measure out. In any case, have a couple of components I'm waiting on from digikey that I hope improves the situation.

Interesting. Sounds safe to assume you've already tested the obvious.. 5V and 12V power. Keep us posted

Yep, bench testing with switcher--5.2VDC at 6800 Vcc. Reset starts low and snaps up to and stays at 4VDC. I found a 2N4403 that looks to be bad in reset circuit but didn't have any on hand. On my scope while inspecting address lines it seems to bounce very rapidly eg from fixed high to momentary waveforms so my theory is it's randomly resetting as reset isn't quite high enough. That said, I tried forcing pin 40 to +5VDC and it still seemed to be noisy on address lines...So wondering if clock isn't clean enough? I pulled RAM and PIA chips just in case but no change.

I grabbed a battery damaged System 3 CPU board off of eBay for cheap--figured worst case can harvest clock generator ic if necessary. But hoping CPU will come up so I can cross compare the two boards.

Ive seen the clock waveforms on a good board and I have to say they don't look very clean. If I get some time this weekend I'll send you a pic.

Thanks! Here's what I measured:

PXL_20230422_005741748.MP (resized).jpg

Interesting.. Here's what I got on each pin of the xtal, vs. the cleanliness of the 5V line..

Xtal (resized).png

After coming across some shuffle bowler 6 digit displays, I was looking for info of how to test them in a williams 3-6 pin - with the hope of swapping the glass into a system 6 pinball. I found info for the 7 digit displays (ribbon cable) but my google fu turned up no info on testing the 6 digit edge connectors from a shuffle alley. The connectors are not the same pinout, so here is what I came up and I made a video:

Cleaner solution would be to use a blank edge connector (arcade suppliers sell them) instead of an old display board, but I was going for 'free' since I had no idea if any of the displays were good. Out of the five, three looked pretty good, one had minimal pimples, and the last was very pimply.

What's a good way to test RAM on these boards - looking for all kinds of methods.

Want to know how to look at RAM with logic probe, DMM, oscope, through troubleshooting rom.. the gamut.

There are some good RAM and CMOS tests in this software package (free):

https://pincoder.ca

If you dont have a chip programmer and a chip, this adapter contains tests for all Williams system 3-7 games:

https://pincoder.ca/index.php/2020/07/10/adapter-2020-06-23-0506/

As these tests run repeatedly, and individually, and test every address on each RAM/CMOS chip you can watch signals on the scope, or logic probe.

So I have gotten back 4-5 mpus with the display strobe decoder chips blown out. It was a head scratcher about what was killing the chip. I finally figured out what is going on with the help a customer and his picture.... 1J2 and 1J6 are keyed the same. 1J2 is power input to the MPU. 1J6 is display digit strobe output. When you reverse those two plugs you shorting out the decoder chip and putting 12v on one output. Chip craps out and sometimes goes bang.

Looks like system 3-6 had series resistors between 1J6 and the decoder chip that got deleted at system 7. I think it would be a good idea to put them back...

Why the heck did WMS key the plugs the same! Seems quite ridiculous they had seven good options of where to key and they repeated the power input plug pattern with a nearby plug.

I Haven't worked on a System 7 display problems for probably 10 years so hoping for some help

I have had a Barracora for a few years that worked great until recently the player 2 and player 4 displays don't come on at startup. If I play an hour or so they might come on also but not always.

The ball credit display does the same but with the middle 2 digits out at first starting to come on after a while.

Looking at the schematics I cant tell what these all have in common except display 2 and 4 both are strobe 10-16. But the credits/ball in play are strobe 1 and 9.

So far I have:

Moved displays around and problem stays with player 2 and 4
Thinking it could be strobes I swapped the CPU with my backup and the problem is still there so its either connectors or the master display
For +90 and -100, I have +58V and -66V at the pins to the glass on both working and non-working displays.

If I dont get a place to start from this post, I will repin the connectors to the CPU, anyone know where to get replacement edge connectors for the master display. I was hoping they would be like traditional connectors but of course not.

Any help appreciated. Pic of current issue showing player 2 and 4 as well as the missing digits on the credit/match display attached. NOTE the master display is missing R15 so I understand why the commas are out on 3 and 4.

IMG_9634 (resized).PNG

Did you check the voltage at the power supply (3J5)?
Maybe the caps need to be replaced.
The lower voltage may also be because of the switching of the displays.
Exchange the displays from player one to player two and see what happens.

If I look closely I can see the 5 in the 100000 glow in display 4.
Outgassing?