I am having problems on my Skateball game. It was not working when I got it and still is not.

The rectifier board was in bad shape and had several hacks. I replaced that with a new GPE board.

I replaced the capacitors and 5v regulator Q20 on the solenoid board. upon testing I had no 5v voltage on the SDB, so I replaced the Q20 (LM323K) regulator again. I now have 5.7 VDC which sounds too high. reading the schematics this 5v section seems very simple before sending it over to the MPU. should I replace the few resistors here (R49, R50) also? connecting the SDB to my 12 volt power supply TP5 I read 5.8vdc between gnd TP8 and TP1 but when I read between the voltage reg metal case Q20 and TP1 I get 4.8volts.

on to the MPU I get no blinks on startup when using the SDB power. I read 5.7 volts here. but when I apply my 5v benchtop power supply to TP1 I get all six blinks, which suggests that my chips are good? also it appears that the resistor R11 is fried this is in the section identified as "valid voltage detector" in the schematics although it appears to be on the 12v section. this is probably an unrelated problem? My MPU looks very clean and has no corrosion.

any suggestions?

IMG_00301_(resized).JPG

the SDB board (Stern SDU 100 revision 3) between TP8 gnd and;
TP1 = 5.7-.8vdc
TP2 = 178vdc (I dialed it down)
TP3= 5.7 vdc
TP4= 220~
TP5= 12.65 vdc
TP6&7= 5.7vdc

checking the Lm323k case to TP1 gives me 4.8vdc??

The MPU board TP 4, ground to;
TP1= 5.7 vdc
TP2=12.6vdc
TP3= 21.6vdv
TP5= 5.7 (I think)

I am suspecting that the 5.7 volts is too high for the MPU, How do I remedy that? After two bad LM323k's I tested this one on the bench with a 12v input and read a 5.2v output. installed it reads 5.7volts

The MPU cycles through the flashes with my alternate bench power (built from an old computer power supply).

I believe that I got the replacement parts right. those capacitors C22, C25 and C29 don't have a polarity requirement do they?

After two bad LM323k's I tested this one on the bench with a 12v input and read a 5.2v output. installed it reads 5.7volts

I have not tried that yet. It does boot with my alternate power supply. everything is pretty much new up to that point, rectifier and C23....?

My concern is if the 5.7-5.8 vdc is too much for the MPU? a recent thread mentioned that this is the high end on the Altech MPU. I doubt the old board likes it either? do I need to get that in line before it leaves the SDB? how?

On the MPU what will cause the big resistor R11 on the valid voltage detector to blow?

I have redone most of my connectors and am about to start on the pins My Hakko desoldering tool comes on Monday.

G-P-E in that recent tread posted:

The Alltek board added some very nice features including a local 'point of use' over voltage protection for the 5V line (they put this protection where it belongs). If it detected too high of an input voltage - this will 'crowbar' (short circuit) the 5V line which will purposely blow the onboard F1 fuse and cut off the 5V signal. Is fuse F1 blown? If so, your solenoid driver board may be putting out too high of a voltage.

The Alltek over voltage threshold is set at 5.7V (which is a decent choice). 5.7V and slightly above is still a useable (but not real safe) voltage which may be why the ST board still worked but may have tripped the Alltek over voltage circuit.

I have the original board not the Alltek.

Quench.. good spotting. I was comparing the two resistors that I got in the Big Daddy kit and that one was different 2.2 ohm is red-red-gold myR50 is not, more like silver-brown yellow. looking more carefully my R72 is a red-red-gold (2.2ohm) supposed to be 120 ohm I think I'll be checking the whole board.

I hope to swap it out tomorrow.

I am still curious how the resistors work in this particular 5v circuit.

Quench, maybe that was my problem, I am color blind! I replaced those resistors and some caps with the proper ones and now I have 5.4 volts. I cleaned up the CPU, replaced R11 and new headers and an improperly seated chip. Now everything lights up.

Now I have a light problem.... I have replaced most of the lights with LEDs and installed an Alltech light board. It looks like all of my controlled lights on the playfield stay lit all of the time. the controlled lights in the back box seem to operate correctly. Any suggestions on where to look now?

Good suggestions, thanks

at power on the lights come on at almost full strength. they flash slightly brighter in attract mode.
I uplugged the jumper which you are instructed to connect from the control ckt back to the alltech board and the lights are one more dimly, maybe 1/4 power but still flash as part of the attract mode

So I swapped the old board back and the lights seem to act normally, I dont even notice any flashing on my LED's. lamp test suggests that I may have a couple of bad sockets or poorly seated bulbs

So why doesn't the Alltech lamp board work?

Yes I have the connector correctly installed. When I first connected the rectifier board there were two pins reversed (sending 43 volts to my playfield GI 5v ckt). I might need to work through the schematics and see if there are anymore issues like that.

Oh, and I did write to Alltek and they responded promptly, suggesting the jumper was probably installed wrong......

does that common wire for the controlled lamps come directly off of the rectifier board? or elsewhere? I have redone most all of my connectors. That is the next place to investigate.

I had my manual open to that page and was comparing the connectors on the rectifier bd when I saw your post. and alas the problem was on J1 in that some of the wires were mixed up. A simple fix and now it is all working.

Thanks for everyone's help Now I am on to tracing some nonworking sockets (most likely the connectors) and nonworking coils.