I just brought home a Sinbad system 1 machine and have gotten it up and running for the most part but there are 2 issues I have not been able to resolve, the first issue is the smallest chime does not fire, I have verified the chime relay and diode is good and the power transistor is good. I have verified the trigger connection is good to the IC and the IC channel does not show open or shorted. The second issue is the upper target bank will reset on a new game or new ball but the relay will hold down till the fuse blows, if I pull power at the fuse while it is held it will drop out and does not re fire when the fuse is re installed, it will hold once again at re-rack. I am not terribly familiar with the system 1 board and hoping for a little push in the right direction. Thanks in advance!

Chimes are good and the transistors fire via tab grounding, in testing I found the knocker is also non working but the driver transistor is good as it fires on tab ground. I traced it back to the pre drive IC (sn7417n) on the CPU and get bad readings on both those channels when compared to the neighboring sn7417n so I'll be ordering a replacement (I'm shocked I don't have one in the boneyard).... As for the locking upper target rack it looks like the mps-u45 pre drive transistor is bad as the drive transistor does not lock the rack when the tab is grounded. I am currently trying to find a substitute for the mps-u45 as those bad boys are expensive at $14 each

Well I had high hopes but struck out. I replaced both the SN7417N hex buffers but still cannot get the knocker or 10's chime to work, it seems that my bad readings were due to the chips being on the board which is always a gamble. As stated before when I trigger the transistor tab the coils fire normally. I'm also having the same lockdown issue of the solenoid #8 (upper target bank) after replacing the MPS-u45 with CEN-u45 so I can only assume that the solenoid control A1753CE is bad which is unfortunate because you cant get them anymore. So it looks like I either have to pony up for a new board or hope I can find somebody with a parts board that has a good solenoid control chip. I am guessing that when the battery failed on the board and took out the trace directly below the battery thats when the damage was done to U4.

So..... if anybody has any other ideas or any hosed system 1 boards that has a good A1753CE on it I am interested.

Woz would you have any idea why S8 (Darlington switched) target bank locks on solid but releases when fuse is pulled and reinserted? I've checked relay resistance and the diode which check good, I also replaced the mps-u45 as well. After further reading I came across the spider chip matching article.

Edit: I just rechecked the drive transistors on S1-S4 and they all test identical so it looks to me like a CPU issue, when I looked at the machine all the coils would lock in when the unit was powered on and I had found that the leaky battery had ate away the trace below the battery and I assume that the attempted use of the game in that state is what probably toasted those chip outputs. Unfortunately my repairs were not enough to reverse the damage already done.

I have not and my driver board is in perfect shape, I may look into moving that driver board into my Buck Rogers and see if it exhibits the same issue.

I bit the bullet and ordered a ni-wumpf for my Buck Rogers and I just got done moving the system 1 board out of Buck Rogers and into Sinbad which brought it back to life 100%. Until the new board gets here I moved the Sinbad board into Buck Rogers and the game functions ala no 10's sound or knocker and the High Score reads as "tb t" just as it did when in Sinbad. I'll keep the gimpy board around for testing and for donor parts which is not a bad idea.

Woz, as it turns out the large transistor was bad and I just happened to have one in the boneyard so the driver board is cleared for duty once again.