Hi all,
I have been working on a Sinbad. I have done the ground mods and all 3 fuses for the small transformer. The previous owner told me that everything was working fine until a target broke. After that he said about smelling something coming from under the playfield. So this is the first time I have tied to power it up. I have nothing connected in the back box at this point, wanted to get a reading off of the A2J1 plug before I plugged into the power board. At first I started to here some popping sounds after about 15 seconds of power. Checked all of the fuses they are all still good and correct amperage. Powered it on again and now no popping but I started to see smoke from lug 8 on the small power supply. I quickly turned it off, the power supply felt warm after words too. I’m really hoping this isn’t fried I posted some pics of the transformer too. With the connector not being plugged in at A2J1 the circuit should be open with no current, or am I missing something here? If there is a short shouldn’t it take out a fuse first too? Any help is appreciated.
Tanks

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Thanks for the quick response. At the moment I don't even have the anything plugged into the power supply. I know I had to replace some of the diodes when I was replacing the caps on the board if I recall they were listed on Clays repair guide. I'll look at the schematics tonight when I get home. I guess my question is if the circuit isn't complete should it still be heating up like that, or would it mean that there's a short some where between the transformer and the A2J1 plug?

Well I had some more time tonight to look into this. I took the fuse out of the 69 volts and turned it back on. There were no noises or smoke. I checked both sides of the open fuse going to pins 7 and 8 both have continuity (power off). I checked both with ground and the other wires at a2j1 and nothing was crossed between them. It seems the circuit is clean, at least to this point. I don't understand with the fuse in and not plugged into the power supply it should act any different. The only other thing I can think of and this is way outside the box. The target that broke was above the power supply. Even it being plastic is there any chance this could have created a temporary short or anything like that? I did find something that looked melted at the foot of the transformer on the main side, not where the smoke was coming from. I really dont want to but unless I here something I think I'll have my meter all ready connected the the 69 v circuit and turn it on for a quick reading then back off. Any other help or ideas is appreciated.

Thanks for the help. Yeah all of the fusees that I added and the ones that are originally there all checked out good. I'll look at the lug tonight I never thought that could be shorting. As luck has it the lug is on the side up against the side of the cabinet, pain to get to for me. your'e correct about the lug not smoking, it was just coming from that area, I'd say 1/4 inch from it coming from the paper. I did pop out the fuse for the 69 Volts and had no smoke.

Thanks, I was thinking about that too. I'm not by the machine and was trying to think what all would have to be done to take it out. I think for me taking it out would be the better route.

Ok, I'm back and removed the screws holding the board down so I can get a better view of the transformer. I think its fried. I remember some of the diodes on the PS were bad and have been replaced. So now to try and find a replacement, or to have it rewound. Since I now have the added fuses and all original fuses are the current amps, if I replace the transformer is it safe from this happening again?

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I got lucky and found a whole transformer board out of another Sinbad. I'm finishing up with the mods and repining some connectors. I'm hoping to try to start to power it up in a day or 2.

Hi I have seen some posts about displays and thought I would ask this. I thought I read in guides that a bad display could mess up your MPU board. So is there a safe way to test a questionable display? I picked 2 up at a show and they appear ok, 2 dots are still black and filament looks to be not broken in both.
Thanks in advance.

I have started working on a Gottlieb Monte Carlo and hoping for some assistance. The machine wasn’t working when I got it and I’m going through the boards and doing the ground mods. Someone has done some work all ready. There is a Swemmer Daughter board installed, the PS had new header pins put in but still the old trim pot, that’s now been replaced. So I took off the sound board and flipped it over and I see this cap installed. I’m not sure if its factory and I haven’t seen anything talking about adding this to the board. Its on A2 leg 8 and jumps to a main line on the top of the board I think is ground. Looking at the schematics it says there is a .1uf cap going from pin 8 to ground. Can anyone confirm or deny this should be there and if its not supposed to be there any idea why it might be?
The other question I have is where to connect the ground mod to this board? It appears to just remove some green protective coating on the top near a board mount and solder the wire there?
Thanks in advance,
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I did find a pic of the bottom of one of these boards in post #1399 It seems it should be there. I can't believe all the time I spent looking it was here. So now just to confirm the ground mod.

Hi, I’m working on a Gottlieb Monte Carlo. At the moment its not Booting, it wasn’t when I got it. I’m getting a constant Hi at U2 at pin 40 which seems to be what I should be getting. The clock circuit before that is working too. I’m getting no displays just GI lighting I have the solenoid fuse pulled because some of them were locking on also.If I connect the reset board I get the displays to mainly flash 0’s while that's happening U2 pin 40 is pulsing too. The piggyback board was replaced with a Swemmer board. I can’t find anything about that either, it has 4 leds that are all green. I have done the ground mods in bottom cabinet along with the boards. I recapped the Aux PS along with the reset board. Replace the 5v trim pot new pins and connectors on the PS. I’m getting 5.1 volts with nothing hooked up to the PS and 5.08 across C1 with the mpu plugged in. Can any one tell me what to look for next, some sort of system to troube shoot this? I have seen different posts that pretty much say check all the chips. The only thing I know is its not working and at leas 1 signal isn’t doing or getting to where it needs to be, I just don't know where to look.

This is more a follow up to post #2596 I have the mpu board out a Monte Carlo out of the machine and testing it. The main question is should the address lines be pulsing from U2? All of the lines I am reading are all high. From what I have read they should be pulsing. If they are what could be holding them high? I have a clock signal pulsing and pin 40 is high. I have tested other z chips and from what I can tell are ok and match what I have seen others get. I plan on getting an eprom burner and do a test rom in the near future. The piggy back board was replaced with a Swemmer and has 4 leds that are all on green. Any help pointing me in a good direction would be appreciated.

I don't have my manual, but I thought that was only for the sound and voice for attracted mode?

On a side note do you have any issues getting the ball to lock for the left war base? Mine is terrible to get it to stay.

Hi, I have been working on a System 80b MPU out of a Monte Carlo. I have developed a new problem in the beginning wasn't there. The main problem I have is pin 40 on the mpu (reset) shows nothing with a logic probe, if I uses a MM its about 1.7v. I checked pin 5 & 6 on Z4 and both are high, pin 4 is nothing with a logic probe and again 1.7v with a MM. I thought it was the chip and swapped it and I'm getting the same thing, does any one have any ideas? I checked z4 pin 4 to ground for continuity and its open.

I also have a shorted c34 that I replaced and is shorted again. I'm not sure if that is throwing the VB off and affecting the z4 chip, I'll look when I get in tonight.

Hope some one has an idea what could be going on. I did check and all the legs the reset circuit runs has continuity.

I thought I would try and see if anyone might shed some light on what’s going on here. I posted in MGoW thread here (https://pinside.com/pinball/forum/topic/mars-god-of-war-club-n-tech-emporium/page/5#post-6229316) So I am working on a MGoW I have 2 of every board with an extra rotten dog mpu board. I did the sound checks with the sound card and everything checks out. I did the ground mods, repined almost everything and even made a new connector between the mpu and driver board. With one of the original board and the rotten dog I am getting all sounds with the exception of the last sound when the game is over. With the other stock mpu if you beat the high score you and you get the 3 credits it will play the ending sound. If you don’t there is nothing. I’ve been checking continuity with all of the sounds and everything seems fine. I don’t know what triggers the ending sound and what sound lines it uses. I also got the test rom and I have tested 1 board with everything except when I need the switch installed, the switch is coming tested fine. I just don’t understand how all of the other sounds are there and correct why this one there is nothing. Hoping for help.