Leaderboard

A quick update, i thought i had got rid of this strange reset issue but alas i had not (well i have now). So running on the golden nudge it cart, 9 times out of ten when you got nudges it would work, however with its own nippy nudger cart it rarely would, normal gameplay fine but as soon as you nudged it would reset. Wiring between the two carts slightly different as it uses different lamp outputs for nudge feature and the coin lockout and one of the meters are swapped. Anyway by total accident i realised it was only when the four lamps in the nudge panel were flashing and you nudged it would reset, take the lamps out and it would be fine, now psu is ok all recapped and new regulator, 5.1v very steady but a 0.4v drop on the 15v (15.2v) when lamps flashing. I was only getting 8.6v across the 9.1v zener but that could well be within tolerance. At this point i cheated a little as the only 9.1v zener i have is a stud mount diode so i put an 8.2v zener in (i do recall Barcrest released some notes on MPU3 about changing the zener on low voltage sites, not that mine is low). It works fine now every time. So maybe it is an iffy zener transistor or resistor on the voltage sense circuit (i dont care now it works)

Whoooo - oooo - ooo 👻 Better (absurdly) late than never! Incoming shortly. (Probably not worth the wait lol)

Still not here yet! hoping in the next few weeks

Hello experts So, Bob is right. I installed the wrong component: T56. 🙄 I was really incompetent. This board has already been repaired, and the previous owner installed the wrong component, BC172. I always check the component and the schematic; and on the schematic, it's a BC172. Hence the mistake. Now it starts; yes; Bingo! 🙂 😀 Thank you; thank you again. But, well, there are some problems: The sound; I'm going to replace T11. The display is acting up a bit. One scroll bar is stuck in HOLD mode. And others... I'm going to check the connectors, the soldering, etc. Thank you very much.

OK, the first thing is this is probably a MOD 2 board being as it has a 74LS03 as IC24. The output is now on pin 11. Does it come out of RESET? On switch on it should stay LOW for about 1 second then go HIGH. Do you have the correct RAM fitted, it takes the smaller RAM (in Bytes) 256x4. HM6561 or equivalent. Because of this it won't run later games. T62 doesn't appear in this revision of the board as it has a thyristor (T56) in the RESET circuit.

Hello everyone. I'm back for a short month. Maybe enough time to repair my second MPU3, if anyone would be willing to help. It won't start. I've replaced the capacitors around the regulator. The 104 capacitors on the MPU, the RAM (NOS), and the transistors in the reset area. (By the way, I don't know where T62 is on the schematic.) So, here are my readings based on what I've read about the MPU3 and my recent experience getting help from Midibob. IC24 74LS03, yes, new. IC10 Pin 3 - 561 Hz square wave. IC18 Pin 12 - 100 Hz R83-84-85-D43-C39 100 Hz R68 and R69 OK C32 and C34 OK IC24 Pin 8: I can't find 2 Hz; nothing. IC9 Pins 10 to 15: only high levels (logic probe). All components in this area have been tested or replaced if suspected. D44 and D45 are also new. No corrosion on the RAM sockets or underneath. Cartridge port is also free. Ah yes, the 5V is at 5.2V. The circled area contains all components that have been tested or are new. So, if you have any ideas where to look, I'm all ears. And whatever happens, we won't throw ourselves into the Thames. :)) Thanks in advance.

Wow! Just seen this. What an absolute gem of a machine. Good luck - would be lovely to see the old girl in action.

For the sound it's worth checking that you're seeing the 15v on the collector of T11, if you haven't already. IC3 only delivers the basic sound bleeps, the main sounds come from IC2. Not sure which one supplies the error sounds? For the Hold button it's possibly one of the associated diodes in the switch matrix unless it's affecting other switches you may not have noticed yet. In that case it could be IC22 or one of the caps C24-28 going short. It's quite easy to fault.

As they say... the end justifies the means.

No, the congratulations are for you, the experts. I'll try to find the right diagram. Thank you. To be continued.

There are three different types of RESET circuit. There is pic of them in the downloads area somewhere and they are all different. Felicitations Lamiral.

You'll tell me; look at your first repaired MPU. !!! Make some comparisons. It's back in its machine and working perfectly thanks to you. I don't want to touch it anymore. Okay, I'm going to investigate my problems. Thanks

T56 should be a thyristor? 2N5061 or 2N5060 at least that's what should have been removed. You had better check!

Good evening, everyone. Thank you for taking an interest in my problem. So, T56 = BC172 (new) As are T57, T58, T59, and T60 (BC172) (new) T61 = ZTX510 (new) I'm going to do some checks, track checks and others. Thanks; have a good evening.

Good Morning, Reset line is on pin 34 of all the 6821`s and a few other places, also easier is the test pin above the power socket, see pic. Connect your logic probe, turn it on and report back what happens. 👍

Classic 777 Heavens graphic layout will be released later this month. Forum member, Thompy, has been supplying me high quality images and technical assistance from his own machine over the last couple of years, just recently he has supplied vital lamp numbers so the emulation can be released with almost 100% accuracy. . 'Thompy' also supplied video and sound of the pull handle mechanism from his actual machine and thanks to our late, great, mfme author, Chris, it is now incorporated into mfme. J