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Thanks that would be great

Will have a look tomorrow should have some

Good evening. Thank you so much for all the details.

I can't remember what the resistance is of the volume control pot but at maximum volume you will have approximately 60 Ohms load so half the power will be dissipated in the 27 Ohm resistor. I think the 10 Ohm is to stop the sound being turned off completely.

Hi everyone I looking for a display for Maygay epoch ,part no 16LF01UA4 rev B,if anyone has one for sale ,thanks in advance

Hello Thanks for the clarification, Bob. Your help is invaluable. I'll look into that. On another note, I have some questions about the volume control board. I've looked at the schematic and I see a 27-ohm resistor! It's original; not modified. Is this resistor related to the 30-ohm resistor of the speaker? And a photo of the series connection would be helpful. Thanks

Some extra info.... The game sounds and alarms originate from IC2 so should appear on IC19 pin 2. The reel alarm should be approx 1.5KHz but I have found that not all games will alarm without the green plug in??? In that case you might need to generate an alarm in a different way. Ordinary switch bleeps (not sure how that will translate) come from IC3 and they are approx 750Hz. IC19 pin 1. All waveforms are squarewave of course. Hope that's useful.

Don't think there was a pc92 game card as the rom mounted to the mpu. I have a sound prom card somewhere buried deep in the boxes of fruity stuff from a bullseye I scrapped.

It depends on what sounds are being generated. This isn't very helpful I know but as you have no sound at all it shouldn't matter. What you could try is to disconnect the green plug then switch on as this will generate an alarm. Then you can check all those outputs from the two chips to see which one (if any) has a waveform on it. If you can't find anything I'll set it up here and let you know for sure which chip sends the alarm tone. Putting two speakers in series is a good idea, just make sure you put them in phase.

Good evening. I need your opinion on a 30-ohm speaker. Since I can't find one, I was thinking of buying two 16-ohm speakers and connecting them in series, which would give me 32 ohms. It's also a question of price: €15 for the pair. What do you think? Regarding the sound itself, with an oscilloscope, should I find a signal on IC19 pins 1, 9, 10, and 13? Or not? Bob mentioned that it came from IC2 and IC3. Am I right or completely wrong? Have a good evening. Many thanks.

hello and welcome sean

Sorry Jimxxx; the translation isn't working properly. I don't understand. Also, you told me to remove a wire; I did, but I didn't realize it. There are times when I deserve a slap. Thanks

Dodgy French switches that is 🤣🤣

Welcome Sean Just up the road from myself(Wigan).

Hello gentlemen. Well, once again, I must apologize profusely. Unbelievable. In the photo, you can see three switches; something should have caught my attention; what? The color of the middle one is black; unlike the others. I took it apart twice; tested it twice: open, closed; closed, open... OK. They are all connected the same way. So, it didn't seem strange to me. Besides, on the schematic, you can clearly see they are open. But even stranger, I didn't change that. So, with the T56 error (see above) and now the switch, I expect more surprises. And I will have some, on the tube matrix, for example, and surely others... Luckily, you're here. To point out my mistakes. Sorry again. HOLD issue fixed. The tube and sound issues remain. Thank you for your help.

They should be normally open (NO) not closed. Maybe it's a translation thing? Mind you if you disconnected the wire it would have showed.

Welcome Sean, Great machines you've listed there, and I think we would all love to own at least one of those. 2p machines from that era, are very rare, and command a high price. There are a few members on here, that might point you in the right direction, of trying to find a good 80's machine. Well, from Chorley, you have Red Rose, plus Retro Fruits / Reel Fruits in Blackpool. I've only been to retro fruits, and I could spend a week in there, very easily. I was local (Liverpool), but currently living in Celina Ohio. I've got 2 machines over here. a Duff Beer Guide and a Big Brother. I'd like to have some 10 JPM machines such as Impulse, Roller Coaster, Monopoly, but the cost of shipping and now tariffs, is not an option currently. Welcome to the forums, we are a pretty relaxed crowd here. Regards Statto

Hi all, I’m new on this forum although I have had a passion for old 1980’s mpu3 machines for a long time I used to work for Nobles back in the late 1980’s and before then I spent a lot of my pocket money in the arcades of Primrose Valley as we lived close by, Filey and Scarborough. I would love to own a classic machine or 2 but they seem to be super rare now and very collectable and therefore cost a fair bit. My dream machine would be something of the big shot / circle skill / razzle dazzle era or perhaps a fruit preserve. I did love the old 2p machines as well - copperwin, blue streak etc I am looking at retiring from teaching soon and would love to treat myself with some of my retirement pot Until then it’s enjoying a few retro arcades - I live near Preston so I’ve been to Red Rose a few times and playing the emulator I would love to hear from any other local enthusiasts - I’m based in Chorley Sean

Hello. My studs are made of metal; what a shame. They'll stay that way; they're well insulated now. Yes, the push-button switch isn't stuck; that's the first thing I checked. I'll double-check this whole area before replacing IC4. As Bob said, it's not easy to do inside the cabinet. jjmXXX; it's a normally closed (NC) contact; if I disconnect a wire, it's the opposite. Thank you for following this adventure.

Does it still do it if you disconnect a wire from the back of the switch?

Those studs are made of plastic (or they should be) so they won't need insulating? The only metal ones are the two fixing the board to the chassis and two holding the ROM cart holder. Before replacing IC4 I would check if any other switches on the same line are working. I would also find out exactly which one it's on (9 or 10) then see what switch it is on the black connector and also the DIL switches. If you can find what they do it will be easy to check that IC4 is OK. You could put the scope on it and see if there's a waveform going in to IC22. With no switches operated there shouldn't be. Are you sure the switch isn't stuck on?

aup

More to come, if you don't mind... My display was completely malfunctioning. But after cleaning and lubricating all the connectors, it's back to normal. (I used brake cleaner and a very small amount of silicone lubricant.) It's probably also because I properly insulated the PCB's mounting points. This prevents short circuits. As you can see in the photos, I used two layers of heat-shrink tubing. I had already done this on the first MPU, but on this one, I had to double it up. Overall, it works; the hold function and sound are still an issue. Plus a few other minor things here and there. Thanks Have a good weekend. Sorry, I can't seem to reduce the video size. Afficheur qui délire.mp4

Good evening. I'm just giving an update. Regarding the stuck HOLD switch, I replaced the 4049 chip, but it didn't fix the problem. I tested all the diodes in the matrix; they're OK. The capacitor bank is OK. This switch is either on position 9 or 10. I'm going to retest this entire area. Otherwise, I might have to replace IC4. Hold coincé.mp4

Hello No, I can confirm, the coil is broken. I searched online, and 30 ohms is unknown. Well, maybe with some adaptation... Or, I could have it rebuilt. But the price won't be good, that's for sure. Thanks