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Mpu3 frustration!


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Evening all,

I have been sorting out my Royal Exchange clubber I’ve the first week of this lockdown! Been doing a few bits to it, first of all the mpu was replaced with a working board, super it fired straight into life, playing it for a few days, with no issues, except reel 1 and 2 were very noisy. I thought I would quickly change the motors from my spares, all went back together and here is where the issues started.

I keep getting a reel A fault, I’ve swapped changed sensors etc. Moved 1 to 2 etc, cleaned all of the plugs, all of the usual. And I continue to keep getting the same fault. If I leave the reels unplugged I still get the same fault.

Has anyone got any ideas of what I can do next please. As it is driving me nuts!

Cheers for any help. 👍

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1 minute ago, riche100 said:

clear the ram of the machine, as it might be remembering the fault 

 

if it doesnt help sorry , just a idea 

 

keep at it 

 

 

Yep that makes sense Rich, I will try that! I have reseated the leads probably 25 times so far 😂😂 bloody things!

But I will give the ram clear a crack! Thanks for the advice 👍

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It is not unknown for previously ok sensors to go faulty, the opto receivers fail like there is no tomorrow these days when pressed into service!! It could be if the motors are now noisy with this board that a motor drive transistors has gone so the mpu is expecting to see a opto pulse at a set time and it doesn’t!! Or perhaps the mpu you have put in has a opto fault

check the lamps on each reel lights and shines through the hole in each reel, and as rich says the plugs!!!!!

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2 hours ago, Andrew96_ said:

It is not unknown for previously ok sensors to go faulty, the opto receivers fail like there is no tomorrow these days when pressed into service!! It could be if the motors are now noisy with this board that a motor drive transistors has gone so the mpu is expecting to see a opto pulse at a set time and it doesn’t!! Or perhaps the mpu you have put in has a opto fault

check the lamps on each reel lights and shines through the hole in each reel, and as rich says the plugs!!!!!

Yes I have checked all the options Lights Andrew, and they are all lit. I Assume I am not missing something here! The board was working fine when I took the reels out. 🤔

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4 minutes ago, MikeB said:

Yes I have checked all the options Lights Andrew, and they are all lit. I Assume I am not missing something here! The board was working fine when I took the reels out. 🤔

Have you tryed another deck from a know working Mpu3 ? Just to see if it’s a deck the problem or leads / board etc .. 

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Now that's weird,getting fault with reels not connected.so that tells me it's not a reel fault.can you try this board in another machine or try another mpu4  in the problem machine.its all a case of trial and error and narrowing it down to find the fault

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It's not just the red and green leads.

I'd unplug all the small green leads on the reel driver board too.

Spray contact cleaner into the end of each lead.

And at each end for the red and Green big leads.

the opto lights should light up when spinning.

If one stays on,that where the problem is!

This fault is usually only a bad contact.

The reel opto lights should remain off when

stationary.

If you move a reel by hand then it will flicker on.

That will tell you that one works ok.

I have to do this with all my mpu3s every few months.

They run pretty sweet now.

Maybe a run over those pins with a fibre pencil may

also rectify this.

Hope you sort it Mike.

 

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4 hours ago, MikeB said:

Cheers chaps, I have got plenty to be trying now. As always some solutions there that will hopefully get her up and running 👍

Pretty sure you will sort it.As Chris said it's more than likely a bad connection.its just finding it.Also get a torch and look straight into the female side of the plug,the metal contacts in those when old can squash down and no longer brush the pins they push onto.I had this with warlord,it would work,then it went wappy displaying odd segments on displays and either losing or not playing with credit,this was down to the female connector on the mpu board where it slides in and out of machine and connects to a PCB in rear of unit.since replacing that socket,about a 12 way I think it's been fine.

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Mike I've had this fault many time s with mpu3 reel decks ..changing sensors is easy but when changing the motors the new ones have to be lined up properly. I would refer to the mpu3 reel assembly manual In the  downloads  section. They literally have to be lined up exactly right or the deck wont spin without alarming .midi bob has found this to be the case last year .those decks are really quite reliable usually but just super fussy on.the opto/motor set up .

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5 hours ago, Line Up Chris said:

Did you manage to sort this Mike.?

Always good news when another mpu3

machine is resurrected 

 

No I haven’t revisited this for a few days, I have been painting the outside of the house! And that is taking up my time! Unfortunately.

I will be back on it and will report back definitely! There are a lot of good suggestions to try 👍

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Check the resistor pack thats connected across the reel opto inputs on the board.

You will get reel A fault with no reels connected !  with nothing plugged in all reels will appear to be jammed. 

If all the reels are spinning normally and your getting reel A fault, look in the back of the machine and see if you can see the reel opto lamps ( early cabs actually had incandescant bulbs for the light source in the opto sensors) lighting up. Sometimes they can die.  If a reel is shuddering or not moving its more likely to be a drive transistor or one of the  ICs buffering the reels (74LS04s, ICs 12 to 15)

 

if the reels are running, and you can confirm that its not the reel backboard at fault as it has a bunch of resistors on board that can fail, then you are looking at replacing T55 , and then checking IC17, the 74ls138 controlling the opto sensor select, is working.

if thats working then you look for pulses on pins 10 -14 of IC5, the 6821 thats interfacing the optos to the cpu.  One of the pins will always be stuck as no reel connected to it ( 4 reel machine)  but 4 of them should slow pulse as the reels go through the optos.  Every time the hole in the reel passes the opto sensor it should pulse ( I think it goes LO to HI briefly but that could be the other way around, to put simply you should see 4 pins pulse when 4 reels moving , if 2 are stuck then thats your problem!)

Also change the smoothing caps on the regulator board because bad caps can cause reel jitter and cause the reel to be in the wrong position when the CPU looks for the optos.

 

 

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Reflow solder on the plugs for red and green also, they easily crack. And look in the plugs both sides make sure youve not got a broken pin the leads are getting on for 40 years old!

 

 

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I have been back on this today.

Christ it’s so frustrating, so to recap I changed the Motors on reel A and B. When put back on the machine I would get a continuous reel A fault. I have every suggestion above, I needed to discount the board being faulty so I took the reel set out of my sweepstake, and it worked first time, so obviously a fault with the reel deck.

I checked that the leds were lit, and the reels would go right through the process, and would only fault after the spin on initialisation, up until that point everything worked. So in desperation I thought I would put the original motor back on reel A, I ran some light lubricant down the spindle shaft as this was extremely noisy, and bolted the reel deck back together. Fired up the machine and let w and behold I got a reel B fault! 🙃, so the same process again,stripped down reel B motor and put the original back on. Fired up the machine and off she went, into attract.

I have just been playing it for about an hour and it’s running fine, and the noises have all gone. 👍

Quite annoying really, could both of the replacement motors have been faulty, well yes I suppose. I am going to rebuild the reel deck that they came from, and see if that works. 

Live and learn as always!

 

 

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Great result mike .not sure if you had two faulty motors which I would say was very very unlikely .more like they just needed putting into position exactly right but the lubricant certainly helps with excessive noise .

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4 minutes ago, Andrew96_ said:

that's great!!! hopefully WD40 NOT used!!! 😁

No Andrew, I don’t use that shite, only professional goods! Hell.

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15 minutes ago, sulzerned said:

Great result mike .not sure if you had two faulty motors which I would say was very very unlikely .more like they just needed putting into position exactly right but the lubricant certainly helps with excessive noise .

It could well of been Nick, I did mark the plates, before removing the first time, it was odd how it went from reel A fault, to reel B. Bloody mind bending sometimes!

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1 hour ago, MikeB said:

I have been back on this today.

Christ it’s so frustrating, so to recap I changed the Motors on reel A and B. When put back on the machine I would get a continuous reel A fault. I have every suggestion above, I needed to discount the board being faulty so I took the reel set out of my sweepstake, and it worked first time, so obviously a fault with the reel deck.

I checked that the leds were lit, and the reels would go right through the process, and would only fault after the spin on initialisation, up until that point everything worked. So in desperation I thought I would put the original motor back on reel A, I ran some light lubricant down the spindle shaft as this was extremely noisy, and bolted the reel deck back together. Fired up the machine and let w and behold I got a reel B fault! 🙃, so the same process again,stripped down reel B motor and put the original back on. Fired up the machine and off she went, into attract.

I have just been playing it for about an hour and it’s running fine, and the noises have all gone. 👍

Quite annoying really, could both of the replacement motors have been faulty, well yes I suppose. I am going to rebuild the reel deck that they came from, and see if that works. 

Live and learn as always!

 

 

if you want a complete mpu3 reel deck anypoint, gimme a shout mike, ive got a few laying about 

 

well done for sorting your machine 

 

happy days 

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Cheers Rich, it was a pain! And I will keep that in mind about the reel decks, I have several Mpu3 machines now! No doubt that would come in handy! Thanks.

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