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cyberbob

MPU4 Motherboard Repair WELL ATTEMPT

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13 hours ago, Cyber Bob said:

There back................Thanks @Andrew96_  Thanks for undoing my mess & can imagine and i knowi left a few problems 

Ill get them open & refit 1, in potluck, ill test very slowly this time :)  update soon :) 

At least i can try to learn from your repairs, learn not to attempt them :) 

so happy, PL is going to be running again right, it failed btw the other day again. 

 

 

 

 

Nice one rich glad you have them back .should last a good while now 

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1 hour ago, sulzerned said:

Nice one rich glad you have them back .should last a good while now 

am sure they will :)  out live me now lol 

 

Edited by Cyber Bob

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with any stuck lamps first thing to check is the transistors 

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@Andrew96_ sorted the tracks, replaced various transistors, & shes alive alive,  This one was holding the 10p solenoid & fried the last one. My fault wrong fuses fitted all quick blow now as i ordered some.  nice neat track repairs, and painted green :) even fly leaded for me so i don't need to stick the soldering iron near it :) cheers 

 I only fitted the volume pot to this one thanks to @fruit58

BOARD 2 

FAULT LOUD SOUND NO SOUND.

Volume adjust pot broken

No Other Faults found.......................................... 

Tested on 4 Reel Machine, 2 LED SEGS with fair size bulb matrix. 
1,00 50p 20p 10p tested, ok acceptance. payout ok

NOTES.......................After rep[air.

Replaced Volume pot now working correctly 
Replaced 8 Caps as a couple broke when giving wiggle test......


Powered up again, worked still  but all 3 12v 34v 46v was connected
this is the board fried the 10p soleniod

6.jpg

7.jpg

8.jpg

9.jpg

10.jpg

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2 hours ago, fruit58 said:

with any stuck lamps first thing to check is the transistors 

I should have said I have replaced all 16 lamp drives as I was getting inconsistent readings from several of them.I had also replaced IC14, the ULN2803 as that chip was driving the drives that were having the most issues. I have since noticed that they do turn off at reset but come back on in a second.

Looking at all 32 lamps that are stuck on now, they are all driven from the green connector.

Green 1, T37, IC14 pin 11, IC3 Port A7

Green 2 T36, IC14 pin 12, IC3 Port A6

Green 13, T26, IC13 pin 14, IC3 Port B5

Green 15, T24, IC13 pin 16, IC3 Port B3

So I am thinking when the PIA is reset and then told to switch the ports to outputs is when the faulty drive is set and the lamps driven full on.

So I am going to replace IC3, the 6821 next.

 

Edited by quattrohead
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Well that's that, Thank you again @Andrew96_

Last 2 tested in Stock The Clock.  

All 3 now resurrected, just hope i didn't cause to many problems with them.   

Well that was the MPU4 Repair attempt Thread,  I hope you do get something from it, a lot to read but some very interesting helpful comments, 

Big thanks to everyone that helped with the repair. 

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Hi there I'm having a go at repairing an mpu4/mod4.

I did my best to select some replacement zener diodes.

Does anyone know if these are ok?

1N5236B ZENER DIODE, 500mW, 7.5V, DO-35; Zener V

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BZY88C4V7 they basically clamp the voltage across them to 4.7v and are connected across the outputs of the driver chip IC8 6821, this is to protect the chip to clamp any spikes to 4.7v so they don't find there way back to damaging the chip outputs.

Edited by Andrew96_
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Ok Thanks!

I've got one last question then I'm hoping to get one of these repaired on my own. Obviously tried to work this out myself.

There's a pair of inverting buffer IC:

MC14049bcp 

Are these ok as a replacement. Just want to double check before I fit any?

CD4049UBE . INVERTING BUFFER, HEX, 4000 CMOS, 16DIP

huge thanks for any help

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Hi Guys.

Sorry to jump on your thread but I'm on topic.

I'm just gathering some parts to refurb my own Mod2 board.

Can i ask a favour please, can someone confirm i have found the right bits so far.

C9-C16 ; 1000pf 100V X7R

https://www.ebay.co.uk/itm/113909598172

T12-T19 ; BC338-40

https://www.ebay.co.uk/itm/202817337000

ZD22-ZD33 ; BZY88 C4V7

https://www.ebay.co.uk/itm/312048126817

 

These Resistors i am less sure about.

Are Metal Film ok? All From the same seller. Are they all 0.5W ?

R83-R86 ; 47 ohm 0.5W ???

https://www.ebay.co.uk/itm/383075899165

R87-R94 ; 33 ohm 0.5W

R95-R102 ; 1k ohm 0.5W ???

R103-R110 100 ohm 0.5W

C47 ?? I can't work this one out

Think thats a good start. Any others i will definately need please let me know.

Thanks for your help

Paul

 

 

 

 

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36 minutes ago, Andrew96_ said:

have a look on RS, so much cheaper than ebay, AND no P & P!

 

https://uk.rs-online.com/web/

Hi Andrew.

I have looked on there.

Agree some are cheaper.

Some not so.

But as an example, these resistors are cheaper, but are metal oxide suitable?

https://uk.rs-online.com/mobile/p/through-hole-fixed-resistors/1870802/

It's because i only want to buy smaller quantities its going to cost me more per unit.

Once someone has confirmed i am looking at the right parts i can shop a little harder to get the prices down a bit.

 

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14 minutes ago, Andrew96_ said:

Why?

Because i imagine the answers might help others too, and they might not see them here on a repair thread.

 

 

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