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Christ knows how you get to the bottom of these repairs! Quite a skill 👌

Great efforts again Bob and a nice post to read about .

Just recently I've had a fair bit of PC92 work coming in and with lots of new avenues I've never been down before. As always I love a challenge with a tech that I thought I knew all about but obviously didn't. As most folks are aware the Procon tech morphed from the early PCL right up to quite a few versions of PC92 and the multitude of mods inbetween is extensive! It's well known that no documentation for PC92 exists in the wild (although I bet someone is hanging on to a copy!) so the only thing to do is to try and capture all the differences and get them documented. I have collated most, but certainly not all, the differences between the released diagrams and the later versions. These I will upload soon once they are double checked. Most functions are easy to work out but I have found there are some tricky ones. The first one I came across was Theme Park which on the bench would always fire up a stake % key error (402). This could be bypassed by activating certain switch connections on the matrix. I was expecting the normal stake key board to be fitted but on the machine in question there wasn't one? This issue is still outstanding but I'm sure there's a silly reason why the key isn't fitted? The second one involves Chico and this one had me going for a bit. This game has a 4x20 VFD but it's not driven off of the VFD port on the board, maybe it wasn't fast enough, cleverer folks than me on here will probably know. In this case the VFD is driven from the 14 way DIL socket which has a feed from the SIO chip. Another thing to note is the VFD gets its 5v supply from a separate Display PSU board which is powered from a 12v feed from the same 14 way socket. This little board also has a transistor on it which reduces the 20v P2P waveform to TTL levels for the VFD. I have to say all credit goes to Magik as this was all gleaned from a PC92 video he did about a year ago where he came across this for the first time. Had his head scratching too. I will post the diagram for this board shortly. Another thing with the 14 way is it needs a link between pins 3 - 13.

Hi gang. Has anyone got a 38mm diameter Bell fruit reel washer that they could spare please? I've stripped down the reels and one of the washers has the tab that locks into the shaft missing 😞

Will do. Cheers

And don't forget to regrease the reel motor. I think you'll find that the original grease has gone (off, hard etc.)

Many thanks Ron. The 3rd reel is a bit stiff to turn. It's making the motor labour. The solenoids seem.fine, but I'll give them a clean whilst I'm at it. I'll try stripping down the reels. Thanks for the pics and the heads up on the type of oil. I'm slightly apprehensive taking stuff apart that's 45 years old - not much choice now

If it's a solenoid sticking then the plunger and the inner sleeve of the solenoid will need cleaning but no oil needed, Check the small hole in the top of the solenoid is clear and not blocked.. Also check the lift arm which is attached to the reel solenoid plunger via a metal link, It has a brass bush and secured to the shaft with a metal clip, you can remove it and apply a small amount of grease to the shaft then refit the lift arm as it needs to be free and not sticking.... If it's the reel drum sticking then it will probably need a reel strip down. Each reel has a clutch which grips the reel drum to spin or nudge the reels, it also slips to reduce the torque on the reel motor allowing it to turn freely when the reels are held in position. The clutches are made of a leather disc which is normally soaked in oil, I use Neatsfoot oil for leather, They dry out over time and causes the reels to stick or slow to start or not spin at all. I soak clutch washers in a jar with oil for at a good 24 hours, the longer the better to allow the leather to soak up the oil, When you rebuild the reel mech, you do not need to refit the clutch washers dripping in oil but dab off the excess. Also while the reels are stripped apply a thin covering of grease to the main reel drive shaft which will lubricate the reel drum bushes so they spin freely too.

Can anyone please point me towards some hints/tips on servicing the reels on my Bell Fruit Black Box Upstairs Downstairs please? One of the reels has gone a bit sticky and I would like to service it. Is there a specific grease or oil to use? Does it just need cleaning? Cheers, Pete

Cool machine!

Yes tried another ls08 in a socket, was thinking IC23 I wish I knew for sure it was a switch issue, will look at the pinpoints for the 138 and maybe probe it for stuck outputs ? thanks Ronnie

I don't think there's even a RESET, it's a two wire serial link! I need to set this all up on the bench but 4x20 VFD's cost about £100 a pop!! I've bought an LCD with a serial i/f and will have a tinker with that. Whether it'll do anything or not I've no idea yet but the learning curve will be of value.

Did you not try a new LS08? (always put a socket in ) Lets hope the PIA is OK, it goes via the LS138 (IC23) first anyway. You can always scope the outputs from the 08 chip to see if all is well there. You could have shorted/leaking diodes too. Luckily yours are all separate and not in those horrible 8 way blocks! Both IC33/34 can also be responsible for weird switch issues but easy to check out with a scope.

I removed the Ls08 and tested it in my programmer, it passed the vector test, not sure if this is a conclusive test? The resistor I replaced did not burn again, if this IC is ok could it have damaged the PIA? I wish I knew what the error code meant. Thanks Ronnie

Awesome... save some pc92s for the rest of us 😅 Yeah see that is strange as Chico is in the cabinet before the front opener? So if thats got the bacta keys but they're not in the later Theme park... could have been some loom pillaging going on at some point with the TP. That does sound like a ball ache... magik is way better on displays than me. How many wires going from the little display board to the display... the usual +V GND Reset Sclk and data?Recently had a ball ache with some 5v vfds myself stopping an m1 machine from booting. Not something like a hole in the Fet? The main problem is you can't really find other parts to swap that so gotta probe it all out.

Thanks bob I’m suspecting the ls08 I guess I could probe it but may as well just change it

That output through the burnt resistor is part of the switch matrix, it that's not working right you'll get all funny things happening with the switches.

Not quite yet. We go off on a bit of a tangent here so bear with me.... I'm also trying to get my head round Chico the bandit. Again no info but have been following Magiks superb vids on Youtube. This does have a stake key fitted and that might shed some light but meanwhile this one has a few funnies of its own. A large 4x20 VFD that doesn't connect to the VFD socket, yep you heard that correctly? It actually connects to the 14 way DIL socket as a serial interface. Not only that it has it's own little display PSU board. I'm trying to get all the info on this so I can get it documented as I know it caught Magik out when he encountered it. So at present lots of head scratching and wire tracing to be done. Will update when I have more info.

Any joy with it Bob?

So I removed the burnt resistor, the diode checks out ok, I test fitted the board, the alpha is back, it reports error 4.0 unexpected PO, I suspect it was doing this before I could see the alpha and again pressing any button resets the machine, away to look at error codes, maybe fit a resistor back and see what happens? EDIT new resistor fitted, no change

Thanks Adrew, will check that diode, will that senario likely have killed the LS08?

the burnt one will be the same as the other 3, 47 ohms, check the zener diode, it's 4.7v the same as the other 3, this damage happens when someone connects a switch up incorrectly and sends 34v from the lamps up the switch matrix! so check the switches are wired correctly and not transposed with a lamp connection!

It may have taken the 74LS08 with it so you may have to do both. As to a cause, not really sure, maybe a short to 5v or 0v back in the loom or switches? I've had a few in recently suffering weird intermittent faults due to corrosion getting in to the cart socket. No amount of cleaning made a solid repair so they had to be swapped out which is a real pain!

Thanks bob not at all, all advice is welcome especially from you, I have ran 7 jumper wires already but component side! Still about 3 to do. I will look at what you Mentioned tomorrow any idea of the fried resistor bob? cheers Ronnie