Zaccaria invaders control

[Body pop]

I read a couple posts up that it should be germanium diodes. If that's the case, BAT85 diodes might work as well and are probably easier to find.

Would these be the type of thing you'd find
In maplin ?

 

[obcd]

We usually shop at Farnell or RS components for our components. Very common switching diodes are the 1N4148 or 1N914, but those have a 0.7V treshold. The BAT85 has a much lower treshold voltage. geranium diodes also had a 0.2 - 0.3V treshold.

 

[Body pop]

Thanks very much
Had a look on farnell website
They list a few different bt85 diodes
Is there anyone in particular to order

 

[obcd]

You don't want to order some smd's and you don't need a reel with 10000 I assume. This already limits the choice a little.

If you remove the defective diode, do the rest of the controls work as expected?

If that's not the case, fitting the new diode won't fix it either. Is it possible that the coin switch is wrongly connected to the normal closed contact. It should measure open when there is no coin passing.

 

[PaulSwan]

I use 1N4148's (per original spec) - the inputs are CMOS.
Paul.

 

[obcd]

In the fifth post, RGP said that the diodes should be germanium types.

That's why I brought up the BAT85. It's a shottkey diode with a low threshold voltage.

(Germanium diodes also have a lower threshold compared to normal Si diodes like the 1N4148)

 

[Body pop]

You don't want to order some smd's and you don't need a reel with 10000 I assume. This already limits the choice a little.

If you remove the defective diode, do the rest of the controls work as expected?

If that's not the case, fitting the new diode won't fix it either. Is it possible that the coin switch is wrongly connected to the normal closed contact. It should measure open when there is no coin passing.

 

Yeah removed it and control issue is the same

Yes def possible that it's wired wrong
There were four wires off , and I connected them to where it seems they go on the diagram they were all off the micro switches

 

[RGP]

In the fifth post, RGP said that the diodes should be germanium types.

That's why I brought up the BAT85. It's a shottkey diode with a low threshold voltage.

(Germanium diodes also have a lower threshold compared to normal Si diodes like the 1N4148)

Sorry, I just remember being advised to get germanium ones but it was nearly 3 years ago, if Paul's using 1n4148's with no issues then its fine.

I "think" they are just blocking the other signal so they don't ghost on the inputs on the CPU, if Nad (Equites) is reading, he'd be able to advise better as he helped me sort out mine along with others but he also repaired the PCB as it was just streaming garbage out.

 

[RGP]

I use 1N4148's (per original spec) - the inputs are CMOS.
Paul.

Ah, its coming back to me now, at the time I didn't have access to the original manual. So disregard what i've said and put what the manual recommends in - as the maker intended so to speak.

 

[obcd]

The 1N4148 is easier to find (Maplin has them) In case you ordered the BAT85, it should work as well. It's just a small signal switching diode which equals an ideal diode better.

The diodes are needed in case multiple switches are activated at the same time. They block a current path between the 2 switches.

Dipswitches on the board can be part of the multiplexed switch matrix as well.

 

[Body pop]

Nice 1 .thanks again for all the advice
Very helpful

 

[Body pop]

I changed the diode (got the maplin one just )
Still the same as you's predicted
I'm starting to think wires are missing
Would anyone be good enough to put a pic of inside
Coin door .
I tried it with coin mech disconnected at the black
Connector
It was still doing the same

 

[Body pop]

Anyone got any ideas where I could go with this now .
On the wiring diagram ,wires at number 14 and 16 on coin mech connector don't seem to go anywhere ?
They start at the power brick type thing
The micro switches on the mech are wired to open
Diodes all seem to be good