Rock Ola 477 Max Display/Write in issues

[smailskid]

Working on a Rockola 477 Max.  Some background....I have a manual and have used it as part of my trouble shooting  process.  I have checked the power supply and have 9.6v.  The logic board tests good per the procedure in the manual.  Otherwise the machine was unresponsive in normal operation settings.


I acquired a NOS profit setter from Victory glass which has helped quite a bit but I am still having an issue.


The profit setter seems to be working properly when put through different tests in the manual. The displays also to appear to be working but the keyboard does not seem to be working. I cannot make a selection, reset a selection, or register any number button push with the keyboard (I can add credits via the profit setter, but this issue persists after credits are added or when in free play.) 

I inspected the keyboard buttons, reflowed the keyboard PCB and checked the wiring between the keyboard PCB and the profit setter. All checked out ok. 


Is this a "Write In" issue?  Any ideas where to investigate?

Thanks for any help.

[jukenorman]

The NOS profit setter you got, was it guaranteed working? The keyboard switches are operated via a switch matrix - there are eleven strobed outputs (D lines) and they are monitored via four K lines. I have taken that from some notes I made about eight years and I'm not certain that I've read my notes totally correctly. Do you have the large fold out schematic? Do you also have something like an oscilloscope or a logic probe that you could use to check these matrix lines?

Norman.

[smailskid]

Hi Norman. The profit setter was tested and sold as working.

I have a manual that has all the schematics and I have a logic probe.

Looking at the schematic your notes look like they are correct.

I will check the matrix lines and report back.

Thanks

Ted

[smailskid]

Both K1 (pin 5 on IC702) and D11 (pin 9 on IC706) are strobing…… and are unchanged….. when keyboard button one is pushed (as shown in schematic) with credits on the machine

Would like to include a part of the schematic to make it easier to understand but I am not sure how to download or attach a photo…..

[jukeboxmarty]

Dec 9, 2023 18:45:22 GMT smailskid said:

Would like to include a part of the schematic to make it easier to understand but I am not sure how to download or attach a photo…..

There is no way to add an image directly to the forum.

You will need to use a third party photo hosting service, then post the link here.

[jukenorman]

I'm not sure that I understand your reply. You will see strobing on the K1 line from any dip switches in the profit setter that are set and monitored via K1. There is an "add unit" pushbutton on the profit setter that is monitored via the K1 line - does that work? Use Postimages, upload your image and then choose the hotlink for forums option, paste that into your reply and it will embed your picture.

Norman.

[smailskid]

Thanks for the help with posting a photo. I included the schematic of the area we are discussing

D11 and K1 lines are both pulsing as they should and did not go high or low when keyboard button 1 is depressed (not sure if they should?). The “add unit” button does work. What do you suggest checking next?

[jukenorman]

When making a selection, the first digit must be a 1 or 2; the 1 doesn't work, does the 2?

I'm not sure if you understand how the switch matrix operates? Pulses are sent out at varying intervals on the D lines and for any pulse received back on a K line, it can be determined which switch was operated - hence D11 & K1 = Keyboard 1. We know you're getting pulses on D11 because you can see them and we know that K1 can interpret them because the "add unit" switch (also on K1) works.

For the 1 not to work, you must have an open circuit - either a poor/open connection or blown diode. Try the 2.


Norman.

[smailskid]

Norman. Thanks for the explanation on the switch matrix. I am familiar with it having worked on pinball machines, but it has been awhile and my knowledge is somewhat basic.

The 2 does not work either (which is why I suspected a bad connection, but the wiring/connector test good.)

[jukenorman]

Stating the obvious - you have got credit? Free play can be set via the dip switches. Otherwise, the 2 also goes in via K1, so it is probably most likely the source of the fault since it is common to both. I don't remember how accessible the diodes on the keyboard are, but you could check whether you're seeing pulses on both sides with the button pushed? That would prove the wiring.

Norman.

[smailskid]

Yes there is a credit. It is currently set on freeplay via the dip switches. I will check the diode with the button pushed. .

Also I have an old profit setter that I could swap out IC702 to see if there is any change. I am not sure if that IC is good, but it may be worth a try.

[jukenorman]

The "add unit" button should prove IC702 or at least the K1 input which is what we're currently interested in. What you could do, if you had a diode kicking about, is link from D11 (IC706 pin 9) to K1 (IC702 pin 5) to see if that brings up the 1 digit?

Norman.

[smailskid]

I will jump K1 to D11 per your description tonight and report back. Thank you

[smailskid]

I jumped K1 and D11.  Nothing displayed when depressing the 1 or 2 on keyboard.

For good measure I went through this testing procedure again and all tested good 



thoughts?

[jukenorman]

Are you absolutely certain that you have credit? When the dip switches are set for free play, I think 99 (maximum) is displayed in the credit window if I remember correctly? You would only get the 1 by linking D11 to K1, to get the 2 to come up it would be D10 to K1. There would be no need to push buttons - maybe you should unplug the keyboard when you do the diode short?

Norman.