6128 Plus Cartridge, ACID on PCB, but....

[GUNHED]

Hi there!

This is a call of help to guys being very well in doing hardware.

I got PCBs and soldered ACID's on them, but now I see that the EPROM does not start the 6128 Plus.
The PCB with ACID does start the 6128 Plus (all ROMs external on an X-MEM), that works perfect.

But as soon as I solder an 27C4001 EPROM on the PCB, it doesn't work any longer. Most of the time the screen stays green, which means that somehow the EPROM does inhibit the ACID from working.

My question: Do you see a wrong track on the PCB? How can I save the PCB (100 have been made and populated with the ACID chip). Please take a look and help if you can.

[Shining]

Since I have one of your boards, I'll take a look.
Please give me a few days (buSy).
But perhaps someone else is faster....

[Shining]

I measured a little bit around  .


For a first go: The EPROM seems to be connected correctly but the chip-select pin is not connected ! This line only goes to the ACID.


When you look at the front of your pcb, you will see that the third connector pin goes to EPROM pin 17 (bottom pins, left), Next connector pin goes to 18 and so on.
But connector pin 8 (from left) has to go to EPROM pin 22, which is not the case. If this is the only bug (I did not inspect the connections to ACID), a simple wire should fix it.


I do not know, if I find some time this evening, but i'll try if it works then.


Edit: Output-Enable is also not connected (EPROM pin 24). So the EPROM is definitely delivering no data....

[Bryce]

You had 100 PCBs made AND soldered on ALL the ACIDs BEFORE verifying the board??  Oops!


Bryce.

[GUNHED]

You had 100 PCBs made AND soldered on ALL the ACIDs BEFORE verifying the board??  Oops!

BluesBrothers told they would work. He just told me that thecorfiot made them, I will contact him, maybe he knows somthing. Oh well. 

[GUNHED]

For a first go: The EPROM seems to be connected correctly but the chip-select pin is not connected ! This line only goes to the ACID.

Ok, what do I need to connect? EDIT: Ah, thats Chip Enable ... as you tell in detail here:

When you look at the front of your pcb, you will see that the third connector pin goes to EPROM pin 17 (bottom pins, left), Next connector pin goes to 18 and so on.
But connector pin 8 (from left) has to go to EPROM pin 22, which is not the case. If this is the only bug (I did not inspect the connections to ACID), a simple wire should fix it.

Yes, I compared with your PCB and it's obvious, also another PIN is not connceted on you PCB, but on the one I got, please see attached picture: And the 2nd PCB contact from the right is not connected in your PCB, so I assume I have to cut this connection on my PCB, right?

I do not know, if I find some time this evening, but i'll try if it works then.

Please do so, it would be too bad to trash 100 units for 1200 Euros.

Edit: Output-Enable is also not connected (EPROM pin 24). So the EPROM is definitely delivering no data....

Which PINs do I need to wire?

[Shining]

You cannot completely compare your and my cartridge cause I have some tracks on another side of the pcb than yours. Also I dont have an ACID on it.


But the good news is that my analysis was right: I just connected the expected pins and tadaaaaaaa, it woks now  .


On the first picture you see the missing wire for chip-select. You can either use my solution: connect the wire to the cpc-connector or you can search for the same pin on ACID and wire it from there.


On the second picture you see the missing connection to output enable. You have to connect GND to this pin and GND is available at many places on the pcb. It is your choice which one to take.

[remax]

Î hope you'll find a solution GUNHED. That would be a shame to see a so long time project of yours being badly beaten by such a problem

[Shining]

I posted the solution already !

[GUNHED]

Thank you very much, will heat the soldering iron up and hope for the best. 
Eventually I will sleep better this night. 

[GUNHED]

Shining you made it!!! Checked faithfully the first patched PCB today, the two wires are sufficient to get the little PCBs working! Thanks again!