[Solved] Help with Aladdin repro

A place that you can discuss reproduction of classic titles or "licensed-for-reproduction" homebrew for personal use.

Moderators: B00daW, Moderators

Forum rules
1. NO BLATANT PIRACY. This includes reproducing homebrew less than 10 years old, with the exception of free software.
2. No advertising your reproductions, with the exception of free software.
3. Be nice. See RFC 1855 if you aren't sure what this means.
User avatar
Fisher
Posts: 1089
Joined: Sat Jul 04, 2015 9:58 am
Location: -29.794229 -55.795374

Re: Help with Aladdin repro

Post by Fisher » Tue Jul 14, 2020 4:48 pm

I heated the board and removed 2 of the epoxy boards that were connected on the address and data buses, leaving only the one which is connected on the CIC, but later I cutted the VCC and the data tracks leading to it.
I tested each pin with the probes on the correct polarities and got no lower readings than the VCC and GND, but got some bigger ones.
Could it be some kind of interference?
I'm attaching some pictures, in the hope it can clarify things a little.

The 74LS139 that is onboard is disconnected.
The pins where the tracks exists are insulated with plastic capes from wires.
I was planning to use this demux instead of the other one.
Attachments
20200714_203932.jpg
20200714_204138.jpg
20200714_204057.jpg

User avatar
Fisher
Posts: 1089
Joined: Sat Jul 04, 2015 9:58 am
Location: -29.794229 -55.795374

Re: Help with Aladdin repro

Post by Fisher » Sat Jul 18, 2020 4:20 pm

Finally!!
I changed the 74'139 one more time, now I used that standard DIP part I did insert and insulated the pins on the place where the CIC should be.
Probably all the SMD parts were busted, wich is not a big surprise...
Or was that old LS vc HC dilema or even bad soldering?
Here's the result:

Front of the cart:
WhatsApp Image 2020-07-18 at 7.49.01 PM.jpeg
Back of the cart:
WhatsApp Image 2020-07-18 at 7.49.11 PM.jpeg
The title screen:
WhatsApp Image 2020-07-18 at 7.49.16 PM.jpeg
The case after cleaning:
WhatsApp Image 2020-07-18 at 7.48.59 PM.jpeg

Just another question: how can I decouple this, if I should ever try?
I'm not sure if the 2 electrolytics I used before would be fine.
I don't know much about decoupling, but I've read that it should not exceed some capacitance, but I'm not sure what's the maximun value I can use.

User avatar
Fisher
Posts: 1089
Joined: Sat Jul 04, 2015 9:58 am
Location: -29.794229 -55.795374

Re: Help with Aladdin repro

Post by Fisher » Sun Jul 19, 2020 3:56 pm

Well, I tried.
Hope I have understand correctly the "recipe":
- 1x 100nf for each IC, as close as possible from it; and
- 1x 2,2MFD for the whole board, as close as possible from the connector.

I could't add a capacitor for the flash that's in the middle of the "sandwich", but managed to add one on top and a very small one on the botton:
20200719_115700.jpg
Please, share your toughts.
Many thanks for all. :-)
Last edited by Fisher on Sun Jul 19, 2020 5:02 pm, edited 1 time in total.

lidnariq
Posts: 9491
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: [Solved] Help with Aladdin repro

Post by lidnariq » Sun Jul 19, 2020 4:29 pm

That's probably fine.

Post Reply