Author Topic: PC Engine GT - Replacement HuCard Slot Board  (Read 455 times)

MuNaught

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PC Engine GT - Replacement HuCard Slot Board
« on: March 12, 2022, 09:59:58 AM »
I am repairing and restoring a PC Engine GT. The usual suspects of leaky capacitors are present, and while the main board and controller board were almost unaffected, the cap juice did a number on the HuCard slot board.

I am now at a point where I am considering two paths:

1) Design and send to fab a replacement HuCard board, I am considering a direct solder FFC 0.8mm /40p ribbon. This will re-use the HuCard slot, new C820 capacitor. Before I go down this path, does anyone else need this board?

2) Chop an IDE ribbon to connect what isnt damaged, and bodge the rest directly to the HuCard slot pins. Sloppy, but functional.


For path #1, here is a rough-in of the replacement.



Or maybe an FFC connector variant.


« Last Edit: March 27, 2022, 04:18:48 PM by MuNaught »
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tawy

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #1 on: March 24, 2022, 05:49:22 AM »
love the idea :)

if you consider using the 1st way, maybe you can try to put a region switch on the PCB.
Maybe it does not worth it when you know that a everdrive could launch game from any region on any console, but if you are working on a PCB (and seems to know how to do it), a single CBT3383 + a component that can handle the BE and BX for the switchless is a plus (a transistor that can keep a H or L state maybe).
https://www.pcenginefans.com/forum/index.php?topic=10112.0
I did the same for the controller PCB, it was at first only for myself but now, people who needs it can buy me one  :thumbsup:
how did you put a clean picture on a pcb ? i am using eagle PCB and it does not look like yours, you are using kicad maybe ? did you vectorize the bee ?

please do not drill your console (BE/BX needs to be H or L to switch between the data lines). a lot of modders does that, i totally hate it ! switchless is the way. i know how to do it on an arduino, but i think there is a way to toogle H or L with a single electronic component.

ps : i will take a good resolution picture of the back sticker. i have 2 pcegt in good condition.
« Last Edit: March 24, 2022, 06:07:11 AM by tawy »

MuNaught

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #2 on: March 26, 2022, 11:38:44 PM »
I use DipTrace.

Prototypes have arrived. Overall, the concept is sound. There are some things I'm not happy with and will work to correct. I also want to add a spacer to allow an FFC connector install on the mainboard as well. I may reverse the entire ribbon bend direction.

I do like the idea of integrating a region free mod. There is real estate and there is mechanical clearance to the motherboard for a CBT3383 and associated components.

I will only consider a "no-cut" path for the switch. I'm going to have to spend some time researching and thinking about this.
« Last Edit: March 26, 2022, 11:45:51 PM by MuNaught »
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tawy

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #3 on: March 27, 2022, 03:04:38 AM »
If you did the 1st version, I can guess what is wrong :)
The flex is not straight when you bend it (sorry for my English). The cable is not aligned to the one on the motherboard maybe ?
GG for your work. Im sure it can interest more people if you do the region free mod.

Edit : finnaly i dont know what is wrong with your pcb you dont design pcb only as hobby no ? It is your job ? Dip trace seems to be very advanced !!!
« Last Edit: March 27, 2022, 03:44:43 AM by tawy »

MuNaught

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #4 on: March 27, 2022, 09:47:45 AM »
I am a mechanical engineer, not electrical. I'm self-taught on PCB design but wouldn't consider myself advanced yet.

Lateral ribbon alignment wasn't an issue. Rather I was getting an interference fit on the FFC ribbon against the battery housing (putting significant stress on the ribbon).





I plan on reversing ribbon direction to resolve, but in doing this the [now flipped] FFC connector to be mounted on the main board cannot be opened due to D205 in the way. A 1.2mm thick spacer with castellated [edge] holes will solve this and will also help get the ribbon plane above the metal shielding if you wish to keep this.

New board with region switch IC and flipped FFC connector. I still need to determine latching switching method so those components are not populated yet.



Main board FFC connector spacer (ignore render glitches, it won't be that way in reality):

« Last Edit: March 27, 2022, 04:14:54 PM by MuNaught »
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MuNaught

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #5 on: March 27, 2022, 11:01:56 PM »
I spent too much time on this today. But I do now have a v2.0 candidate with region free capability. The only soldered wire needed to select region is the "SELECT" button input used to toggle region on power up.

« Last Edit: March 27, 2022, 11:19:30 PM by MuNaught »
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Astral

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #6 on: March 28, 2022, 04:25:28 AM »
A select button solution is a very simple and so so practical solution. Great idea.

tawy

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #7 on: March 31, 2022, 03:07:04 AM »
great !
can you tell me which component did you use to do the toggle H or L on power up ? and what is the schematic to do this 8)
I am very interested !

MuNaught

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #8 on: March 31, 2022, 07:59:54 AM »
NOR gate from low select button, reset to send +5V to BX. Once BX gets 5V it switches over, and I'm using one of the spare I/O groups on the CBT3383 to latch that 5V to BX once switched. The only way to reset this latch is a power cycle.

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tawy

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #9 on: March 31, 2022, 10:09:36 AM »
thank you for taking your time for making this answer !
I understand your design, you use the group 5 of i/o to make that "switch" i just don't understand why 5B2/BX keeps the initial value (i can read a datasheet, but this one is too complicated for me ^^).
i hoped you used a transistor :) i am looking for that kind of schematics for my project... if you just can guide me on the right way...

MuNaught

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #10 on: March 31, 2022, 10:25:26 AM »
Once BX is switched over, 5A1 is connected to 5B2, and the 5V is maintained into BX indefinitely until a power cycle.

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tawy

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #11 on: March 31, 2022, 06:54:50 PM »

MuNaught

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #12 on: April 03, 2022, 02:42:51 PM »
This has been a very busy week and I've had no time to work on this project. I have other unrelated projects I'm working on as well, and once those are validated I will send this to the fab. I'm probably a few weeks out from having v2.0 HuCard boards in my hands for testing.
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MuNaught

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #13 on: April 21, 2022, 09:13:19 PM »
I have good news and bad news. The good news: The v1.1 and v2.0 boards arrived, which are the direct replacement and region-free boards respectively. I had an opportunity to test the v1.1 board which works great. The FFC connector is certainly way nicer than the original crispy direct soldered ribbon. The main board FFC connector is on a riser which is different than my original design that I had to abandon because the fabs couldn't support the castellated holes at the small size and spacing needed; the new riser design works great though. The PCE GT pulls 4.0 watts at 9.0v. I haven't tested the v2.0 board yet, I need to order some components and will test it soon.

The bad news is the audio does not work, neither do the II and I face buttons. Probably an issue with the controller board. Further investigation is needed.

Does anyone know if aftermarket HuCard sockets are available anywhere?











« Last Edit: April 21, 2022, 09:34:41 PM by MuNaught »
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tawy

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Re: PC Engine GT - Replacement HuCard Slot Board
« Reply #14 on: April 22, 2022, 09:45:55 AM »
this board fits a specific need, the FFC connector is A LOT better than the original soldered one, making it "roll over" himself is a good idea to avoid stressing and fold to much the cable.
the only way to get a replacement connector is to sacrifice a PCEngine :-/ maybe find a connector with the same pitch and add a 3D printed "groove" to slide the hucard properly...