Author Topic: Pc Engine duo R glitch - video interference  (Read 91 times)

Earthshaker

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Pc Engine duo R glitch - video interference
« on: February 15, 2020, 04:51:44 AM »
Hi guys, I really need your knowledge and experience to repair my PCE duo-R.
I got the machine around two months ago and it was working fine, then I decided to install the RGB as I had some rgb boards with 7314 on it at home.
Unfortunately something went wrong as I broke 2 solder pads (n.60 and 58) of the board where the HUC6260 is soldered :'( 
I checked the schematic of the HUC6260 and that legs are labeled as "TEST". However I decided to finish to mod the console and check the results but unfortunately the console doesnt work properly. As I made even the rgb cable I thought that way be the problem, but even by the "old" composite cable the image glitches.
The glitch is not stable.. its more similar to an intereference with kinda of greenish stripes that appears on screen. Sometimes everything seems normal...  :-k
I double checked with multimeter everywhere, I tried another 7314, i rewired the rgb cable, tried different games, without  game, connected and disconnected the c.sync.... but same result.
I want to reconnect the legs, but I dunno where... I got another pc engine duo from a friend to check where that legs go.. but I cannot find it!! :-k #-o
I am not a novice in soldering and I really feel stupid for what I have done there.. can't forgive me.  ](*,) ](*,) ](*,)
Hope you can help me guys  :pray:!
Here some picture of the board.



Video:
https://youtu.be/W3b-8dzh7f0
« Last Edit: February 22, 2020, 04:00:09 AM by Earthshaker »
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MNKyDeth

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Re: Pc Engine duo R glitch
« Reply #1 on: February 19, 2020, 05:24:29 PM »
Disconnect the white wire for the sync. You already have composite video that will act as sync unless you cut that trace.

Just desolder it from the 8 pin din and test. That way you can see. I think most people that try to use the sync from the chip instead of composite video is more for those without CRT TV's.

EDIT:
NVM, guess I didn't read the full post. You already tried without that sync hooked up. Honestly that would have been my first thing to check.

Next up, replace your caps. Pull the 5v and ground from a different location. I would still not run the sync from the HuC chip anyways, so I would run without that wire.
Quickly looking over a PCE Duo, those pins don't seem to go anywhere.
« Last Edit: February 19, 2020, 05:35:19 PM by MNKyDeth »

Earthshaker

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Re: Pc Engine duo R glitch
« Reply #2 on: February 20, 2020, 07:11:41 AM »
Thank you for your reply.
I will try to replace the caps nar the chip then. I tried to get the 5v from a different source and I got the same result. I have doubt the problem may be the rgb board mod, then I am considering to try the rgb mod hooking up the chip rgb legs directly to the socket temporarily. If the glitch disappear then its the shitty pcb and I will buy another one.
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Earthshaker

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Re: Pc Engine duo R glitch
« Reply #3 on: February 21, 2020, 02:36:26 PM »
New update, I tried the PCE without RGB board and I got the same result. I also tried to replace a cap close to the hu6260 which seemed a little bit damaged. Result? same. Always random interference.
I am really getting annoyed and I am losing my hopes. Today worked perfectly for 20 min and suddenly interferences appeared again...  ](*,)
My last hope is to buy a new RGB cable, othwerise I will use my old the composite one.  :'(
Where do you use to buy RGB cables? any recommendation? I live in Europe.
Thanks
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MNKyDeth

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Re: Pc Engine duo R glitch
« Reply #4 on: February 21, 2020, 06:08:24 PM »
This site is UK based.
https://www.retrogamingcables.co.uk/

They might have what you need.

You have these video issues with the original composite cable?

Earthshaker

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Re: Pc Engine duo R glitch
« Reply #5 on: February 21, 2020, 06:21:15 PM »
Thank you.
No, actually the composite seems to work fine. I always created my own cable scart without problem, but this pce does not wanna collaborate  :lol:
Do you recommend me to buy Csync or Sync over composite cable?
« Last Edit: February 22, 2020, 02:59:49 AM by Earthshaker »
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Keith Courage

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Re: Pc Engine duo R glitch
« Reply #6 on: February 21, 2020, 07:28:52 PM »
You do not need a special C-sync cable.

So you only get this issue over RGB?

That sync wire you have running to the composite out either needs to be disconnected or you need to cut the composite video signal trace so the two signals do not go together. It can damage the Video chip having both on the same line.

If you decide to cut the composite video trace. You will need to add a 220uf or higher cap to the c-sync line from the hu6260 chip. Video will get all grainy otherwise.


I've never seen random Greenish stripes before.

I did take a look on another DUO board and those two pads you lifted on accident don't go to anything important. They are just for test. So the trace just runs to a small solder blob that one can use to test with a multi-meter more easily. The pads didn't by chance go under the chip did they? I wonder if a couple traces are touching one another under there.




« Last Edit: February 22, 2020, 02:02:32 AM by Keith Courage »

Earthshaker

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Re: Pc Engine duo R glitch
« Reply #7 on: February 22, 2020, 03:57:48 AM »
Yes only RGB
After testing few games I can say the the problem is an intereference, not always greenish (depend of game). I will take another video later.
However I will desolder the c.sync wire (even if I tried it before) and test it once more. I hate this interference coz sometimes it takes up o 10 minutes to appear.. it deceives me XD

The pads didn't by chance go under the chip did they? I wonder if a couple traces are touching one another under there.

I don't think so.. but I would need to remove the chip to be sure 100%.
« Last Edit: February 22, 2020, 04:10:07 AM by Earthshaker »
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Earthshaker

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Re: Pc Engine duo R glitch - video interference
« Reply #8 on: February 25, 2020, 03:56:33 PM »
Hi guys, just want to inform you that the problem was the sync wire! I disconnected it and now finally the console works fine.
Yesterday I got other two pce duo that need to be repaired, but that's another story... XD
Thank you very much for your help!
by the eay do you use caps or resistors into your pce rgb scart cable on the RGB signal? coz the image is slightly dark
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Necromancer

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Re: Pc Engine duo R glitch - video interference
« Reply #9 on: February 25, 2020, 04:13:27 PM »
Congrats on figuring it out and getting 'er fixed up.  Another system ready for another 25+ years of being awesome!   :mrgreen:
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Keith Courage

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Re: Pc Engine duo R glitch - video interference
« Reply #10 on: February 25, 2020, 07:13:00 PM »
It looks like your RGB amp already has the required capacitors on it. So there should only be the one 180ohm resistor in the scart cable that goes from the 5V pin to the blanking signal pin.

Earthshaker

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Re: Pc Engine duo R glitch - video interference
« Reply #11 on: February 26, 2020, 03:52:20 AM »
It looks like your RGB amp already has the required capacitors on it. So there should only be the one 180ohm resistor in the scart cable that goes from the 5V pin to the blanking signal pin.
I see! thank you  ;)
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