ukVac.com Homepage
Forum Home Forum Home > Technical > Tech, Maintenance & Repairs
  New Posts New Posts RSS Feed - Pi2Jamma Display Corruption
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Skin:


Pi2Jamma Display Corruption

 Post Reply Post Reply Page  <123>
Author
Message
Fantazia2 View Drop Down
User
User
Avatar

Joined: 13 Aug 2015
Location: Darlington
Status: Offline
Points: 2045

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote Fantazia2 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 2019 at 7:18pm
Looks like standard Gert666 wiring so like on this link below.

https://pinout.xyz/pinout/gertvga_666

If you have put it in backwards as mentioned before, you've probably ended up putting 12v through either the 5v or 3.3v system on the board, as all the joystick/button inputs are pulled to 5v or 3.3v through the 10k resistors around those 3 large ICs just above the jamma connector.

That would probably explain all the burning of the pins on the left hand side of the GPIO connector as those are the 5v and 3.3v in/out from the Pi. (See link above for the pinout)

Have you tested all the inputs to see if they work, as if it was put in backwards it might have damaged the shift registers used for the inputs.

I think 2 of those 100ohm resistors could be for the Horizontal and Vertical Sync signals that then get combined into a single connection on the Jamma connection, Ideally you would need to trace with a multimeter to see where they go to and come from.

Not sure what the 3rd one would be, and the 12k and 6k ones may be linked to the 3 large ICs mentioned above for the controls, the 3rd 100 Ohm one could also be part of this.

I think those 3 big pads below them are there for testing purposes, as they match the 3 connections needed on the GPIO for the controls (Latch, Clock and Data)

They are daisy chained together for the controls and the GPIO is linked to the Clock, Data and Latch pins on the first one (Possibly the left hand one) and the clock and latch will be connected to the other 2 as well, the data pins links to a data input on the chip next to it.

Do you another PI you can test it with, could possibly be that the GPIO on it has been damaged if all the resistors are checking out ok, I suppose you could test the GPIO connections for the video signals to see if you are getting voltage out of them while its running.


Edited by Fantazia2 - 07 Mar 2019 at 7:20pm
Back to Top
Fantazia2 View Drop Down
User
User
Avatar

Joined: 13 Aug 2015
Location: Darlington
Status: Offline
Points: 2045

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote Fantazia2 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 2019 at 7:25pm
Its a shame those boards are so expensive, as other than the PCB itself the other parts on them are pretty cheap to buy.

You could probably make one yourself out of stripboard, a Jamma Edge Connector and a GPIO breakout for well under £30.

The design could also possibly be improved to remove the audio cable and have the sound come directly out of the GPIO instead.
Back to Top
sapporo46 View Drop Down
User
User
Avatar

Joined: 24 Jan 2014
Location: North West
Status: Offline
Points: 252

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 2019 at 10:31pm
Hmm, have more doubts about this now - measured the banks of resistors labelled 10K and got varied readings between 10K and 5.69K Confused
Back to Top
sapporo46 View Drop Down
User
User
Avatar

Joined: 24 Jan 2014
Location: North West
Status: Offline
Points: 252

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 2019 at 10:48pm
@Fantazia2 only saw your replies after posting mine... I think I tested the controls briefly. Will check again.

The 10K resistors I mentioned are in the bottom right of my photo, looks like 4 banks of 4. I'm 99% certain these are the ones you're referring to so it would seem I've overloaded the voltages as you described. F***wit Clap
Back to Top
Fantazia2 View Drop Down
User
User
Avatar

Joined: 13 Aug 2015
Location: Darlington
Status: Offline
Points: 2045

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote Fantazia2 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 2019 at 11:58pm
Actually I just had a look at another photo of the board, and I think I was wrong about those 10K ones, its the long row of 200 ohm ones next to the edge connector that are the pull up resistors for the controls.

I think the 10K ones are for setting certain things on the Shift registers. They are LS165A chips from the picture Im looking at. I dont think the ohm rating is that important as long as they are not shorted or open.
Back to Top
sapporo46 View Drop Down
User
User
Avatar

Joined: 24 Jan 2014
Location: North West
Status: Offline
Points: 252

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2019 at 4:25pm
So do you think it's still possible that it's those other ones (12k and 6.8k measuring 9.02 and 5.43) that are failing?
Back to Top
John Bennett View Drop Down
Senior Member
Senior Member
Avatar

4 Years of Supporting ukvac.com!

4 Years of Supporting ukvac.com!



Joined: 01 Jan 1998
Location: Newcastle
Status: Offline
Points: 10317

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote John Bennett Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2019 at 4:32pm
That diode test I suggested is good for testing for blown processor I/o. Do it with the power off. Should get similar readings for the pins - if one is duff, you’ll see a big difference.
http://www.philwip.com -sibling 'fix-off' (I’m losing by miles).
Back to Top
Fantazia2 View Drop Down
User
User
Avatar

Joined: 13 Aug 2015
Location: Darlington
Status: Offline
Points: 2045

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote Fantazia2 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2019 at 6:40pm
Originally posted by sapporo46 sapporo46 wrote:

So do you think it's still possible that it's those other ones (12k and 6.8k measuring 9.02 and 5.43) that are failing?

They are only for the controls and not part of the video circuitry.

If all the controls work I wouldnt worry about them too much.
Back to Top
sapporo46 View Drop Down
User
User
Avatar

Joined: 24 Jan 2014
Location: North West
Status: Offline
Points: 252

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2019 at 9:56pm
@John - I did do that test last night but wanted to double-check I was doing it properly (electronics isn't really my thing). However I did get substantial differences, I think - I'll do it again over the weekend.

If that is the case and the GPIO connector is damaged, then it's new board time I guess.
Back to Top
John Bennett View Drop Down
Senior Member
Senior Member
Avatar

4 Years of Supporting ukvac.com!

4 Years of Supporting ukvac.com!



Joined: 01 Jan 1998
Location: Newcastle
Status: Offline
Points: 10317

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote John Bennett Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2019 at 10:03pm
You can actually do it four ways for every pin if you want to get a fuller picture:

Black to 5V, red to pin.
Black to pin, red to 0V

Red to 5V, black to pin.
Red to pin, black to 0V.

The first two are the key tests to do. I've no idea what a PI would give, but, for example 600mV is a typical reading.
However its' when one pin is radically different to the others (e.g. zero or well over a thousand) that you want to look a bit further.
Having said all this, you have got a ladder-DAC of resistors on the pins, so that might make them read differently. Maybe unplug the PI from the JAMMA thingy to test it.
http://www.philwip.com -sibling 'fix-off' (I’m losing by miles).
Back to Top
sapporo46 View Drop Down
User
User
Avatar

Joined: 24 Jan 2014
Location: North West
Status: Offline
Points: 252

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2019 at 4:08pm
Sorry John - the diode test is for the Pi2Jamma PCB, yes?

The Pi is OK - I booted it off the NOOBS for Raspberry Pi image (Raspbian OS) and it looked fine on the TV.
Back to Top
John Bennett View Drop Down
Senior Member
Senior Member
Avatar

4 Years of Supporting ukvac.com!

4 Years of Supporting ukvac.com!



Joined: 01 Jan 1998
Location: Newcastle
Status: Offline
Points: 10317

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote John Bennett Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2019 at 4:53pm
It was actually for the PI, for the GPIO driving the resistor circuit on the pi2jamma.

So you’ve tested something else using the same pins to VGA?
http://www.philwip.com -sibling 'fix-off' (I’m losing by miles).
Back to Top
sapporo46 View Drop Down
User
User
Avatar

Joined: 24 Jan 2014
Location: North West
Status: Offline
Points: 252

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 10 Mar 2019 at 9:48am
Ah, I follow you now. I'd tested the GPIO pins on the Pi2Jamma card. Electronics is not my thing
Back to Top
sapporo46 View Drop Down
User
User
Avatar

Joined: 24 Jan 2014
Location: North West
Status: Offline
Points: 252

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 11 Mar 2019 at 11:10pm
An update of sorts: I borrowed a Pi and tested it out. All looked good!

I have to return it tomorrow so checked it one more time, about 30 mins ago. The audio cable smoked and the same thing has happened

I switched it off quicker this time but WTF?? I definitely didn't have it plugged in the wrong way this time, now I'm wondering if I ever did.

Bearing in mind that this was a supergun running off an ATX power supply too...

Edited by sapporo46 - 11 Mar 2019 at 11:23pm
Back to Top
John Bennett View Drop Down
Senior Member
Senior Member
Avatar

4 Years of Supporting ukvac.com!

4 Years of Supporting ukvac.com!



Joined: 01 Jan 1998
Location: Newcastle
Status: Offline
Points: 10317

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote John Bennett Quote  Post ReplyReply Direct Link To This Post Posted: 12 Mar 2019 at 6:20am
So it’s two trashed Pi’s?

Without knowing the circuit (any chance of an aerial photo showing all the boards and cables?), I’d be looking at the power supply area. Sounds a bit like it’s putting the ground power connection through the audio/video, although I’m not sure how that’s possible (interesting failure if so).
http://www.philwip.com -sibling 'fix-off' (I’m losing by miles).
Back to Top
sapporo46 View Drop Down
User
User
Avatar

Joined: 24 Jan 2014
Location: North West
Status: Offline
Points: 252

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 12 Mar 2019 at 8:16am
Certainly in terms of the GPIO connector, yes

I'm gutted, was going to buy another Pi and problem solved. The only common factor is that the damage occurs when the audio cable is plugged in. When I first tested the other Pi yesterday I didn't connect the audio cable until after it had booted.

Is this a factor somehow??

I'll upload a photo ASAP.
Back to Top
John Bennett View Drop Down
Senior Member
Senior Member
Avatar

4 Years of Supporting ukvac.com!

4 Years of Supporting ukvac.com!



Joined: 01 Jan 1998
Location: Newcastle
Status: Offline
Points: 10317

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote John Bennett Quote  Post ReplyReply Direct Link To This Post Posted: 12 Mar 2019 at 9:39am
What does the audio go to? An amplifier somewhere?
http://www.philwip.com -sibling 'fix-off' (I’m losing by miles).
Back to Top
sapporo46 View Drop Down
User
User
Avatar

Joined: 24 Jan 2014
Location: North West
Status: Offline
Points: 252

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 12 Mar 2019 at 10:53am
I'd have to check, but it connects from the standard 3.5mm jack on the Pi and ultimately it sends the audio to whatever GPIO pins go to the JAMMA speaker connections. So it may not be related, I don't know.
Back to Top
John Bennett View Drop Down
Senior Member
Senior Member
Avatar

4 Years of Supporting ukvac.com!

4 Years of Supporting ukvac.com!



Joined: 01 Jan 1998
Location: Newcastle
Status: Offline
Points: 10317

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote John Bennett Quote  Post ReplyReply Direct Link To This Post Posted: 12 Mar 2019 at 12:43pm
I find that a bit confusing as JAMMA is amplified audio for driving big 8 ohm speakers - that’s why you’ve got amps on game boards with heatsinks on them. I’d have imagined something intended for headphones will toast itself if you stick speakers on to it.

I need to read up on the circuits to be honest though - I can’t imagine it would be like that!
http://www.philwip.com -sibling 'fix-off' (I’m losing by miles).
Back to Top
sapporo46 View Drop Down
User
User
Avatar

Joined: 24 Jan 2014
Location: North West
Status: Offline
Points: 252

Feedback: 5
Post Options Post Options   Thanks (0) Thanks(0)   Quote sapporo46 Quote  Post ReplyReply Direct Link To This Post Posted: 12 Mar 2019 at 11:22pm
For info, here is how the supergun is setup.

This photo shows how the Pi2Jamma PCB connects to the Pi itself. In the cabinet, the Pi2Jamma PCB plugs into the JAMMA harness the same as on the supergun.

Here is another image of how the audio cable connects.

To answer your earlier question: according to this info, the audio cable *does* go to an amplifier.

I now have no confidence in plugging this stuff in, is the adapter board zapping the GPIO somehow? It must be, but how? Cry
Back to Top
 Post Reply Post Reply Page  <123>
  Share Topic   

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.718 seconds.