Totally bizarre A2000 video output!

[Fingerlickin_B]

Hey folks, here's a noodle scratcher for you all!

My new A2000 won't display though A520 module connected to a TV.

It however displays perfectly on the 1081 monitor & gives a B/W signal from the composite RCA connector.

I just tested the A520 with my CDTV & then with my A1200...it works perfectly with those...so why isn't it working with the A2000?

Surely it can't be the RGB port, since that works perfectly when connected to 1081 as stated above.

What on earth could be the problem here?!?!

PZ.

[TheCorfiot]

Fingers me old mate...

I was about to say that not all supply voltages req for the A520 are present on the A2000 Video port & then remembered I used an A520 temporarily when repairing my spare.

My Motherboard rev is 6.3 main (used with Microway FF though)
& 6.2 used with A520 succesfully,

I'm sure rkauer has stated +5V voltage availability issues between big box amigas & A500/1200/600 when designing his component RGB special 520 as he was looking into voltage regulators.

What rev is the A2000,

You can of course use a meter to check for the presence of the +5V (and indeed the others too). Then follow the tracking on the board if the +5V is absent due to no track then you can solder in a link but would advise an inline fuseable resistor to protect your A2000 PSU.

Anyway Checking the Voltages are available on the port I think is a good place to start

Hope I'm pointing you in the right direction.

[Fingerlickin_B]

Excellent suggestion man, can you tell me which pin to check for 5v?

I'll go pop the lid off to conform the revision version & report back ASAP!

PZ.

*EDIT* - It's a Rev 6

[Zetr0]

Pin 23 is +5v the schematic will show you m8y

[TheCorfiot]

Originally Posted by Fingerlickin_B

Excellent suggestions man, can you tell me which pin to check for 5v?

I'll go pop the lid off to conform the revision version & report back ASAP!

PZ.

Bugger, I'm in work & don't have schems to hand mate...

Obtain a Gnd from one of the PSU connectors (middle 2)

Try Pins 21,22 & 23 if memory serves 22 is +12V & 23 is +5V

Check this thread to be sure

http://eab.abime.net/showthread.php?t=37187

Good luck mate,
If the +5V track is present it may not be populated or a fuseable may be O/C

Don't forget the Rev Number...... Maybe revs 6.2 onwards had the full voltage supplement wired. unsure about this

[TheCorfiot]

Originally Posted by Zetr0

Pin 23 is +5v the schematic will show you m8y

Ah my dear friend to the rescue,,,
+5V pin confirmed

Cheers Zetro,,,,

[Fingerlickin_B]

Thanks guys, this is really leading somewhere fast!

I've confirmed that pin 23 is giving 5v, BUT pin 22 is giving 0.05v instead of the 12v it should have.

Since there is *some* voltage present at pin 22 I'm hesitant to run 12v to it, as it'll probably go back "up stream" from the port & blow something

PZ.

[TheCorfiot]

Originally Posted by Fingerlickin_B

Thanks guys, this is really leading somewhere fast!

I've confirmed that pin 23 is giving 5v, BUT pin 22 is giving 0.05v instead of the 12v it should have.

Since there is *some* voltage present at pin 22 I'm hesitant to run 12v to it, as it'll probably go back "up stream" from the port & blow something

PZ.

Right I got it the wrong way round no +12V but +5V present...

Not sure if the 50mV being read could be true or meter error.

Fingers, unless Zetr0 can suggest otherwise, you need to get the Motherboard out, give it a good brush & clean while we are at it, nudge nudge & of course ahem some lovely piccies.

Check the PCB traces & see if a fuseable (looks like a green "snot" coloured resistor) is in pin 22's line. if so check if it's O/C.

Need someone to confirm if Rev 6.0 had the +12V to the Video port tracked before we consider any hacks
It maybe that the tracks are there but unpopulated.

But Bottom line That's why the A520 doesn't work

[Zetr0]

Hmmm you could run a 12 volt regulator from the Pin 23

its quite simple let me yomp a little schema

[Zetr0]

Okay, double check this, as its off the top of my head.

I think it should work but give yourself a 10 minute google


(this would have to be built inside the A520 and the 22 pin line de-coupled)

[TheCorfiot]

Originally Posted by Zetr0

Okay, double check this, as its off the top of my head.

I think it should work but give yourself a 10 minute google


(this would have to be built inside the A520 and the 22 pin line de-coupled)

Zetro,

Don't think that will work mate.

You can't obtain +12V from a +5V input using a std 78xx device, you would need to use a charge pumping type device such as a Max with associated capacitors to develop the voltage.
You can obtain +5V from a +12V input using a 7805. as it's voltage drop.

I think finger's best bet is for someone to verify The Rev 6 Mobo's +12V capability so we can ascertain if it's broken or simply not incorporated, if it's broken we need to fix it, If it's missing he can use a wire link with associated fuseable to "upgrade" his mobo.

Still awaiting piccies though, I'm just in the mood for some nice BIG BOX Hardware Pr0n, as you know m8y -- "Hardware Pr0n , Cause every little helps!!"

Regards

[Zetr0]

@TC

LOL indeed my friend, Because Hardware Pron DOES matter

sorry about the schematic... I am sure there is a part that takes a 5v source and outputs a 12v (pending on caps) although it drops the amps considerably... i must research it...

@Fingers

my friend, it would seem that TC has saved you a 10 minute google

[TheCorfiot]

Hey Zetr0, my dear & esteemed friend

Why apologise, your knowledge has solved so many problems, We would be lost without you... (& your charisma of course)

Expanding on Finger's problem, I think rkauer probably has the answers as he has researched voltages on the Video port between amiga models for the design of his component RGB box of tricks.

Lets see if Rod finds this thread & sheds some light for us.

[Fingerlickin_B]

Thanks to both of you sooo much...I love getting on here when you guys are "working"!

I think TC nailed it right on the head;

Here is a pic of the "naked" mobo still in the case:
http://img512.imageshack.us/my.php?image=f5zc5.jpg

And here is "F5":


F5 runs directly to pin 22 & is not letting anything through, no continuity whatsoever.

So, now we know what the problem is...I obviously can't get it's specs when it is dead...anyone know what I should buy to replace it with?

PZ.

[TheCorfiot]

Fingers,

Got an old A500 MB lying about.... pinch it I do have the specs but they are at home at the moment.
If not lash up a temporary fuse of about 200mA, solder the fuse either side of the O/C fuseable. Watch the heat though so you don't damage the fuse. (or A2000)

I have to order some of these fuseables for my A2000 as I have a temp part in the Mouse / Joy +5V supply so maybe I can send you some too.


A big Tip regarding the A2000 (and probably other Miggy's), Allways power down completly befor connecting / disconnecting ANYTHING including mice.... I never used to untill both My A2000's lost Mouse movement down to that fuse...

Let us know................


PS I have some usefull Fault finding docs at home, I will email later

[Fingerlickin_B]

Sounds good man...although I've got nothing like 200mA here...lowest is 10A...lolz!

I'll go grab one after work tomorrow & give it a blast.

Thanks again to both you & Zetro!!!!

PZ.

[Fingerlickin_B]

Just another thought...

To make sure this is the only cause of the problem, would it be dangerous for me to temporarily connect 12v from the PSU directly to pin 22 of the A520?

PZ.

[TheCorfiot]

Fingers you are welcome me good mate do let us know how you get on, you'll get my email later...
Can't see those pix though???? Need my fix of Big Box hardware pr0n

Take care B

PS I like your reference to "working".

Mmmm Zetro & I.......It's a bit like "The Dangerous Brothers" isn't it

[Fingerlickin_B]

Originally Posted by TheCorfiot

Can't see those pix though???? Need my fix of Big Box hardware pr0n

I think it's a problem with this bl00dy Mac I'm using, god love it!

Try right-clicking & choosing "open in new window"...that worked for me, but still being on the Mac I dunno...they are just regular jpegs from the camera though.

Also, couldn't use my usual pic hoster, as the account is full

What about the temp "check it" fix I mentioned? Safe? Deadly to A2000/A520?

PZ.

[TheCorfiot]

Originally Posted by Fingerlickin_B

Just another thought...

To make sure this is the only cause of the problem, would it be dangerous for me to temporarily connect 12v from the PSU directly to pin 22 of the A520?

PZ.

Simple honest answer, No, You would be putting your PSU at risk & possibly the tracking on your mobo SHOULD a short occour, or the A520 develops a fault, unlikely I know but that's the honest answer !

You know the A520 is good cause you have tested it.
To gain confidence regarding the A2000, simply but carefully measure the voltage while the A2000 is running on both sides of F5, should be +12V on the PSU side & 0V on Pin 22 side.

Surprised you dont have an old A500 Mobo mind under your busy bench
You need one now for spares.