Amiga 3000 video problems (ie: NONE) (UPDATE: Success)

[vk3heg]

Hello Amiga Experts and Guru's :-D

I've just finsihed making changes to the leads on a 250W PC AT powersupply for my A3000 to go into a tower case from information here Amiga power supply guide. When I switch her on, I get no video on either the 15khz port or the 31khz port (Used a 1084 and my 17" LCD). The A3000 is booting as the install disk for 3.1 get's accessed and goes though the boot process. If I have no disk inserted nothing happens. There are no resister packs on the mb, as I have no hd connected as yet. I have pushed down the chips that have socket's, reseated the zips. Felt the other chips (they are not even warm). Some time ago (couple of months) I removed the battery from the MB.

Can anyone give me some pointers, and before anyone ask's. NO I don't have the orignal powersupply.

[vk3heg]

KThunder wrote:
i would double quadruple check your connections
use a voltmeter to make sure voltages were good.
try a game disk to see if audio works.
connect a hd (some early rev 3000s wont boot without at least one scsi device, even with actual kickroms)
is this a mobo known good? (i assume yes) did you get it  on ebay or something?

I rechecked the voltage levels both before and after connecting power to the computer. Only one of the 12v leads is half a volt down. All the other's are fine. On the website listed, they didn't have pin5 connected (5volts acording to the mb circuit diag). I have now done that. I have just tryed supperfrog and the audio is working, so the mb has some life.   :-P

I purchased the mb from ebay USA, (No one in Australia had one at a decent price) and it was from a working system (Listed in the add)

The mb is a rev 9/01, Fat Angus has these markings:

8372A B
318069-03
(Is it pal/ntsc capable?)

I have set jumper J200 to pal (Tryed NTSC) and J350 to internal VSYNC. (Was in a bit of a rush this morning [it was 1am afterall]).

[vk3heg]

UpDate: I have tryed reseting the chips that I can remove (not the square guys). I have also tryed the Paula and Denise from my A500. Still get no video at all, just a blank screen. Sound and the loading of supperfrog work though.

[vk3heg]

dnelsonfl wrote:
Let's back up a moment.

vk3heg wrote:
Some time ago (couple of months) I removed the battery from the MB.

Had the battery started to leak before it was removed? Check that area of the motherboard carefully for traces of damage from the battery acids. The damage could affect amber and the video circuit.

I removed the battery as soon as I got the mb. Didn't want it going up in smoke  :-D  Here's some pics of the area's. To me the area is very clean, and there is only a small amount of leakage (hence my removall of the battery.)

Could it still have effected the video?

Battery 1

Battery 2

Battery  on mb

[vk3heg]

Olecranon: yes I used the J350 jumper to generate the internal TICK signal.

jiffydos: I have used both my 17"lcd and 1084 monitor, with the same result.

[vk3heg]

Castellen wrote:
Yep, I'd agree with Olecranon, check again that J350 is in position 2-3 (A500 position).  If you have an oscilloscope handy, check on that jumper, or on U350 pin 19 that there is a square wave present. I forget what the frequency is, I don't have my notes handy, but can look it up if you want.

An interesting thing with the A3000 is that it has a seperate +5V power supply for the video section, referred to as +VID. It's supplied on pin 1 of the power connector (look for the square pad on the solder side of the board) and check you have got 5V on U450 (Denise) pin 19, this is the +VID supply.

You can join pins 1 and 2 of the power input socket together which just makes +VID the same as +5V.

I dont have an oscilloscope, so cant check that point. I have trippled (or more) that jp350 is set for the use when a tick isn't present from the power supply. I just checked pin 19 of Denise, and there's only 2volts present.

So what's the next step?

[vk3heg]

Castellen wrote:
2V on the +VID supply is a bad thing, that's probably why it's not working.

Check on pin 1 of the motherboard power connector (it's the one that has a square shaped pad on the bottom side of the board).

If you have 5V on there, there is a supply interruption somewhere.  I don't think there's any fuses on the +VID line, I'll look over the schematics later if you can't work it out.

If you don't have 5V on pin 1 of the power connector, just join it to pin 2 (link power supply socket pins 1 & 2 together) then you should be in buisness.  Pin 2 is the main 5V logic supply, which is obviously working, else the computer wouldn't run at all.

Forget about checking the state of the TICK line at the moment, get the +VID supply working first, which will probably solve all the problems anyway.

We have success! :-D  :-)  :-(  On the website I was using for referance it has this statement about AT powersupplys: "Note: from my research I found that you need to connect the Orange power good signal, to one of the +5V wires for this PSU to work properly."

I had the orange power good line hocked upto pin1. When I used the multimeter on pin1 (While not connected to the Amiga) there was 5volts present, leading me to think that that would be enough for the +VID line. (I have mow left the orange powergood line not connected)

Tonight I changed that so that it was drawing power from another 5volt line (the one for pin2 in this case). I then proceded to powerup the amiga, with no floppy connected and got the amiga's insert disk display on my 1084. Connecting my 17"lcd to the scandoubled 15pin port also resulted in a display.

Powerd down the system and hooked the floppy up with the supperfrog disk in the drive and had the intro with a display on both screens.


I just wish to thank the user's of Amiga org for the great support and helpfull idea's. Esp: Castellen for giving me some great pointers to solving this problem. (I'm still learning about Electronics).  :-P