A500 Rev5 Green screen on power on

[Wolfy]

I recently acquired an A500, very clean in comparison to my other 500s, none the less when I plugged it into a known good psu all I was greeted with was a green screen.

The back story for this machine is that the person I got it off had been given it 17 years ago by a friend and it never worked, and has been sat in the box since yesterday...

As requested by Zetro here is some pictures of both sides of the board, sorry they are the best quality wise my camera can manage.

 

[Wolfy]

I should also note, there was no expansion in the trapdoor slot.

Thanks for taking the time to have a look

 

[Zetr0]

Hiyas Wolfy

okay my friend lets start a little test first

1. unplug (remove GARY) from the socket and then hook up the motherboard and power it up.

report back

2. put gary back and try a power up again

report back

3. remove agnus and power up again

report back

4. replace agnus and power up once more

report back

=)

 

[Wolfy]

Good morning

I have hooked up the board to a 1084s and A500 PSU, powered up, green screen.
Powered down
Removed gary, took a while gently easing him out just applying the slightest leverage to each corner one by one slowly raising gary upwards till he was completely free and able to lift straight up, noticed the 2 end pins oposite end from the notch where bent as if gary has been removed before a little more roughly.

closed curtains, powered on and all I got was a few dots on one scanline mid screen for say 1 frame... otherwise blank screen

So I am now sat looking at a powwered down board minus gary.

I should say I have 2 spare 500`s that maybe scruffy but do work, no idea of board revs and such as not opened yet, but they are about for donar parts if necessery.

---------- Post added at 11:27 ---------- Previous post was at 10:43 ----------

(had coffee)
Ok, gently straightened the 2 slightly bent legs and reseated gary, alas green screen

 

[Wolfy]

Friend came by to take me shopping...

Just sat and removed agnus, that was a task! patience is the key...
anyway powered on and again just blank screen.

off for another coffee and let dogs out and then I`ll try re-inserting, brb.

 

[CrashMidnick]

Green screens is often a chip ram problem. As Zetro said, try to remove Agnus (becareful the socket is fragile), clean the pins in the socket and on Agnus chip and then replace Agnus.

Other possibility is that one ore more chip ram are dead...

EDIT : Did not see you just reply about Agnus...

 

[Wolfy]

Ok, replaced agnus and powered on to a real nice suprise!

 

[Geraldine]

Yaaay, so it was just dodgy seating on the agnus chip after all. Well done Wolfy, thats another miggy brought back to life

 

[Wolfy]

I have a KS2 rom (from TC) an AMRam 1.5 meg expansion (Bazzaq) and a sidecar IDE HD+2megs ram (Bebek) sat waiting, and this is just the girl!... but in the meantime, doggy playtime.

This has made my day!

 

[CrashMidnick]

Well done mate, another Amiga saved !!!

 

[TheCorfiot]

Wolfy.......Fantastic mate

With 500's it is so often bad fitting Agni, usually moved in transit, when you get a green screen.

TC

 

[Zetr0]

Ahhh its good to see the classic check list of pull and reseat worked =)

the trick here is if you had pulled gary and still got a green screen - then you would of had a dead agnus. - very pleased you haven't!

 

[Wolfy]

Aaah, I was wondering why you wanted me to power on without gary in place.

Anyway, she has been running fine, I have upgraded to KS1.3 and installed the amram card I had + card from rojaws...

Without any card - about 400k available
With rojaws card - about 900k
With just AmRam 1.5 - again 900k
With AmRam 1.5 and Amram from rojaws piggtbacked - 1.9megs

Plays old demos just fine, floppy purrs so softly, sound is crisp and clean

Anyway, heres some piccies...

Thanks Zetro

 

[Zetr0]

my friend, theres no need to thank me... that check list has been about.... ohhh... probably as long as the amiga has LOL

I am glad it worked

you have my thanks for sharing the pictures!

I really like picture 4!

 

[Geraldine]

That is one clean miggy you have there Wolfy and I like picture 3. It looks like it came from one of the Amiga ads of the 1980s

 

[ChrisUnionNJ]

Wow never thought to reseat the agnus I have 2 500's with green screen's
now I really what to mess with those..

 

[Mr B]

The back story for this machine is that the person I got it off had been given it 17 years ago by a friend and it never worked, and has been sat in the box since yesterday...

This is just sad. Did you tell the person you got it from, that it was simply a chip that got dislocated and needed re-seating for it to work? It's 17 years wasted doing absolutely nothing due to a 5 minute fix.

Glad you got it working tho.
Cheers.
B!

 

[CrashMidnick]

Those green screens are really common now... If you try to put a megachip inside an A2000 for exemple, you have 9/10 chances to have this beautifull screen (in my case 100% : 2 A2000 and 1 A500 ) this is mainly due to the plastic used for making PLCC sockets wich is not enough rigid to maintain chips in place so pins are not making good contacts...

2 solutions :

1) replace the socket by a new one (but you will have the same problem later)
2) Just pull a little on pins inside the socket (only one side of the square, it is enough)

Same problem on some Indivision AGA 1200, PIV...

 

[deicidal]

Should really have a go at doing this tonight with a a500+ I aquired last year, if for anything to tidy some space up seeing as it is currently stripped down.

Glad to see you got yours working

 

[Wolfy]

Yeah worth a try.
I found agnus was a bit tough to get out but maybe I was not applying enough force?
Just eased one corner, then the opposite (there are 2 little notches), took maybe half a dozen attempts but she just popped out

Anyways, one more piccie then I gotta start an album to show off my toys of course we all know what a miggy looks like but still...
This is the 500 hooked up to my projector playing some simple demos.
I like this old girl, she has made me realise that a demo can be simple and well, I am inspired to play a little with blitz basic...