Amiga 500+ fails at powerup

Reynolds · 06 June 2010, 22:18

Hi folks,

I need some advices. I bought an A500+ recently. It was advertised as "dead", so I wasn't surprised, altough I'd like to fix it.
The first thing I did after it's arrived, that I removed the plastic, and metal covers. Then, when I came back from unconsciousness, immediately removed the leaked barrel battery. Sadly the mobo around it was affected in it's melting, so i've started to clean it. Bad think that the Gary chip also fave been influenced by the acid, and when I removed it from the socket, it was broken into pieces. The chip itself still working, but I have had to replace the socket. Now it's done, but still got only a dark purple screen, and the machine stops during the selftest. The floppy drive doesn't reacts, but the Caps Lock is blinks as usual during reset.
BTW, does the A500+ gives colour signal on the Composite output or still B/W as the A500?
Thanks in advance.

davideo · 06 June 2010, 23:08

Quote:

Originally Posted by Reynolds

BTW, does the A500+ gives colour signal on the Composite output or still B/W as the A500?
Thanks in advance.

AFAIR only the 2000 gives BW output on the composite.

Good luck with fixing the 500+

Dave G

Zetr0 · 07 June 2010, 01:41

@reynolds

take some pictures of the area, we might be able to offer som suggestions.

My initial thoughts lead me to believe that it is quite likely that the GARY chip needs replacing, do you have a spare?

Hewitson · 07 June 2010, 05:39

Quote:

Originally Posted by davideo

AFAIR only the 2000 gives BW output on the composite.

Good luck with fixing the 500+

Dave G

Nope. 500 and 2000 definitely do. No idea about the 500+. Being in Hungary, wouldn't you have a SCART TV anyway?

alexh · 07 June 2010, 09:47

A500+ is B&W on composite.

Reynolds · 07 June 2010, 11:29

Quote:

Originally Posted by davideo

AFAIR only the 2000 gives BW output on the composite.

Good luck with fixing the 500+

Dave G

Thanks, Hope I'll have success. I have so many nice pieces of hw for this machine, I'd like to "play" with 'em.

Reynolds

Reynolds · 07 June 2010, 11:31

Quote:

Originally Posted by Zetr0

@reynolds

take some pictures of the area, we might be able to offer som suggestions.

My initial thoughts lead me to believe that it is quite likely that the GARY chip needs replacing, do you have a spare?

I've replaced the Gary with an other one, had the same result.
Tonight I'll make some shots.
BTW, what can be used to remove the dried acid from the components, solderpoints? (I know, there can be already a discussion in another thread, but asking is faster for me.

Thanks,
Reynolds

Reynolds · 07 June 2010, 11:36

Quote:

Originally Posted by Hewitson

Nope. 500 and 2000 definitely do. No idea about the 500+. Being in Hungary, wouldn't you have a SCART TV anyway?

I have telly with scart connector, but it's in the living room and there is not too much space for tryouts. And I don't want to turn everything upside down. I have a small 14" Sanyo for these checks.
I'm asking this because when I turn on the tv for the A500+ I see dark purple screen what I can't understand, as I thought that this machine should give B/W screen on composite out, so I was surprised.

Reynolds

Zetr0 · 07 June 2010, 12:06

@Reynolds

strangely enough lemon juice or vinigar are great at removing the compounded acidic oxides, after that I would suggest some IPA (isopropyl alcohol) or a dilute (car screen wash) and a smige of water to finish off.

That will neutralize the acidic oxides and stop the copper from corroding more of itself away.

I would then inspect the area for damaged traces and use a multimeter to buzz out suspected tracks. Also look at other effected chips and sockets, I once had an A2000 that the acid had eaten its way to the CPU legs. The acid reacted with the zinc in the metal of the cpu legs - so much so it wouldn't conduct electrickery...

Once I removed the cpu from the socket i gently brushed my finger alongside the the legs on one side of the CPU, and they just fell off and fluttered away like paper... the CPU is now on my keyring =)

Reynolds · 07 June 2010, 13:31

Good, then I'll "give a bath" for the affected area.
The Gary seem to have no problem, as all the legs have been coverred by the crystallized acid, but also all of them still strong enough and no visible color change on them.

davideo · 07 June 2010, 18:24

Quote:

Originally Posted by Hewitson

Nope. 500 and 2000 definitely do. No idea about the 500+. Being in Hungary, wouldn't you have a SCART TV anyway?

An old body and an older brain don't always remember correctly

Although the above is correct if you stick a modulator (A520) in the Miggy you can use the video out and get colour

(That's the way I was remembering because that's what I used to do it years ago.)

Dave G

Reynolds · 07 June 2010, 23:32

Here are the photos I did:

http://imgur.com/k3ciw.jpg
http://imgur.com/NfbYC.jpg
http://imgur.com/1k7Zy.jpg
http://imgur.com/mjFLe.jpg
http://imgur.com/pCr48.jpg
http://imgur.com/SJyxQ.jpg
http://imgur.com/Xaxgj.jpg

Hope these are good enough.

alexh · 07 June 2010, 23:55

Quote:

Originally Posted by Reynolds

I'm asking this because when I turn on the tv for the A500+ I see dark purple screen what I can't understand, as I thought that this machine should give B/W screen on composite out, so I was surprised.

Not surprising at all. The TV supports colour composite. Whatever is coming out of the A500 (which is only capable of B&W) is so incredibly wrong it is being interpreted as colour bursts.

Zetr0 · 08 June 2010, 02:07

@Reynolds

Its not looking good =(

Ground Plane Damage

Bottom right of GARY (next to RP105)
From C12 (on the right of U12)
U12 (pin 20) ground plane looks damaged

Power Plane Damage

on the right of BT9 (battery) *just before the Audio filter*

Jumper Damage

JP9

Track Damage

Lots

Suggestions
If you want to attempt to save the board you will need some 800 fine grit wet/dry sandpaper.

remove the chips, sockets and discrete components from the affected area and gently take off the top laqure of the pcb and the oxidizing copper.

repair the tracks that have been destroyed (with 30awg Kaynar or Jumpwire) replace the discrete components with new ones (thats resistors / dioded and caps)

solder in the sockets and IC's

protect the board with PCB laqure.

You are looking at a good 8 hours work here even with a plan of attack (schematics). Unfortunately theres NO garantee that it will work. I should also mention there may be damage on the reverse of the motherboard pcb also.

Unless it is something you hope to learn from, this board should be resigned to the Amiga Heaven in the Sky, of course, remove all sockets, chips and ports that are worth saving and responsibly recycle the rest =(

Reynolds · 08 June 2010, 11:45

This is more than I can do by myself. It means that I will rescue the other components, and let this pcb rest in peace. If once the A500 ++ will be available, then I'll have housing for it.
Still, buying this one I can say I haven't regret, as I won an original box, some other bits 'n' pieces and a Kickstart switcher with 1.3 and 2.0 chips.
I think the A500 mobos are indestructable, and the A500+ as well, if you remove those #@&%! batteries in time...

rkauer · 08 June 2010, 21:10

A500 units have their own issues, too.

Brittle Agnus socket, too sensitive RAM and CIA chips.

06 June 2010, 22:18	#1
Reynolds Alien Breeder Join Date: Dec 2007 Location: Szigetszentmiklos / Hungary Age: 46 Posts: 1,096	Amiga 500+ fails at powerup Hi folks, I need some advices. I bought an A500+ recently. It was advertised as "dead", so I wasn't surprised, altough I'd like to fix it. The first thing I did after it's arrived, that I removed the plastic, and metal covers. Then, when I came back from unconsciousness, immediately removed the leaked barrel battery. Sadly the mobo around it was affected in it's melting, so i've started to clean it. Bad think that the Gary chip also fave been influenced by the acid, and when I removed it from the socket, it was broken into pieces. The chip itself still working, but I have had to replace the socket. Now it's done, but still got only a dark purple screen, and the machine stops during the selftest. The floppy drive doesn't reacts, but the Caps Lock is blinks as usual during reset. BTW, does the A500+ gives colour signal on the Composite output or still B/W as the A500? Thanks in advance.

08 June 2010, 02:07	#14
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@Reynolds Its not looking good =( Ground Plane Damage Bottom right of GARY (next to RP105) From C12 (on the right of U12) U12 (pin 20) ground plane looks damaged Power Plane Damage on the right of BT9 (battery) just before the Audio filter Jumper Damage JP9 Track Damage Lots Suggestions If you want to attempt to save the board you will need some 800 fine grit wet/dry sandpaper. remove the chips, sockets and discrete components from the affected area and gently take off the top laqure of the pcb and the oxidizing copper. repair the tracks that have been destroyed (with 30awg Kaynar or Jumpwire) replace the discrete components with new ones (thats resistors / dioded and caps) solder in the sockets and IC's protect the board with PCB laqure. You are looking at a good 8 hours work here even with a plan of attack (schematics). Unfortunately theres NO garantee that it will work. I should also mention there may be damage on the reverse of the motherboard pcb also. Unless it is something you hope to learn from, this board should be resigned to the Amiga Heaven in the Sky, of course, remove all sockets, chips and ports that are worth saving and responsibly recycle the rest =(

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07 June 2010, 01:41	#3
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@reynolds take some pictures of the area, we might be able to offer som suggestions. My initial thoughts lead me to believe that it is quite likely that the GARY chip needs replacing, do you have a spare?

07 June 2010, 09:47	#5
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,331	A500+ is B&W on composite.

07 June 2010, 12:06	#9
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@Reynolds strangely enough lemon juice or vinigar are great at removing the compounded acidic oxides, after that I would suggest some IPA (isopropyl alcohol) or a dilute (car screen wash) and a smige of water to finish off. That will neutralize the acidic oxides and stop the copper from corroding more of itself away. I would then inspect the area for damaged traces and use a multimeter to buzz out suspected tracks. Also look at other effected chips and sockets, I once had an A2000 that the acid had eaten its way to the CPU legs. The acid reacted with the zinc in the metal of the cpu legs - so much so it wouldn't conduct electrickery... Once I removed the cpu from the socket i gently brushed my finger alongside the the legs on one side of the CPU, and they just fell off and fluttered away like paper... the CPU is now on my keyring =)

07 June 2010, 13:31	#10
Reynolds Alien Breeder Join Date: Dec 2007 Location: Szigetszentmiklos / Hungary Age: 46 Posts: 1,096	Good, then I'll "give a bath" for the affected area. The Gary seem to have no problem, as all the legs have been coverred by the crystallized acid, but also all of them still strong enough and no visible color change on them.

07 June 2010, 23:32	#12
Reynolds Alien Breeder Join Date: Dec 2007 Location: Szigetszentmiklos / Hungary Age: 46 Posts: 1,096	Here are the photos I did: http://imgur.com/k3ciw.jpg http://imgur.com/NfbYC.jpg http://imgur.com/1k7Zy.jpg http://imgur.com/mjFLe.jpg http://imgur.com/pCr48.jpg http://imgur.com/SJyxQ.jpg http://imgur.com/Xaxgj.jpg Hope these are good enough.

08 June 2010, 11:45	#15
Reynolds Alien Breeder Join Date: Dec 2007 Location: Szigetszentmiklos / Hungary Age: 46 Posts: 1,096	This is more than I can do by myself. It means that I will rescue the other components, and let this pcb rest in peace. If once the A500 ++ will be available, then I'll have housing for it. Still, buying this one I can say I haven't regret, as I won an original box, some other bits 'n' pieces and a Kickstart switcher with 1.3 and 2.0 chips. I think the A500 mobos are indestructable, and the A500+ as well, if you remove those #@&%! batteries in time...

08 June 2010, 21:10	#16
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	A500 units have their own issues, too. Brittle Agnus socket, too sensitive RAM and CIA chips.

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