A500+ Black screen, was working then just stopped

steelej80 · 10 February 2021, 19:55

Hey Guys,

Yesterday while retrieving something from my loft my old Amiga box caught my eye and at that very moment getting it up and running seemed to be the most important task on my list, lol. It didn't seem to want to work at first, I thought I wasn't seeing anything due to my scart to hdmi converter but I also noticed no click from the floppy drive. I reset a couple of times just using ctrl+amiga+amiga and it kicked into life. Worked for a few hours then just went back to black screen.

I've never changed the battery on this so I opened it up and the battery was fuzzy and looked like it had leaked some on the board, I've now removed the battery. Overall the board looked pretty clean, it's been in a clean dry and reasonably warm loft for the last 15 years or something so I couldn't see much if any corrosion on the board except for around the battery area. I've attached a few pics, it looks to me like some of the tracks are broken coming from R112 and R101 and others around that area. Would this be the likely cause of my black screen? While I'm somewhat technical I wouldn't say I was great at electronics repair so any tips on how to repair those tracks would be appreciated if it's the likely cause of my issue.

Thanks guys for any assistance in this very important task that wasn't even on my radar this time a few days ago

John.

Vypr · 10 February 2021, 22:13

First thing you want to do is get some white vinegar or lemon juice and splash it on the battery area to neutralize the battery alkali that has leaked on the board because that stuff lingers and will continue to corrode the board even though the battery has been removed.

Get a multimeter and start checking continuity on the traces from components around that area. In my experience, it's always the tracks under U12 that go first and there is a lot of corrosion visible on the pins. You wouldn't get a black screen from that , the symptoms you get from that are a Green screen because that chip is a buffer for the RAM.
Also pull the Gary chip and check the socket, it's likely the socket is corroded. Taking the chip out and giving the socket a good scrub with an old toothbrush and some IPA alcohol would help although you may have to replace the socket.

steelej80 · 11 February 2021, 15:01

Thanks Vypr,

I've reseated and cleaned all the chips I can but no difference, the Gary socket looks quite clean but again I'm no electronics expert

I'll break out the multimeter and see what I can find

John.

steelej80 · 11 February 2021, 21:13

all the traces around the battery area are showing good continuity, for the sake of a tenner I've ordered a new CPU to try incase that's gubbed.

I'll report back once I've tried it.

John.

mart1n · 11 February 2021, 23:11

Haven't got that much to add other than it looks like you have quite a lot of alkaline "north" of Gary as well. All of the small specks on your photo is most likely alkaline. I would clean the entire PCB with isopropanol before extracting most of the socketed chips in order to assess the damage. Then use vinegar too neutralize the alkaline.

btp · 11 February 2021, 23:51

After neutralizing the battery alkaline and properly cleaning everything use Amiga PCB explorer (https://www.amigapcb.org/) to verify continuity on as many traces as possible.

steelej80 · 12 February 2021, 14:06

Thanks all, will keep plugging away at it

John.

steelej80 · 16 February 2021, 16:32

Hey Guys,

Coming back to this one, the Amiga lives again!

It was pin2 from Gary to the resistor pictured that wasn't right, I now need to go and make this a permanent repair

thanks for all the help and advice.

John.

mart1n · 17 February 2021, 00:09

Great stuff! The A500+ is by far my favourite Amiga but it will need attention especially when dealing with battery leakage. Make sure to clean everything so that you can enjoy it for years to come.

steelej80 · 17 February 2021, 13:29

my next question is on that, what's the best way to deal with the decent sized bit of corrosion at the battery? do I need to scrape it all away, will it continue to corrode like an old Ford Escort if I don't remove it or treat it in some way?

John.

Jope · 17 February 2021, 16:17

Pour strong vinegar on it and then wash it away after the bubbling has stopped.

Vypr · 17 February 2021, 16:50

You need to neutralize any remaining alkali form the battery leak as I described in my first post (White vinegar or lemon juice), clean it up with some isoprpyl alchol. Use a fibreglass pen to clean off any remaining corrosion then apply a coat of PCB lacquer would be the best way to finish up.

steelej80 · 17 February 2021, 17:28

Fab, thanks all.

John.

10 February 2021, 19:55	#1
steelej80 Registered User Join Date: Feb 2021 Location: Scotland Posts: 7	A500+ Black screen, was working then just stopped Hey Guys, Yesterday while retrieving something from my loft my old Amiga box caught my eye and at that very moment getting it up and running seemed to be the most important task on my list, lol. It didn't seem to want to work at first, I thought I wasn't seeing anything due to my scart to hdmi converter but I also noticed no click from the floppy drive. I reset a couple of times just using ctrl+amiga+amiga and it kicked into life. Worked for a few hours then just went back to black screen. I've never changed the battery on this so I opened it up and the battery was fuzzy and looked like it had leaked some on the board, I've now removed the battery. Overall the board looked pretty clean, it's been in a clean dry and reasonably warm loft for the last 15 years or something so I couldn't see much if any corrosion on the board except for around the battery area. I've attached a few pics, it looks to me like some of the tracks are broken coming from R112 and R101 and others around that area. Would this be the likely cause of my black screen? While I'm somewhat technical I wouldn't say I was great at electronics repair so any tips on how to repair those tracks would be appreciated if it's the likely cause of my issue. Thanks guys for any assistance in this very important task that wasn't even on my radar this time a few days ago John. Attached Thumbnails

11 February 2021, 15:01	#3
steelej80 Registered User Join Date: Feb 2021 Location: Scotland Posts: 7	Thanks Vypr, I've reseated and cleaned all the chips I can but no difference, the Gary socket looks quite clean but again I'm no electronics expert I'll break out the multimeter and see what I can find John. Attached Thumbnails

16 February 2021, 16:32	#8
steelej80 Registered User Join Date: Feb 2021 Location: Scotland Posts: 7	Hey Guys, Coming back to this one, the Amiga lives again! It was pin2 from Gary to the resistor pictured that wasn't right, I now need to go and make this a permanent repair thanks for all the help and advice. John. Attached Thumbnails

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10 February 2021, 22:13	#2
Vypr Registered User Join Date: Dec 2016 Location: East Kilbride, Scotland Posts: 452	First thing you want to do is get some white vinegar or lemon juice and splash it on the battery area to neutralize the battery alkali that has leaked on the board because that stuff lingers and will continue to corrode the board even though the battery has been removed. Get a multimeter and start checking continuity on the traces from components around that area. In my experience, it's always the tracks under U12 that go first and there is a lot of corrosion visible on the pins. You wouldn't get a black screen from that , the symptoms you get from that are a Green screen because that chip is a buffer for the RAM. Also pull the Gary chip and check the socket, it's likely the socket is corroded. Taking the chip out and giving the socket a good scrub with an old toothbrush and some IPA alcohol would help although you may have to replace the socket.

11 February 2021, 21:13	#4
steelej80 Registered User Join Date: Feb 2021 Location: Scotland Posts: 7	all the traces around the battery area are showing good continuity, for the sake of a tenner I've ordered a new CPU to try incase that's gubbed. I'll report back once I've tried it. John.

11 February 2021, 23:11	#5
mart1n Registered User Join Date: Feb 2021 Location: Stockholm Posts: 18	Haven't got that much to add other than it looks like you have quite a lot of alkaline "north" of Gary as well. All of the small specks on your photo is most likely alkaline. I would clean the entire PCB with isopropanol before extracting most of the socketed chips in order to assess the damage. Then use vinegar too neutralize the alkaline.

11 February 2021, 23:51	#6
btp Registered User Join Date: Aug 2017 Location: Greece Posts: 145	After neutralizing the battery alkaline and properly cleaning everything use Amiga PCB explorer (https://www.amigapcb.org/) to verify continuity on as many traces as possible.

12 February 2021, 14:06	#7
steelej80 Registered User Join Date: Feb 2021 Location: Scotland Posts: 7	Thanks all, will keep plugging away at it John.

17 February 2021, 00:09	#9
mart1n Registered User Join Date: Feb 2021 Location: Stockholm Posts: 18	Great stuff! The A500+ is by far my favourite Amiga but it will need attention especially when dealing with battery leakage. Make sure to clean everything so that you can enjoy it for years to come.

17 February 2021, 13:29	#10
steelej80 Registered User Join Date: Feb 2021 Location: Scotland Posts: 7	my next question is on that, what's the best way to deal with the decent sized bit of corrosion at the battery? do I need to scrape it all away, will it continue to corrode like an old Ford Escort if I don't remove it or treat it in some way? John.

17 February 2021, 16:17	#11
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,879	Pour strong vinegar on it and then wash it away after the bubbling has stopped.

17 February 2021, 16:50	#12
Vypr Registered User Join Date: Dec 2016 Location: East Kilbride, Scotland Posts: 452	You need to neutralize any remaining alkali form the battery leak as I described in my first post (White vinegar or lemon juice), clean it up with some isoprpyl alchol. Use a fibreglass pen to clean off any remaining corrosion then apply a coat of PCB lacquer would be the best way to finish up.

17 February 2021, 17:28	#13
steelej80 Registered User Join Date: Feb 2021 Location: Scotland Posts: 7	Fab, thanks all. John.

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