English Amiga Board


Go Back   English Amiga Board > Support > support.Hardware

 
 
Thread Tools
Old 17 July 2019, 21:14   #1
KLund1
Registered User

 
Join Date: Oct 2018
Location: Livermore CA
Posts: 24
Amiga 2000 Green Screen, nube help please

Hi
I got a 2000 that boots to only a green screen. The power red LED blinks 10 times then a quick blink then repeats. I have stripped the machine down to just the motherboard and PSU. As I pulled parts off, one at a time and retested, I got the same results. The battery was pulled off long ago, and there looks to be just minor corrosion that dose not appear to have moved to the CPU. The CPU pins and socket are clean. no visible corrosion near the socket or near by long resistors and 62402.

I have pulled all the socketed IC's and reseated them. No change in output.


I am still pretty new to Amiga and am asking for a bit of guidance on trouble shooting this. MB pic attached.
Thanks
Attached Thumbnails
Click image for larger version

Name:	DSCN2965[1].jpg
Views:	62
Size:	1.06 MB
ID:	63794  
KLund1 is offline  
Old 17 July 2019, 21:48   #2
DofD
Registered User

 
Join Date: Jun 2018
Location: Victoria, Canada
Age: 51
Posts: 134
Hi there.

The green boot screen generally means there is a chip RAM issue. The power light blinking is telling that some error was found during the self tests. The repeating pattern is the A2000 rebooting and trying to start again.

I would suggest cleaning and neutralizing the green battery corrosion asap. The corrosion can get into the copper traces and can destroy them over time. The resistor right by the battery may need replacing.

Another thing is that the Agnus chip may be bad or not seated correctly. Try pulling it, cleaning the chip and socket, then reseat.

Something else to try is to get a Diag ROM to help diagnose the problem to a lower level.
DofD is offline  
Old 17 July 2019, 22:56   #3
KLund1
Registered User

 
Join Date: Oct 2018
Location: Livermore CA
Posts: 24
Many thanks, I'll do that.
Which is the Agnus chip? the smaller ic near the cpu?
I can burn and eprom. Where is the file for that? What size eprom? I do not see a socket that would fit most eproms, where would a diag rom go?
Again thanks for the reply!
KLund1 is offline  
Old 18 July 2019, 00:08   #4
R4M
Registered User

 
Join Date: Jan 2019
Location: /home
Posts: 63
You can download the Diagrom at diagrom.com.

The ROM is the chip on the right side of the CPU on all board revisions that I checked.

Agnus is the big square PGA one.
R4M is offline  
Old 18 July 2019, 00:27   #5
Vypr
Registered User

 
Join Date: Dec 2016
Location: East Kilbride, Scotland
Posts: 132
Quote:
Originally Posted by KLund1 View Post
Many thanks, I'll do that.
Which is the Agnus chip? the smaller ic near the cpu?
I can burn and eprom. Where is the file for that? What size eprom? I do not see a socket that would fit most eproms, where would a diag rom go?
Again thanks for the reply!
Agnus is the PLCC chip marked on the board as 'Fat Lady', you will need a PLCC extractor tool. For the love of Bob do not use a screwdriver or a normal chip extraction tool, you'll just wreck the chip and/or the socket.

For an EPROM you will need a 27C400 chip, you can find them on eBay for a few bucks each and if you have a programmer then it's handy to buy a couple spare.

What kind of EPROM programmer do you have? If it's a TL866 then you will need an adaptor board as they don't support the 27C400 natively.
Vypr is offline  
Old 18 July 2019, 02:41   #6
KLund1
Registered User

 
Join Date: Oct 2018
Location: Livermore CA
Posts: 24
Thanks everyone!
I had already reseated the Agnus IC with the correct puller. No change. Pins and socket look good. But it still could be a bad chip.
I found a 40 pin eprom. Had to dig deep for that many pins. It is an 8752. I'm using a TL866CS to program it.
I found the DiagRom files. Since I only have the one eprom, I must assume I need to use the 16bit file to program it. Y/N? But there are several files to choose from. Perhaps I should use DiagRom or DiagRomA1K file? I'm skipping the hi/lo, odd/even sets of files.
Thoughts?
KLund1 is offline  
Old 18 July 2019, 08:33   #7
demolition
Unregistered User
demolition's Avatar
 
Join Date: Sep 2012
Location: Copenhagen / DK
Age: 39
Posts: 3,952
16bit.bin is the one you need to use for an A2000.

When you write 8752 do you mean 87c52? Because that is a microcontroller and not an EPROM so that will not work. You need something like a 27c400/800.
demolition is offline  
Old 18 July 2019, 18:58   #8
KLund1
Registered User

 
Join Date: Oct 2018
Location: Livermore CA
Posts: 24
it is a Intel D8752BH, oh well.
I'll just get a programmed unit from ebay.
KLund1 is offline  
Old 18 July 2019, 19:03   #9
KLund1
Registered User

 
Join Date: Oct 2018
Location: Livermore CA
Posts: 24
Just to check, I only need a single chip version for my board? see pic 1. I am not sure which version of board I have.
Thanks
KLund1 is offline  
Old 18 July 2019, 20:13   #10
DofD
Registered User

 
Join Date: Jun 2018
Location: Victoria, Canada
Age: 51
Posts: 134
Yes, the A2000 only uses one ROM chip. From the picture, I can't make out which revision you have. It looks to be written on the motherboard at the front of the Zorro slots.
DofD is offline  
Old 18 July 2019, 21:59   #11
KLund1
Registered User

 
Join Date: Oct 2018
Location: Livermore CA
Posts: 24
Thanks!
Ordered one from ebay.
Looks this board is rev 4.4
I'll check back with results when the chip arrives.
I appreciate everyones input!!
KLund1 is offline  
Old 14 August 2019, 00:43   #12
KLund1
Registered User

 
Join Date: Oct 2018
Location: Livermore CA
Posts: 24
OK, I'm back to this. The diagRom 1.1 arrived today. Took a while to get here.
Now which socket do I put it into?
Thanks
KLund1 is offline  
Old 14 August 2019, 01:03   #13
demolition
Unregistered User
demolition's Avatar
 
Join Date: Sep 2012
Location: Copenhagen / DK
Age: 39
Posts: 3,952
On Rev6 boards the ROM is called U500.
demolition is offline  
Old 14 August 2019, 01:09   #14
KLund1
Registered User

 
Join Date: Oct 2018
Location: Livermore CA
Posts: 24
I figured out where to put it.
I get a green and red flashing screen on power up.
After a couple minutes it changes to red horizontal lines with 2 shades or green or or red 1/4 screen horizontal sections.
KLund1 is offline  
Old 14 August 2019, 01:10   #15
KLund1
Registered User

 
Join Date: Oct 2018
Location: Livermore CA
Posts: 24
This board is rev 4.5
KLund1 is offline  
Old 14 August 2019, 01:27   #16
demolition
Unregistered User
demolition's Avatar
 
Join Date: Sep 2012
Location: Copenhagen / DK
Age: 39
Posts: 3,952
The flashing is normal and indicates various running tests, but you should see a menu after a little while. I can recommend to connect a PC with a null modem to the serial port so you can see the progress (I use a USB-RS232 adapter as my PC do not have a native COM port). This will also enable you to run tests even if you get no screen output.
demolition is offline  
Old 14 August 2019, 04:23   #17
Vypr
Registered User

 
Join Date: Dec 2016
Location: East Kilbride, Scotland
Posts: 132
Quote:
Originally Posted by KLund1 View Post
I figured out where to put it.
I get a green and red flashing screen on power up.
After a couple minutes it changes to red horizontal lines with 2 shades or green or or red 1/4 screen horizontal sections.
That means there was a problemduring the RAM check. Either1 or more of the RAM chips are dead or there are 1 or more broken traces somewhere. I would break out a multimeter and try and find a schematic.

I've had an A500+ and a Rev 6 A2000 give me this error before. On the 500 it was broken traces caused by battery damage and on the 2000 a power surge from a faulty PSU killed the chips
Vypr is offline  
Old 20 August 2019, 20:09   #18
KLund1
Registered User

 
Join Date: Oct 2018
Location: Livermore CA
Posts: 24
Thanks everyone!
I do not see any damage to the traces near the memory. They are too far from the small damage left by the battery. But it could deeper in the board. I have a logic probe. Could I use that to find the bad chip(s). If so, how? Or like Atari XL/XE's do they become a lot hotter than other chips? What about piggyback testing?
If I get a null modem to serial (I have a modem to serial, not null) I would need to run some software on the PC. WHere to get, how to use?
KLund1 is offline  
Old 20 August 2019, 20:20   #19
Vypr
Registered User

 
Join Date: Dec 2016
Location: East Kilbride, Scotland
Posts: 132
First thing I would do is carefully prise the CPU out of it's socket and check for corrosion on the pin and socket. Pins 1 to 5 are closest to the damage and they often corrode badly. Since they are data lines if they are not making good contact you will get a green screen at boot.
Get some contact cleaner and an anti static brush (or a toothbrush, works as well) and give the socket a good scrub. Then give it a test.
If you are feeling brave enough and semi-decent with a soldering iron, it may be better to replace the whole socket.
Vypr is offline  
Old 20 August 2019, 20:24   #20
demolition
Unregistered User
demolition's Avatar
 
Join Date: Sep 2012
Location: Copenhagen / DK
Age: 39
Posts: 3,952
Quote:
Originally Posted by KLund1 View Post
Thanks everyone!
I do not see any damage to the traces near the memory. They are too far from the small damage left by the battery. But it could deeper in the board. I have a logic probe. Could I use that to find the bad chip(s). If so, how? Or like Atari XL/XE's do they become a lot hotter than other chips? What about piggyback testing?
If I get a null modem to serial (I have a modem to serial, not null) I would need to run some software on the PC. WHere to get, how to use?
On my A2000, several bus lines were broken close to the battery area. Although the memory chips themselves were not close to the battery, several of the signals ran just past the battery. Mine is a rev 4.4 so it may be different on a rev. 4.5. I don't know that one.


Follow the schematic and check the bus lines systematically one at a time from IC pin to IC pin using a continuity tester and you should be able to find if there are some broken ones. You need to check the busses on either side of the bus interface ICs. And as there is probably a bit of oxidation on the IC pins, you may need to 'scrape' the surface a bit to establish contact with the probe.



To debug using the serial port, you need a terminal program. I use PuTTY for Windows or minicom in Linux/BSD.



FYI, DiagROM v. 1.2 was just released which has several improvements that could be useful.
demolition is offline  
 


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
Amiga 500 Rev 6a green screen Mark sealey support.Hardware 11 25 April 2019 17:06
Amiga 1000 Green and Black screen only arjanv support.Hardware 2 06 June 2017 20:02
Amiga 600 green screen and blinking powerled realsector support.Hardware 14 21 December 2015 23:19
Amiga 500 green screen when on...after connecting sega pad Cadderlik support.Hardware 10 16 February 2015 11:00
Amiga 500 green screen and problematic A501 Solo761 support.Hardware 9 02 May 2014 09:10

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +2. The time now is 14:59.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Page generated in 0.08414 seconds with 14 queries