Dead Amiga 4000 motherboard; what next

[MastaTabs]

there are propably only two possibilities.

1. Shortcut against ground or vcc. Might be caused by a borked ttl chip or resistor.

2. another driver driving on the same net the same time ramsey is active.

At first I'd check all data and address lines from/to ramsey for short curcuits against vcc/gnd. If thats not the cause then have a look at the schematics and check for possible ttls or gals with connections to ramsey. At first possibly only with connections to ramsey as other parts don't seem to get hot.

[PulsatingQuasar]

Whoohoooo.

Other Amiga 4000 mainbord giving a Kickstart screen now. The one with the overheating Ramsey.

On a German forum I read some people with a overheating Ramsey because of R79( below the CPU board connector next to the screw hole on the Ramsey side) having died. For me that was not the case. R79 measured it's exact value.

So after some measuring of the SIMM's and the Ramsey pins for a short cirquit I thought what if one of the tracks in relation to R79 has been broken and hey presto!! That was it.

The small 7 mm track between resistor R79 and the via at the side of the motherboard was broken. Don't know what the previous owner did to manage that but glad that was it.

Tomorrow I'll test to see if something else is broken. I hope not.

[freqmax]

Couldn't repair information like.. if RAMSEY is overheating then check R79. Be collected in a Amiga wiki such that people can keep the remaining Amigas working ..?

[PulsatingQuasar]

Did some more testing now.

All RAM banks are OK. Keyboard and mouse are working and the floppy drive is also working.

Haven't tested the harddisk yet but I don't think the IDE port is dead.

I have already changed all capacitors by new ones. Now only to add a new battery and this motherboard is fully functional.

[rkauer]

 If you want to sell one of those 4k boards, I might be interested.

 I have one here that is totally destroyed ( 1/8 of the board is corroded away by a battery leak). All traces of SIMM banks (including chip RAM), RTC, mouse/joy area all simply wiped out!

 Daughter board is perfect.

[Dale]

Whoohoooo.

Other Amiga 4000 mainbord giving a Kickstart screen now. The one with the overheating Ramsey.

On a German forum I read some people with a overheating Ramsey because of R79( below the CPU board connector next to the screw hole on the Ramsey side) having died. For me that was not the case. R79 measured it's exact value.

So after some measuring of the SIMM's and the Ramsey pins for a short cirquit I thought what if one of the tracks in relation to R79 has been broken and hey presto!! That was it.

The small 7 mm track between resistor R79 and the via at the side of the motherboard was broken. Don't know what the previous owner did to manage that but glad that was it.

Tomorrow I'll test to see if something else is broken. I hope not.

First off I know this thread is old, but I want to thank you for writing this down. I have the same exact problem and it was the same small trace between R79 and I believe 5V. Unlike yours, Mine had other issues with my clock that I repaired and tested already, put it back into the case and I get a grey screen. I did not even think to check the Ramsey until I found this article, so I dropped my 030 board in there and did the same thing and found the Ramsey to be hot as well. So did the same checks you did and noticed the same exact problem. Thank you!