Resurrecting an old A600?

[alenppc]

Ok, so I got my hands on my own very first A600. It had been thrown somewhere in storage for a huge number of years. Since then I had owned just about every existing Amiga (the only exceptions being 3000/CDTV/CD32), and I have another working A600 which is in great shape and I have restarted using daily.

So, I decided to see if The Number 1 could be brought to life. I remember that one of the on-board 8520s had been damaged since a long time ago due to a faulty peripheral, but the Amiga would still sort of work: at least it would power up. Years ago, that is.

So I took the motherboard out and tried to power it up. No luck :/ There is a short circuit somewhere. I inspected the motherboard and found that apparently years ago I had burned and patched a trace going from the PSU connector. This still appears to be patched and connected properly and not causing a short with anything else. God knows how I managed to do that... I wasn't very kind to my hardware in my early years, clearly.

I have no memory of anything causing the short circuit though. The last I remember, it would still power up. So something else must have happened during the long years of storage that causes the short now... Not sure if anything can be done now at this point... and now clue where to start looking even.

[kipper2k]

Originally Posted by alenppc

Ok, so I got my hands on my own very first A600. It had been thrown somewhere in storage for a huge number of years. Since then I had owned just about every existing Amiga (the only exceptions being 3000/CDTV/CD32), and I have another working A600 which is in great shape and I have restarted using daily.

So, I decided to see if The Number 1 could be brought to life. I remember that one of the on-board 8520s had been damaged since a long time ago due to a faulty peripheral, but the Amiga would still sort of work: at least it would power up. Years ago, that is.

So I took the motherboard out and tried to power it up. No luck :/ There is a short circuit somewhere. I inspected the motherboard and found that apparently years ago I had burned and patched a trace going from the PSU connector. This still appears to be patched and connected properly and not causing a short with anything else. God knows how I managed to do that... I wasn't very kind to my hardware in my early years, clearly.

I have no memory of anything causing the short circuit though. The last I remember, it would still power up. So something else must have happened during the long years of storage that causes the short now... Not sure if anything can be done now at this point... and now clue where to start looking even.

Hi,

Depending on which 8520 is fried (and how) this can affect the boot up. You never said if you used a known good psu to try to power up the A600, thats the first test.

if the PSU is good (which you can test by using it on known good Amiga) then you need to look on the motherboard to see if you have leaking capacitors which once they go can cause trace damage and generally not provide enough power for the Amiga to boot up.
Also check voltage levels at different areas of the motherboard to see if power is reaching floppy header, joystick/mouse ports (Pin 7, 5v on both ports) etc. That will tell you if power is actually making it through the board. Check your trace fix to see if its still holding up. if you have KS 3.1 and you do not hook up floppy drive and a HDD then the A600 will take up to 30 seconds to boot so you may not be waiting long enough. if all your checks fail you could send to me and i can check it out for you

[alenppc]

Originally Posted by kipper2k

if the PSU is good (which you can test by using it on known good Amiga) then you need to look on the motherboard to see if you have leaking capacitors which once they go can cause trace damage and generally not provide enough power for the Amiga to boot up.

Hi!

Thanks for the suggestions. The PSU that I am using is good, it's a PC AT power supply to which I have added the square Amiga connector that I regularly use with the other A600, as well as 500s, 1200s and so on.

The PSU in fact immediately goes into protection mode as soon as I switch it on indicating a short somewhere (squealing noise), after which I immediately switch it off. I can try to look at the caps tomorrow. I am also going to try to add some load onto the PSU by adding a HDD onto a separate connector in case it's the bare motherboard that draws too little power that's causing this.

I am not sure which 8520 is damaged: i know it's the one controlling the parallel port, since it was a faulty printer that killed it, although that can be replaced eventually.

[alenppc]

@kipper2k, do you have the equipment necessary for fixing SMD components?

[ramparts]

Hi from Portugal i think i had a talk with kipper last year i burned something while dessoldering the motorolla mc68000 to conect a propper socket ,i recomended that you have the propper equipement plus the no clean soldering liquid or else you burn and desolder the via or the traces with a multimeter try to check every circuit ,this month i took alive an zx spectrum +3 of my collection because it wouldn´t read tapes just the floppy and was 3 stupid in4148 that i dessoldered when arrive because i think it was a not expert hands on it, and in fact amstrad realises one thing:

fuc...cking shit i forgot 3 in4148 and 3 more components on the project !!!!.
oh well let´s solder them ,on the solder side

[kipper2k]

Originally Posted by alenppc

@kipper2k, do you have the equipment necessary for fixing SMD components?

Hi,

Yep, i can remove and replace smds, sockets etc. I've fixed quite a few machines If you don't have the proper tools then don't try as you will probably rip up traces. There are a few ways of removing them, Chipqwik, hot air, desoldering braid and combinations thereof. and lots of patience

[lloyd]

Cool - so if you know how to do all this, thats a start.

First I'd suggest finding out if you really do have a short circuit, and if so, in which circuit is it in. Remember that the Amiga has a 5 and 12 volt line. See which part of the supply is actually at fault.

If it has been stored for a significant period of time, I'd suspect that the electrolytic capacitors have failed. Don't even bother checking them, just replace with brand new ones - and that includes the tantalum capacitors also, especially those used for supply decoupling/filtering, they are well known for going short circuit. Honestly, tantalum caps are nowhere near as reliable as some people would have you believe.

[ramparts]

Smooooking
Let´s bring amigas from the dead i hear thriller already

[kipper2k]

Originally Posted by ramparts

Smooooking
Let´s bring amigas from the dead i hear thriller already

@Ramparts,

i cant send you a msg as you have that option disabled, heres what i tried to msg you...

The only way to test the spares safely is to put a 68 pin socket on the motherboard and then put the 68000 chip into the socket, anytime you remove a chip off the board its always best to put a socket on. Only way i know of testing the cpu is to put a socket on a working A600 and put in the cpu to be tested

[ramparts]

Sory kipper i had make some changes on page i hope now it works since contacted some persons and really not geting any info.if can please sent me a test message,and thank you for the reply the socket is already on amiga 600 board ,but i am still not getting to work ,after dessoldering the motorolla was working fine,but i think my mistake was putting the same desoldered motorola on the socket and plug it in,i remember when i done this before switch the power for few seconds showed the white screen as a normal boot ,then black screen forever...
maybe when i get time i will pickup on this since i have a mc 68881 to test on it

[kipper2k]

Originally Posted by ramparts

Sory kipper i had make some changes on page i hope now it works since contacted some persons and really not geting any info.if can please sent me a test message,and thank you for the reply the socket is already on amiga 600 board ,but i am still not getting to work ,after dessoldering the motorolla was working fine,but i think my mistake was putting the same desoldered motorola on the socket and plug it in,i remember when i done this before switch the power for few seconds showed the white screen as a normal boot ,then black screen forever...
maybe when i get time i will pickup on this since i have a mc 68881 to test on it

private msgs still doesnt work

[alenppc]

I know better than to mess about with SMD stuff without the proper equipment! I think that whatever we can repair, we should, there is only a finite amount of the original amiga stuff left and it's not increasing in any way.

[kipper2k]

Originally Posted by alenppc

I know better than to mess about with SMD stuff without the proper equipment! I think that whatever we can repair, we should, there is only a finite amount of the original amiga stuff left and it's not increasing in any way.

Time to show you a little video of your A600 that you sent me, quite a few things wrong with it, still a work in progress, but watch the video...

http://www.kipper2k.com/allenpc/allenpc.html

When i received it there was a jumper wire that i fixed on the 12v line, and black screen on boot up, no initialisation at all, I removed the CIA as shown in the video and it booted up to splash screen once. I then removed and replaced the caps on the right side of the board (the 10uf was really green, no trace damage though). As the CIA chip is too close to the 34 pin header i may have to solder a replacement CIA chip directly to the mobo which i hate doing. The A600 is booting to splash screen almost every time now

Also the other caps will need to be changed as well, but there is hope

[alenppc]

Oh dear! What a sight. Looks absolutely lovely!

I am surprised that it can boot up without a CIA chip on board! Quite an amazing job. Thanks a lot for spending time on this!

[kipper2k]

Ok,

all capacitors changed, CIA chip not yet back on, i booted up my CF card and the A600 boots up to workbench . Boots every time

No sign of the floppy as thats to be expected as those functions are part of the missing CIA. Time to decide whether i socket or direct solder

[rampartsagain]

Inpressive !! as cia chip is responsable for the kickrom booting worked ok is this correct kipper ?

[kipper2k]

Originally Posted by rampartsagain

Inpressive !! as cia chip is responsable for the kickrom booting worked ok is this correct kipper ?

The CIA chip was shorting preventing the initialisation to get past the check CIA status portion of the bootup. The capacitors were not charging enough to allow the A600 to complete the initialization process. Booting from the IDE port does not affect the loading of workbench (which i tried and successfully worked), but would obviously affect floppy access etc

[rampartsagain]

yep mine boots black too bu i don´t think was the capacitors since no bang after dessoldering motorolla with heat gun although i will try your technick if chips would be socketed much more easy´r
great work an lots of patience

[kipper2k]

CIA chip is soldered back on again, i elected to go with direct solder to the motherboard. Boots up fine, loaded The Addams Family from floppy and it boots fine. Hopefully its time to clean up and package up, i'll leave it in demo mode on a game all night and see if it behaves

edit; mouse/joystick functions are ok on both ports

[rampartsagain]

that is excellent another amiga 600 recovering from operation