A4000 wont boot after replacing caps

[jaymanu]

Hi to all amigans !
It's the first time i'm posting here.
Here's the story :
I  live in Paris and I couldn't resist when I saw an A4000 complete with  its 1942 monitor, pickable near me on ebay. Was a child dream, as I was  an A500 then A2000 user as a teenager.
It worked good, i upgraded the ram and roms. I also put a cf card, dvd rom, and network card.
But  after a while, it began to show its age, having crackling audio and  unstable video. So i disconnected everything from the motherboard and  sent it for caps replacement to amigakit in england. I have very little  soldering skills, but wouldnt dare to put my hands on this vintage item  
It took quite a long time, but it went back to me with amigakit "QC passed".
Now  i resettle everything, and sadly it doesnt boot. I got red screens so i  suspected the roms and bought new ones. Now i can only get gray, or at  times purple, screen. The disk drive is not reacting. I did the  caps-lock test, it blinks 6 times then sticks off.
Could this be the  CPU card ? I kept it and didnt send it with the MB. It's a phase 5  cyberstorm carrier with a 040 CPU. Or maybe the RAM ? With the chip only  or even all slots empty, i get the same results.
Do you have any  clue ? Do you think something went wrong when they fixed the board ? Or  maybe there's a jumper setting that i missed ?
Thanks in advance !
JM

[zipper]

Perhaps they have tested with another make of CPU card and changed the jumpers.

[jaymanu]

well both clocks are set to EXT, which is how the cyberstorm manual tells to set them.
I also tried both rom speeds, without success.

[spirantho]

If you're getting a dark grey or purple screen, and the ROMs are good, it's probably a bad connection on the custom chips.

Try running it with no RAM at all - you should get a green screen. If you don't, then the CPU is doing nothing at all. If this is the case, it's probably waiting for the chipset to come back and say it's ok. If the Caps Lock light stops responding after a few presses, then it certainly sounds like the CPU is doing nothing.

If you're certain that the jumpers are set correctly, then there's not much more you can do without a multimeter at least. If you have a multimeter, then check the power rails are within tolerances. The A4000 will boot if the +5V line is more than about 4.7V but if you want it to be reliable you should be aiming for at least 4.9V. The machine will sit and wait until the voltage stabilises at a level it's happy with.

Have you tried just leaving the machine on for an hour or so?

Amigakit know what they're doing, but it's possible a capacitor may have come loose in transit back to you.

Try a different CPU card if you possibly can though, preferably a simple one like the basic '030 one.

Edit: I just re-read your post, and saw you've tried with no RAM. So no CPU then...

Can you please confirm that your 68040 is 40MHz and not the 25MHz? Because if it's 25MHz you want the clock jumpers to be set to INT not EXT...

[Castellen]

Try a different CPU card if you possibly can though, preferably a simple one like the basic '030 one.

Can you please confirm that your 68040 is 40MHz and not the 25MHz? Because if it's 25MHz you want the clock jumpers to be set to INT not EXT...

Agreed, AmigaKit will have certainly tested the board.  Sounds as though something has been upset with the Cyberstorm board when it's been removed and refitted.  Could be anything from dirty connectors to cracked/intermittent solder joints.  It's not a Cyberstorm mk3 by any chance?  I'd agree that a known good CPU board is the best way to test.

I'm intrigued as to why the clock source jumpers should be set to internal when the CPU board is operating at 25MHz, please fill me in here.

By my understanding, a board such as the Cyberstorm is clocked using its own on-board oscillator, so obviously the A4000 main board needs to be exactly synchronised for all bus communications with the CPU board, which is the entire point of shifting the jumpers to 'EXT' so that the timing of the main board is identical to that of the CPU board.  If the CPU board and main board are using different clock sources (jumpers set to INT) then both clock sources must be identical in phase and frequency.  From memory the stability of those oscillator modules are around 20ppm or worse, so to have two oscillators running at exactly the same phase and frequency for any length of time is practically impossible.  Which would mean the computer will either fail to boot, or not run for very long at all.

[jaymanu]

Hi !
Thanks for these quick and quite complete replies !

Well yes i tried with no RAM and both INT and EXT.
I'm not sure though which romspeed i should select, i thought the longer the safer.
I checked the voltages and i get 4.8, the 12v is quite good too.
I'm not sure (shame), but I think the 40 is a 40MHz one, the crystal says 80 so I guess there's a divider.

Thanks for the link, I don't have this same board but i'll try pressing again everything again, specially the CPU. I sprayed contact cleaner in the big connectors between MB and carrier, and between carrier and CPU.

I didn't also leave the system on for an hour, i'll do that. I'm pretty scared of turning the power on and off very repeatedly will all my tries..

I'll keep trying and tell you if I manage to get the green flag

I don't know anyone in paris hacking amigas, so trying another CPU module would be quite expensive..

I'll let you know, thanks.

JM

[danbeaver]

What about contacting AmigaKit?

[mechy]

Agreed, AmigaKit will have certainly tested the board.  Sounds as though something has been upset with the Cyberstorm board when it's been removed and refitted.  Could be anything from dirty connectors to cracked/intermittent solder joints.  It's not a Cyberstorm mk3 by any chance?  I'd agree that a known good CPU board is the best way to test.

I'm intrigued as to why the clock source jumpers should be set to internal when the CPU board is operating at 25MHz, please fill me in here.

By my understanding, a board such as the Cyberstorm is clocked using its own on-board oscillator, so obviously the A4000 main board needs to be exactly synchronised for all bus communications with the CPU board, which is the entire point of shifting the jumpers to 'EXT' so that the timing of the main board is identical to that of the CPU board.  If the CPU board and main board are using different clock sources (jumpers set to INT) then both clock sources must be identical in phase and frequency.  From memory the stability of those oscillator modules are around 20ppm or worse, so to have two oscillators running at exactly the same phase and frequency for any length of time is practically impossible.  Which would mean the computer will either fail to boot, or not run for very long at all.

If memory serves me the cyberstorm MKII uses the motherboard jumpers set to internal while the other cyberstorms all use external. i guess it uses some type of PLL to keep it all in sync..

[mechy]

Hi to all amigans !
It's the first time i'm posting here.
Here's the story :
I  live in Paris and I couldn't resist when I saw an A4000 complete with  its 1942 monitor, pickable near me on ebay. Was a child dream, as I was  an A500 then A2000 user as a teenager.
It worked good, i upgraded the ram and roms. I also put a cf card, dvd rom, and network card.
But  after a while, it began to show its age, having crackling audio and  unstable video. So i disconnected everything from the motherboard and  sent it for caps replacement to amigakit in england. I have very little  soldering skills, but wouldnt dare to put my hands on this vintage item  
It took quite a long time, but it went back to me with amigakit "QC passed".
Now  i resettle everything, and sadly it doesnt boot. I got red screens so i  suspected the roms and bought new ones. Now i can only get gray, or at  times purple, screen. The disk drive is not reacting. I did the  caps-lock test, it blinks 6 times then sticks off.
Could this be the  CPU card ? I kept it and didnt send it with the MB. It's a phase 5  cyberstorm carrier with a 040 CPU. Or maybe the RAM ? With the chip only  or even all slots empty, i get the same results.
Do you have any  clue ? Do you think something went wrong when they fixed the board ? Or  maybe there's a jumper setting that i missed ?
Thanks in advance !
JM

I have fixed many a board where a trace under a cap has been damaged by cap leaks. maybe this is the case for you. Its very well possible it worked fine at amigakit but in shipping the marginal trace quit making contact-Its tough to find things like this sometimes especially when they are working and you have no reason to suspect it.. I wouldn't of believed this but it happened to me! In any case, i would try a A3640 or other accelerator before assuming its the amiga. Also pull the roms and make sure a pin didn't get bent under when they were installed.

you might try and contact Cosmos,not sure where in France he is but he may be of help.

[AppleIIGuy]

If memory serves me the cyberstorm MKII uses the motherboard jumpers set to internal while the other cyberstorms all use external. i guess it uses some type of PLL to keep it all in sync..

So true, if the 2 jumpers are set wrong with a CS MK II you get a blank screen. IIRC the jumpers select where the motherboard clock signal comes from. INT means the its generated on the motherboard. EXT means it is generated on the CPU board

[jaymanu]

Hi !
I'm back from holidays and trying again with your help.
I'm now having the machine powered on, will wait an hour to see if anything more happens. I measured the output voltages from the power unit, i'm reading 4.9 and 11.88V : does that sound enough ?
I removed all the RAM and nothing happens on screen. The caps lock still blinks 7 times before dying. So nothing really new nor positive for now.

... unfortunately after 3 hours i'm reading the same voltages. They seem to be enough so I have to fear something else is dead