dying a600

[systmcrsh]

first hello!

i have an a600hd thats been nice to me for years. a few months ago it started having problems booting. what happens is when i power it on, all the LEDs come on and stay on (caps, floppy, pwr). there is no floppy activity, nor does the system boot.

if i leave the system on like that it will typically boot after 10-15 minutes - almost like its warming up or something. i should note here that if i do a soft-reset (ctrl-a-a) after it boots fully, the cycle repeats - no boot again for 10-15 mins

i tried removing the extras, hard drive, memory, pcmcia - but the problem persists.

thinking it might be a dying power supply, i tested the pins on the PS with a multimeter. it was my first time using a multimeter, but during the test of each pin the readout of the multimeter fluctuated and wouldn't settle.

anyways, i made a new power supply from an ATX, and am 95% confident i did it correctly. the same thing happens booting with the new power supply - all LEDs light, will not boot.

any suggestions? anyone experienced/solved a similar issue? i really love my amiga & i have a show in 2 weeks (i make music on it - protracker).

thanx!

[darksun9210]

hmmm, doesn't sound good. if you haven't already, you may want to open it up to check the capacitors on the board. small round components. you're looking to make sure that none of them have started leaking. look for fuzzy dull looking solder pads and joints.
otherwise, give the rom chip a good push back into the socket.

you don't get any colours on the screen during the time the amiga doesn't boot do you?

[countzero]

this is a common problem with a600's. your smd caps are dying. you should replace them ASAP. search forum for 'a600 woes' for more info.

[systmcrsh]

thanx!

i am going to give my soldering skills a shot before ordering a replacement or sending away for repairs...

i read the woes post and it was reassuring. after googling i found these pages not specific to the 600, but should provide enough info to get me started.

http://amiga.serveftp.net/audio_repair.html#Capacitor1
http://amiga.serveftp.net/SMD_soldering.html

ill post up here with an update

[Damion]

I agree with the others. I have three motherboards (two A600 and one A1200) that show signs of failing caps. I get random lockups on the A600's with an accelerator attached, and sound loss on one channel of the A1200. (My Escom A1200 board still looks fine.) I'm going to replace them all this winter... should be lots of fun. :/

[systmcrsh]

well, got home and dismantled the machine & inspected the mobo. most of the caps look generally ok... but i found a culprit right underneath the floppy. there are 2 x 22u caps that have leaked quite severely. im confident i can replace those caps easily... but the leakage has caused bluish rusty looking damage to a chip marked M236 / LF347M. i dont have a digital camera handy atm, but it looks just a tad worse than a similar chip in a 4000 pic here: http://www.amiga.org/gallery/index.php?n=1421=12

i guess im gonna go ahead and replace the caps tomorrow and maybe clean the corroded LF347M chip as much as possible with iso alchohol... if im ambitious maybe i will try to touch up the solder points of that chip, but i dont have a tip that fine.

so far, doesn't look good

[Argus]

I had a dead A600 with exactly that problem, the caps under the floppy drive leaked.  One of them actually fell off so I cleaned the PCB with some alcohol and replaced the caps with a couple from a CD32 m/b and boom...powered right up!

[systmcrsh]

well i gave it an honest shot.

desoldering the caps is HARD. not only is my soldering iron too big, the ancient solder is very hard to desolder. i ended up failing... because when removing the capisitor, it ended up sticking to a track on the motherboard while i removed it, and probably destroyed the track it was attached to. evein if i had been succesful replacing the cap, i still suspect the corrosion of the circuit nearby was severe enough that who knows how long it would have lasted me, if at all.

my 600 is going into the closet now minus 2 essential 22uF capisitors in case there is anything else salvagable from it at some point.

do the capisitors leak even when not powered up? ... im curious because if i end up purchasing another machine/mobo and a spare motherboard --- if that spare is just as likely to leak?

[countzero]

systmcrsh wrote:

do the capisitors leak even when not powered up? ... im curious because if i end up purchasing another machine/mobo and a spare motherboard --- if that spare is just as likely to leak?

in my experience the more they sit in the closet the more prone to leaking they are. Regularly used miggy's create less problems. Maybe because the charge keeps the liquids inside the caps in place.

[systmcrsh]

thanx.. maybe ill keep the spare in a freezer haha

[smf]

@systmcrsh

Why dont you try to just bend the caps until the legs breaks?
I replaced some caps in an dying A4k a few weeks ago and i first attempted to desolder them but it was too hard for me with my equipment.. then i tried to snap them of by bending gently  and they snaped off pretty quick without any risk of damaging traces. when the caps was gone it was easy to desolder the rest of the legs even with a bad soldering iron

[countzero]

yes, this works a treat. Usually the legs are eaten by acid anyway so they come off pretty easy. I always use this method and have yet to raise a solder pad. (ok, I did lose some pads in my first trials, till I figured the correct angle and force to bend.)

[spirantho]

The caps on the 600 are just little tin pot thingies - nothing to bend except the solder joint, which is a high risk of breaking the contact on the board. They do often come off easily just from prying (my A600s did) but beware.

Incidentally, don't feel you have to replace like with like - I stuffed some bog standard non-SMT electrolytics in my A600 and it works just fine, while being rather easier to solder.

[systmcrsh]

yeah it was the solder pads that were destroyed... 1 of which lifted a trace while being removed. ive managed to trace the pads to very tiny pinholes. im going to attempt threading new capisitors through them today, bypassing the broken trace.

[spirantho]

Those are probably the through-board holes for tracks between layers. A blob of solder on them and a wire is enough to get a useful connection if you're careful. Not very tidy, but then you're not displaying it are you?