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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Darmaster70 on October 28, 2002, 08:56:07 PM
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My amiga 4000 desktop boots up just fine. I do not get the dark gray light grey boot up screens, my screen stays dark blue. The computer seems to work just fine no problems with programs locking up, screen looks ok but when I try to play some mod files using octamed my sound is crackly and very low in volume. Does anyone have any ideas.
Thanks
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I had this problem with my a1200 after i intalled the Z4 add-on card. It turned out that one of the screws shorted out and burned out the -5V rail on the motherboard. Try measuring the -5V on the PSU. Not sure what the pinout of the a4000 is though.
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If your pooter has rca jacks for audio, you might
check the soldering of the jacks with a magnifier.
A more dangerous way is to wiggle them while
trying to play sounds.
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I s it just with octamed?
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Octimed is the only program i have tried. It used to work fine but now it doesn't (octimed that is). I understand the blue screen means i might have a problem with the custom chips but not sure.
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8-) =error found in ROMS
:-D =error found in Chip Ram
:-( =error found in custom chips
:-? =if the CPU found an error b4
the guru was running.
:-D :pint:
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Blue is cool, I never had a blue screen.
All my amiga's died with the green screen
of DEATH which usually turned out to be bad
chip memory. (Sometimes reseating agnus
cures).
Anyways, custom chips should be cheep.
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@ Darmaster70,
octamed my sound is crackly and very low in volume
By chance, have you had or still have an internal CD-ROM audio cable connected to the internal audio connector on the motherboard?? If you acquired the computer second hand, it's possible that the previous owner had the connection made. I found that when I connected mine to my CD-ROM drive, the native Amiga audio did exactly what you're describing. Unfortunately, when I removed the cable, the problem still happens. Apparently, there is a fix for it, but it involves soldering of some sort on the motherboard. I have not been able to find the details for it.
Could someone please let me know where to find such audio fix documentation ???
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I do not have an internal CD-ROM audio cable connected to the internal audio connector on the motherboard
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Did you acquire the machine used??? If so, a previous owner could have had it connected and caused the problem. Still looking for the motherboard fix .... anyone ???
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Yes I bought it used but it had an external cd-rom. I installed a scsi internal cd drive but i didn't attach anything to the motherboard. I used to get the dark grey light grey screens during boot up but now all i get is a dark blue screen through the boot up process. When i first got the machine it worked fine. I replaced the barrel shaped battery but it was not leaking anything on the mobo. I may have messed something up when i removed the battery but other than having no sound the computer seems to work fine.
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It is caused by a fried track on the PCB, near to the audio mixer connector. It's happend to two of my A4000s in the past. Fast Compuers in Tanner Street, London SE1 know exactly how to fix the fault.
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And if you don't live in the UK? My A4000 developed the same problem a while back.
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O.K. Back to this problem again - especially when it is caused by connecting the internal audio cable from a CD-ROM drive to the A4000 motherboard internal audio mixer connection. I have since disconnected the cable, but my A4000 still has little to no output and it always produces static/noise through the speakers regardless if anything is actually trying to play.
So, where can I find documentation on how to fix this problem?? Or who/where, in the U.S., can fix this for me???
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One question for you silver dragon, when your computer boots do you get the dark grey light grey white boot colors?
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Well, my computer has the same problem as Silver Dragons, and I don't get any different boot colors.
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I get no colors at all during bootup.
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Well i had the same problem on the output sound on my A4000...so i decided to look on the Mainboard and discovered that Batterys aren´t the only things that leaks acid on the boards...Capacitors can do the same damadge...look the capacitors ( C433 22uF 16v ) there are two, between Paula and the RCA jackets...for my Amiga was too late i hope my experience can save others Amigas...well...my A4000 is not dead...it works, but...no Sound :-(
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P.S.
PC´s are good machines, only if tey´re runnin Linux :-D
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Thanks for the information, My wife made me put the 4000 in the closet. She hates it when my desk gets messy. Her desk is pristine. I've got my 2000 hooked up right now as well as my Dell pc. I use the Dell for internet and work purposes and I hate windows with a passion. I think I'll pull out the 4000 this weekend and have a look.
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@ zeewolf,
I will have a look at my A4000 motherboard when I get a chance. Thank you for the information.
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there is on the net an Hardware hack explaining how to repair this problem...but i have no knowlege on electronics...so the simple solution is to remove those capacitors "i´ve done that" and buy a 2nd hand sound card...somewone tryed to sell me one, a tocatta sound card for...350 € ???!!!???
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@ zeewolf,
there is on the net an Hardware hack explaining how to repair this problem
I've been looking for it, but cannot find it. Where is it please - URL ???
(I'd love a sound card, but am saving cash for an AmigaOne system.)
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ok, here it is.
http://joj.home.texas.net/amigacap.html
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So if this is what is killing the sound on my 4000, I should be able to see leakage? I don't see anything leaking, but am wondering if it could still be the same problem and if I need to do the capacitor fix anyway.
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Hmm, oh well. Guess I'll throw the 4000's in the dumpster then.
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Okay, let's take this in another direction. (Well first, did this fix help the other flaky sounding 4000's out there?) If I get a sound card (Where can I get one of the Melody cards that uses the 1200 clock port?), is there a way to make all sound go through that instead of using the system sound?
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Over the Christmas holiday, I took my A4000T to my dealer in St. Paul, Minnesota (Raymond Computer). We hooked everything up so I could let him hear the problem. Unfortunately, he was pretty busy that day, so the only thing we were able to do for testing stuff on the motherboard was use his Advanced Amiga Analyzer package. Plugged in the port dongles which have LEDs on them for checking certain pins. Powered up and discovered that the +12 volt supply is not present on any of the ports that it's supposed to be. That supply, along with the -12 supply, also powers the op-amp chips that produce sound from the motherboard. Obviously, without it being there will produce the lack of or very low sound output. Thankfully, that +12 supply for the ports and the sound is on an isolated circuit. So, he thinks likely a fuse is blown or a trace is burnt out somehow. We'll be investigating that later.
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Does any of this leakage happen on an A3000? I've looked and cant see any problems on mine other then the battery that I removed just in time. I have a lot of caps on the motherboard too!
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Thanks for the info Mike, wish I had an amiga repairman close to me, would like to take my 4000 in and run some tests on it. Please let us know what the final diagnosis is on your machine.
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@ Darmaster70,
You're welcome. As far as Ray being close to me, he's not really. It's a six hour drive. Only reason I went there was because I was already visiting my parents for the holidays. They live much closer to Ray's store (only 1.5 hours drive time).
Currently, Ray is looking for a replacement A4000D motherboard for me. When he finds one, I will get that from him and he will get my current one with the sound problem. That way I can keep using my computer, and he can further investigate the problem. I will keep you informed on the progress.
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Wow, an Amiga repair man. Well, I got another A4000 mobo over the holidays as a throw in with a Microvitec tower. The sound on it works, but the daughterboard slot doesn't! *shakes head* Just can't win.
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This exact problem was fixed on my A4000D motherboard over the weekend!! The capacitors on my board have been replaced by the non-polarized type. However, upon putting everything back together, the sound on my A4000 was still terrible (the same as it was prior to the capacitor replacement). After 7.5 hours of messing around with the hardware (different motherboard, accelerator, removing expansion cards, removing Zorro expansion daughter board), my dealer and I found the problem with the help of his son's girlfriend (she works on electronic stuff all the time). It was as simple as the -12 volt and its associated ground wire not making proper contact in the main 6-pin motherboard power connector. Prior to the capacitor change, I had done some other work on my A4000T. In the process of putting it back together after that work, the -12 volt line and its associated ground wire got pushed out of the connector somehow so they weren't making good contact in the main power connector for the motherboard. The op-amps (operational amplifiers) that produce sound on the Amiga require both +12 volt and -12 volt lines and their associated grounds in order to function properly. Without either one, the sound output is very bad because they are unable to generate full waveforms. We connected the main power connector and then wiggled and pushed in all of the wires with a pair of needle-nosed pliers. After that, perfect sound from my system!