Jp-8000 very low sound output

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Jp-8000 very low sound output

Postby wawilojr » 03:22, 11 December 2013

Hello, I just bought this jp-8000 off of ebay and it looks like new. The problem is the battery is bad and it say memory damaged( not mentioned in the listing of course). Also the sound out put is very low on all 3 outputs. you can hear it at about a 1/4 of the output when hooked to the headphone jack but only about 5% when wide open from either of the stereo jacks(also not mentioned). My question is would a battery change fix this or what does it need. Im thinking about sending it back but I hate to because look wise it is great.
please help with any info you could give. thanks
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Re: Jp-8000 very low sound output

Postby aron » 21:42, 17 December 2013

Hey, the filter caps need replacing. Mine is like this as well and I need to change them as well. Try leaving it on for a while - (more than 30 minutes) then see if it gets louder. I think the op amp bias voltages get screwed up and there's very little output. I also did a mod which basically routes the headphone outs to the main outs to get more volume.

The keyboard sounds so good. One of the best I own.
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Re: Jp-8000 very low sound output

Postby Macska » 15:00, 20 December 2013

I have a JP 8000 from ebay as well, and it has a dead battery "memory damaged," all that. And mine doesn't have any volume problems. Have you performed a factory reset? I wonder if the volume in the AMP section could be saved really low on every patch.
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Re: Jp-8000 very low sound output

Postby wawilojr » 04:14, 25 December 2013

I actually kept the jp-8000 with about a 40% refund. I replaced the battery and did the reset but still little to no sound. The sound is so low through the headphone jack the mod wouldnt help it.Unfortunately the midi out is not working either. It will receive midi but wont send it. It just says waiting on the midi test. I set the channel and went through all of my troubleshooting tests but no luck.The bad part is it looks close to new. I have it in my local repair shop now so hopefully its not totally wasted. He wasnt real optimistic about it being fixable which worries me. I will post the good or bad news when I hear from him(looked like he is pretty piled up with work). My finger are crossed. If anyone else has had one repaired or this problem please post it.
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Re: Jp-8000 very low sound output

Postby johnxyz » 03:11, 26 December 2013

Yes, have you checked the amp pot and turned that up also (far right pot). Prob not that but worth a shot. Sounds to me all like more serious issues - hope I'm wrong.

Just purchased immaculate one myself and using it live - it needs about 10% more mixer volume than my other synths - but thats no issue.
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Re: Jp-8000 very low sound output

Postby wawilojr » 03:46, 26 December 2013

Yep i checked all the pots buttons and sliders in the test mode and everything worked 100%(oddly enough you cannot check the volume pot in test mode).I considered trying to update the firmware because it will receive midi but wont send it. I backed out because i was afraid it would only receive half of it and brick it. I bought one of these in 1998 new but sold it about 8 years later. Just my luck to buy one on ebay and it be messed up. Im hoping the repair guy says he can fix it but he is thinking someone plugged something hot into the outputs or maybe the kiss of death lightning hit it. I cannot believe no one else has had any of these issues with theirs thats what worries me the most. I took a gamble with it but I probably should have sent it back for a full refund.
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Re: Jp-8000 very low sound output

Postby johnxyz » 18:25, 26 December 2013

Maybe you could still return it?
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Re: Jp-8000 very low sound output SOLVED!!

Postby wawilojr » 04:20, 21 January 2014

I finally got my jp-8000 back from the shop today and the verdict was 20 bad caps on the processor board. They had started leaking and acid got on the board. He said another year of sitting and it would have been unrepairable. From the looks of the board it spent a long time boxed up and not used and he said that is what caused them to go bad. The lack of use is worse than using it. He actually swapped the caps with better caps . He said the old ones were 16 volt and he replaced them with 25 volt caps. It sounds great compared to stock ones no noise and a better sound. luckily I only had to come out of pocket $40.00 after the partial refund I got on it so not too bad. Everything is like new or better now. Would i recommend you
buying one in the condition it was in hell no unless you are an electronics repair guy. The tiny caps looked like they would be a chore. Thanks to everyone for your info and I hope this info helps someone else.
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Re: Jp-8000 very low sound output

Postby johnxyz » 02:26, 26 January 2014

So what exactly are those caps - what do they do?
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Re: Jp-8000 very low sound output

Postby wawilojr » 13:57, 27 January 2014

They were all on the sound processor board. The synth must have been put away for a long time and the capacitors started leaking all over the circuit board. He said that they had the sound processor nearly shut completely down. If you are having the low sound output issue then you probably have the capacitor problem. He told me that if it went another year that the acid from the leaking caps would have destroyed the circuit board. The problem is that when Roland built it they put cheap capacitors in it rather than using better ones( it may have cost them another $30.00 to use good ones). These were not cheap when they were new so you would think they would use better components. Hope this helps
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Re: Jp-8000 very low sound output

Postby ladislavbrezovnik » 11:33, 5 April 2016

I've owned my JP-8000 for many years and it had developed similar low output issues and noise over a long time. The number one cause was the main volume pot which was replaced but while it was on the table having surgery I replaced all of the electrolytic capacitors on the main CPU board and the jack board. I also replaced the mute transistors just in case, the old ones all tested fine. Sounds like new now.

The silver SMD caps pictured here.
The brown caps & transistors pictured here.
Here is a sound test. The melody is from Out Of The Blue by System F. Only external Lexicon Hall reverb was added and as you can here it sounds very nice (If you like Trance).
You can find some resorces for the JP-8000 synth here.

Kind Regards,
Simon
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