Great videos thanks - I was opening up my JX8P to install a vecoven ROM and came across it. Love you detailed description of how the synth operates, I learned a lot thanks
Thanks for the great overview of the JX-8P voice architecture. It is always fun to see the 80's digital logic systems and to appreciate their complexity and the ingenuity of the engineers who designed it. Nowadays, that whole digital section could be replaced with a single microcontroller and maybe a GPIO expander. Also, I think the synth CPU generates the envelopes and LFO's - correct me if I'm wrong about that!
Do you have an email I can contact you at with some issues I'm having with my jx8p? Basically the buttons for key mode and aftertouch seem to be off. If hit the button to the right of the one I want, then the one I want will ligjt up, but only sometimes. It's more detailed than that but was wondering if you might help? Thanks
Love your videos. BTW Most Roland keys come up great after a short cycle in the dishwasher! Works a treat with zero effort, just have to dry them off well.
Most welcome! I love restoring Roland synths too! Juno 60, 106, Alpha Juno2, MKS-70 so far : ) I will pick up a nice condition JX8P in two days, and will be able to look at the gain of the AT circuit, thanks for that.@@bradthx
Thanks for this! That was so instructive. You've got good knoweledge about the main board schemmatics!! Some years ago I restored my JX8P that had supply problems, worn capacitors and some dirty contacts, did the same things you did!!. Subscribed! Are you going to repaint the unit? If you find new decals, please let me know... That corrupted ram sound..... cool!
Awesome detailed explanation as usual, thanks! Waiting anxiously for part 3 as my JX-8P has some dead/sticky keys and no after touch, topic which hopefully you will address... right? : )
I have one that I bought new in the 80's last time I had it out it was not booting fully, maybe that is a power issue, So I might pull it out and attempt a fix.
Thank you for your awesome videos, I'm restoring my beloved JX with your help. One issue that puzzles me is that I have 2-3 notes on the keyboard that hold forever and I have to press the keys repeatedly to stop them. It also happens when I'm playing with an external midi keyboard! Do you have any idea of what could it be?
In the context of 18:25, my present query is how come the square wave generator of DCO 1 of my own 8p somehow become inoperative circa 2007, about a year-and-a-half before it came my way. What might’ve caused that to happen? Would getting that repaired entail scraping around for replacement chips, and which ones should I search for, if so? My other issue with my 8p, damaged outputs, is (likely) more easily dealt with by a repair person.
Did you solve the issue with low output on the output jacks? I have a JX8P in about the same condition as yours - output on the main outs is very low, headphone output is fine though. I'll try some cleaner into the switch! The other issue on mine is the pitch bend range switch not working, with pitch bend always being 2 semitones.
Brad..glad to cath this and the bit on the last vid on these bridge rec.s. The JX8P I just got has cooked the front one or somebody made a rec like you did and left huge glob of solder on top and left it all "open"..The synth does power up and boot correctly ,but haven't checked any audio yet as i have to deal with the rec.s ,a broken pitch bender and all 6 side case holes broken out, the plastic stand offs or sockets completely gone. am not worried about these 2 problems,,maybe you can throw in your .02 on the case problem. Is there enough info between your dialogue and the parts specs sheets to get the 2 correct upgrade rec.s? I heard you say 2 amp then 6 amp so am not sure of the best choice,but am going to add heat sinks to both. I just want to make sure I get the best parts,then move on thanks in advance.I'm sure I'll be watchin these 8P vids over and over.lol Aside from the screw holes,the rest is in great,not perfect shape and have already started on a custom box for it. going to use matching metallic gray hammerite on it,rather than tolex I think..i've got the owners manual downloaded but not perused it yet..
Sounds like you have a handful, all worth fixing though :) Go bigger on the bridge rectifiers, I would say 4A minimum with a heatsink. I had originally though going to 2A would be enough, but was not happy with how hot they ran.
@@bradthx you confirmed my thinkin and the front rec is definitely a homemade pile of solder with diodes stickin out.. the case screws ,not worried. the bender mount ,not worried. I did find another issue the level switch on back is either gone or "pushed in"...may have to replace it, keep an eye out if you would. One thing more. Got a chance today to play an alesis A6 andromeda..WOW!!!!! I thought the ion was a decent thick modelin synth, and was gonna may go on the wish list,but.. What is your take on the A6? I wasn't allowed to openit up, but I read cheap parts picked by the "suits".. If I find a broken one, I'm sendin it to you!
There is no factory reset, because ALL the presets load automatically and instantly when it boots. The internal memories are for user storage and will be wiped if you do not connect 3v when changing the battery. Connect 3volt to prevent this.
Related to the JX-8P are the M-16C memory cartridges. They use a CR 1/3N battery with solder leads. Unfortunately there is no source for these with the leads professionally attached. You wouldn't want to supplement this video with an additional one demonstrating how to solder leads to such a battery. I understand it is possible with application of flux to the battery and pre-application of solder to the lead so the iron is only applied to the battery for 1 second. Is this correct? Care to demonstrate?
