Roland JX-8P Troubleshooting, No Luck?! but check out part 2

[@olafwagner]

Wow, I had almost EXACTLY the same problem with my Roland MKS-30 (which has very similar power supply design). The 5v rail tested perfectly without load, but the voltage dropped when connected (and the digital components cannot function properly). In my case the problem was the bridge rectifier, and I replaced it with a new 2W01G and it worked perfectly. The way I tracked it down was to disconnect the 5v rail pins from the power supply, and connect that to a bench power supply (so I used the internal power supply for all the other power rails except 5v which I supplied from my bench power supply) and by switching them both on at the same moment, the synth immediately worked.

[@waheex]

hi thanks for the reply and detailed explanation of your JX-8P problem, it really helps others who stop by. I was able to sort the problem in mine finally so check out the fix in part 2.

[@robinsutcliffe_video_art]

Many Roland synths of that era and later, you can just change the tap on the primary side of the transformer to convert the ingoing AC voltage requirement. I think some Japanese models only had 110v though.

[@robinsutcliffe_video_art]

My JX8P, and JX3P, and Juno 106 all have a 240v winding, it's the red wire which goes to NC (not connected) in the JX8P. I have reconnected all 3 synths to use the 240v winding, as Europe and UK standardised to nominal 230v back in 2003. It will work on the 220v winding, though we have 234vAC in the house, so it's better suited to use the 240v winding

[@jonfroin]

Shame you didn’t have more time with it - I was ready to enlist the help of Fred Vecoven and Guy Wilkinson!

[@Shred_The_Weapon]

Might you be the one who could answer a question for me, Mondbourner? My JX-8p’s DCO1 square wave generator stopped working before I took possession of it in January 2010. What could’ve caused that? Could it be taken care of without needing either to hunt down or 3D print replacement chips? I have considered reaching out to Syntaur or PBCWay if I had to have the chips printed.

[@forgivemeforihavesynthed]

Thanks for the vid was informative:) Pity it wasn’t fixable .

[@PWMaarten]

Well it probably is but he didn’t have the time with it to find the culprit.

[@waheex]

yes I 'think' the synth may be fixed now as it might have turned out to the RAM. I'm just not 100% on that

[@KarlHamilton]

My God

[@robinsutcliffe_video_art]

Is that your Aelita?

[@waheex]

yes it's a banger

[@robinsutcliffe_video_art]

@@waheex I know they are indeed. I had an RITM2 once, they are awesome as well, very well implemented single osc synth