Search found 721 matches

by Yekuku
Sun Apr 18, 2021 9:11 am
Forum: HELP!
Topic: Juno 6 Negative Rail
Replies: 1
Views: 41

Re: Juno 6 Negative Rail

Hi and welcome to the forum. Obviously there is a damaged component on the voice board that is dragging the negative power line down. The affected component should get warm or hot, there are several ways to identify it like using a thermal camera, or if you have the appropriate experience, using fre...
by Yekuku
Thu Apr 15, 2021 5:47 pm
Forum: HELP!
Topic: Prophet T8 left voice board lower volume
Replies: 4
Views: 423

Re: Prophet T8 left voice board lower volume

Hi Ryan, Panpot feeds the U607 opamp (LM348) then signal goes through U605 analog switch (4016). My bet is on the 4016 , I have seen some of them fail. Concerning the LF353 replacement, to get the best results you need to tweak the surrounding components too, swapping just the opamp with one with be...
by Yekuku
Tue Apr 13, 2021 8:11 am
Forum: HELP!
Topic: Prophet T8 left voice board lower volume
Replies: 4
Views: 423

Re: Prophet T8 left voice board lower volume

Your assumptions are probably correct.
The last opamp LF353 is the main suspect, which is a Jfet input opamp.
by Yekuku
Sun Apr 11, 2021 8:17 am
Forum: HELP!
Topic: Yamaha SY-1 expression pedal usable with CS50?
Replies: 11
Views: 2414

Re: Yamaha SY-1 expression pedal usable with CS50?

Good work Stephen !
by Yekuku
Sun Mar 07, 2021 10:11 pm
Forum: HELP!
Topic: Yamaha SY-1 expression pedal usable with CS50?
Replies: 11
Views: 2414

Re: Yamaha SY-1 expression pedal usable with CS50?

Hi again Stephen, I researched this further and I think it is compatible. The Cs series pedal takes - 15 V from the tip and powers a 24v light bulb; ( you need to confirm if it is -15V or 15V.) A photosensitive cell on the other side produces voltage depending on how much light passes through the ho...
by Yekuku
Sun Mar 07, 2021 6:04 pm
Forum: HELP!
Topic: Solved! CASIO CZ-5000 distorted output
Replies: 16
Views: 4883

Re: Solved! CASIO CZ-5000 distorted output

Well, to me it looks like the 4051 got damaged first and since it is powered from Vdac, the excessive current demand made the zener fail too. What is worth mentioning is that the problematic 5.6V zener regulator diode had exactly 5.6V at its cathode thus testing ok in circuit. I never had a Casio an...
by Yekuku
Sun Mar 07, 2021 2:24 pm
Forum: HELP!
Topic: Yamaha SY-1 expression pedal usable with CS50?
Replies: 11
Views: 2414

Re: Yamaha SY-1 expression pedal usable with CS50?

Hi Stephen here is an interesting video from organ fairy : https://www.youtube.com/watch?v=1pBG2zW8__o What organ fairy figured out , is that the SY pedal accepts 15V on the Tip , Ring is the CV out from the pedal, and Sleeve is Ground. Can you please insert a TRS cable on pedal input of the CS50 an...
by Yekuku
Sun Mar 07, 2021 12:37 pm
Forum: HELP!
Topic: Yamaha SY-1 expression pedal usable with CS50?
Replies: 11
Views: 2414

Re: Yamaha SY-1 expression pedal usable with CS50?

Hi Stephen, sorry I have not tried connecting a pedal to a cs-50 , but I have researched this a bit. Syntaur used to sell a pedal for CS series, this one: https://syntaur.com/Items.php?Item=CVP100 This a custom build obviously similar to the Moog Model 1120 pedal , according to Syntaur. The Moog Mod...
by Yekuku
Sun Mar 07, 2021 10:50 am
Forum: HELP!
Topic: Solved! CASIO CZ-5000 distorted output
Replies: 16
Views: 4883

SOLVED ! Re: CASIO CZ-5000 distorted output

Well we have success ! After replacing the 5.6V zener diode on the PSU and having Vdac recovered to 5V I went back on the DAC circuit and inspected all ICs one by one. Guess what, it was the expander circuit causing the distortion. When the Vdac recovered , the distortion persisted but it turned out...
by Yekuku
Fri Mar 05, 2021 12:29 pm
Forum: HELP!
Topic: Solved! CASIO CZ-5000 distorted output
Replies: 16
Views: 4883

Re: CASIO CZ-5000 distorted output

Well I have been scratching my head for weeks, there is an update but the problem persists. After checking the PSU and found all components to work as expected, I went ahead and replaced the zener diodes on Vdac 5V line although they were regulating the voltage correctly in circuit. To my surprise V...
by Yekuku
Sat Feb 20, 2021 10:37 am
Forum: HELP!
Topic: KORG M1 - No sound / Low battery indication. SOLVED!
Replies: 62
Views: 52303

Re: KORG M1 - No sound / Low battery indication. SOLVED!

I assume that the psu is not generating any voltage. Since the fuse is ok, you should test the switch , with the psu offline test for continuity on the power switch pins. Working on the primary side of the psu is dangerous, it can be lethal, so you need to be extra cautious. Assuming that you are on...
by Yekuku
Fri Feb 19, 2021 3:51 pm
Forum: HELP!
Topic: KORG M1 - No sound / Low battery indication. SOLVED!
Replies: 62
Views: 52303

Re: KORG M1 - No sound / Low battery indication. SOLVED!

Testing coil L3 in circuit and off circuit should have the same results, that is strange.
Probably the fuse was blown, that is why the psu is not generating any voltage now.
Did you check/replace the fuse ?
next thing is to measure voltage across D6 with the psu powered on.
by Yekuku
Thu Feb 18, 2021 7:57 am
Forum: HELP!
Topic: KORG M1 - No sound / Low battery indication. SOLVED!
Replies: 62
Views: 52303

Re: KORG M1 - No sound / Low battery indication. SOLVED!

L3 is a coil and it should have very low (aprox 0 Ohm) resistance. It looks open, remove it from the pcb and test it.
by Yekuku
Mon Feb 15, 2021 9:34 am
Forum: HELP!
Topic: KORG M1 - No sound / Low battery indication. SOLVED!
Replies: 62
Views: 52303

Re: KORG M1 - No sound / Low battery indication. SOLVED!

Hi and welcome to VSE.
the psu is not generating -5V, how come you are measuring -5V?
With no load on the PSU, what voltages are you getting exactly?
The diode could be a suspect , remove it from the the pcb in order to test it properly.
Check L3 for continuity, and share a pic of the PSU.
by Yekuku
Tue Feb 09, 2021 9:13 pm
Forum: HELP!
Topic: Solved! CASIO CZ-5000 distorted output
Replies: 16
Views: 4883

Re: CASIO CZ-5000 distorted output

Thanks for the help ;) So far , no luck. I checked all components on the PSU section that generate VDac and I didnt find any problem, everything tested ok off circuit. Zeners, the usual leaky suspects, work in specs in circuit. Still VDac is 4.8V, in other circumstances I would not see this as a pro...