Search found 698 matches

by Yekuku
Sun Jan 24, 2021 8:36 pm
Forum: HELP!
Topic: CASIO CZ-5000 distorted output
Replies: 2
Views: 74

Re: CASIO CZ-5000 distorted output

Thank you for your reply Tomas. Unfortunately adjusting VR2 does not have an effect on sound. VDAC is 4.8V which I think is the problem. Checking the PSU without load the VDAC is 5.2 V which I think is good, when connected to the mainboard it drops to 4.8V. I tried to track where VDAC is used and it...
by Yekuku
Sat Jan 23, 2021 1:40 pm
Forum: HELP!
Topic: CASIO CZ-5000 distorted output
Replies: 2
Views: 74

CASIO CZ-5000 distorted output

Hi guys, Well it looks like that it took me some time, but I have just joined the CZ-5000 cult! I bought an unrepairable unit for a good price, hoping that I could repair it. The unit sounds distorted (digital harsh) on all outputs. I suspected the infamous relay, but after bypassing it , the issue ...
by Yekuku
Fri Jan 22, 2021 12:46 pm
Forum: HELP!
Topic: HELP: Identifying vintage synth (from video still)...
Replies: 2
Views: 83

Re: HELP: Identifying vintage synth (from video still)...

Ha ! I have one ! it is a Korg Micropreset.
Image
by Yekuku
Thu Jan 21, 2021 10:03 am
Forum: HELP!
Topic: Recapping my M1 - PART 2
Replies: 20
Views: 1323

Re: Recapping my M1 - PART 2

Could it be that a cable is not properly connected to the main board ?
The PSU looked good, but we need to measure voltages with load in order to figure out whats going on.
My guess is that the 5V line does not go to the mainboard or the 5V is down due to a short / failing component.
by Yekuku
Tue Jan 19, 2021 3:26 pm
Forum: HELP!
Topic: Recapping my M1 - PART 2
Replies: 20
Views: 1323

Re: Recapping my M1 - PART 2

In a situation like this , it is recommended to have the multimeter probes already in place before switching on . Instantly , switch on and take readings then power off and go to the next voltage rail. What you dont want to see is more than 6V on the 5V rail, this could be bad news for the digital I...
by Yekuku
Tue Jan 19, 2021 11:32 am
Forum: HELP!
Topic: Recapping my M1 - PART 2
Replies: 20
Views: 1323

Re: Recapping my M1 - PART 2

The voltages are a bit on the high side, but there is no load on the PSU , so the chances are that the PSU is ok. In order to be 100% sure , you have to add a load and measure the voltages again. According to my thread from more than a decade ago : I have disconnected the power supply from the main ...
by Yekuku
Mon Jan 18, 2021 1:00 pm
Forum: HELP!
Topic: Recapping my M1 - PART 2
Replies: 20
Views: 1323

Re: Recapping my M1 - PART 2

Hmm, voltages might be ok since there is no load.
You are measuring the 12v rail wrong.
-12v : ii||

12V :||ii

Please measure these again and let me know.
by Yekuku
Wed Jan 13, 2021 8:40 am
Forum: HELP!
Topic: Sudden Death - KORG Prophecy
Replies: 31
Views: 1739

Re: Sudden Death - KORG Prophecy

Well congratulations Denmla, this was a tough one !
Out of curiosity , near all prophecies that I had used had low output volume, are you experiencing this issue ?
by Yekuku
Tue Jan 12, 2021 11:22 am
Forum: HELP!
Topic: Sudden Death - KORG Prophecy
Replies: 31
Views: 1739

Re: Sudden Death - KORG Prophecy

What about a replacement psu like this : https://www.meanwell-web.com/product/image/large/pt-45c_1.jpg https://www.meanwell-web.com/en-gb/ac-dc-triple-output-open-frame-power-supply-output-pt--45c this one has an extra -15v power line, a small resistor as a load might be needed if the -15v is not us...
by Yekuku
Mon Jan 11, 2021 9:30 pm
Forum: General Synthesizers
Topic: Korg DW-8000 - Version E (Expanded)
Replies: 2
Views: 704

Re: Korg DW-8000 - Version E (Expanded)

Hi again Z, upon further research , here is what I have found out. The so called Version E was an expansion / modification manufactured and installed by Vertrieb Marburg , the German KORG distributor at that time, and it was approved by Korg. Some units had an extra button installed which is differe...
by Yekuku
Mon Jan 11, 2021 2:06 pm
Forum: HELP!
Topic: Sudden Death - KORG Prophecy
Replies: 31
Views: 1739

Re: Sudden Death - KORG Prophecy

I have noticed it , thats why I have asked :? The bridge rectifier could be a suspect, also the optocoupler and all diodes. I doubt that you can find the faulty component, just by removing it from the pcb and testing it. It is the inrush current that is making it fail, personally I would replace all...
by Yekuku
Sun Jan 10, 2021 11:47 pm
Forum: HELP!
Topic: Sudden Death - KORG Prophecy
Replies: 31
Views: 1739

Re: Sudden Death - KORG Prophecy

Do you have the schematics of the power supply ?
It looks like there is a component in the PSU that doesn't like the large peak of current .
by Yekuku
Sun Jan 10, 2021 8:40 pm
Forum: HELP!
Topic: Sudden Death - KORG Prophecy
Replies: 31
Views: 1739

Re: Sudden Death - KORG Prophecy

WOW ! I am speechless and clueless! watch out when hot plugging power connectors, if the ground pins make contact after the voltage pins , there is risk of damaging components.
Did you measure the voltages when it booted up ?
by Yekuku
Sun Jan 10, 2021 7:45 pm
Forum: HELP!
Topic: Sudden Death - KORG Prophecy
Replies: 31
Views: 1739

Re: Sudden Death - KORG Prophecy

If you want you can use electronic devices that you have at home instead of resistors , for applying load. Lets say an old cellphone on 5V and a 12V computer fan on 15V( some 12v fans can work up to 15V, but others fail, you have to test first with another psu that the fan works on 15V) . Aprox 0.5A...
by Yekuku
Sun Jan 10, 2021 6:51 pm
Forum: General Synthesizers
Topic: Korg DW-8000 - Version E (Expanded)
Replies: 2
Views: 704

Re: Korg DW-8000 - Version E (Expanded)

Hi Z, I have only heard of the Turbo expansion made from Musictronics. https://www.deepsonic.ch/deep/docs_manuals/korg_dw-8000_musitronics_angelcity.pdf Waveform expansion is possible : http://www.strellis.com/dw6000.shtml Audio input modification for the delay should not be difficult to implement. ...