I have a problem with my Roland Synth which keeps rebooting after 10 or 30 minutes, I have read it may be a bridge rectifier. I have located a 4 pin bridge rectifier, and tested it with a multi-meter. When I test each pin, by putting the negative multi-meter on the + bridge rectifier and then put the + multi-meter and test the two middle pins I get around 570 on each pin, but I dont get a doubling when i put the + multi-meter on negative bridge rectifier, I get 750, could this be the problem, should it be higher?

 

Service manual here. https://www.nodevice.com/service-manuals/musical-instrument/roland/jv-1080/399642


Here's a snapshot of the psu page17, there are two bridge rectifiers , check each one from the+ to ~ pin and - to ~ pin. They should read about 650 mV one way and open circuit the other way.
Check the supply voltages from the regulators +/-12V , and the 5V one.

 

Service manual here. https://www.nodevice.com/service-manuals/musical-instrument/roland/jv-1080/399642


Here's a snapshot of the psu page17, there are two bridge rectifiers , check each one from the+ to ~ pin and - to ~ pin. They should read about 650 mV one way and open circuit the other way.
Check the supply voltages from the regulators +/-12V , and the 5V one.


View attachment 306370

Thanks Dave, I will check the other rectifier, and regulator tomorrow.

Sometimes the synth maybe on for hours and decides to reset to the first preset, the same preset when you turn it on, I am sure it’s a power issue. I have read online the same from other people

 

Thanks Dave, I will check the other rectifier, and regulator tomorrow.

Sometimes the synth maybe on for hours and decides to reset to the first preset, the same preset when you turn it on, I am sure it’s a power issue. I have read online the same from other people

Service manual here. https://www.nodevice.com/service-manuals/musical-instrument/roland/jv-1080/399642


Here's a snapshot of the psu page17, there are two bridge rectifiers , check each one from the+ to ~ pin and - to ~ pin. They should read about 650 mV one way and open circuit the other way.
Check the supply voltages from the regulators +/-12V , and the 5V one.


View attachment 306370

Hi Dave sorry the late reply, I checked the bridge rectifier ( D3SBA20 ), as you suggested, and yes its open one way, and reads around 560mV when testing the other way, but when just testing the two middle pins ~ it beeps in continuity mode and reads 001mV.

 

Did you check the rectifier out of circuit, if not then you will be reading the transformer secondary windings.

 

Did you check the rectifier out of circuit, if not then you will be reading the transformer secondary windings.

Thanks Dave, No I checked it in the circuit, I guess not the wisest option.

When testing the - and the ~ I get 560mV. Should I get a doubling in voltage when testing the + and - , In this test I get 760mV