Roland JP-8000
Today I want to show you the repair of a classic Roland. The repair itself was quite typical for instruments of this age. The instrument had a very low output signal level. This was caused by the natural aging of the electrolytic capacitors in the output audio path. This increases their series resistance and causes a low signal level and/or distortion.
Interestingly, after replacing these parts, the output signal was no longer available at the outputs at all (it was only present on the headphones, but distorted). This was caused by a damaged electrolytic capacitor in the muting circuit and incorrect control of the transistors responsible for this function. In short – standard case – all electrolytic capacitors needed replacement.
Additionally, it turned out that two transistors in the muting circuit were damaged. After replacing all the electrolytics and the two transistors, the unit works like new!
