Amps and effects
A chorus from the -80:s, the Yamaha CH-01. Based on the MN3009 256 stage BBD chip and the MN3101 clock generator.
Had the circuit recaped and trimmers adjusted for bias, clock speed and depth.
And here we have a chorus once again delivering.
/Krister
Found the the time to recap the preamp for the Yamaha RA-100 published in an earlier post. Pictures before and after.
/Krister
These two arrived for repair.
/Krister
Got a Yamaha RA-100 in for repair. A quite nice looking solidstate amp with the feature of two rotary speakers. It’s in a nice condition but it blows fuses in the poweramp amp.
Here’s a caption of the rotary speakers and the poweramp.
I ripped the poweramp out and after some measurements I found that the power trannys on side was blown, causing the fuses to blow. I replaced the power and drive trannys for both side and had the circuitboard recaped since some of the electrolytic capacitors was in a bad state.
Look at the size of an old electrolytic capacitor from the -70:s compared to a modern one with much higher voltage rating.
The circuitboard totally recaped with new power and drive transistors.
So it was finally time to hook everything up and fire it up. Here’s a video from the tryout.
I must say it was nice bringing this one back to life.
/Krister