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Dear Folks of this Forum and especially Bio77

i managed to get my blueshift back in working order.

I guess i am not the only one who has tried to "improve" something in a build and ending up butchering it and having to fix it after hours of desperate searching.

In short i had no more signal from the BBD section 2 with test point 2.

having 2 identical BBD lines i started to swap around BBD chips (3207), BBD drivers (3102) and even Compander chips -> didn't help.

I measured , audioprobed and scoped in the circuit in the section where signal comes from the BBD chips and enters the outputting Compander 571. I was getting very confusing dc offsets.i started to suspect the transistors before the compander and even the dc blocking elkos. even swapped those around -> no improvement.

in the end i started to examine the rc network before said transistor and found the connection between R24 and TP2 broken -> jumpered it and there was the sound back.

Hallelujah.

Biased it and boxed it.

My initial Reason to start tinkering with it again was the fact that i always found the sound of it rather subtle compared to a DC2 Wazacraft, beautiful but subtle .Maybe thats just the way it is.

breaking this connection certainly was my mistake because it worked for two years before. on the other hand two years ago right after building it required a jumper between C5 and R7. That trace is clearly visible on the PCB but made no connection. so maybe this board may be somewhat fragile.

So far this problem is solved for me. I might start exploring again why it is rather subtle.

thank you all

Regards

Philipp

Dear Folks
 i have a problem with my blueshift build.

let me say first that this thing worked well and beautifully for like two years but the i had to try to improve it and subsequently mess someting up.

The BBD Path 1 is working fine (Observable with Oscilloscope at TP1).  Path 2 however is not putting out any wet signal anymore.

I tried tracing the Signal by generating a sine wave and following it through the circuit.
At the Output pins of the BBD Chip Mn3207 IC3 (pins 7 & i still get correct signal reacting to the Bias Trimmer in the expected fashion no problem there. also it somewhat obviously still applies Vibrato as the Clock Signal at BBD Chip is cleany observable.

From there on i still get my signal at the Base of the Q4 2N5088. Collector seems to be on 9V as written in the schematic. At its Emitter though my Signal is dead. I suspected the Transistor, changed it for a new and unused one i had around -> no change.

For the sake of Experimentation i removed the NE570 Output Compander right after Q4 and my Signal immediately returned at the Emitter of Q4 cleanly reacting to Bias trimmer in the expected Fashion.

I started to suspect the Compander Chip IC11 NE570. I swapped it out for two clearly functioning Companders from 2 Lectric DC-Echos that i have -> same Result,no Improvement.
I also swapped the compander chips in the other Direction (from the Blueshift into the DC-Echo) and they seemed to be working just fine.

Result Compander Chip in the Circuit -> No Signal at TP2, Compander Chip out -> nice Signal at TP2

I anyone here familiar enough with this Circuit to give me a hint about what might be happening.

Both 3207 Chips and Compander Chips seem to be just fine.

I like the Sound of this Circuit enough that i would consider building a second one if this is not fixable but deep down i am pretty sure it should be straightforward to fix.

Bless you and all and

Thanks

Philipp