New (broken) pedal day!

[Pepe]

Okay, I will try that, then. The old way.

EDIT: Or is it a safe way to use a 1kOhm resistor instead of shorting the legs? I just want to hear the pedal's reaction to find out what is what.

[laurie]

Okay, I will try that, then. The old way.

EDIT: Or is it a safe way to use a 1kOhm resistor instead of shorting the legs? I just want to hear the pedal's reaction to find out what is what.

1k should be fine. Let us know what you find....

[Pepe]

For future reference, if anybody needs information about the trimpots of the Pearl AD-33, this is what I found out:

AVR1: Feedback Channel I
AVR2: Feedback Channel II
AVR3: BBD Bias (not 100% sure)
AVR4: Clock Cancel (not 100% sure)
AVR5: Clock Frequency
AVR6: Filter

I maximised the Clock Frequency for the longest possible delay time (surprisingly not too many artifacts to be heard - I suspect that a trimpot of higher value could enhance the delay time and sound artifacts). At first I turned the filter trimpot to the maximum position for the brightest sound, but that resulted in a too high noise-floor, especially at medium delay times. I left it at about 55% for the best compromise between performance and sound. And I optimised the feedback amount of both channels so they have both the ability to self-oscillate at demand. The manual says that factory wise Channel II has higher feedback. I thought that it was by far still not enough.

[laurie]

For future reference, if anybody needs information about the trimpots of the Pearl AD-33, this is what I found out:

AVR1: Feedback Channel I
AVR2: Feedback Channel II
AVR3: BBD Bias (not 100% sure)
AVR4: Clock Cancel (not 100% sure)
AVR5: Clock Frequency
AVR6: Filter

I maximised the Clock Frequency for the longest possible delay time (surprisingly not too many artifacts to be heard - I suspect that a trimpot of higher value could enhance the delay time and sound artifacts). At first I turned the filter trimpot to the maximum position for the brightest sound, but that resulted in a too high noise-floor, especially at medium delay times. I left it at about 55% for the best compromise between performance and sound. And I optimised the feedback amount of both channels so they have both the ability to self-oscillate at demand. The manual says that factory wise Channel II has higher feedback. I thought that it was by far still not enough.

Thanks!

[Pepe]

In July a friend from Switzerland sent me a faulty BOSS RPS-10 Digital Pitch Shifter/Delay. He had two working units plus this one that at some point stopped working. Someone already tried to repair it. I don't know if this person has ever used a soldering iron before. It led to a really awful mess around Q5 on the circuit board. Some eyelets have come off and a few conductive paths were destroyed. As a result the unit was always in effect mode and instead of the delay and pitch shifter only the tuner out signal somehow was in the signal path.

When I received it I replaced the transistor and tried to repair the conductive paths. But the problem was that there were no high resoluted pictures of the circuit board to be found in the internet. There was a service manual somewhere, but it was not in the best resolution, either. I was not able to spot the fault with it. So I left the unit disassembled for a few months. I had to do so many other things anyway.

Then last week I won an ebay auction of a working RPS-10. It was not really too cheap, but I wanted to get the repair done now, so I bought it as a reference unit. When I opened it up and compared the area around the two transistors Q4 and Q5 I almost immediately saw that there was a missing connection that was destroyed by that genius with the soldering iron. I soldered a wire between these two solder points - and the unit was properly alive again!



Now I have two fully working units. I am going to sell the one that I have repaired to fund the purchase of the second unit.

For future reference I uploaded pictures of the circuit board in high resolution that will open if you click on the smaller pictures below.

[laurie]

Nice!! Great save.

[Pepe]

And it's a fantastic unit. The Keyboard input on the back is awesome! I can do automatic pitch shifting with my synthesizers with activated arpeggiator or sequencer so that a single chord moves the two octaves up and down. There are a lot of completely unheard-of sounds in this box this way!

[fuzzbuzzfuzz]

In July a friend from Switzerland sent me a faulty BOSS RPS-10 Digital Pitch Shifter/Delay. He had two working units plus this one that at some point stopped working. Someone already tried to repair it. I don't know if this person has ever used a soldering iron before. It led to a really awful mess around Q5 on the circuit board. Some eyelets have come off and a few conductive paths were destroyed. As a result the unit was always in effect mode and instead of the delay and pitch shifter only the tuner out signal somehow was in the signal path.

When I received it I replaced the transistor and tried to repair the conductive paths. But the problem was that there were no high resoluted pictures of the circuit board to be found in the internet. There was a service manual somewhere, but it was not in the best resolution, either. I was not able to spot the fault with it. So I left the unit disassembled for a few months. I had to do so many other things anyway.

Then last week I won an ebay auction of a working RPS-10. It was not really too cheap, but I wanted to get the repair done now, so I bought it as a reference unit. When I opened it up and compared the area around the two transistors Q4 and Q5 I almost immediately saw that there was a missing connection that was destroyed by that genius with the soldering iron. I soldered a wire between these two solder points - and the unit was properly alive again!



Now I have two fully working units. I am going to sell the one that I have repaired to fund the purchase of the second unit.

For future reference I uploaded pictures of the circuit board in high resolution that will open if you click on the smaller pictures below.

well done! very neat.

[Pepe]

A few days ago I received another Ibanez pedal from the 10-series, this time a BE10 Graphic Bass EQ. The slide potentiometer for the lowest frequency band had a fault. As so often in the last months I bid on it, hoping that it would be an easy fix. What it was in the end!

The 63 Hz potentiometer did only produce a full boost, turning it to the minimum position caused an interruption of the whole effect signal. Obviously a short. At arrival the slider knob was bent and askew. Apparently the previous owner had accidentally stomped on it. The problem caused by that mistake was that the bare wire for the wiper had full contact with one of the terminals (maximum position) of the carbon resistive element. So turning the knob to the minimum position made all the three pins have full contact with another, resulting in a textbook short.

I had to use a very fine screwdriver with flat head to carefully bend the wire so that it had no further contact with the rivet of the one terminal anymore. Once that was done, the potentiometer was fully working again. What a relief!

Anyone who has ever tried to search for a replacement of an old slide potentiometer (in this case a 20 kOhm G type fader!) knows that there is almost no chance to find an equivalent for a 40-year-old unit with the same amount of pins at the same positions. Normal potentiometers are no problem in most cases, but slide potentiometers can be a sheer torment.

Despite the worn look and the flaking paint, the pedal is working great again. Not the tiniest crackling anymore and even the switch is working reliably again after I disassembled it and cleaned the metal parts with isopropyl alcohol. And of course I renewed the solder joints of the jacks and DC input, the weak point of this series.

Saved from the bin, ready to do the job for another 40 years!

[laurie]

Nice job pepe!

Another one saved from the parts bin.

Yes - I have great empathy for the frustration finding parts like this!