Hello firstly let me thank you all for the help and advice given to me in the past much appreciated .I am currently trying to fix a Boss PH2 phaser and seems like i am running around like a headless chook cause i have no idea on how commander circuits work neither about the other chips in the unit i have a schematic that i can post the issue with the unit is that in bypass mode i do get clean sound from the guitar to the amp but when in effect mode the unit is quiet i have swapped the HD14053 chip with a CD4053(guessing its the same chip correct me please) also replaced the the NE570n with another from an old Roland unit but still no joy any hep and assistance woul be very much appreciated thank you in advance.regards
Roque.

 

To track down a proble in a system like this a device called a signal tracer can be very useful. the procedure is to provide an input signal of an appropriate level to the input, and then, using the circuit diagram, trace it through until you find a point where it stops, or becomes distorted. The parts connected to that node are then suspect and can be checked by standard methods, such as an ohm meter.

 

To track down a proble in a system like this a device called a signal tracer can be very useful. the procedure is to provide an input signal of an appropriate level to the input, and then, using the circuit diagram, trace it through until you find a point where it stops, or becomes distorted. The parts connected to that node are then suspect and can be checked by standard methods, such as an ohm meter.

Thanks Bill...done that i am at at stage suspecting the NE 570 chip i did swap it over with another used pcb...but not sure if the one i swapped is defective too...also suspecting the ic 1.i guess will need to swap over with new parts...

 

The Se/Nw570 is an unusual IC, which I believe has a gain control input as well as opamp inputs. One worthwhile approach would be to do a check of the voltages at the various pins and compare those readings with the "typical" ones from the data sheet. If you are able to put in a socket for the IC it will certainly help avoid damage to the PC board as you change parts. My experience with the newer guitar amps is limited to my Fender "ultimate chorus" amp, which some fool damaged the input jacks. But the circuit on that one is impressive, and the way that they get multiple functions from the foot pedal is brilliant.

I made my suggestions about diagnostics based on my recent observations that some of the folks in these postings have very little or absolutely no background in anything. But it sounds like you have experience and understanding.

 

The Se/Nw570 is an unusual IC, which I believe has a gain control input as well as opamp inputs. One worthwhile approach would be to do a check of the voltages at the various pins and compare those readings with the "typical" ones from the data sheet. If you are able to put in a socket for the IC it will certainly help avoid damage to the PC board as you change parts. My experience with the newer guitar amps is limited to my Fender "ultimate chorus" amp, which some fool damaged the input jacks. But the circuit on that one is impressive, and the way that they get multiple functions from the foot pedal is brilliant.

I made my suggestions about diagnostics based on my recent observations that some of the folks in these postings have very little or absolutely no background in anything. But it sounds like you have experience and understanding.

Thanks Bill once again.... I have replaced the ne570 chip from an old roland chorus unit the space echo units with a tape for echo that was used ..it was a functioning unit that had the ne570 so i swapped it accross but no joy...i compared voltages of all ics and transistors to someone who had a similar issue and he posted the voltages they seemed exact ...the confusing bit is he had the same issue.

 

The Se/Nw570 is an unusual IC, which I believe has a gain control input as well as opamp inputs. One worthwhile approach would be to do a check of the voltages at the various pins and compare those readings with the "typical" ones from the data sheet. If you are able to put in a socket for the IC it will certainly help avoid damage to the PC board as you change parts. My experience with the newer guitar amps is limited to my Fender "ultimate chorus" amp, which some fool damaged the input jacks. But the circuit on that one is impressive, and the way that they get multiple functions from the foot pedal is brilliant.

I made my suggestions about diagnostics based on my recent observations that some of the folks in these postings have very little or absolutely no background in anything. But it sounds like you have experience and understanding.

Sorry about the delayed replies i guess we are at opposite parts of the world i am downunder in Australia..our timings vary.

 

The next step is detailed signal tracing, But the IC devices don't seem to have numbers on all of them. SO, which one is the ne570? That will help in developing the sequence of points to check. Also checking all of any adjustables in the path that is not working.
The way that some phasor boards work is that they have what has been called a "bucket brigade delay line", which is probably that IR3109 IC . Those need a clock signal, which ought to be a square wave that is generated by IC8, and controlled by the circuit just downstream of it. So tracing through that section is a logical step, since if the delay line is not being clocked nothing will pass through.

 

The next step is detailed signal tracing, But the IC devices don't seem to have numbers on all of them. SO, which one is the ne570? That will help in developing the sequence of points to check. Also checking all of any adjustables in the path that is not working.
The way that some phasor boards work is that they have what has been called a "bucket brigade delay line", which is probably that IR3109 IC . Those need a clock signal, which ought to be a square wave that is generated by IC8, and controlled by the circuit just downstream of it. So tracing through that section is a logical step, since if the delay line is not being clocked nothing will pass through.

 

View attachment 149876

The ic mentioned ic6 at the top right is actually IC3 a mistake in the schematic
I get a raw sound when i jumper pin 1 of m5218 and to pin 2 of ic3 i get a phaser sound but its distorted and sort of not clean but can hear the pulses and it varies according to the setting from the pots.

 

The next step is detailed signal tracing, But the IC devices don't seem to have numbers on all of them. SO, which one is the ne570? That will help in developing the sequence of points to check. Also checking all of any adjustables in the path that is not working.
The way that some phasor boards work is that they have what has been called a "bucket brigade delay line", which is probably that IR3109 IC . Those need a clock signal, which ought to be a square wave that is generated by IC8, and controlled by the circuit just downstream of it. So tracing through that section is a logical step, since if the delay line is not being clocked nothing will pass through.

A sad case i am i have an old oscilloscope but i have forgotten how to use it ....shame on me

 

I did look at the circuit of my Fender "Ultimate Chourus" and it also uses that clock oscillator. If that waveform is not right then nothing will sound right.

 

The IR3109 is a transconductance amplifier, which does not need a clock. That's how phasers are usually made, by using voltage-variable all-pass filters. I use the LM13700 in phaser circuits, it's a similar part (but not a replacement). I've also seen different designs that use JFET's as a variable resistance for the all-pass filters, instead of the OTA.

BBD's are used for flangers.

 

Looks like i may have mucked up the pedal..i tried to replace the aca 12v dc adaptor circuit to work on 9v dc and accidentally shorted diode D5 dont know what was i thinking ... now i dont get the clean sound in effect bypass mode....will need to sit and start from scratch all over..thanks guys for your inputs will keep you posted as to what is busted... Cheers.

 

The IR3109 is a transconductance amplifier, which does not need a clock. That's how phasers are usually made, by using voltage-variable all-pass filters. I use the LM13700 in phaser circuits, it's a similar part (but not a replacement). I've also seen different designs that use JFET's as a variable resistance for the all-pass filters, instead of the OTA.

BBD's are used for flangers.

Whatever the device is? My "ultimate chorus" amp has an almost identical oscillator to the one in the lower left corner of the big circuit schematic, and although I did not go through a detailed study of the whole circuit, my point was that a failure in an auxilliary part of the system could also stop it from working.