Hi guys.
A friend gave me today a SansAmp Bass Driver DI that makes erratic noise when using the XLR or TRS outputs into any console or amp. Someone had fixed it before but after a few days of use the issue came back. So he asked me if I could fix it.
I have no idea what the other tech did to this stompbox.
The symptoms are:
Erratic noise when used between an instrument and an amp. The noise is no hum nor a hiss.
When plugged to a console using phantom power on a balanced XLR cable, signal passes through the unit but the pedal does not activate (LED off). When turning off phantom power the signal dies.
Friend told me that sometimes it works but most of the time it doesn't.
I was thinking of a cold solder joint. The problem is that this unit has been opened before and in order to do that, all connectors (3 TRS and 1 XLR) have to be desoldered before the PCB can be taken out.
I did not jet open it, the solder points to the traces can easily be compromised the more I desolder all these joints. Also, I usually don't do SMP stuff...
Any ideas what the problem might be, before I take it on?
A friend gave me today a SansAmp Bass Driver DI that makes erratic noise when using the XLR or TRS outputs into any console or amp. Someone had fixed it before but after a few days of use the issue came back. So he asked me if I could fix it.
I have no idea what the other tech did to this stompbox.
The symptoms are:
Erratic noise when used between an instrument and an amp. The noise is no hum nor a hiss.
When plugged to a console using phantom power on a balanced XLR cable, signal passes through the unit but the pedal does not activate (LED off). When turning off phantom power the signal dies.
Friend told me that sometimes it works but most of the time it doesn't.
I was thinking of a cold solder joint. The problem is that this unit has been opened before and in order to do that, all connectors (3 TRS and 1 XLR) have to be desoldered before the PCB can be taken out.
I did not jet open it, the solder points to the traces can easily be compromised the more I desolder all these joints. Also, I usually don't do SMP stuff...
Any ideas what the problem might be, before I take it on?
So today I started working on the SansAmp. It really is a pita, after desoldering all jacks and the XLR, I got the pcb out.
When I turned it around and looked at the components, I wasn't able to identify any numbers on resistors or caps, even using a magnifying glass. Only the larger quad op-amps and similar IC's. Unfortunately, I forgot to take any notes of the numbering.
However, I modified all connectors and put wires on them, in order to take the pcb out much easier, without the need to desolder all jacks, each time someone has to take it apart.
It still has he same symptoms...
When I turned it around and looked at the components, I wasn't able to identify any numbers on resistors or caps, even using a magnifying glass. Only the larger quad op-amps and similar IC's. Unfortunately, I forgot to take any notes of the numbering.
However, I modified all connectors and put wires on them, in order to take the pcb out much easier, without the need to desolder all jacks, each time someone has to take it apart.
It still has he same symptoms...
Maybe somebody finds the Factory schematic, but for starters here you have a reverse engineered clone, might help for tracing your issue.
Most probably part designations will not match, but actual schematic/parts will or be very close.
Would not be surprised about typos on redrawn schematic.
Way more complex than I expected, but doable.
I would inject signal, say 100mV 1kHz and follow it end to end, to check where it disappears or becomes garbled/noisy.
Also check for DC at all Op Amp pins; I´d expect about +9V on all 4 pins on quad Op Amps, pin 8 of duals, 0V on pins 11 and 4 respectively, and about 4.5V on all other pins.
Most probably part designations will not match, but actual schematic/parts will or be very close.
Would not be surprised about typos on redrawn schematic.
Way more complex than I expected, but doable.
I would inject signal, say 100mV 1kHz and follow it end to end, to check where it disappears or becomes garbled/noisy.
Also check for DC at all Op Amp pins; I´d expect about +9V on all 4 pins on quad Op Amps, pin 8 of duals, 0V on pins 11 and 4 respectively, and about 4.5V on all other pins.
Google finds more traced schematics. Link seems dubious so schematics attached so no one else needs to click it 
Schems found here https://drugscore.blog.fc2.com/blog-entry-286.html
While can't help whats the problem with your devices my intermittent problems on all kinds of devices have been cold solder joints and bad jack sockets mostly. Then there has been problems with pots and switches, but that is usually obvious when using the device.
Schems found here https://drugscore.blog.fc2.com/blog-entry-286.htmlWhile can't help whats the problem with your devices my intermittent problems on all kinds of devices have been cold solder joints and bad jack sockets mostly. Then there has been problems with pots and switches, but that is usually obvious when using the device.
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Hello! Yes, this is a bit old discussion, but I have recently very much same kind of thing ongoing.
I have Sansamp Bass driver V1 late model as my understanding, second hand. It worked well some time, but one day it went silent during the use.
First the output TRS signal died, but worked ok from DI connection. Now it is totally silent, so DI doesn't work either anymore. It might work sometimes(1 out of 30..) ok for a while, and signal will go through and effect will engage ok but mostly it wont. I haven't yet desoldered the TRSs to get it fully opened, but I'm looking for some advice if there might be any similar with same kind of issues ones out there? It seems that all the connections and TRS are ok, so I assume the problem might be one of the capacitors or OPs perhaps. Any kind of tips are welcome! Cheers.
I have Sansamp Bass driver V1 late model as my understanding, second hand. It worked well some time, but one day it went silent during the use.
First the output TRS signal died, but worked ok from DI connection. Now it is totally silent, so DI doesn't work either anymore. It might work sometimes(1 out of 30..) ok for a while, and signal will go through and effect will engage ok but mostly it wont. I haven't yet desoldered the TRSs to get it fully opened, but I'm looking for some advice if there might be any similar with same kind of issues ones out there? It seems that all the connections and TRS are ok, so I assume the problem might be one of the capacitors or OPs perhaps. Any kind of tips are welcome! Cheers.