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Hello and thanks for your help,
I recently completed the build of the Sabotage Pcb. I attempted to rock it before I boxed it and found there was no effect. I could hear only a slight oscillation. I double checked all component values and found I had put the MPSA18 in Q1 according to the silk screen. As I walked through the schematic, I realized it needed to be backwards. Consulting this forum confirmed that, so I switched it around. I tested it and the results were the same. I have hit a wall with troubleshooting and need your help.
Steve – I’d start with a reflow of the solder joints – hot and quick with flux. Also, considering the MSA18 was heated twice, you may want to check it to ensure it wasn’t toasted.
Post a photo so that we can see and trace the DC jack and 3PDT wiring to the in and out jacks and pcb in and out T pads
Thank you Cybercow and Billy. In response to cybercow, I have not done any off board wiring. I have a ground and + 9 voltage wire in place along with the in and out wires. I have a test rig that I am using to troubleshoot before I box the effect.
Cybercow, I reflowed solder and cleaned off the board with isopropyl. I used my Audio probe and found that the MPSA18 in Q1 is working properly. There is a nice gain boost. When I probe any of the 2n5485 I hear only oscillation. If I understand the circuit correctly, I should be getting a boost from each transistor. I should at least hear the audio path. I think I purchased some bad transistors. I am thinking I should buy the originals from the guitar pcb website and swap all 5 out. Does this seem like the solution? Thanks for your time and expertise.
That very well may be the issue of course. I cannot guarantee that.
Do you have other JFET to try? Like J201 or 2N5457 etc.? If you are going to do that I suggest a socket approach.
Steve – what Barry said is an important aspect of pedal building. Socketing active components like chips and transistors is a good practice. I always leave my chips socketed. But for transistors, I solder them only AFTER I’ve verified the socketed transistors work. Getting the proper FETs from GuitarPCB is your best bet. Good luck!
I am pretty sure they do Billy. I had to mentally rotate the board in my mind from the backside to see that but it looks to be correct.
Thanks everyone,
I ordered some new transistors and sockets. I’ll make the swap when these components arrive and report back. I’m sure that is the issue.
Hi all,
I ordered some transistors and sockets from the website and installed them. The pedal now works as described. Thanks to Barry for the help and quick parts delivery. I don’t know why I didn’t socket the transistors: I just wanted to show off for the pedal build ladies.
PS: Thanks for the informational cards. they will come in handy
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