Repair of Digitech BP8

[abarson]

I've gotten the power supply sorted out (faulty TL079 recitifier, new jack and socket), but the "Down" footswitch doesn't operate, and the green "Program" LED just above it is constantly lit. I've got the schematic, but I'm not seeing either components listed. Anyone have any experience with repairing this effect unit?

 

[BrentSimons]

Send it to Digitech. The last time I knew they still repaired the BP8 and the older RP units. I've always had great customer service from them.
Hope this helps,
Brent

 

[abarson]

Oh, but I'm so close...!

 

[JonnyAngle]

DigiTech Pedal Multi-Effects Button Switches (5) for RP1, 3, 5, 6 or XP100, BP8

These?

 

[abarson]

DigiTech Pedal Multi-Effects Button Switches (5) for RP1, 3, 5, 6 or XP100, BP8

These?

That's helpful!

Still hoping for a solution for the LED.

 

[Weathergeekee]

Soooo who has a schematic for the digitek BP8 they can direct me to? My bass player's girlfriend spilled a coffee into it and it's over caffeinated something's dead in the output area, lights work, processor works senses the input and overload, but static for outputs and headphone. He's had it forever and I'd like to fix it for him (again please help me help him out.

 

[abarson]

Found it!
I would recommend opening it up and carefully cleaning all the liquid residue out of it first. It's also an opportunity to spot any obviously defective components.

 

[Weathergeekee]

Thanks a million abarson!! It's been 3 weeks since the, ahem, 'incident' so all was dry inside. I cleaned the board of any obvious residue, old flux between pins, and pulled/washed the pushbutton panel that was 'sticky'. Powers on, 12AX7 tube lights (Russian SOVTEK), senses overload, output just produces a little static when driving the input. I should be good with this roadmap though. Siggen and scope and I'll let you know how I do, fingers crossed. Again, can't thank you enough for the quick reply!!!!

 

[Weathergeekee]

Thanks a million abarson!! It's been 3 weeks since the, ahem, 'incident' so all was dry inside. I cleaned the board of any obvious residue, old flux between pins, and pulled/washed the pushbutton panel that was 'sticky'. Powers on, 12AX7 tube lights (Russian SOVTEK), senses overload, output just produces a little static when driving the input. I should be good with this roadmap though. Siggen and scope and I'll let you know how I do, fingers crossed. Again, can't thank you enough for the quick reply!!!!

Update, all fixed After cleaning all the coffee and flux residue, I traced the signal path from input to the input of U37 with a signal generator and scope. I found the main problem was an intermittent circuit trace from U26-12 to U47-11 which was preventing the U37 digital audio attenuator from getting loaded via the SPI bus from the Z84 microprocessor, so it was always at high attenuation. Pressing on the board slightly caused the broken connection to 'make' and start working. Jumped the connection (blue wire in the pic), lubed the pots and switches with DeoxIT Fader F100L, and a general gleaning and good as new! Thanks again for this forum and schematic from abarson!!

 

[Weathergeekee]

I've gotten the power supply sorted out (faulty TL079 recitifier, new jack and socket), but the "Down" footswitch doesn't operate, and the green "Program" LED just above it is constantly lit. I've got the schematic, but I'm not seeing either components listed. Anyone have any experience with repairing this effect unit?

The little push button switches get worn or crap inside, sometimes stick 'ON' and might hang the processor. Dissemble down to the circuit board level and see how the switches operate with a small screwdriver and ohmmeter to check 'make/break resistance. Also, I've seen the plastic posts from the pedal to the switch get worn and not activate the switch unless really stomped on, then causing other issues like physical damage, broken solder joints, cracked boards etc. Lots of skinny traces on that board so you might have a cracked trace like I had. Point to point checks with a multimeter in the problem area might help track down a broken trace.

 

[bassbrad]

So happy you were able to resurrect the beast, great sounds in there. I would use mine more but for the size and fragility.

 

[Weathergeekee]

Boss BP8: They actually did a pretty good job isolating the pedals from the circuit boards with rubber pads in between. However, I have had to improve the physical contact to the pedal #1 switch by extending the 'pedal post' that pushes the switch with a small plastic sleeve. The switch was somewhat worn and needed extra 'stomping', not good for the rest of the unit. The 12AX7 tube has a retaining bracket to keep it in place under shock. Chassis is all steel so is strong and resists magnetic field interference. Keep all the bottom screws in place and it stays pretty solid. Circuitry is all analog with digital switching control and has the adjustable input and output with overload LED indicator so you can maximize s/n without unwanted clipping. All in all a nicely designed unit.