Locobox - Mysto-Dysto Distortion Unit
Posted: 01 May 2014, 13:08
Got one of these in for repairs. To begin with, original pots were fastened with hot glue, stomp switch had turned into momentary, DC jack was shattered and the battery snap was dead. Swapped the broken parts and tested it. Sounded really nice. I figured that there has to be a schematic available on the web as it quite old and very nice sounding OD/Dist. So i packed it up with a ton of packaking tape, ready to be sent back to the owner.
In the evening i started to watch some Voyager episodes on the couch, armed with a mug of cola and a laptop. Started looking for a Mysto-Dysto schematic as i figured i might want to clone one for myself at some point. Damn. No schematic anywhere. Only some random mentions about the circuit being OD250/Dist+ with BMP-style tone control. Just a few hours back i had the unit wide open on my desk and a camera about one meter away from it. Didn't occur to snap some photos at the time. Asked around for the schem, and no-one had a copy. Or even seen one.
The next day i opened the parcel i had taped shut last night and opened the Mysto-Dysto up again. Snapped couple of photos and wrote the component values down.
Haven't have time to trace it to a schematic yet (nor will have in the next week or so). But i thought i'd share the values and photos anyway.
Opamp is 6552, there are two 2SK30As and four 2SC1815 transistors in there. All three diodes seem to be Si signal diodes. Should be pretty close to modern 1N4148s.
Pots are: Distortion C500K, Tone A100K, Volume A100K (I'd suggest trying linear for tone and volume...)
"Bypass" switch is latching SPST. LED-, SW2, Dist lug 3 and DC jack tip connect to ground with in/out jack sleeves I have no idea what colour the original LED was. Swapped the hot glue blob for a 5mm diffused red. Works fine...
In the evening i started to watch some Voyager episodes on the couch, armed with a mug of cola and a laptop. Started looking for a Mysto-Dysto schematic as i figured i might want to clone one for myself at some point. Damn. No schematic anywhere. Only some random mentions about the circuit being OD250/Dist+ with BMP-style tone control. Just a few hours back i had the unit wide open on my desk and a camera about one meter away from it. Didn't occur to snap some photos at the time. Asked around for the schem, and no-one had a copy. Or even seen one.
The next day i opened the parcel i had taped shut last night and opened the Mysto-Dysto up again. Snapped couple of photos and wrote the component values down.
Haven't have time to trace it to a schematic yet (nor will have in the next week or so). But i thought i'd share the values and photos anyway.
Opamp is 6552, there are two 2SK30As and four 2SC1815 transistors in there. All three diodes seem to be Si signal diodes. Should be pretty close to modern 1N4148s.
Pots are: Distortion C500K, Tone A100K, Volume A100K (I'd suggest trying linear for tone and volume...)
"Bypass" switch is latching SPST. LED-, SW2, Dist lug 3 and DC jack tip connect to ground with in/out jack sleeves I have no idea what colour the original LED was. Swapped the hot glue blob for a 5mm diffused red. Works fine...