Rockman X100 Rev. 10 Schematic Release

Cybercow

Well-known member
With the successful completion of the (Rockman) RMS X100 Rehouse Project V1 & V2, Josh Ledford and I are happy to finally release the fully corrected Rockman X100 Rev 10 circuit schematics. Over the course of almost four years, as many as four people have collaborated with analyzing, testing, measuring and drawing out the many details wrapped inside Tom Scholz’s signature sound circuit.

The original schematics found on the US Patent site are by no means complete, accurate or even workable when compared to what we eventually discovered with all of the analysis we’d completed on over 2 dozen Rockman X100 units. The attached schematics are accurate, tested and verified as we’ve produced over 40 of the RMS Rockman X100 builds.

(The blue component IDs are those IDs used on our V1, V2 & V3 PCBs. The IDs in black are those used on the original 1980s X100 rev 10 boards.)
Board_100_Schematic_Marked_Updated_ to_BOM.png Board_200_Schematic_Marked_Updated_ to_BOM.png

The first 18 months or so was spent on analysis, schematic corrections & creation, cloning the original PCBs and parts sourcing. The original concept was to simply rehouse an X100 into a pedal with foot switches for faster access to MODE & FX changes. After producing a working set of PCBs, populating and successful testing, the next step was to sort out how change the slider switches to stompswitches. But the stompswitches available are just insufficient to meet the complex switching arrangement Scholz used in his units. That was about where I came on board to help with a working, reliable switching system for these pedals. Old school sequential logic switching proved out to be the easiest approach without having 8 or more stompswitches on a pedal to accommodate all the MODES & FX. So, one stomp to cycle thru all four MODES and and one stompswitch to cycle thru the three FX with an added “Dry” option (no FX). Naturally, a true-bypass 4PDT stompswitch was included to facilitate the mono-in/stereo-out circuit.

Another discovery with X100 prompted us to develop a unity-gain recapture circuit, as the X100 is a below-unity-gain circuit. So with the switching and output levels to manage, we added the ‘sequential logic switching’ and ‘low-level output’ (LLO) circuits.

X100_Mode_DCBE_Switching_Schematic_Legend_01.png X100_LLO_Boost_Schematic_Final.png

There is a lot to be said about the differences between the original Rockman X100 and the updated V3 units we are about to produce. The evolution from the simple “rehousing” idea to the latest RMS Rockman X100 V3 is another long story that will also unwind as time allows.

With the disappearing availability of the MN3011 BBD chips, we will drop the use of the MN30xx BBD chipsets altogether and use the SpinSemi FV-1 DSP chip. This greatly reduces the overall noise, large footprint & parts-count of the PCB. And it allows us to go with a smaller, more readily available 1590D enclosure, using the same sequential logic switching for the MODE options. The FV-1 FX switching will be a standard SP8T rotary switch. About 6 months was spent in learning and developing the FV-1 FX patches to match the original X100 FX sounds. The bonus with the FV-1 is that it allowed us to add 5 more unique FX patches to the Rockman sound. And we already have a working prototype of the FV-1 infused V3.

X100_V3_1590DD_Concept.png FX100_Prototype_Test _01.jpg

For the most part, all is said and done. Except for the completion of the V3 portion of this massive project.
 
I am finding it hard to believe I am the first to comment on this post. Congrats and thanks for sharing the results of all the time an effort put into this. Can't wait to see and hear the final results.

Do you guys plan on keeping the 2n4339 or can it be subbed with a J201?
 
Do you guys plan on keeping the 2n4339 or can it be subbed with a J201?
We've found that most any JFET that exhibits/measures a Vgs(off) value of -1.00V ~(±0.10V) can be used. And with finding the 2N4399, 2N4398 & J201 JEFTs commonly enough falling into that range, those JFETs can be used. I've already used a few J201 in some of these builds. At first, we were all about being quite explicit in our reproductions, using only exact matching part numbers. But then we started running into shortages and expensive exact part IDs; so we payed closer attention to what each section of the circuit was doing to understand what the various signal controlling parameters were doing. That afforded us the chance to look for alternate parts.

The real challenge was developing/finding a reliable power supply section and marrying the main board set to the switching circuit, the LLO, and all the enclosure mounted parts.
 
Surprisingly lower than I anticipated. Nice!
Yes. We were surprised too. During our initial testing of just over 2 dozen original Rockman X100 units, we found that with batteries and the original Rockman power supply units, they consume about 420mA. Dunno how or why the BC modules exact a lower draw for the same circuit. It may well be just how batteries drain vs the BC modules.
 
Wow this is very cool!!! can't wait to hear some of the sound tests... I'm curious though as reading the OP I was thinking "what about an FCB1010 behringer MIDI control pedal" but I don't know anything about connecting MIDI to the circuit... Or how to make it work in there or if it's even feasible or how hard it would be!?!? I just thought man the FCB1010's got plenty of stomp buttons and a couple of expression pedals on it! Might be a cool thing to add later if you know how to do all that MIDI control stuff internally.

Being older than probably most people here I remember the days when we would have loved had a rockman but couldn't afford it and they sounded awesome!!! So I'm very psyched to hear this news!
 
Wow this is very cool!!! can't wait to hear some of the sound tests... I'm curious though as reading the OP I was thinking "what about an FCB1010 behringer MIDI control pedal" but I don't know anything about connecting MIDI to the circuit... Or how to make it work in there or if it's even feasible or how hard it would be!?!? I just thought man the FCB1010's got plenty of stomp buttons and a couple of expression pedals on it! Might be a cool thing to add later if you know how to do all that MIDI control stuff internally.

Being older than probably most people here I remember the days when we would have loved had a rockman but couldn't afford it and they sounded awesome!!! So I'm very psyched to hear this news!
If you're interested, this video demo of one of our RMS X100 builds just dropped today on YouTube.
 
Using a Truetone 1 SPOT mA Meter and Cable Tester, I'm seeing it draw just under 250mA.
Would you be willing to elaborate on how you're coupling the two buck converters into a +/-6V supply? It looks like you've got an electrolytic cap (220uF seems pretty common in the designs I've seen) between each rail and 'ground', but then there's also something else I can't read from the photo. I've blown up a number of buck converters connecting the input backwards, so I'm hoping to collect some more knowledge before I 'mess around and find out.' :)
 
Would you be willing to elaborate on how you're coupling the two buck converters into a +/-6V supply? It looks like you've got an electrolytic cap (220uF seems pretty common in the designs I've seen) between each rail and 'ground', but then there's also something else I can't read from the photo. I've blown up a number of buck converters connecting the input backwards, so I'm hoping to collect some more knowledge before I 'mess around and find out.' :)
Not all BC modules support the ±V idiom. I did find that the MP21584EN BC module capable of such support. We also found that using any filter caps above 22µF directly after these BC modules can interfere with the BC module boot-up process and cause them to lock up and that 100nF caps for final filters on these are quite sufficient.

Here's the diagram I share for assembling two of them to achieve a ±V supply . . . .

BC_Modules_Dual-Rail.jpg
 
Thanks so much! Like I said, I've blown up so many buck converters over the years that I've started ordering 'em in bulk, expecting the worst, but I also try to take much more care and know what I'm getting into, if I can. Thanks again!

Edit: Hah! This is the exact part that I already have a boatload of! How convenient!
 
So, I figured I'd share: I've had some successes and some "failures" in trying to make this work.

I have the basic arrangement working... with a bench supply for the input power. When I try to use a standard 9v guitar-pedal wall wart, things go south.

This application appears to be right on the edge of what the wall warts I have can supply. This seems odd, because the bench supply says that it's drawing 80mA and 0.7W (in 'constant voltage' mode, which tracks by math), and the wall wart claims it can put out 9V@1A, but I don't trust that rating at all, at this point.

The ammeter on my DMM maxes out at 200mA, and I assume I'd just blow the fuse if I tried to put it into the fray, so I ordered a new DMM that does up to 10A DC, but seriously: The difference between 80mA and 1A is... an entire order of magnitude, so something is squirrelly here, for sure. It looks like there's enough current draw from this power supply to drop the voltage from the wall wart to ~3.5V, even though that makes no sense.

I did add in a 1N4001 rectifier diode to help keep from blowing up buck converters. My next step will be to short out the diode and see if that makes the difference. Since this is a hobby project and not a work project, I've not been keeping the exhaustive engineering notes I would for work product, but I feel like I had it working off of the wall wart before I put the diode in, so it seems like a reasonable thing to try.

In a separate, but related, effort, I was able to cram two buck converters, wiring, and filter caps (but no rectifier diode) into an incredibly small package (see attached pic). Initial fitment tests suggests that it should be easily able to fit into the void next to the battery area in the X100, which would be fantastic... except: Unfortunately, the 2.1mm female barrel receptacles I have on hand only have a single pole switch built into them, and I really need a DPDT switch to make this work right (that's what the factory 3/8" power jacks on the later X100s do: switch both the +6V and -6V lines between battery and external power).

I'm not super up-to-date on my analog electronics, so I don't know if a solid state relay is viable for 'up-converting' a single pole switch to a DPDT switch or not, but a 'classic'/magnetic relay is going to add another ~20mA to the current draw (which appears to already be a problem) and would probably make it harder to fit everything in the void next to the battery compartment. (Being able to switch between battery and external power is important for the player I'm building this for.)

Probably more than anyone wanted to read about this, but I figured I'd share, just in case anyone else was trying to do this.

Edit: It appears very likely that there is a large start-up surge current (judging from watching the voltage drop across the supply line at startup). Not sure if that's from the Rockman or from the buck converters, but it appears to be substantial. I'll know more when I get my new ammeter next week. :confused: :dmm: Shorting out the 1N4001 did not make any difference.

Another discovery: If the (unpowered) Rockman's power switch is in the ON position, and you attempt to plug in a live, external power supply using the 3/8" stereo jack on the side, it will put the Rockman into a confused/non-functional state. I'm guessing this is because the insertion process momentarily connects the +6V tip of the male stereo plug with the (-6V) ring contact within the female stereo jack, which seems to be enough to confuse the Rockman. Cycling the power switch on the Rockman control panel solves the problem. I also observed that if the 3/8" cable is already plugged in, but the external supply is not (itself) powered yet, applying source power to it works just fine, without having to cycle the Rockman's power switch, further lending credence to the theory that the +6V plug tip momentarily touching the -6V socket ring contact is problematic. (I'm starting to see why the B5 amps power supply might permanently remove the ability to use batteries; switching back and forth seems fraught.)

I don't have an 'official' SR&D external 3/8" power supply, nor a Rockadaptor, so it's hard to say whether all these hiccups are the fault of my power supply or of the Rockman's design. I guess building a 3D-printed Rockadaptor-style thing could work -- it would at least avoid this 3/8" plug/switching problem, at the expense of some added pain from having to remove the batteries to switch back and forth. 🤷‍♂️ Ah the wonderful world of analog...
 

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With the successful completion of the (Rockman) RMS X100 Rehouse Project V1 & V2, Josh Ledford and I are happy to finally release the fully corrected Rockman X100 Rev 10 circuit schematics. Over the course of almost four years, as many as four people have collaborated with analyzing, testing, measuring and drawing out the many details wrapped inside Tom Scholz’s signature sound circuit.

The original schematics found on the US Patent site are by no means complete, accurate or even workable when compared to what we eventually discovered with all of the analysis we’d completed on over 2 dozen Rockman X100 units. The attached schematics are accurate, tested and verified as we’ve produced over 40 of the RMS Rockman X100 builds.

(The blue component IDs are those IDs used on our V1, V2 & V3 PCBs. The IDs in black are those used on the original 1980s X100 rev 10 boards.)
View attachment 57022 View attachment 57023

The first 18 months or so was spent on analysis, schematic corrections & creation, cloning the original PCBs and parts sourcing. The original concept was to simply rehouse an X100 into a pedal with foot switches for faster access to MODE & FX changes. After producing a working set of PCBs, populating and successful testing, the next step was to sort out how change the slider switches to stompswitches. But the stompswitches available are just insufficient to meet the complex switching arrangement Scholz used in his units. That was about where I came on board to help with a working, reliable switching system for these pedals. Old school sequential logic switching proved out to be the easiest approach without having 8 or more stompswitches on a pedal to accommodate all the MODES & FX. So, one stomp to cycle thru all four MODES and and one stompswitch to cycle thru the three FX with an added “Dry” option (no FX). Naturally, a true-bypass 4PDT stompswitch was included to facilitate the mono-in/stereo-out circuit.

Another discovery with X100 prompted us to develop a unity-gain recapture circuit, as the X100 is a below-unity-gain circuit. So with the switching and output levels to manage, we added the ‘sequential logic switching’ and ‘low-level output’ (LLO) circuits.

View attachment 57024 View attachment 57025

There is a lot to be said about the differences between the original Rockman X100 and the updated V3 units we are about to produce. The evolution from the simple “rehousing” idea to the latest RMS Rockman X100 V3 is another long story that will also unwind as time allows.

With the disappearing availability of the MN3011 BBD chips, we will drop the use of the MN30xx BBD chipsets altogether and use the SpinSemi FV-1 DSP chip. This greatly reduces the overall noise, large footprint & parts-count of the PCB. And it allows us to go with a smaller, more readily available 1590D enclosure, using the same sequential logic switching for the MODE options. The FV-1 FX switching will be a standard SP8T rotary switch. About 6 months was spent in learning and developing the FV-1 FX patches to match the original X100 FX sounds. The bonus with the FV-1 is that it allowed us to add 5 more unique FX patches to the Rockman sound. And we already have a working prototype of the FV-1 infused V3.

View attachment 57026 View attachment 57027

For the most part, all is said and done. Except for the completion of the V3 portion of this massive project.
In the stereo output should the 10uf just before the A50k be shown as an electrolytic, with the polarity reverse between the L/R outputs?
 
In the stereo output should the 10uf just before the A50k be shown as an electrolytic, with the polarity reverse between the L/R outputs?
We're not using electrolytic caps there and have had zero issues using 10µF MLCC caps there. No polarity to fuss with.
 
Hope I'm not too late to the party, I'm very interested in the analog V2 versions. Happy to populate myself, if that helps. I realise those BD IC's are getting hard to get, but damn do I love that sound. Also, thank you for bringing this back to life!
 
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