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MoonWatcher
Bronze Member
USA
98 Posts |
 Posted - 11/15/2009 : 19:38:50
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Hi Folks -
I really want to add an HM-2 to my lineup. Problem is, there's now a cult following for this pedal (as I'm sure many of you know). Cash on hand is short, I don't really enjoy the process of trying to procure stuff on eBay, and I'd like a fairly CLEAN HM-2. A tall order - I'm a man on a mission.
...So my hair brained idea is to build a (somewhat) brand new HM-2, and retrofit it into a Boss 4 knob box that I have on standby...
Long shot I know, but I have to ask - do you think that Roland would supply a replacement pcb for this pedal? I think I already know the answer, but I just have to ask.
In the event that they don't, I'm ready to etch my own - I etch boards all the time. IDK what kind of efforts that would require as far as finding pcb layouts that I could use for toner transfer or similar, or a dead on shot of the pcb? I can rebuild layouts in graphics software.
I realize that I'm probably making this way more complicated than it need be. I guess that a HM-3 could be backdated to a 2, but not sure if I have any better luck finding one of those.
Any ideas on how to proceed would be appreciated.
Thanks! |
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zerksies
Double Platinum Member
USA
3406 Posts |
Posted - 11/15/2009 : 20:10:45
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it would be easier if you got one off  ebay |
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 11/15/2009 : 21:44:14
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The HM-2 is quite a large circuit. It is certainly possible. However, if you can fit a mechanical switch you can additionally reduce the main circuit quite a bit, e.g. flip-flop circuit, jfet and input-output buffers.
Good luck on your endeavours and keep us up-to-date. |
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MoonWatcher
Bronze Member
USA
98 Posts |
Posted - 11/15/2009 : 22:05:54
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quote:
Originally posted by cctsim
The HM-2 is quite a large circuit. It is certainly possible. However, if you can fit a mechanical switch you can additionally reduce the main circuit quite a bit.
I just may do that quite a bit, as I do scratch build quite a bit of stuff.
The HM-2 circuit is actually fairly sparse in comparison to many of my scratch builds. I will probably use an E-Switch in place of the momentary and flip flop, and might even go to DIP8's for the op amps if I can figure a way around the existing traces to do it. Losing the flip flop componentry should give me ample clearance. A DIP16 would be another possibility.
I'll keep you folks posted on my progress. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 11/15/2009 : 23:28:30
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There is no easy way to do it....
If you need a clear hi-res shot of the copper side of my HM-2 board let me know.
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MoonWatcher
Bronze Member
USA
98 Posts |
Posted - 11/16/2009 : 00:40:39
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Actually, problem solved (mostly)!
I've been saving the pcb from an old DOD FX59. I just came to find out that the FX56 and HM-2 were basically the same thing.
...The FX59 subs in a JFET in the place of the PNP BJT 2SA970/2N3906 for Q7 in the HM-2/FX56 - this is the biggest difference.
The most work will have to be done in the EQ section. The FX59 uses a single tone pot in place of the separate hi and low in the HM-2. And the combined treble and mid are shelved a little differently. So a pot and a cap will fix that. And a third pot would allow for T/M/B, but I want mainly the stock HM-2 flavor.
Perhaps the biggest plus with the FX59 is that it uses DIP8's, and they're LM1458N's, which I really like.
I'll keep everyone posted on the final outcome. Too bad the DOD board won't fit in a Boss enclosure.
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Topic |
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Spawning a new HM-2
