Does anybody have a complete schematic for the Boss HM-2?

[Peter Snowberg]

Does anybody have a complete schematic for the Boss HM-2?

I have the simplified one already and am looking for the factory schematic (or a good drawing) that includes the switching.

Thanks!  

[toneman]

I don't have a "factory" service manual.
just the schemo with no switching.
U can try the "factory"---Roland US  in SmogTownUSA=LA.
afn
tone

[eaze]

Hi...

I don't have its factory schematic too.
But I have pics of HM-2's PCB.
It shows 9*TO-92 package.

This schemo shows only 3.
http://www.mif.pg.gda.pl/homepages/tom/files/hm-2.gif

BOSS usually use 4 = 2*JFET + 2*Tr for ON&OFF switching.
SPDT-switching is made by them.

3 + 4 = 7...

plus, there must always be output buffer amp.

7 + 1 = 8

last 1 is...?

This is only my guess.
http://www.mif.pg.gda.pl/homepages/tom/files/DS-2.gif
JFET added like this... by Q21, against bleeding(lump?) of fx-line.
DPDT-swtiching is performed now.
In the high-gain DIST/OD, BOSS is mostly done so.
BD-2, OD-3...etc.

[Peter Snowberg]

Thanks eaze!

[eaze]

Hi,Peter

By using Google image search,
I found another schematic drawn uniquely.
http://heavypage.narod.ru/shem.htm
This also lacks flip-flop & jfet switches again.
However output buffer stage is contained. that's a typical BOSS-style.

If you omit J1 and input into C2 - Q2 directly,
Input impedance is lowered... like the input stage of BMPI.
According to input stage, the overtone will change so much.

It may be said output stage[Q1] is also omitted.:roll:

[Peter Snowberg]

Thank you again eaze!

Domo arigatou!