Boss DM-2 v1 and v2, question about 3101/3102 clock polarity

[aion]

The Boss DM-2 had two versions, one with the MN3005 and a revised version with the MN3205. Here are the schematics:

V1:


V2:


I know the MN3000 and MN3200 series run on opposite polarity, and you can invert the power and ground pins and the pull-up/down resistor(s) to retrofit one for the other. The DM-2 shows this in action, with no other circuit changes than the BBD and clock.

The clock is what's confusing me. The DM-2v1 (MN3101) shows a diode D5 from +V to pin 1 of the clock, with pin 3 grounded. The DM-2v2 (MN3102) shows pin 1 connected directly to  +V, and the diode from pin 3 to ground. This goes against the 3101 and 3102 datasheets which indicate that the clocks are powered the same as their respective BBDs (the 3101 needing negative supply and the 3102 needing positive).

The 2-jumper method (I believe Scruffie was the one who first came up with it) has become sort of the de-facto practice for implementing BBDs when there's a chance that either the 3000 or 3200 series may be used. But I don't see this ever used for the clocks, e.g. in Madbean's DM-2 or CE-2 projects, even though they support both the 3101 and 3102. And the original DM-2 seems to reinforce that negative ground can be used for both chips, although the diode does switch positions between the two.

So...

1) Why do they power the MN3101 with positive supply in the DM-2?

2) What's the D5 diode doing in the two versions?

3) Is it true that you definitely can't use the MN3102 or v3102 to drive the MN3000 series? The 3102 is readily available from Coolaudio, but it seems that the MN3101 is starting to dry up with no reissues. So while it's great that Xvive has reissued the MN3005 and MN3007, without a corresponding clock it'd be a bit of a letdown. (To compound the confusion, Xvive does produce a MN3102 reissue, but all their BBD reissues are the 3000 series!)

[ElectricDruid]

1) Why do they power the MN3101 with positive supply in the DM-2?

They don't. They connect the "Ground" pin to +V, and the "-V" pin to ground, giving an effective negative supply.

The trick is the pins switch names in the datasheets between the two versions.

2) What's the D5 diode doing in the two versions?

Good question. My guess would be that it's hoping to keep clock noise out of the the supply, but it's only a guess.

3) Is it true that you definitely can't use the MN3102 or v3102 to drive the MN3000 series? The 3102 is readily available from Coolaudio, but it seems that the MN3101 is starting to dry up with no reissues. So while it's great that Xvive has reissued the MN3005 and MN3007, without a corresponding clock it'd be a bit of a letdown. (To compound the confusion, Xvive does produce a MN3102 reissue, but all their BBD reissues are the 3000 series!)

I don't know. "Try it" is the way to be sure. The two types have very different supply voltage ranges, so if it is possible, it would only be possible in the range in which they overlap (4-10V versus 8-16V). The MN3000 series chips were designed for a 15V supply. The MN3200 series work down to 5V, which makes powering them from a droopy 9V battery a realistic possibility. But at 9V, both chips should work, and I would suspect they'll work together.

However, there's nothing magical about either of these clock chips, and they're not even that great at what they do, so have a look at a few other options for clocking your delays. The 4047 is one good bet, since it has a biphase output.

[aion]

1) Why do they power the MN3101 with positive supply in the DM-2?

They don't. They connect the "Ground" pin to +V, and the "-V" pin to ground, giving an effective negative supply.

The trick is the pins switch names in the datasheets between the two versions.

Sneaky, I didn't notice that. The MN3200 series kept the ground and Vdd pins the same as the MN3000 series (just expecting the Vdd to be positive instead of negative) so I didn't even check whether the clocks did as well. That does clear things up a bit.