Micro Pog Mod

[hahafender]

Anyone have any idea how t1m does his micro pog mod?
his mod is here: http://this1smyne.com/shop/micropogpresetmod/

or there's JHS's mod as well, which seams a bit simpler:
http://www.jhspedals.com/products/mod-shop/micro-pog-quadra-pog-mod/

If anyone has any ideas, that would be pretty cool

[IvIark]

We'd need a look inside to know for sure, but as he's added a new set of pots it looks as though the second stomp is simply selecting which pot set are in circuit, which is a pretty straightforward addition. If you think of the switch like this:

1---4---7
2---5---8
3---6---9

Then you would solder the appropriate lug of each pot to the outer throws with the centre common lug going to the point on the board where the original pot connected.  For instance just looking at one pole as an example, if one of the pots was used as a simple variable resistor to ground, say with lug 2 connecting to the circuit and lug 1 connecting to ground.  Then you would keep lug 1 of both A and B pots connected to ground permanently, and lug 2 of the pots would connect to 1 and 3 of the first pole of the stomp.  Then lug 2 of the stomp would connect to the point on the board where lug 2 of the original pot connected.  So one stomp will put pot A in circuit, the next stomp will put pot B in circuit.

It can get more complicated with some pots because you may need to switch more than one lug, but as he's doing this with a single stomp which can be a maximum of 4 poles unless he's using a bank of relays, then it's probably not too complicated.  I'd need a schematic or to open one up to say for sure, but it definitely isn't going to be rocket science.

[hahafender]

very interesting. i have a micro pog myself. im not sure if it's possible to send you a gut shot and maybe it can be figured out that way with a drawing of the mod? For me, I'm not too experienced enough to know which lugs go where and stuff. still trying to learn and catch on to everything. But let me know if you want a gut shot, and id be happy to send one!

thanks for the reply! i appreciate all you do on this blog. you're awesome man!

[IvIark]

Cool, if you can get a close front and back pic of the board and post here that would be great.  But also email them to me so I get the full resolution in case the one here is reduced in size by the provider.  My email address is guitarfx at hotmail dot co dot uk

[hahafender]

Just emailed them. Here they are as well:

[hahafender]

CONTENTS DELETED

The author has deleted this message.

[Kinski]

Whoa, this would be very useful. I'm always crouching down the adjust the knobs as fast as possible. I'd love to add the this1smyne mod!

[hahafender]

any word on this man?

[IvIark]

I've just had a look over your pics and it's impossible to tell from it what is going where, and although there are some clues it would be a lot of guess work.  I've tried to find a schematic so I would know exactly what is going on but can't find one.  I do have a POG schematic but that is very different because of the number of pots, and uses a pot multiplexer.  

Could you use a multimeter and check all 9 of the pot solder lugs and see which ones give you continuity.  That may give me enough information but I suspect I'm going to need one in front of me to know for sure.

[hahafender]

i can check whatever you want. But how exactly do you want me to check the pots? one pin to ground and the other to each of the 9?

[IvIark]

Yes check which are grounded but also which are connected to the other lugs (if any).  The reason for this is I don't know how the pots interact with each other and need to know which connections of the new pots I can make permanent such as grounded lugs, or which lugs have a common source from anywhere other than ground like vref maybe or just a common signal from elsewhere in the circuit.

It doesn't look like any of them are just simple variable resistors where only two lugs are effectively being used, but they may link elsewhere or from a via which isn't obvious, so I can't be sure of that either unless all the lugs are checked for continuity.

If all 3 are voltage dividers with a least one common lug on them all which may be ground, then you would need 6 poles to switch the remaining lugs, but that obviously isn't the case because he's using a 4PDT stomp.  We don't know whether his mod is done in an "electrically correct" manner where there is no interaction between the two pots, or whether he has had to make compromises in order to switch them with only 4 poles.  

For instance, if you think of a normal volume control you have the signal going into lug 3, lug 2 is the output and lug 1 is grounded.  So to switch that correctly so that there is no interaction between the two pots, lug 1 of both can be grounded, but then both lugs 2 and 3 need to be switched.  If not there will always be some resistance of the pot switched out of circuit in parallel with the pot which is switched into circuit.  So I need to try to work out if he has made compromises and if so where.

Some compromises like this can have allowances made for them by doubling the value of the pot, but we aren't going to know whether he has done that unless we can check the values used in one of his modded pedals.  But hopefully with the right information we can make those allowances ourselves to do the same job even if our version switches in a different way from his.

[hahafender]

on every pot.... lug 1 is grounded.
lug 3 on both octave up and octave down pots are connected

that's it, as far as I can tell.

[IvIark]

One thing that has just occurred to me is that he also adds an LED which obviously requires one of the poles, and that has simplified it.  He can only be using 1 pole for each pot and so has to have compromised that resistance from both pots will always being in circuit no matter which is selected.  That would explain why the existing pots have changed, because he's almost certainly replaced all the 5K pots with 10K to compensate for the way they have to be switched (two 10K pots in parallel equals 5K).

If one lug of each pot is grounded that would make it all much easier though, although that may be hoping for too much

[IvIark]

hahafender wrote

on every pot.... lug 1 is grounded.
lug 3 on both octave up and octave down pots are connected

that's it, as far as I can tell.

Awesome, it's simple then.  I'll do a little layout for it but it'll be in the morning now because it's 2:16 here.

[hahafender]

BTW pot values are B5k

Wow... didn't know it was such a big time difference! well, great to hear! goodnight  

[hahafender]

just changed the pots to reverse log and they're perfect!!!

[IvIark]

Excellent

[hahafender]

the ones i got though... the plastic ones... are no good. because they cant screw onto the enclosure. so im gonna have to order a whole new set -.- any recommendations?

[hahafender]

this1smyne has a picture of a bunch of mini pots that are c5k.... i think he uses those for the POG. will that work?

[IvIark]

They'll work but they won't work properly.  If you used 2 x 5K pots the maximum resistance of the pot in circuit would be 2.5K so it wouldn't have the range of the original.