Hi! Did anyone consider re-soldering good pots?
I mean I do not know if any problems could come with just finding good quality pots and resoldering.
What do you think?
Hi pdro333,
Here's some observations from when I opened mine up last night, this is what I found, you might find it useful before opening up yours:
1) None of the pots on the OB-6 are secured to the fascia with a nut, which is the only way to truly hold them solidly in place.
2). There is sadly not enough space on the fascia to take a threaded pot', without reaming out EVERY single pot hole on the fascia. The hole for the pot is only marginally bigger then the pot' shaft's diameter.
3) The fascia PCB board is separate to the main motherboard holding the six sound cards, and connected to it by an IDE-type locking cable. Good engineering. Both motherboard and fascia PCB are quite beautifully etched, and the construction of the case is excellent. No criticism there. Exactly what I'd expect in terms of quality inside a Sequential synth.
4) The potentiometers are soldered onto the fascia PCB board with two metal lugs either side of the pot. Usual setup for board-secured pots on less expensive synths, in addition to the normal 3x electrical connections for the pot' itself.
5) As suspected, the pots are cheap and nasty, the plastic type with a short, stubby plastic shaft. This is true for all except a few on mine, with a handful of random ones which have a metal shaft, but even those are still cheap and nasty, and also wobble. Your mileage may vary.
So there you go folks.
My **opinion**, separate from the facts I've presented above, is that because, in contrast to the rest of the OB-6, all of the pot's are only secured to the PCB and are all cheap and nasty when you open it up, I strongly suspect all of the OB-6's pots will begin to wobble after some time. Even on units that currently do not suffer from the problem. They're not fixed to the fascia with a nut, hence they take all of the mechanical strain on the pot itself and will eventually begin wobbling with use. In addition, on mine there is a degree of wobble of the shaft within the pot itself, so I strongly suspect a better quality pot, although still PCB mounted, may be at least partially remedial, maybe fully.
It's a shame, and more than anything else, I feel disappointed, because I guess that everyone who's a member of this forum and is reading this is probably, like myself, a big fan of both Tom and Dave and of DSI/Sequential's synths.
I cannot for the life of me figure out why so much expense and good design was put into on the rest of the synth, which is, to its credit beautifully constructed, only for the cheapest, unsecured pot's to be chosen for the one place where end users notice it: The tactile user interface. It feels like someone had a bad afternoon when designing this part of the OB-6, and it totally lets the side down, which I feel slightly sad about given their historical reputations. I'm just amazed no-one caught it before it went into production.
Taking Apart the OB-6pdro333, with regards to your post, yep, they could be removed and replaced. It's simple to take it apart.
Here's how to disassemble for the desktop module:
First: Make a note of the pots that wobble before disassembling, as the amount of wobble will not be as noticeable once the pots are removed - the pot' shafts are only 6-7 mm long.
Remove the 2 rows of four screws each on the back and underside of the module;
Remove 2x2 screws holding the wooden end cheeks ; under which there are another pair of hidden screws on either side holding the two halfs of the case together.
Once pulled apart, flip the IDE toggles either side of the cable that connects the fascia PCB to the motherboard holding the six voice cards.
Pull the cable from the IDE socket and put the lower half of the synth with the motherboard and voice cards to one side.
Either pull off the pot knobs (difficult), or use a plastic lever, or a flat screwdriver secured inside a thin plastic fold to remove the pot knobs, as (at least on mine) they are attached to an inhumanly tight degree and don't just pop off. Do not use a metal instrument without a cover, otherwise you'll scratch the fascia to shreds.
Remove 14x silver screws from the underside of the fascia motherboard. Each requires around 13-14 screwdriver turns (6-7 complete turns for reference when reassembling).
Finally, lift out the fascia PCB and do your thing with replacing the pots. I'll not quote markings or type here, as it's best to find out what was used on your own individual model version and order exact replacements, and note the values of the faulty pots if you're not replacing all of them, as I'm assuming they're not all the same resistance value (but haven't checked), as it's obvious some are OK and some not.
Nothing too complex and nothing that will catch you out.
Hopefully that's useful to anyone who's competent with a soldering iron and willing to take a crack at fixing the problem out of warranty.
It's not difficult to do, but I'd recommend against attempting it if you've not got the appropriate skills. Totally at your own risk.
Cost wise, it'll depend on your desire to change all of the pots, or just those that wobble. But even at an inflated $5 each, a full re-fit of all 43 pots at around $200 would give you an improved build.
Another option would be to consider something like an outboard MIDI controller such as the FaderFox PC12, which would give you more than enough knobs and is much better built, but you're looking at over twice the cost of replacing the pot's, albeit without any of the soldering hassle and risk.
Anyway, mystery solved.
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