From Brian Willoughby Sent Sat, Jan 6th 2018, 02:27
From Brian Willoughby Sent Sat, Jan 6th 2018, 02:27
Sam has more experience with this than I do. I only opened the EPS a few = times, and have forgotten some of the details. His reply reminded me = that there was EPROM as well as a processor. My take away is that any socketed chip should reseated to clear up any = potential oxidization (provided you don=E2=80=99t damage the pins). So, = it=E2=80=99s not terribly important to identify the main chip - just = make sure you put them back where you found them. Brian On Jan 5, 2018, at 5:39 PM, Tomislav Babic <xxxxxxxx.xxxxx@xxxxx.xxx> = wrote: > awesome info, thanks to both Sam and Brian. >=20 > i have an EPS as my poly at controller slash lofi sampler. it works = atm but its good to know=20 > if the keyboard starts misbehaving. >=20 > PS what is the name of that main chip in EPS KPC, i mean how can i = identify it? >=20 > thanks >=20 > On Fri, Jan 5, 2018 at 4:46 PM, Sam Mims <xxx@xxxxxxx.xxx> wrote: >> The VFX-sd and SD-1 also use the same KPC board, so you can swap it = between these keybeds. But there are different firmware versions (on = that KPC EPROM chip), and they are not all compatible. So if you do = swap KPC's from another Ensoniq model, you may need to keep the EPROM = with its original keyboard. >>=20 >> Sam Mims >> Syntaur >>=20 >> -----Original Message----- >> From: Brian Willoughby [mailto:xxxxxx@xxxxxxxxxxxx.xxx] >> Sent: Friday, January 5, 2018 7:49 AM >> To: Sam Mims >> Cc: Andrew Dean; Analog Heaven >> Subject: Re: [AH] SQ-80 problems >>=20 >> In addition to Sam=E2=80=99s excellent suggestions, there is one = other thing you can try if you have the KPC board. >>=20 >> I only recommend this for people who have experience removing and = replacing chips. It=E2=80=99s far too easy to bend a pin, and the chips = on these old boards are no longer made. However, if you know what = you=E2=80=99re doing then you can probably =E2=80=9Cfix=E2=80=9D the KPC = by simply removing the main chip and replacing it. The process of = removing and reinserting the chip will clean decades of oxidization off = the pins and can cure some problems. >>=20 >> I discovered this on my EPS after working way too hard to fix its = KPC. I tried replacing the headers for the ribbon cables with brand new = gold-plated versions. I bought a VFX to swap the KPC from that keyboard. = I even hooked up a logic analyzer until I ran out of clips for all of = the parallel signals and gave up on an idea to create a custom debugging = environment specifically for the KPC. I discovered that the KPC board = from the VFX worked perfectly in the EPS. I also discovered that the = main chip from the VFX KPC worked fine in the original EPS KPC. The only = problem was that I had to sacrifice one keyboard to save the other. >>=20 >> In the end, once things were working, I tried one last test, and = restored all of the original parts to the EPS. Basically, I moved the = original main chip back to the original KPC and put it in the EPS. To my = surprise, it worked perfectly. I almost kicked myself, because all of = that soldering to replace the header with a gold-plated one was probably = not necessary, and buying the VFX could have been avoided if I had just = reseated the main chip. But I kinda like the VFX and it=E2=80=99s great = to have a backup keyboard that is also capable of polyphonic aftertouch. >>=20 >> By the way, you might be surprised to learn how much electronic gear = can be restored after decades of use (or disuse) by simply reseating = chips. It certainly worked for my surround sound system. The only = downfall is that folks who are all thumbs might do more harm than good = by bending pins. I=E2=80=99ve lost at least one vintage arcade game = electronics - irreplaceable - by accidentally bending a pin that broke = off. So, caveat repairer! >>=20 >> In my case, the EPS keyboard was completely dead. It didn=E2=80=99t = send out crazy notes like yours, but I assume there might be some = relation to the symptoms. >>=20 >> Brian >>=20 >>=20 >> On Jan 3, 2018, at 8:03 AM, Sam Mims <xxx@xxxxxxx.xxx> wrote: >> > Our keyboard kit definitely will not fix that =E2=80=93 it replaces = physical key action parts, and nothing electronic. When it is not going = crazy, does every individual key play as it should? If every key plays = correctly, that eliminates the possibility that one of the metal plates = on the bottom of a key has come loose and is messing with the keyboard = scanning. >> > >> > It=E2=80=99s great that you have been able to isolate the problem = to the keybed itself. You have probably already reinitialized the = SQ-80, but if you haven=E2=80=99t, I would try that. It may not help, = but it=E2=80=99s free and worth a try if it happens to be a software = issue. >> > >> > If the problem persists after a reinitialization, then the next = thing to eliminate is the ribbon cable from the keybed to the main = board. Try unplugging and reseating this at both ends. I=E2=80=99m not = confident this will help, but it too is free, so you may as well try it. >> > >> > Assuming the problem is still there after messing with the ribbon = cable, then the issue is either with the KPC board (if you have one), or = with the coil boards, or with the connection between the coil boards. = Some Ensoniq keybeds of that era have a KPC board (roughly 4 x 5 inches = or so) that is mounted to the bottom of the keybed chassis. Some = SQ-80=E2=80=99s had this, and others did not - that circuitry was built = into the coil boards instead of having a separate KPC board. And of the = two coil boards (the long, skinny PCB=E2=80=99s underneath the keys), = some have a =E2=80=98press fit=E2=80=99 connection between them, while = others have a soldered ribbon cable to connect the two. If yours has = the press fit, you might try removing the boards, and hitting that = connection with some DeOxit. If yours have a soldered ribbon cable, = there could be a bad solder joint at one of those points. But it may = well come down to replacing these boards (either or both coil boards, = and the KPC board, if you have one) to fix the problem. >> > >> > So if you=E2=80=99ve done all of the above, and it seems to be a = circuit board issue, contact me off-list and I=E2=80=99ll help you get = this fixed. >> > >> > Good luck! >> > >> > Sam Mims >> > Syntaur >> > >> > From: Andrew Dean [mailto:xxxxxxxxxxxxx@xxxxx.xxx] >> > Sent: Tuesday, January 2, 2018 11:53 PM >> > Subject: Re: [AH] Synth Wizards Episode 4: Desert Island SQ-80 >> > >> > Thanks a lot for this Sam, great video. >> > >> > My SQ80 sends plays random notes and send them over midi as well. = When I disable the on board keyboard, everything seems fine, so it = appears to be a keyboard fault. Does this sound like the kind of fault = your keyboard kit fixes? >> > >=20