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Ideas for Eventide H3000 photo-interrupter replacement? Monitor Controllers
Old 23rd December 2010
  #1
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Ideas for Eventide H3000 photo-interrupter replacement?

For the last year or so I've been wrestling with a couple of Eventide H3000's that have bad photo-interrupters.

Behind the big knob on the front of the unit is an optical encoder assembly which includes a Sharp GP1A16R (edit: some units used Sharp GP1A16R) bi-phase photo-interrupter and a disk with 18 black bars. The disk diameter at the center of the bars is 1.5", making the resolution approx. 3.85 lines per inch.

The problem is that the photo-interrupters fail and despite much searching I have found no source for them. Eventide doesn't have them, and in fact told me that unavailability this part was one reason they stopped production of the H3000.

Of course, there are lots of photo-interrupter modules on the market but they are built with specific resolutions, and all the ones available seem to have much higher resolutions.

I could use a higher resolution module then I'd have to fabricate my own disks, and add a divider circuit. That's a lot of effort just to fix a few bad units. It would be ok to change the resolution slightly, but it should stay close, to keep the original feel and menu speed.

Simplicity is the key thing here. Any ideas will be appreciated; thanks in advance.
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Old 24th December 2010
  #2
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S2udio's Avatar
 

Simplicity sez.....?
Re black the bars with a permant ink...carfully !
Clean the photo eye TX-RX lenses...
OR ...component failure TX / RX led aging ???
up the drive current
There cant be that many maths going on here ?
At the end of the day....sacrifice and experiment..you never know
Old 24th December 2010
  #3
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Space Station's Avatar
Hi David, I would look at other electronics of a similar age to see if there is better available substitute. The Moog Source synth uses a similar encoder wheel, they are also seen in a lot of vintage arcade machines controllers IE atari trackballs, steering wheels on racing games..even reels in slot machines.
Old 24th December 2010
  #4
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Quote:
Originally Posted by S2udio View Post
Simplicity sez.....?
Re black the bars with a permant ink...carfully !
Clean the photo eye TX-RX lenses...
OR ...component failure TX / RX led aging ???
up the drive current
There cant be that many maths going on here ?
At the end of the day....sacrifice and experiment..you never know
Thanks but the problem is in photo-interrupter, which has active electronics inside. I've tried some other approaches without success, but didn't want to clutter my post with too many details. Basically, I'm hoping to find some replacement part that will go in without a lot of modding.

Quote:
Originally Posted by Space Station View Post
Hi David, I would look at other electronics of a similar age to see if there is better available substitute. The Moog Source synth uses a similar encoder wheel, they are also seen in a lot of vintage arcade machines controllers IE atari trackballs, steering wheels on racing games..even reels in slot machines.
Some good ideas there! I will pursue some of these things.
Old 24th December 2010
  #5
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SP2016's Avatar
David,
You ask for the GP1A16R, but your photograph shows a GP1A13R.
You know that there is a difference between the two ?
The 13R has a slit pitch of 1.6mm and the 16R has 0.7mm.
Also the High level and Low level output voltages are different.
Thought to let you know....

Richard.
Old 24th December 2010
  #7
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nucelar's Avatar
 

Hi David,
I've played with some photointerrupters before and don't understand your concerns about resolution. A photointerrupter like the one in your picture is merely a LED and a phototransistor facing each other (5 pins in total). It will read whatever it sees. Resolution is the pattern on the disc. How much you must turn the wheel to increment +1. Your only concern for simplicity should be finding a part that is mechanically compatible. An old mouse (with ball) will have two photointerrupters that might work for you.
Good luck!
Old 24th December 2010
  #8
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I guess I don't see the issue either.

Other than a little mechanical fabrication to mount a photo-interrupter in
the right position, and maybe a schmitt trigger inverter or two to clean it
up and get polarity right on a little "surfboard" ?

I've got bags of optics here, we use them in some stepper motor controls
we build. How many you want?
Old 24th December 2010
  #9
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Nuclear and Dan,

As mentioned in the original post, the photo-interrupter is a bi-phase (quadrature) type. It uses 2 LED's and 2 pickups with a 90 degree phase relationship between the two outputs, so the pitch is critical. To maintain the 90 degree relationship, the spacing of the two sections of the pickup needs to closely match the spacing between the lines on the disk. If not, the output signals will be garbage and the rotary encoder won't work right at all.
Old 24th December 2010
  #10
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Yeah, that occurred to me just after I posted.

But still, you only need two photo-interrupters spaced to catch the leading and falling edges in the right positions, they don't need to even see the same set of black/clear transition blocks, just the right edges.

So spread them out over two blocks, it'll give plenty of room to mount stuff.

There's a bit of slop room, especially in a manually spun wheel that never gets moving too fast.
Old 24th December 2010
  #11
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Thanks for pointing out the discrepancy on my original post. Reviewing this, I see that Eventide actually used both of these types. If the pitches are different, as you say, they must have used two slightly different disks as well. And thanks for the vendor lead, I contacted the company. They might be one of those annoying brokers that claim to have everything but then can't deliver, or maybe they can really get the part. Fingers crossed, will report back.

Dan, the two photo-interrupters idea occurred to me and yes, it would probably work with a little mechanical adapting. I'll probably go that route if I can't come up with a simpler solution.

I also thought about using one of those self contained encoder assemblies, with leads coming out the back. Maybe there's something suitable with similar resolution and a 1/4" shaft, that could be retrofitted to the front panel.
Old 24th December 2010
  #12
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Grayhill and Bourns both make some nice quadrature encoders, I've used both with no problems and they're low enough mass that you can mount them to the pcb and just rig a shaft extension.

McMaster Carr is your friend!
Old 24th December 2010
  #13
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nucelar's Avatar
 

Hi. Sorry for not reading carefully. I missed the quadrature thing. As others said, I would try to substitute it with a regular encoder which outputs quadrature signals right away. Some surrounding elecronics may be needed to adapt levels, but I guess it could be done. The other idea of mounting two PIs in an offset is also nice, but will require precise placement, maybe adjustable wit a set screw. Anyway good luck!
H
Old 24th May 2014
  #14
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HI Folks,

This is my first post here and I know forums tend to not trust the first post of new folks, but please believe me, I'm legit... I own an Eventide H3000 and it's my most favorite piece of rack gear ever... Sometimes I even refer to it as my favorite musical instrument.

Anyways, the guy who wrote code/algorithms for Eventide named Italio <[email protected]> runs a yahoogroups list [Eventide Rack] and he sent me here when I asked him how to fix my failing optical encoder...

From what I've read both here and elsewhere no one has found a replacement part for this problem because of the primitive nature of the big knob as explained by the original poster. It's just too difficult to fix with spare parts that aren't compatible.

But I did read here: Fixing the H3000 Knob (Optical Encoder) .: Audio Division Knowledgebase that what does work is changing the resistor. Specifically:

"We have found that varying the value of the small resistor next to the block (2.2K in this photo) can frequently solve the problem, at least for a usably long period. Values are typically between 220 ohms and 2.2K ohms. So if you have the problem and want to tackle it, vary that resistor! If that doesn't work, we recommend sending the unit to us."

Because this device is so old it looks like a pretty easy soldering job but I completely lack any experience in changing out a resistor and want to get some feedback on this before I start snipping stuff on a pre-historic electronics board that I can't afford to replace. IF you were in my shoes what resistor would you try first, second, third? Also how would you do the work to minimize the risk of damaging my beloved Ultra-Harmonizer?
Old 24th May 2014
  #15
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We now have the exact replacement part in stock and here is the link: Exact Replacement Jog Wheel Optical Encoder for Eventide H3000 and H3500. EA
Old 23rd May 2015
  #16
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Hi David will these come back into stock?
Old 24th May 2015
  #17
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We now have more in stock and I have updated my store listing.
Old 25th May 2015
  #18
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S2udio's Avatar
 

Excellent you found stock David
BTW
You would'nt happen to have an ADDRESS/DECODE PAL chip for a H3000 lying around anywhere would you ,would get my spare dead one back to life ........!!!!
If you need the chip circuit ID let me know please, not holding out much hope for this one though, as its a PAL multi gate array flashed by eventide (argghh)
Any help would be mucho appreciated.
Thanks
S2udio

Last edited by S2udio; 25th May 2015 at 12:11 PM..
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