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Finding EPROMs for Oberheim DX
Old 3rd January 2019
  #1
Gear Maniac
 

Finding EPROMs for Oberheim DX

I want to burn some EPROMs for my DX and was wondering if somebody could let me know if this will work.

The EPROMs are 2764s. Are new EPROMs in larger sizes compatible? 2764s are a bit hard to find but the larger EPROMs 27c256 are cheap and seem to have compatible pinouts.

I am looking at this programmer: V8.11 XGecu 100% Original TL866ii Plus EEPROM Programmer TL866A TL866CS Bios Nand Programmer PIC AVR 24 93 25 MCU Bios EPROM-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group

And these chips: 10pcs/lot M27C256B 10F1 27C256 CDIP 28 In Stock-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
Old 4th January 2019
  #2
Here for the gear
 
Plum Age's Avatar
I can vouch for the TL866 programmer, i've used mine for any concievable chip for years!

A larger EPROM will absolutely hold all your code, you will just have to adjust the pinout. What I usually do is to bend out the surplus address pins after programming and solder a fine wire to them all and to gnd. that way the eprom will act like a smaller chip. Compare the pinout of the two and see the difference - most pins are identical but 26+27 are re-purposed as the higher address bits.

If you bend them out horizontally and solder them both to pin 14 (gnd) they'll permanently be 0 and the chip is essentially a 2764 - IN USE! not in programming!

You probably could program it as a 2764 but then you can't count on the programmers built-in info on voltages and program times. either way, buying more EPROMS is probably cheaper than bothering getting the UV erase lamp.

Somebody has probably made some nifty adapter boards but I've made this work multiple times for a range of EPROMS.

Hope that helps.
Old 4th January 2019
  #3
Gear Head
 
Johnny T's Avatar
 

I would personally get the correct type of EPROM chips (assuming your programmer supports them).
The 2764 is not that hard to find, just take a look on eBay.
Old 4th January 2019
  #4
Gear Maniac
 

Aren't pins 26 and 27 grounded on the DX?

It looks like it will be easier just to get the correct chips.
Old 4th January 2019
  #5
Here for the gear
 
Plum Age's Avatar
Oh it will definately be easier to use the correct spare part, it usually is. 2764's should be obtainable at a resonable price too. I'd reccomend getting a few more than you need, some of the older NOS ones can have stuck bits and such.
Old 12th April 2019
  #6
Gear Nut
 
vekter303's Avatar
Theres a lovely looking DX available and Im really tempted...
Theres also a Drumtraks.

Question to DX owners is this, can the pitch/tone of the drum sounds on the DX be tweaked in realtime during playback?

I cant see why not, but all demos have shown the tweaking and the patterns playing independently...
Old 15th April 2019
  #7
Gear Maniac
 

Quote:
Originally Posted by vekter303 View Post
Theres a lovely looking DX available and Im really tempted...
Theres also a Drumtraks.

Question to DX owners is this, can the pitch/tone of the drum sounds on the DX be tweaked in realtime during playback?

I cant see why not, but all demos have shown the tweaking and the patterns playing independently...
The pitch knobs are on the back, so it's not super convenient for live tweaking.
Old 15th April 2019
  #8
Gear Nut
 
vekter303's Avatar
Quote:
Originally Posted by suckerformimi View Post
The pitch knobs are on the back, so it's not super convenient for live tweaking.
Thanks for replying, I have since seen another demo so it appears possible and whilst not that easy, managable as much as pitch shift of the clap or hats would need...

I missed out on the Drumtraks, holding out hope for the DX now.

Cheers!
Old 16th April 2019
  #9
Gear Maniac
 

Quote:
Originally Posted by vekter303 View Post
Thanks for replying, I have since seen another demo so it appears possible and whilst not that easy, managable as much as pitch shift of the clap or hats would need...

I missed out on the Drumtraks, holding out hope for the DX now.

Cheers!
I don't know Drumtrax well, but one came up for sale locally and I passed, based on what I have read. So I don't think ur missing much.

The DX is another story. It sounds fantastic in a mix. I bought mine as a curiosity but now I use it even more than my 808.
Old 14th May 2019
  #10
Gear Nut
 
vekter303's Avatar
DX landed today!

Its a clapping behemoth, heh...

Actually its not even been fired up, until I convert her or get a step down.

Wanted to ask about EPROMS. Some of the circuits around the voices look different to each other.

So, my question is this. Will any replacement EPROM work in any voice slot?

I really wanted to change out the shaker, but it appears to share the EPROM with the clap, which is a massive part of the DX appeal...

Cheers!
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