ta7136 substitution

Some of the System 700 modules use Toshiba TA7136 SIP opamps (datasheet), which are long obsolete and semi-sought after by DIY guitar types because it was used to apparently pleasing effect in a Boss distortion pedal. An eBay seller is trying to get the best part of twenty quid for one.

A while back I bought a bunch from Utsource, and when I eventually got round to making a board to test them I found they were fake…

TA7136 vs fake

…booo.

I made up this adapter for an alternative op amp, ‘cos I don’t think using this particular chip is that important (for now, anyway).

TA7136 to TL071

Here’s a strangely moody photo of the resulting stripboard.

TA7136 > TL071 stripboard adapter

After this I cut one chunk out of one side of the board to indicate pin 1.

I’ve had this working in the 708 noise/ring mod and the 711 output module, and it works fine, although I’ve not had a chance to compare it directly to the 7136.

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i’d rather multiple jack

710 multiple clone

OK I know, but it’s a start.

3mm acrylic is bendy, so I reinforced the back with 1.5mm aluminium to make it much stiffer, but it’s still not as solid as I’d like it.

Clone System 700 multiple from the back, showing the metal reinforcement

I should have really made the metal plate wider than I needed on one side, and bent it up to form an L-shape to totally stop the bending.

No chance for recessed jack sockets like on the original, my metal working just isn’t that good. 4.5mm panel depth is really the limit for these jack sockets, and it’s borderline for rotary pots.

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rainbow wiring

Roland 702A VCF wiring fun

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