Roland Juno 60 recommended IC manufacturer

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Medicin

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Hello there, I am currently repairing an old Juno 60 synthesizer. Re-capping and need to replace two IC's I am a novice so dont know where to start looking for the IC's or their modern equivalent. Can anyone help?
 

volker

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Which ones do you need to replace? If it's the IR3101 or the IR3109 there is only vintage, no modern replacement. For standard stuff like the 4558s, it doesn't really matter which you choose.
 

Medicin

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Thanks for the response:) Both chips are from the Chorus Board. The HD14051BP Hitachi 16P DIP i have found on ebay. says its 'original' but i am having trouble finding the μPC125ZHZ ic chip or equivalent. limited knowledge knowing where to start. The two chips are bottom right on the board. Hd bottom right. the other just to the left of it
 

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Bo Deadly

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That's a VCA chip:

1632151413028.png
You could probably find a sub like one of the THAT VCA parts maybe. But it might not be pin-compatible. You could maybe put a different one on a "surf-board" or have a tiny PCB made from OSHPark and then just mount the customer PCB in place with bits of bus wire.

But maybe someone knows a source for that.

Update: Looks like THAT 2180 might be a drop in replacement.
 
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zamproject

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May 11, 2010
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Hello and welcome
What make you think those two IC are dead ?

The first is a multiplexer used as remote switch for HPF RC network
The second as already say is an audio VCA, according to datasheet it's probably a dbx licenced, given for -5.9mV/dB at CV

Substitution may be possible with some circuit/wiring adaptations.

Best
Zam
 

Medicin

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Thanks. Yes me and a friend who's good with electronics have been trying to get rid of a nasty buzz and saturation, the trail led to these two chips and sure enough they were badly corroded. So now i am just looking for replacements. i seem to have found them, but will take a while shipping and a lot for P&P
 

Medicin

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Thanks for your help people. Im just trying to find best options now for these new chips in terms of quality and p&p to Spain
 

dom

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It's probably not worth seeking out or paying substantially more money for the original HD14051BP chip. Any modern CD4051 or a similar MUX will almost certainly work without too much fuss.
 

Medicin

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The chip im finding really hard to get equivalent for is the UPC1252H2. Some sellers on ebay have them but i dont trust them tbh and delivery time is months!
 

rogs

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I think you might find it worth while checking out Bo Deadly's suggestion in post #5 --
It looks as if there's a good chance you can use a THAT 2180 as a drop in replacement ...
Might be worth checking out the THAT data sheet notes on the control port drive impedance, which might require you modify the connections to pins 2 and 4 (see page 9 of the data sheet)
 

rogs

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Further to my post above -- it seems that the THAT 2159 is a direct replacement for the uPC1252 (according to THIS POST from a THAT representative on this board some years ago).....

And it looks as it you can still find those --see HERE for example.....
 

Whoops

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You should replace all those Electrolytic caps and try the unit out even before thinking about randomly changing the ICs.
Probably the IC's are fine...
 

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