The Sweeper

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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ricker
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Post by ricker »

I have one of these. It works, though it is part now. The footswitch is missing.

Anyone ever seen or heard one? Kind of a funky little box that I'd like to get back together once I order a switch.

Here is an ebay auction of one for reference. This is not my auction!;

https://www.ebay.com/itm/280605038618?s ... 1423.l2649

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Post by rocklander »

do you have the facility to take gutshots? :block:
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Post by ricker »

Sure do. I'll try and get some put up tonite.

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Post by ricker »

Here are the shots;

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Post by rocklander »

can't find much info on the TA75747P
on google, I see an AD7574 8 bit DAC.. (whatever that means) :lol:
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Post by lolbou »

Looks Coron-esque and phase 90-esque too...
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Post by pedalgrinder »

an 8 bit dac is a digital to analog converter 8 bit but i very much doubt thats what its using i also searched the net high low up and down and found nothing on that IC bit of a mystery hardly worth tracing if we can't work out what the ic is.
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Post by mictester »

rocklander wrote:can't find much info on the TA75747P
It's a cheap dual op-amp. Back in the 1980s it was considered "low noise".

Looking at the effect, it looks very much like an unusual layout for a basic four-stage phaser.
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Post by tube-exorcist »

mictester wrote:
rocklander wrote:can't find much info on the TA75747P
It's a cheap dual op-amp. Back in the 1980s it was considered "low noise".
Since when a (dual) 741 was considered "low noise" back in the 1980s ?

TA75747P = µA747 = dual 741
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Post by ricker »

I found this. Hope it helps;

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Post by ricker »

Resized. Hope this one fits. Sorry.

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Post by pedalgrinder »

The problem here is not working where the tracks go and the values it's what are the TA75747p Toshiba chip is. Once thats worked out the pedal can be traced and schematic can be created.
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Post by tube-exorcist »

pedalgrinder wrote:The problem here is not working where the tracks go and the values it's what are the TA75747p Toshiba chip is. Once thats worked out the pedal can be traced and schematic can be created.
Careful reading can be helpful occasionally:
tube-exorcist wrote:TA75747P = µA747 = dual 741
µA747 = LM747
www.national.com/ds/LM/LM747.pdf
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Post by mictester »

tube-exorcist wrote:
mictester wrote:
rocklander wrote:can't find much info on the TA75747P
It's a cheap dual op-amp. Back in the 1980s it was considered "low noise".
Since when a (dual) 741 was considered "low noise" back in the 1980s ?

TA75747P = µA747 = dual 741
According to the specification I've seen, it was supposed to be akin to a dual 741S (which was the "low noise" version). I always suspected that the "S" versions were just "selected" - the ones that hissed a bit less in their test jigs! I remember these ICs being used in Marantz tuners as the audio output buffers!
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Post by ricker »

Thanks for all the comments! I found this list, which I'm sure you are aware of;

http://www.ic2ic.com/search.jsp?sSearchWord=TA75747P#

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Post by pedalgrinder »

If thats just a dual 741 why is it so damn hard to find out what it is. I read exactly the letters i could see on the chip. What else can you go by. Is there somewhere online i don't know about. Or is that from experience you know that chip is that. I don't say that sarcastically i want to know how you did it so i can in the future. Thanks
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