Obscure IC info required.

[digi2t]

I`ve been intrigued by the Japanese Micro Synth project for a while now, but I`m hung up on an IC, the Toshiba TA7125P. 7 pin SIP, and the only info I`ve found on it is «Tone control».

the link for the schematic is here;
http://experimentalistsanonymous.com/diy/Schematics/OOP%20Japanese%20Electronics%20Book/gtr-synth.gif

It`s the IC in the lower right corner. That section is labeled as the VCA. Apparently, there was a work around for this chip, but the link is dead (http://www2.odn.ne.jp/chietronix/TA7125P.pdf).

Guess I`m on another hen`s tooth quest. Info anyone?

Mark?

[armdnrdy]

This is the PDF for the TA7120P. This should be in the same family and give you a start toward a replacement.

http://cs.utsource.net/goods_files/pdf/16/161498_TOSHIBA_TA7120P.pdf

[gritz]

Internet archive to the rescue!

http://web.archive.org/web/*/http://www2.odn.ne.jp/chietronix/TA7125P.pdf

Click on one of the blue highlighted dates (in Nov / Dec) and you should be able to download the pdf. It's not much more complicated than a CA3080, an opamp buffer and a transistor. Hope this helps.

[Mark Hammer]

I seem to recall hunting around for one a few years back...in Canada...with no success.  Many of these obscure Japanese TA and M-prefix chips are a) occasionally cross-referenced to an AN-prefix unit, and b) likely to be found in a place that caters to TV/VCR/Satellite/Stereo repair shops (hence carries a lot of Japanese parts).

[armdnrdy]

Hey Jonathan,

Good find!

This example looks like it show how to make a "work around" TA7125P out of various components.

[gritz]

Heh, my involvement in this thread stems from thinking "7125, that sounds familiar..." So I had a root through all the old salvaged boards that I had and eventually found the one I was looking for...

But unfortunately the chips on there were TA7325P (muting ICs). Bummer!

So that spurred me to have a trawl through the interwebz. I haven't found the proper datasheet yet, but if it's out there...

[Mark Hammer]

Dino,  Looking through my datasheets, I have a small hand-drawn schem I found somewhere (although some Japanese synthesizer site sounds about right) of a suitable semi-discrete replacement for a TA7125P, that uses a 3080 and a non-inverting op-amp.  Whoever drew it shows equivalent TA7125 pins in the drawing.

I can't post from work, but I'll post here once I get home this evening.

[digi2t]

You guys.... YOU GUYS!!

I bow humbly before you all. Mucho appreciado for the wayback link, I have to add that to my favs. You rock Jonathan!

Mark, if you could shoot that on here tonight, that would be great. I have the other IC`s (the HEP will be replaced by a TL074, or LM324), and the role of the SC dual transistor will be played by a LM394.

I have 3080`s on hand, so I`ll try the work around. I think I`ll put a good solid square-wave fuzz in front of this. Going to try and cop the Schulmann PLL sound.

Now... back to work on my Infinitphase.

[Mark Hammer]

Possible that whatever Larry posted (can't see it here) is identical to what I was going to post.  I guess I'll find that out later tonight when I can actually SEE things.

[Mark Hammer]

Tel que promis...

I can't speak to its accuracy...it's just all I have.  Hope it is useful.

[digi2t]

Yup, that's what I got from Jonathan.

And... from the believe it or not department....

I may have found some TA7125P's. I requested a quote from UTSOURCE (China), and they replied that they have them, at 3$ a piece. Fake or not? Who knows. I'm taking a chance on two of them. I'll report my findings when I get to this project.

Many thanks again to everyone!

[armdnrdy]

If you are going to place an order with Utsource you may as well order a 2SC1583 or two. Utsource has them in stock. The price is few bucks.

Using the dual NPN instead of a LM394 will save you a bit of room on the board.

[armdnrdy]

I may have found a TA7125 in the US of all places!

http://matelectronics.com/prestashop/en/a-z-semiconductor/6206-ta7125.html

[digi2t]

I'm not trustful of UTSOURCE, but I did find some at a cheap price, so I'm going to try both the LM394 and 1583.

I tried MAT Electronics a few months back for the 7125, and they emailed me saying that they no longer had them.