<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> </head> <body><div class="auto-created-dir-div" dir="auto" style="unicode-bidi: embed;"><style>p{margin:0}</style>Hi Florian and list,<br><br>Japanese datasheet with internal circuit is here:<br><div> https://wakamatsu.co.jp/biz/products/detail.php?product_id=13140412</div><p><br></p><p>Its internal circuit is basically like 741, but input npn pair is replaced by N-channel JFETs.</p>If slow response is essential, LF13741 is a candidate.<br><div><br></div><p>Best,</p><p>Sam HOSHUYAMA</p><p>Kawasaki, JAPAN</p><p><br></p><blockquote style="margin: 0 auto; padding: 0 2em; border-left:2px solid #00ADE5; white-space: pre-wrap "><br><br>------ Original Message ------<br>差出人: "Florian Anwander" <fanwander@mnet-online.de><br>To: "*SYNTH DIY" <synth-diy@synth-diy.org><br>送信済み: 日曜日, 2025/1/5 00:27<br>件名: [sdiy] Datasheet Toshiba TA7505M / modern replacement<br><br> Hello,<br> <br> I built a replacement for the SSK board in a Yamaha CS15, essentially using Old Crow's approach. My schematic is here:<br> <a class="moz-txt-link-freetext" href="https://florian-anwander.de/yamaha_cs15/CS15_SSK_FA__Nano_2_sch.png" target="_blank">https://florian-anwander.de/yamaha_cs15/CS15_SSK_FA__Nano_2_sch.png</a><br> The original schematic is here:<br> <a class="moz-txt-link-freetext" href="https://florian-anwander.de/yamaha_cs15/Yamaha_CS-15_Servicemanual.pdf" target="_blank">https://florian-anwander.de/yamaha_cs15/Yamaha_CS-15_Servicemanual.pdf</a><br> <br> Everything works perfectly. Only after switching on, VCO2 plays in an extremely wide range, while VCO1 only plays over one octave across the entire keyboard. I can "cure" this by briefly interrupting the CV connection to VCO1.<br> <br> The difference between the two VCOs is that the TA7505M OpAmp, which provides the buffering for the portamento circuit, is connected directly to the IG00153 of VCO1; while for VCO2 there is an additional OpAmp stage before the IG00153 that provides the detune voltage. In my circuit I use a TL072 instead of the Toshiba TA7505M.<br> <br> Now I am looking for the datasheet of the TA7505M to find out what could cause the problem. There doesn't seem to be the datasheet on the web.<br> <br> Do any of you have a Toshiba Databook from the late 70s? Or does anyone have an idea how I could solve the problem in a simple way without having to make a new board (it is clear that I could also put a buffer in front of the IG00153).<br> <br> <br> Best regards<br> Florian<br> <pre class="moz-signature">-- 
<a class="moz-txt-link-freetext" href="http://www.florian-anwander.de/" target="_blank">http://www.florian-anwander.de/</a></pre> <hr>________________________________________________________<br>
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