{"id":9538,"date":"2020-09-24T20:13:00","date_gmt":"2020-09-24T19:13:00","guid":{"rendered":"https:\/\/stevepedwards.today\/ElectronicsStuff\/?p=9538"},"modified":"2020-10-10T23:42:03","modified_gmt":"2020-10-10T22:42:03","slug":"sony-ex50-no-left-channel-output","status":"publish","type":"post","link":"https:\/\/stevepedwards.today\/ElectronicsStuff\/sony-ex50-no-left-channel-output\/","title":{"rendered":"Sony Ex50 &#8211; no left channel output"},"content":{"rendered":"<p>The power out from 60Vpp is:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-9540\" src=\"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/09\/SonyEX50.png\" alt=\"\" width=\"692\" height=\"475\" srcset=\"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/09\/SonyEX50.png 692w, https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/09\/SonyEX50-300x206.png 300w\" sizes=\"auto, (max-width: 692px) 100vw, 692px\" \/><\/p>\n<p>56.25W per channel into 8 ohm<\/p>\n<p><iframe loading=\"lazy\" title=\"Sony EX50 no left output\" width=\"1778\" height=\"1000\" src=\"https:\/\/www.youtube.com\/embed\/EuA25gVsjMw?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p>Hmm..no schematic? No phono input so no pre amp, so first amp is 8 pin JRC7004E - tests ok at pins 1 and 7 ouputs.<\/p>\n<h3><a name=\"cpSTK4171V\"><\/a>STK4171V\/STK4181V\/STK4191V - ECG1317<\/h3>\n<pre class=\"\">Audio Power Amp, 50 W, 8 ohms, Vcc = +\/- 35.5 V, 18 pin SIP.\r\n\r\nPin 1: Left channel input (-)\r\nPin 2: Left channel input (+)\r\nPin 3: Compensation\r\nPin 4: Compensation\r\nPin 5: Compensation\r\nPin 6: Muting\r\nPin 7: Compensation\r\nPin 8: Compensation\r\nPin 9: -Vcc\r\nPin 10: Left channel Output\r\nPin 11: +Vcc\r\nPin 12: Bypass\r\nPin 13: Right channel output\r\nPin 14: -Vcc\r\nPin 15: Compensation\r\nPin 16: Gnd\r\nPin 17: Right channel input (+)\r\nPin 18: Right channel input (-)<\/pre>\n<p>Odd readings on the only 8 pin op amp (Mitsubishi 5218A) by the tone controls, so will remove and test it..op amp ok. Something is dragging down the negative side of this op amp to just above ground, and seems linked to the faulty direct\/mute switch circuits, but components there test ok, with correct voltages as shown on circuit.<\/p>\n<p>Been through the vol board voltages from schematic to find why the output of pin 10 is 0.5V not 2.5V, with full 7.8V B+ line at the 10k resistor R200 - the diode D109 was changed but checked ok:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-9547\" src=\"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/09\/pin10.png\" alt=\"\" width=\"355\" height=\"467\" srcset=\"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/09\/pin10.png 355w, https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/09\/pin10-228x300.png 228w\" sizes=\"auto, (max-width: 355px) 100vw, 355px\" \/><\/p>\n<p>This B+ line also feeds the mute and source transistors (22k resistors built in and pricey at -\u00a33.50 each!), that also don't work, after changing the LEDs and the BA1F4M transistors from with good ones from the input switch circuits - though one tranny was probably duff - but didn't solve their no switching fault. I removed the MC14052 mux chip and ordered a new one, adding a chip holder. If it's not that I'm stumped..<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-9550\" src=\"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/09\/trans.png\" alt=\"\" width=\"809\" height=\"668\" srcset=\"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/09\/trans.png 809w, https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/09\/trans-300x248.png 300w, https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-content\/uploads\/2020\/09\/trans-768x634.png 768w\" sizes=\"auto, (max-width: 809px) 100vw, 809px\" \/><\/p>\n<p>10\/10\/202<\/p>\n<p>This is the biggest pain amp I've ever had! I cannot find this fault! Something dragging the voltage down somewhere to cause B+ at pin 7 out of the op amp and for the mute\/source circuits to not switch...The tracks are bastards for coming away when desoldering, totally sick of it now...<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The power out from 60Vpp is: 56.25W per channel into 8 ohm Hmm..no schematic? No phono input so no pre amp, so first amp is 8 pin JRC7004E - tests ok at pins 1 and 7 ouputs. STK4171V\/STK4181V\/STK4191V - ECG1317 Audio Power Amp, 50 W, 8 ohms, Vcc = +\/- 35.5 V, 18 pin SIP. <a href=\"https:\/\/stevepedwards.today\/ElectronicsStuff\/sony-ex50-no-left-channel-output\/\" class=\"more-link\">...<span class=\"screen-reader-text\">  Sony Ex50 &#8211; no left channel output<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-9538","post","type-post","status-publish","format-standard","hentry","category-uncategorised"],"_links":{"self":[{"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/posts\/9538","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/comments?post=9538"}],"version-history":[{"count":10,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/posts\/9538\/revisions"}],"predecessor-version":[{"id":9586,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/posts\/9538\/revisions\/9586"}],"wp:attachment":[{"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/media?parent=9538"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/categories?post=9538"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stevepedwards.today\/ElectronicsStuff\/wp-json\/wp\/v2\/tags?post=9538"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}