{"id":243,"date":"2020-03-09T17:12:14","date_gmt":"2020-03-09T17:12:14","guid":{"rendered":"https:\/\/blog.andytather.co.uk\/?page_id=243"},"modified":"2020-04-21T21:35:35","modified_gmt":"2020-04-21T21:35:35","slug":"modulus-686-testing","status":"publish","type":"page","link":"https:\/\/blog.andytather.co.uk\/index.php\/lm3886-build-thread\/modulus-686-testing\/","title":{"rendered":"Modulus 686 Testing"},"content":{"rendered":"\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/02\/20200223_162904-1024x768.jpg\" alt=\"\" class=\"wp-image-201\" srcset=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/02\/20200223_162904-1024x768.jpg 1024w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/02\/20200223_162904-300x225.jpg 300w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/02\/20200223_162904-768x576.jpg 768w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/02\/20200223_162904-1536x1152.jpg 1536w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/02\/20200223_162904-2048x1536.jpg 2048w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/02\/20200223_162904-1200x900.jpg 1200w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/02\/20200223_162904-1980x1485.jpg 1980w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>The Modulus-686 is a bridge-tied-load (BTL) amplifier and therefore can&#8217;t be measured in the normal manner using a scope probe and grounding lead to the +\/- of the output, as that would cause a <strong>short circuit<\/strong>.<\/p>\n\n\n\n<p>  <\/p>\n\n\n\n<p>Leaving the scope probe grounding lead floating (i.e. not connected to anything) also causes issues with the measurements sometimes looking okay and other times causing malformed waveforms like below right.<\/p>\n\n\n\n<figure class=\"wp-block-gallery columns-2 is-cropped wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\"><ul class=\"blocks-gallery-grid\"><li class=\"blocks-gallery-item\"><figure><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_162917-1024x768.jpg\" alt=\"\" data-id=\"222\" data-full-url=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_162917-scaled.jpg\" data-link=\"https:\/\/blog.andytather.co.uk\/index.php\/lm3886-build-thread\/amp-assembly\/20200307_162917\/\" class=\"wp-image-222\" srcset=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_162917-1024x768.jpg 1024w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_162917-300x225.jpg 300w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_162917-768x576.jpg 768w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_162917-1536x1152.jpg 1536w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_162917-2048x1536.jpg 2048w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_162917-1200x900.jpg 1200w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_162917-1980x1485.jpg 1980w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_122111-1-1024x768.jpg\" alt=\"\" data-id=\"220\" data-full-url=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_122111-1-scaled.jpg\" data-link=\"https:\/\/blog.andytather.co.uk\/index.php\/lm3886-build-thread\/amp-assembly\/20200307_122111-1\/\" class=\"wp-image-220\" srcset=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_122111-1-1024x768.jpg 1024w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_122111-1-300x225.jpg 300w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_122111-1-768x576.jpg 768w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_122111-1-1536x1152.jpg 1536w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_122111-1-2048x1536.jpg 2048w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_122111-1-1200x900.jpg 1200w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200307_122111-1-1980x1485.jpg 1980w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure><\/li><\/ul><\/figure>\n\n\n\n<p>This can lead to thinking that there is a problem when there isn&#8217;t.<\/p>\n\n\n\n<p>The scopes probe grounding lead should be connected to the power GND of the amp, but for BTL we also need to use both scope leads for the +\/- output and both scope grounding leads connected to the power GND.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200308_202617-1024x768.jpg\" alt=\"\" class=\"wp-image-229\" srcset=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200308_202617-1024x768.jpg 1024w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200308_202617-300x225.jpg 300w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200308_202617-768x576.jpg 768w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200308_202617-1536x1152.jpg 1536w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200308_202617-2048x1536.jpg 2048w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200308_202617-1200x900.jpg 1200w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200308_202617-1980x1485.jpg 1980w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>One further step is required to show the actual signal that the speaker will exhibit. Use the scopes Math function to perform a CH1 &#8211; CH2 operation on the signals.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"768\" src=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200310_181021-1024x768.jpg\" alt=\"\" class=\"wp-image-274\" srcset=\"https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200310_181021-1024x768.jpg 1024w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200310_181021-300x225.jpg 300w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200310_181021-768x576.jpg 768w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200310_181021-1536x1152.jpg 1536w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200310_181021-2048x1536.jpg 2048w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200310_181021-1200x900.jpg 1200w, https:\/\/blog.andytather.co.uk\/wp-content\/uploads\/2020\/03\/20200310_181021-1980x1485.jpg 1980w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p class=\"has-text-align-center\"><a href=\"https:\/\/blog.andytather.co.uk\/index.php\/lm3886-build-thread\/guardian-686\/\">Next Page: Guardian 686<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The Modulus-686 is a bridge-tied-load (BTL) amplifier and therefore can&#8217;t be measured in the normal manner using a scope probe and grounding lead to the +\/- of the output, as that would cause a short circuit. Leaving the scope probe grounding lead floating (i.e. not connected to anything) also causes issues with the measurements sometimes [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":6,"menu_order":31,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"_links":{"self":[{"href":"https:\/\/blog.andytather.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/243"}],"collection":[{"href":"https:\/\/blog.andytather.co.uk\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/blog.andytather.co.uk\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/blog.andytather.co.uk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.andytather.co.uk\/index.php\/wp-json\/wp\/v2\/comments?post=243"}],"version-history":[{"count":11,"href":"https:\/\/blog.andytather.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/243\/revisions"}],"predecessor-version":[{"id":287,"href":"https:\/\/blog.andytather.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/243\/revisions\/287"}],"up":[{"embeddable":true,"href":"https:\/\/blog.andytather.co.uk\/index.php\/wp-json\/wp\/v2\/pages\/6"}],"wp:attachment":[{"href":"https:\/\/blog.andytather.co.uk\/index.php\/wp-json\/wp\/v2\/media?parent=243"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}