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Thread Tools |
16th October 2020, 12:03 PM
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#1 |
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diyAudio Member
Join Date: Aug 2010
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Digital Deaigns M4A
I do not get any rail to rail oscillation on the outputs .
I checked all of the regulators and all seem to work fine . I checked all the 47mh inductors all are fine . I get both positive and negative rail voltages . Any ideas or common issues with this design of amp as to why it won’t oscillate |
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16th October 2020, 12:54 PM
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#2 |
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diyAudio Member
Join Date: Aug 2010
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I’m gonna try replacing the smd transistors on the audio driver board since some appear a brownish color from heat
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16th October 2020, 12:54 PM
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#3 |
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diyAudio Member
Join Date: Nov 2003
Location: Louisiana
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Black probe on the negative rail, what's the DC voltage on terminal 2 of the 21844s?
Do you have signal reaching the driver board?
__________________
Anyone who purchased the repair tutorial, email me (babin_perry@yahoo.com) if you want to download the latest version. |
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17th October 2020, 10:23 PM
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#4 |
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diyAudio Member
Join Date: Aug 2010
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The muting transistor is defective .
It’s marked K30A So I’m assuming it’s a KSC30A Do you happen to know if any good replacements for that transistor ? |
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17th October 2020, 10:31 PM
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#5 |
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diyAudio Member
Join Date: Nov 2003
Location: Louisiana
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K30A is a jfet. It doesn't read like other transistors.
What do you read 1-2, on ohms? Then read 2-3 on diode check. Reverse probes and read again.
__________________
Anyone who purchased the repair tutorial, email me (babin_perry@yahoo.com) if you want to download the latest version. |
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17th October 2020, 11:03 PM
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#6 |
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diyAudio Member
Join Date: Aug 2010
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Amp has no output I took it out of the amp and the amp plays audio so it’s defective
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18th October 2020, 06:03 AM
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#7 |
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diyAudio Member
Join Date: Aug 2010
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Any ideas on what I might be able to use ?
Legs1-2:Ol Legs2-3:1.455 Proves reversed Legs1-2:OL Legs2-3:1.455 |
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18th October 2020, 12:24 PM
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#8 |
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diyAudio Member
Join Date: Nov 2003
Location: Louisiana
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Do you have any J111 jfets?
__________________
Anyone who purchased the repair tutorial, email me (babin_perry@yahoo.com) if you want to download the latest version. |
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18th October 2020, 12:44 PM
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#9 |
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diyAudio Member
Join Date: Aug 2010
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Yes
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18th October 2020, 12:49 PM
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#10 |
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diyAudio Member
Join Date: Nov 2003
Location: Louisiana
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Check one like you checked the k30 and post.
__________________
Anyone who purchased the repair tutorial, email me (babin_perry@yahoo.com) if you want to download the latest version. |
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