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20th December 2012, 10:55 PM
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#11 |
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diyAudio Member
Join Date: Nov 2003
Location: Louisiana
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What is the DC voltage on all legs of Q2?
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21st December 2012, 08:53 AM
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#13 |
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diyAudio Member
Join Date: Nov 2003
Location: Louisiana
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The transistor is defective. It should be marked BE. If so, it's a 2SB1260.
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22nd December 2012, 05:01 AM
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#14 |
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diyAudio Member
Join Date: Dec 2012
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Perry.. You sir know your stuff. Got the amp back into protect.. haha never have I been happier to see an amp in protect.
So I power up. I get RED GREEN RED.. No relay engagement. All Output fets removed all PS fets removed. Audio board removed. New Gate Drive Transistors 139 replacing 3228 for NPN 140 replacing PNP Voltage on 7500 P 9 10 11 12 13 14 15 16 0 0v 12.6v 12.6v 5v 5v 5v 0v I get 5v and saw tooth at 48kHz Must be something else on the PS card then? I get 0V on PS gates before and after resistors. Thanks for the help, Mo |
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22nd December 2012, 01:05 PM
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#15 |
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diyAudio Member
Join Date: Nov 2003
Location: Louisiana
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Post the DC voltage on pins 1-4 of the 7500.
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Links >> Basic Car Audio Amp Repair * Basic Car Audio Electronics * New Site * Basic Switching Power Supply Design * Basic Computer Skills << Links |
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22nd December 2012, 06:11 PM
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#17 |
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diyAudio Member
Join Date: May 2010
Location: Washington State
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Are you sure you dont have a burned trace somewhere?
__________________
Pyramid 52 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch |
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22nd December 2012, 06:29 PM
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#18 |
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diyAudio Member
Join Date: Dec 2012
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I'm pretty sure. I've looked over the board carefully. I'm all too use to seeing blown traces. But I don't see anything bad. None of the traces on this amp are thin enough for me to easily miss. I do think that some of the diodes by the speaker terminal are shorted. But I haven't taken them off to test yet I think it shouldn't have anything to do with the Ps board not powering up the gate transistors allowing me to get power at the gates of my ps fets What's q225 and q 226 used for ?
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22nd December 2012, 06:38 PM
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#19 |
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diyAudio Member
Join Date: May 2010
Location: Washington State
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Q225 I believe is connected to those diodes by the speakers terminals. I replaced both of them in the last amp I repaired and used the BD139 and BD140.
__________________
Pyramid 52 Amp Power Supply----Fluke 787 Processmeter----Tektronix 465 Scope----Velleman HPS40 Scope----Soldering Iron----Desoldering Iron----Hejet HJ 500-S Heatgun----DM4070 Digital LCR Meter----Propane Torch |
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22nd December 2012, 06:44 PM
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#20 |
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diyAudio Member
Join Date: Dec 2012
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I'm pretty sure. I've looked over the board carefully. I'm all too use to seeing blown traces. But I don't see anything bad. None of the traces on this amp are thin enough for me to easily miss. I do think that some of the diodes by the speaker terminal are shorted. But I haven't taken them off to test yet I think it shouldn't have anything to do with the Ps board not powering up the gate transistors allowing me to get power at the gates of my ps fets What's q225 and q 226 used for ?
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