JLHD750/1 sounds growls very loud!!! - diyAudio
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Old 8th June 2011, 01:48 AM   #1
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Default JLHD750/1 sounds growls very loud!!!

Hello! Im just newbie here...thanks I found this forum!

Can you please help me to determine what is the exact problem of my JL amp, it growls very loud and IRF 7225 output transistors keeps heating...Ive checked the transistors but is OKs, I replaced IR2010 drivers but no changes...replaced the biased capacitors and diodes for IC drivers but still no changes...Im now on dead end...Please help I spent to much here...and cant afford to buy a new one..this is very expensive in our country Philippines.

Note: This amp had gone major repair on power supply side...dont know If i have noisy power supply.

thanks in advance!!!!
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Old 8th June 2011, 01:52 AM   #2
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Quote:
Originally Posted by nonprof View Post

Note: This amp had gone major repair on power supply side...dont know If i have noisy power supply.

thanks in advance!!!!
You could measure the power supply voltages and see if they are in spec.
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Old 8th June 2011, 03:22 AM   #3
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Originally Posted by nigelwright7557 View Post
You could measure the power supply voltages and see if they are in spec.
I think the +VDD rail supply is slightly high...it measure 110VDC...I'll check it again what's on spec. do you think if I have 10VDC higher it will cause a growling output? thanks to your reply...
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Old 8th June 2011, 06:49 AM   #4
MOER is offline MOER  United States
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Default HD750

The power supply to the main class D FETs is +90v DC

If it is higher your main switch mode supply regulator is bad due to incorrect feedback


Steve

Zed Audio
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Old 8th June 2011, 07:13 AM   #5
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Quote:
Originally Posted by MOER View Post
The power supply to the main class D FETs is +90v DC

If it is higher your main switch mode supply regulator is bad due to incorrect feedback


Steve

Zed Audio

Do you have an idea where I can start isolating the problem on switch mode regulator? I will be having difficulty on finding the problem, im not excellent on electronics. I can send JLHD750 main schematic if you want...
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