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Old 03-29-2021, 09:59 AM   #1
ghiotom
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Default Bose Lifestyle 48 Acoustimass PS Issue

I've had this system for 20 years with no problems. One day, all audio is missing and it turns out the ps mosfets are blown along with associated components including controller IC. Found a guy on YouTube with similar problem and replaced the parts he mentioned as well as 1 additional mosfet in the feedback circuit. The system worked great for 3 months, now back to original problem with blown mosfets, etc. There are 2 10uF 25V caps on secondary with ESR of 8.6-8.8 ohms, my replacement cap measures 1.2 ohms. Does the ESR on the secondary caps seem high enough to take out the mosfets or should I be looking elsewhere? Remember the repair lasted 3 months, it didn't blow right away.
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Old 03-29-2021, 10:15 AM   #2
b seshu
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Default Re: Bose Lifestyle 48 Acoustimass PS Issue

Z8v x16
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Old 03-30-2021, 06:06 PM   #3
sam_sam_sam
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Default Re: Bose Lifestyle 48 Acoustimass PS Issue

Quote:
Originally Posted by ghiotom View Post
There are 2 10uF 25V caps on secondary with ESR of 8.6-8.8 ohms, my replacement cap measures 1.2 ohms. Does the ESR on the secondary caps seem high enough to take out the mosfets or should I be looking elsewhere? Remember the repair lasted 3 months, it didn't blow right away.
Yes this is extremely high as you have found out if you compare it to a new one

I would highly recommend that you check all capacitors that are less than 100uf at a minimum or just checking all of them highly recommend
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9 PC LCD Monitor
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30 Desk Top Switching Power Supply
10 Battery Charger Switching Power Supply for Power Tool
6 18v Lithium Battery Power Boards for Tool Battery Packs
1 XBox 360 Switching Power Supply and M Board
25 Servo Drives 220/460 3 Phase
6 De-soldering Station Switching Power Supply 1 Power Supply
1 Dell Mother Board
15 Computer Power Supply
1 HP Printer Supply & Control Board * lighting finished it *


These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
2 Hem Saw Computer Stack Board

All of these had CAPs POOF
All of the mosfet that are taken out by bad caps

Last edited by sam_sam_sam; 03-30-2021 at 06:08 PM..
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