405-2 fuse blown.

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07-Sep-2018 03:09 PM

Not Available

Posts: 24

I just turned on my Quad 33 and there was no power coming from the 505-2, So I took the cover off and found that the main fuse was blown. I replaced the slo blo 2 amp fuse and tried again but that also blew. What is the best way to check if all is alright before I put in another?

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07-Sep-2018 08:09 PM

Ton

Ton

Posts: 30

Isn't there a 2.5 amp AT slow blow instead of the 2 amp you used ? 

Perhaps you should try a 2.5 first and see what happens.

Then check the rectifier and the smoothing caps if they are ok.

After that, take a look at the 405-2 service data manual page 6 (download section) for clues.


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09-Sep-2018 12:02 PM

EJP

EJP

Posts: 1511

The mains fuse is T2.5A in every published 405 schematic. You should investigate the DC fuses in each channel and if blown the power transistors and drivers.
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11-Sep-2018 11:37 AM

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Posts: 24

I found a couple of rectifier diodes short circuit - took them out and the fuse didn't blow, so hopefully replacing them will fix it.
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