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Amplifier keeps blowing fuses where to start and how to start troubleshooting?

By on May 10, 2008

Dear Jestine Yong,

Recently I got involved to electronic repair service but my knowledge is very limited, I read your e-book again and again to find down if there is some information that I can use to the problem I’m having now but until now I could not figure out. I send you this email attached 3 pictures hopefully you can have me some ideas where need to check to find down what parts short cause the fuse blown.

The red round mark on the picture that the diodes I tested good, the cross red mark on 2 filter capacitors that new ones replaced, what next one need to test please show me by the red mark on the picture attached. Thanks, hope to hear from you soon, my customer have been waiting a month, I feel very embarrassing

Hi Hung,
When a fuse blow, normally it could be due to shorted semiconductor like diode, fet, transistor ic, mistake made by ourselve like wrong solder joint, installing e-cap the other way round and etc. Try to check these first and let me know how is the outcome!

Dear Mr Jestine Yong,

I’m going to give up, tried four times , the last one took more than 3 minutes but I could not find any hot components, I attched pictures please tell me what components possible short cause the fuse keep blown, as many components on this power board I don’t have much time to take out one by one to check. Please give me your advice. Thanks

Hi Hung,
Try to remove all the transistors from the heatsink and retest again. Please make sure you write it down the value and location first. Sometimes i wish that i can go to your place and take a look at the board as it also made me curious why the fuse keep blowing. Did you replace with an original fuse. If original is a slow blow fuse and you replaced with a fast acting fuse, the fuse will blow again upon switch “On”. If the fuse blown was caused by a solder bridge in the circuit you can’t test on the components that will get Hot. Did you measure the output voltage from the transformer? By the way, thanks for supporting me again on my LCD Monitor Repair Ebook!

Hello Mr. Jestine Yong,

I’m so happy I solved the problem. Following your instruction I removed 6 transitors on the heat sink and retested, the light did not come on anymore, testing with my Smart teetzer it shows 2 of 6 transitors short based on your book how to test transitor, replaced 2 transitors A1186 and C2837 every thing works fine now. Thanks you again, I have been reading your next book how to repair LCD monitor and going to invest money to buy oscilloscope can you recommend me one, I plan to use this one to repair TV LCD and Plasma TV as well.




Hi Hung,
Its great to hear that you have solved the problem! The harder we can repair an equipment the more we understand about electronic repair! Okay back to the scope, i suggest that you get at least a 100mhz scope so that you don’t need to upgrade again. You can buy any brand from ebay dot com and they have many choices too. Here is a good scope that you may consider:

Remember, if you have the budget get a new scope if not get a used one from ebay. Have a good day!

Best regards,
Jestine Yong

sencore sc3100


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