My new MJI5003 output transistors are getting red hot

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18-Aug-2019 07:08 PM

faststore1

faststore1

Posts: 1

Hello all.  I bought both kits to upgrade my Quad 303 from you.

    All went well until I replaced the output transistors to MJI 5003 as suggested by yourselves.

My problem is that after an hour of working perfectly the output transistors heat up excessively the original transistors are ok running at 80F

 .I bought these transistors from the reputable company  Radio Spares in London what do you think could  be the problem.

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05-Sep-2019 11:22 AM

Stefaan

Stefaan

Posts: 618


Probably a bad connection somewhere. I would check the new soldering-joints with a multimeter and make sure everything is connected the right way with the schematic.

MJ15003 is the correct transistor for the 303 and it should not heat up.

Also re-check the quiescent current (see the revision manual) after installing new transistors.

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