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May 20, 2019, 11:37:46 am

Author Topic: Square Peg in Round hole  (Read 481 times)

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Offline Alonzo

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Square Peg in Round hole
« on: August 02, 2017, 05:47:40 pm »
Total rookie mistake about 30 minutes ago.  Swapped the 2A3 Mesh tubes for 2A3-40's and turned on the amp to warm up while I take the work suit off.  Came back in the room to smell something burning and saw a wisp of smoke  coming from the amp.   Shut off the amp and after a suitable amount of sailor language I unplugged it and pulled the tubes.   Hmmmmm, that tube isn't the same as the other.... Hmmmmmm, it isn't as hot as the other....hmmmmm.
Looks like I rotated the right 2A3 ninety degrees and installed it.  There's some discoloring on the A side of the board at the connections for the MJ5731 and a little around the A side LED's.
Is there anything else I should be looking at replacing while I'm under the hood?
Alonzo B
BeePre, Kaiju, some Stereomours (I's and a II) to DT150 tweeters, FE206/ Eminence 15A's open baffles and a pair of Frugal horns IIIs, and a Mainline with HD800

Offline Paul Birkeland

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Re: Square Peg in Round hole
« Reply #1 on: August 03, 2017, 07:30:22 am »
Inserting the 2A3 off 90 degrees can seriously damage the 2A3 and potentially your plate choke but shouldn't do any damage to the C4S driver board.

Before replacing anything, it's best to do a voltage check and look for issues.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Alonzo

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Re: Square Peg in Round hole
« Reply #2 on: August 06, 2017, 09:16:11 am »
Well the Dowdy chokes held up fine, same with the JJ2A3-40's.  My voltages were different from my initial build check but within 5%.  Couldn't tell if the voltage change is due to the age of the parts or from my mistake.  It's back playing and seemingly all is well.
Alonzo B
BeePre, Kaiju, some Stereomours (I's and a II) to DT150 tweeters, FE206/ Eminence 15A's open baffles and a pair of Frugal horns IIIs, and a Mainline with HD800