News: Trouble logging in? Log in from the login page.
September 20, 2020, 04:03:27 PM

Author Topic: [RESOLVED] Up in Smoke (resistor between 44L and 30L)  (Read 635 times)

0 Members and 1 Guest are viewing this topic.

Online Paul Birkeland

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 13552
Re: New Build - Up in Smoke (resistor between 44L and 30L)
« Reply #30 on: May 21, 2020, 05:54:04 PM »
Hey, that's great.  You have both HV branches operating with both 2A3s.

Next you will want to attach the red wire back where it went, fire up the amp, then keep an eye on the voltage at pin 1 on the 4 pin socket on the dead side.  If it settles to about 375 again and just sits there, then you can measure the output voltage of each side of the C4S board (easiest to just probe the metal tab on each MJE5731A).  If they are both around 220V, then your amp is ready to listen to.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline WK3K

  • Full Member
  • ***
  • Posts: 83
  • Beginning to see the light...
Re: New Build - Up in Smoke (resistor between 44L and 30L)
« Reply #31 on: May 21, 2020, 06:56:25 PM »
Gents. Sitting in the living room listening to music!

Ran all the voltage checks and everything was right where it should be. Time to sit back and enjoy.

My best guess on the original issue is that the 130ohm resistor between 27L and 30L was too close to the terminal strip and one of the leads shorted against something wired into 28 or 29. This blew both the 130's on that side. Replacement resistors more carefully wired seemed to do the trick.

Thanks PB for all your help and to Jamie for the spare 130's that brought this baby to life. I'll post pictures and impressions once I have put in some listening over the long weekend!
Witold

Rega P3-24 w/ Rega Exact > Eros II> Quickie w/PJCCS > Stereomour II w/ DC filament supply > Blumenstein Orca Mini/Max 2.1

MacBook > Grace SDAC > Crack w/ Speedball > Sennheiser HD6XX

Offline Jamier

  • Sr. Member
  • ****
  • Posts: 336
Re: [RESOLVED] Up in Smoke (resistor between 44L and 30L)
« Reply #32 on: May 22, 2020, 05:28:24 AM »
Witold,

     I’m happy to hear that it all worked out.

Jamie
James Robbins

Offline Jamier

  • Sr. Member
  • ****
  • Posts: 336
Re: [RESOLVED] Up in Smoke (resistor between 44L and 30L)
« Reply #33 on: May 22, 2020, 08:38:41 AM »
I learned an important lesson about parts availability when I had my mishap with the 130/2W resistors. When I blew mine up, I ordered those resistors from Mouser, but they said they were out and the lead time was 12 weeks. I thought, surely, it couldn’t possibly be 12 weeks, right? So I placed the order and then called Eileen to see if she had any that weren’t already allocated to kits that were in process. She did have some that were available and she sent them to me. I got them in a couple days, put the amp back together and lived happily ever after (Eileen is, often, the best friend you’ll ever have). Anyway, having forgotten about the Mouser order, 12 weeks later those resistors showed up in my PO Box. So, the moral of this story is; when Mouser says it will take 12, or whatever number of weeks to get something, they aren’t kiddin’. That event also showed me the wisdom of using clip leads, instead of probes, when testing in tight spots. When that resistor blew it was like a firecracker goin’ off.

Jamie
« Last Edit: May 22, 2020, 11:09:49 AM by Jamier »
James Robbins