Thermal cycling

ALphabloom · 1381

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Offline ALphabloom

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on: March 20, 2018, 11:14:01 PM
Hi everyone,

Recently my base crack has been having some problems. For 2 weeks or so, it has been working wonderfully but recently when ever I turn it on, the left channel generates a loud noise which when turning the pot only changes it to the other side. Im guessing somewhere on the amp is a bad solder and that it might have been acerbated by high temperatures (100C/212F or so when I stick a probe in the vent up top)(Could it be generating that much heat as I'm using 240v mains?). How to I start diagnosing where the problem is and so I can re-flow the solder/ re-solder that area?

Has anyone invested in anything to cool the amp? I was thinking a USB powered laptop cooler to elevate it some more and have a fan push some air in.

Thanks


Offline Paul Birkeland

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Reply #1 on: March 21, 2018, 04:15:47 AM
Do you have feet on the amp?  Do you have a Speedball?

I would guess that when you put a temp probe in the amp, you're getting a high reading because of the 3K/10W resistors that are right below the vent.

Since you're using 240V mains, I'm guessing that you purchased the 240V power transformer?  (If you didn't, the fuse wouldn't hold)

How are your voltage measurements?  I could think of a few different loose connections that would dramatically increase the heat dissipated by the 3K 10W resistors, but none of this will happen without some pretty serious differences in measured DC voltage.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline ALphabloom

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Reply #2 on: March 21, 2018, 12:34:54 PM
I have the rubber feet on it, but I feel like it might need more cooling for the sake of longevity of the overall build. I was thinking of adding the speedball to it this week until problems started appearing. I think I was given the 240v transformer, I mean I wired it the way I was meant to for 240 mains. As mentioned, it has worked for 2 weeks or so before problems came to be, as such, it had passed all of the voltage and resistance checks.


Offline Doc B.

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Reply #3 on: March 21, 2018, 12:42:08 PM
Black wires connected to the headphone jack.

Dan "Doc B." Schmalle
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Bottlehead Corp.

Offline ALphabloom

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Reply #4 on: March 21, 2018, 11:44:32 PM
Tried re flowing the black wires leading to the headphone jack and it still has that issue.



Offline Paul Birkeland

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Reply #5 on: March 22, 2018, 04:04:01 AM
Can you recheck the voltages?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

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