Crack + Speedball. Everything was working for two days, fuse blown today

vlitzer · 1583

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Offline vlitzer

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on: October 31, 2015, 07:04:30 AM
I used my crack for months. Two days ago, I assembled the speedball, checked the voltages, and started listening since then, including a very long strech yesterday. Today, I turn it on, and the tubes are not glowing, checked the fuse and its blown.
Any ideas on Why?


Offline Paul Birkeland

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Reply #1 on: October 31, 2015, 08:03:52 AM
Try a new 1A fuse, just to be sure that there is an issue. 

If the amp blows a second fuse, let us know and we can point you in some different directions.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline vlitzer

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Reply #2 on: October 31, 2015, 02:00:47 PM
Replaced the fuse with a 1 amp one, and it seems to be working now (couple of minutes on).
I understand that 0.5 Amp is a pretty low fuse, but I was just wondering, could be something wrong or its expected to get blown fuses from time to time?


Offline vlitzer

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Reply #3 on: October 31, 2015, 03:35:15 PM
Right, but I have been listening on the crack for months, and two days after I added the speedball!


Offline Paul Birkeland

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Reply #4 on: October 31, 2015, 06:00:43 PM
We used to ship the Crack with a 0.5 amp slo-blo fuse, then later switched to a standard 1A fuse, as a lot of folks were having a tough time finding replacement slo-blo fuses (and those suckers went out of stock with alarming frequency).

If your amp is running on the 1A fuse, you have nothing to worry about. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Online Paul Joppa

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Reply #5 on: October 31, 2015, 06:28:54 PM
Yeah, the thing about fuses ... most amps, SS or tube, will have a large inrush current before they settle down to the operating current. And fuses have a time constant, which is longer for the slow-blow types. Ideally you would match the time constants, but this is never really possible. The big problem is, that for the SAME FUSE RATING AND TYPE, different brands (or even production lots) will have different time constants. So the 0.5A slow blows that we had on hand were quite reliable, but then we got a new batch... took a long time to sort that out.

Paul Joppa

Offline vlitzer

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Reply #6 on: October 31, 2015, 06:36:10 PM
That makes sense.
Thanks for the responses! Indeed it seems to be working just fine (been listening since I posted :))


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