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Post by Johnkenn on Jan 27, 2018 18:28:36 GMT -6
So my Upton PS has been blowing fuses. Probably gone through about 5-7 in the last month. I had what I thought was a 12AY7 in it, but apparently it's a Mullard 12AT7. So I thought that could have possibly been the issue. So I put the EH 6072 back in...well, now another fuse has blown. So maybe that wasn't the issue after all. I measured the voltage and it was correct at least unloaded. My voltages unloaded were 145.5 DCV and 6.3 DCV...so that's normal per the picture that Billy sent (below.) Any ideas why this might be happening? I've got it connected to a Furman power conditioner. It just all-of-a-sudden started doing this.  |
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Post by Johnkenn on Jan 27, 2018 18:30:40 GMT -6
Oh - Zephyr Slow Blow 0.5 Amp fuses.
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Post by popmann on Jan 27, 2018 18:58:59 GMT -6
Any relation to the fall in terms of timing?
I mean, it blows because something shorts and pulls more than designed. So, even though the fuse is in the PS....damage at the mic could cause it to pull more current. I would think. But, my knowledge of electronics is...you know....lacking would be kind.
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Post by Johnkenn on Jan 27, 2018 19:26:07 GMT -6
Man, could be...damnit. Guess I need to check what it's pulling when it's connected. That makes me a bit nervous, though.
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Post by svart on Jan 27, 2018 19:33:39 GMT -6
Does it pop during power up, power off, or during being on for a while?
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Post by mulmany on Jan 27, 2018 19:43:24 GMT -6
I assume that when you had the capsule repaired the whole mic and PSU were sent in. Seem like Shannon would have noticed if something was off with the voltages.
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Post by Johnkenn on Jan 27, 2018 20:12:35 GMT -6
Does it pop during power up, power off, or during being on for a while? Turns on when I put a new one in and does fine. Then I can turn it off and it will blow when turning on. Well, they seem to last a couple cycles...but I just turned it off and back on and it blew. |
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Post by Johnkenn on Jan 27, 2018 20:17:50 GMT -6
You know I didn’t think about power off being an issue. But this last time I saw the light come on for a split second when I flipped it on.
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Post by johneppstein on Jan 28, 2018 1:08:22 GMT -6
Could be an electrolytic starting to go bad. Could also be an intermittent short in the cable or a slightly crushed wire. I'd start with replacing the filter caps in the supply.
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Post by reddirt on Jan 28, 2018 6:05:18 GMT -6
Check your lead between mic and PSU is seated properly. That can do it.
Cheers
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Post by Johnkenn on Jan 28, 2018 8:05:02 GMT -6
You mean it could be loose from the socket on the power supply? I was looking and I believe this issue with the fuses preceded the fall.
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Post by svart on Jan 28, 2018 8:12:59 GMT -6
You know I didn’t think about power off being an issue. But this last time I saw the light come on for a split second when I flipped it on. Yeah, that's a good clue that it's pulling a lot of current when turning on. Inrush current they call it. I don't know that a fall could suddenly cause something to pull more current unless it caused something inside the mic to short.. But even then if it was a hard short, it'd blow every time. It could be the HV arcing to the chassis or tube of the mic sometimes. |
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Post by Johnkenn on Jan 28, 2018 9:11:52 GMT -6
You know I didn’t think about power off being an issue. But this last time I saw the light come on for a split second when I flipped it on. Yeah, that's a good clue that it's pulling a lot of current when turning on. Inrush current they call it. I don't know that a fall could suddenly cause something to pull more current unless it caused something inside the mic to short.. But even then if it was a hard short, it'd blow every time. It could be the HV arcing to the chassis or tube of the mic sometimes. So I guess the only way to narrow the problem down is to try and get the fuse to blow without the mic attached - and if there’s no problem there, it’s obviously something in the mic? |
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Post by Johnkenn on Jan 28, 2018 15:40:06 GMT -6
OK - definitely happening only when the mic is connected. I can flip on and off without it being connected with no problem. Once I connect the mic, I can turn it on and it works. If I flip it off and then back on, it blows.
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Post by Johnkenn on Jan 28, 2018 16:10:36 GMT -6
Er...switched IEC cables and everything has been kosher for about 5 cycles now. Gonna live with it a while and see if it happens again. Could it have been that easy?
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