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Post by jeromemason on Oct 3, 2014 20:00:19 GMT -6
Doesn't matter what guitar I have plugged in if I turn any of the pots or pickup switch I get crackling and popping, once I don't move it of course it stops. Like I said it's on every guitar I plug into it so it's got to be something with the amp. Just wondering if anyone had this issue before? It's a point to point 5E3.
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Post by mobeach on Oct 4, 2014 7:18:46 GMT -6
You tried different cords too? Is this a head you built yourself?
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Post by swurveman on Oct 4, 2014 8:34:06 GMT -6
Doesn't matter what guitar I have plugged in if I turn any of the pots or pickup switch I get crackling and popping, once I don't move it of course it stops. Like I said it's on every guitar I plug into it so it's got to be something with the amp. Just wondering if anyone had this issue before? It's a point to point 5E3. I bought a point to point amp amp from a well known boutique California amp maker and just had a crackling/popping/pooped out problem that didn't go away the 3rd time I used the amp. I just sent it back to get it repaired. Can't help you with the solution to your problem yet, but was disappointed at such a quick failure of a point to point amp after owning tons of mass produced amps over the years that worked fine over a long time. When I hear back from the amp maker, I'll let you know what the problem was if you want to know. |
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Post by jeromemason on Oct 4, 2014 10:41:42 GMT -6
You tried different cords too? Is this a head you built yourself? Yeah tried different chords, and it's a head I built, but I checked for DC on the inputs and wasn't getting anything. I guess it could be a bad filter cap but I don't want to pull it apart if someone had something similar and it was simple. I guess I could try a couple of different chords though, I've only tried two so far. I put a couple of old preamp tubes in just to make sure it wasn't that, didn't help. |
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Post by jeromemason on Oct 4, 2014 10:42:00 GMT -6
Doesn't matter what guitar I have plugged in if I turn any of the pots or pickup switch I get crackling and popping, once I don't move it of course it stops. Like I said it's on every guitar I plug into it so it's got to be something with the amp. Just wondering if anyone had this issue before? It's a point to point 5E3. I bought a point to point amp amp from a well known boutique California amp maker and just had a crackling/popping/pooped out problem that didn't go away the 3rd time I used the amp. I just sent it back to get it repaired. Can't help you with the solution to your problem yet, but was disappointed at such a quick failure of a point to point amp after owning tons of mass produced amps over the years that worked fine over a long time. When I hear back from the amp maker, I'll let you know what the problem was if you want to know. Yeah for sure, let me know what they found. |
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Post by jeromemason on Oct 5, 2014 16:33:38 GMT -6
So I found DC on the input jack, about 3/4 of a volt but that would be definitely enough to cause arching which would be what is causing the popping and cracking. I'm guessing it's a bad cap on the board and it's allowing the dc to reach the input jack. I'm thinking about ordering a new cap and resistor kick and just re-wiring the whole damn thing.
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Post by svart on Oct 6, 2014 7:06:28 GMT -6
3/4 of a volt is a LOT. Pots will crackle with as little as a couple hundred millivolts.
Can you take a picture of the inside, particularly the input section and wiring? Do you have a schematic of the amp?
If you pull the first tube out, do you still have the voltage?
Is the volume of the guitar through the amp correct, or is it low?
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Post by jeromemason on Oct 6, 2014 12:04:51 GMT -6
svartActually called up the kit supplier, because I live in the great state of FL with an average humidity of 70% the fiber eyelet board can absorb moisture and cause this to happen, guy said it happens a lot. So I'm going to put an .047 coupling cap between the jack and eyelet instead of a solid wire. Should do the trick and not mess with the tone or anything.
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Post by svart on Oct 6, 2014 12:12:07 GMT -6
If you do that, you might want to add a grid bleed resistor to keep the cap from charging up. it'll keep the cap DC referenced so that it's not just floating.
Anyway, it's also common on these amps that when the input jacks aren't grounded well enough to the front plates, and the front plates aren't grounded well enough to the chassis, that you'll get some DC charging. I'd pull the jacks and make sure you scrape/sand some of the metal clean and then install the jacks again. Also, if it doesn't have it, add a couple grounding straps from the front panel to the chassis.
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Post by jeromemason on Oct 6, 2014 12:15:25 GMT -6
If you do that, you might want to add a grid bleed resistor to keep the cap from charging up. it'll keep the cap DC referenced so that it's not just floating. Anyway, it's also common on these amps that when the input jacks aren't grounded well enough to the front plates, and the front plates aren't grounded well enough to the chassis, that you'll get some DC charging. I'd pull the jacks and make sure you scrape/sand some of the metal clean and then install the jacks again. Also, if it doesn't have it, add a couple grounding straps from the front panel to the chassis. What value on the resistor? 220k? Just strap it across the cap? |
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Post by svart on Oct 6, 2014 13:31:05 GMT -6
If you do that, you might want to add a grid bleed resistor to keep the cap from charging up. it'll keep the cap DC referenced so that it's not just floating. Anyway, it's also common on these amps that when the input jacks aren't grounded well enough to the front plates, and the front plates aren't grounded well enough to the chassis, that you'll get some DC charging. I'd pull the jacks and make sure you scrape/sand some of the metal clean and then install the jacks again. Also, if it doesn't have it, add a couple grounding straps from the front panel to the chassis. What value on the resistor? 220k? Just strap it across the cap? Nah, it goes from the grid to ground on the grid side of the cap. Like so:  The 1M resistor from grid to ground on the tube side of the 100nf input cap is a grid bleeder(AKA grid leak resistor). I'd say try 2M ohm and then maybe change the 1M ohm input Z resistor on the amp to 2M as well, that way your net input Z is still 1M, roughly. |
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Post by svart on Oct 11, 2014 23:10:31 GMT -6
How'd this turn out?
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Post by jeromemason on Oct 11, 2014 23:43:08 GMT -6
Great! Something was causing that 1/2 volt to feedback into the inputs, so I ended up having to put .047 caps on both the bright and normal channels. But, amp sounds great, is working like it was brand new again. I might order another small parts kit and rebuild the board and drop it in just so I don't have any more issues, but I will probably wait to drop it in after something else pops up. I'm not sure what's causing that voltage to get to the inputs, but the designer said it was the humidity and the fiber board and it just happens sometimes. After I replace the board I might put some silica caps in the head while I'm not using it. That would keep any moisture from getting into the fiber again.
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