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Messages - Bakeacake08

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1
Amplifier Discussion / Re: Frontman 15G Suddenly Died
« on: October 04, 2016, 04:03:55 PM »
I got him and occasionally some random radio station came it very clearly. That was fun.

I got him on the following pins:

U1: 2, 3, 6
U2: 2
U3: 3, 6
U4: 1

Guitar input and Aux inputs still functioning correctly.

2
Amplifier Discussion / Re: Frontman 15G Suddenly Died
« on: October 03, 2016, 07:45:09 PM »
The power cord leads tested fine. I partially reassembled it and both the guitar and Aux inputs played normally. The "Enzo Whacking" procedure did nothing to recreate the fault. I just thought to test the outlet I was using, but everything there looks normal as well. Where to next?

3
Amplifier Discussion / Re: Frontman 15G Suddenly Died
« on: October 03, 2016, 12:46:21 AM »
Well, one of my worst fears happened: I opened up the box and pulled the chassis and when I turned it on everything appears to be working normally again.  :) I haven't tried sound yet, but the LED is on and all voltages seem to be appropriate.

22.7
-22.7
15.7
-15.0

I'm not sure how else to test a zener, but CR11 and CR12 both acted like a normal diode on the DMM (as I [think] I should expect).

So where do I go from here? Count it as a fluke and put everything back together? Leave the chassis out and olug in my gear to try replicating the problem? I know I had the volume quite low (night time, so barely on), if that means anything to anyone. Awaiting further instructions.

4
Amplifier Discussion / Frontman 15G Suddenly Died
« on: October 02, 2016, 12:35:25 PM »
I have a Fromtman 15G I've been using as a practice amp (and live a couple times) for about a year and never had a problem with it. Last night I was playing on it with my phone plugged into the auxiliary input. I played for a few minutes and heard a kind of popping/scratchy noise, like you'd hear if you moved a bum cable the wrong way. It happened once for about a half second and ten went back to normal. Then give or ten minutes later it made the noise again and the amp *s!!t* down--no noise, LED off, like it was unplugged. I opened it up and checked the fuse and continuity on the switch. Both were good, so now I'm out of ideas.

In typing this out I realized I should check the transformer secondary and make sure the IEC plug is working. Assuming those are okay, where should I look next?

Schematic here:
http://www.thetubestore.com/lib/thetubestore/schematics/Fender/Fender-Frontman-15G-Schematic.pdf

5
Tubes and Hybrids / Re: Crackling noise from Peavey Valveking 100
« on: May 09, 2016, 09:38:01 PM »
"They don't make 'em like they used to," as they say. Of course, they also used to cover houses with lead-based paint, so I guess we might have to take the good with the bad? The good news is the the amp is all sewn up and ready to go home. After hearing Phatt's explanation and seeing the jack for myself, that's definitely where I'm going to start next time I come across (non-musical) funky noise coming from an amp. Thanks to everyone for your help!

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Tubes and Hybrids / Re: Crackling noise from Peavey Valveking 100
« on: May 08, 2016, 07:15:01 PM »
Sounds good! Where do I measure? I'm not familiar with how these jacks work mechanically.

7
Tubes and Hybrids / Re: Crackling noise from Peavey Valveking 100
« on: May 08, 2016, 06:10:01 PM »
Success? The amp was noisy on the other side of town where my buddy lives, so I knew it was something inside the amp. Turning all the knobs to zero made no change. I plugged into the FX send and nothing appeared on the second amp. When I plugged into the FX return, the noise went away. Then when I unplugged from the FX return the noise stayed away. So I'm thinking there was dust or something in the contacts that got knocked loose with the plug inserted. Is there anything further I should look for before returning the amp, or does that sound like a reasonable explanation?

8
Tubes and Hybrids / Re: Crackling noise from Peavey Valveking 100
« on: May 05, 2016, 01:32:09 PM »
I cleaned up the solder joints and put everything back together. It's still making that little popping noise. It sounds similar to the pops you might hear from a little bit of dust when listening to vinyl records. I tried tapping components/tubes to see if I could figure out the source, but no luck. Is this something I can fix or just the nature of large tube amps?

9
Tubes and Hybrids / Re: Crackling noise from Peavey Valveking 100
« on: February 15, 2016, 01:39:05 PM »
Oh right. That makes sense.

10
Tubes and Hybrids / Re: Crackling noise from Peavey Valveking 100
« on: February 15, 2016, 01:10:59 AM »
Finally had time to dig in and here is what I found. About half the solder joints look like they punched through when the amp fell over, so the obvious first step is to clean those up.


When this board was still connected to the circuit (with now power), I plugged in a cord to easily check the connections, and for some reason it was reading as having no resistance between the tip and the sleeve. It was the same for both output jacks, and again when I checked it on the actual solder connections. It was an open circuit after I pulled this little board off. What might cause this to happen? The outputs seemed to work fine when I last tested it, so I found that rather odd.



11
Tubes and Hybrids / Crackling noise from Peavey Valveking 100
« on: December 07, 2015, 12:57:22 AM »
My buddy asked me to repair his Peavey Valveking VK 100 amp head for him; he left the speaker cord in and the amp fell over, so now the jack needs to be replaced. He also asked me to try to figure out another issue he has been having since he's owned it (so before the damage), which is a sort of scratchy, crackling noise it makes. The noise is a little pop sorta like when you plug in a guitar cable while it's on. It's not very loud though, easily overpowered while playing. It does not come at regular intervals and can be anywhere from once every couple seconds to a couple every second. None of the pots seem to have an effect on it. It is considerably louder on the gain channel and faint (though still noticeable) on the clean channel. I tried hitting it a little to see if it was an obvious mechanical thing, but nothing changed. I played through the amp for about twenty minutes or so and afterward didn't notice it before I turned off the amp. I didn't have time to tell if it was totally gone or just taking a break. I haven't opened it up yet because I haven't had time to put together my light bulb limiter. Your thoughts?


Oh, and I have also had trouble finding a proper schematic for this amp. All my searches seem to point me towards either the Valveking combos or the new line of heads. Anyone know how to find one for this specific model?



12
Tubes and Hybrids / Re: New Build Power Amp IC
« on: November 05, 2015, 03:21:09 AM »
Its main purpose is educational--namely to see if I can get it to work. If successful, I'll probably build a cabinet and use it as a practice amp. I did already have a PCB designed for it, so that's good to hear. I'll definitely post results whenever I collect all my parts and throw it together.

13
Tubes and Hybrids / Re: New Build Power Amp IC
« on: November 02, 2015, 01:45:53 AM »
That sounds simple enough. In a normal tube circuit, the ground rail is connected to the earth safety ground. Are there any safety concerns with having it connect instead to the negative rail?


Here is the original circuit I'm working from. I am basically replacing everything after the n-channel JFET with either the lm1875 or lm3886. (I'm also probably going to take out the standby switch and take out one of the LEDs.)

14
Tubes and Hybrids / Re: New Build Power Amp IC
« on: November 01, 2015, 02:43:59 AM »
35 volts was available locally, so that's where that came from. I'm likely ordering online now, so anything' possible. I went with a single supply because the tube preamp. I couldn't figure out how to do a dual supply that wouldn't leave the tube voltage unreferenced to anything (which intuitively I assume is unstable/dangerous). Is there a way to mix in a tube on a dual supply? If there is, I like the lm3886 kits I've seen. Fairly inexpensive and all the hard parts done. If not, the lm1875 seems easier to veroboard for the single supply.

15
Tubes and Hybrids / Re: New Build Power Amp IC
« on: October 30, 2015, 04:15:51 AM »
Also, this is more of a SS question and I didn't realize I was in the hybrid section. Feel free to move it if needed.

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