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Messages - paelgin

Honey Amp / Re: Got my kit!
May 03, 2021, 05:34:43 PM
I received mine today, and the box was smashed almost flat, split open on both ends, and had stickers that said "RECEIVED DAMAGED".  Apparently the only thing lost were any stickers, since I checked all components and they were all accounted for.  I would like a sticker!

I did not understand the note on the schematic that reads "For gain circuit, do not populate R0 and C0".

Phil from gorgeous Young Harris, Georgia, USA
Howdy all.  I bought a broken Peavey PV215D (powered speaker system with two 15" speakers and a quasi-3-way output) ("does not pass signal", but found it really out blows fuse) and searched for an electrical schematic for it.  Peavey had not responded to my request in a week, so I went deep-diving in the Internet.

Attached is the schematic I found and downloaded (for free, although it says "Buy it").  If there is a problem with posting this here, please let me know.

In troubleshooting the powered speaker amplifier, I found so far that the power supply is the initial problem.  I found the -VCC side had a shorted FMG22R (dual "fast-acting" diode with common anode in TO220 type package).  I have one on order so I can see what else is wrong, if anything.  One of the two diodes in that package is a total short, and with that device removed from the board, the power supply caps both build up resistance (where the one on the -VCC was always 0 ohms with the device in the circuit).

The amp uses what they call class D amplification, and for the 700 watt rated output, doesn't seem too robust, so it must be very efficient.  (I hope the Peavey watts are as loud as the Fender watts, lol).

I post this in case anyone else needs this and to give back to this forum for the help I've gotten.

Phil in gorgeous Young Harris, Georgia, USA
I'm in!  Thanks for the opportunity.

Now if I could just get a compressor added into the circuit! :cheesy: 

I wonder if I can stack with pedals...

Phil from gorgeous Young Harris, Georgia, USA
As suggested, I reached out to Behringer (The Tribe?) and received a reply:
"Dear Phil,
Thank you for your patience. We do not provide schematics.
We can offer a non-warranty repair for you, If you'd like to continue with service, we can start a claim for Non-Warranty repair. The charges are as follows:..."

So I replied and said that I had been told that but in these times I should try anyway.  I also said that I would not pay to repair it since I can do it myself but I need just the USB portion of the schematic.  Waiting for another reply.

I had sworn that I would never, ever buy a Behringer anything but I got carried away with this broken one at a good price.  My personal feeling of Behringer is that it is the Walmart of shopping, the Yugo of cars, the ... nevermind. 

Right to repair is a big issue in some cases, and Apple (and others including John Deere) are involved in lawsuits regarding some of this.  I just appreciate when a manufacturer cooperates with the end user, specifically on stuff out of warranty.  Fender and Peavey have been great to work with, while Mackie, Line 6 and now Behringer have stuck solid walls around their proprietary information (and not without cause but there should be limitations and exceptions).

Phil in gorgeous Young Harris, Georgia, USA
Schematics and Layouts / Re: 5th Gear Overdrive v3.0
April 16, 2020, 06:17:16 PM
Well, I just finished assembling and testing my building of this pedal.  My thought process about how to build it went through several different versions. Since I had this little box that I thought would work (boy it is really tight), I decided against my original plan for a perfboard construction.  I decided for point to point in free air.  Now all I have to do is insulate everything and fold it into the little box.  Here is a picture.

It really does have almost clean tones when the gain is dialed down.  And it gets really gritty when up!  I need to adjust the volume (output level) when I change the gain, but for testing, I just suffered...  Because I am mostly a rhythm guitarist, I probably won't use this full on, although for some boogie-woogie (Key to the Highway shuffle, for example) I might use it. Also attached is a voice memo converted to mp3 that I made while testing.

I think I will try this on my bass.  That might be pretty cool!

Thanks for posting the schematic and construction tips.  It's a fun little project.  I added an off-on switch since I got non-switching jacks although I think I could have gotten one that connects the -9 volt (ground) lead only when plugged in (but I was in too much of a hurry to research and think it through).

Phil in gorgeous Young Harris, Georgia, USA
Howdy Joe.  Thanks for the thought.  Originally, I had looked for any link that would get me to Behringer support and they all led to "the tribe".  This morning (April 15, 2020) I tried again but cannot connect to anything Behringer: all websites are down and clicking on any links (from Goggle for example) leave the browser just spinning with no results.

Regarding my repair, I got parts and installed the two resistors.  On the burnt one with no pads left, I scraped the traces down to copper on both sides, tinned them then soldered in the resistor on one end.  Then I added a short jumper wire (single strand from a 20 gauge stranded wire) by soldering it to the trace and then onto the top of the resistor.  I'll attach a picture. The resistors are inline with the plus/minus 15 volt rails fed to the two dual OpAmp chips (one for left, one for right) feeding the headphone jack.  Not ideal, but may be sufficient.  If I could not get that to work, I was going to run an axial 1/4 watt 47 ohm resistor between pin 8 and another chip pin 8.

When I reinstalled the power supply and turned it on, I carefully watched my Watts Up inline power meter. When the power went to 79 watts (compared to 24 watts before), I quickly turned it off, but not before a wisp of smoke came up from the solder flux left behind.  I decided to replace the two chips those resistors were "protecting". 

With the two inline 8-pin through-hole OpAmps replaced, I tested and found input power used was 24 watts again. While the headphones do work, the volume in the left channel is much lower than the right.  I found two more resistors out of spec inline with the left side output (supposed to be 47ohm, but are over 1k each.  The right side was not affected.  I wonder what happened to smoke the OpAmp (left side, but maybe both).

As before, the USB is two channels sent to the PC (Main Mix supposedly), but right now, both are incorrectly controlled by just the left channel.  I looked at the USB board but without a schematic and with no obvious trauma on the board, I did not know what else to look for.

Thanks again for the suggestion to try Behringer; I will try again.

Phil in gorgeous Young Harris, Georgia, USA

ps, I am not in love with this mixer.  The Design might be fine, but the components used (pots and switches, for example) are not impressive.  And the inputs are on the noisy side (to check for pot crackling on the channel strips, I just turned up the gain and heard the white noise while I spun the pots up and down and listened for crackling as an indication to apply DeOxit Fader Lube).
Howdy all (both of you who read these threads). Here is the picture showing the area of circuit board where I removed the two surface mounted resistors.  One had burnt the board before failing, and I don't know if I will need to wire a jumper or how I will attach a new resistor yet.

Once I get the parts (should be Tuesday), I will see what I can do.

Any comments or suggestions are welcome.

Phil in gorgeous Young Harris, Georgia, USA
Howdy all.  I need a schematic for the USB version of the Xenyx X1832 mixer.

I bought a broken Behringer Xenyx X1832USB mixer on Ebay and am cleaning and repairing it.  I have the schematic for the non-USB version, which I was hoping would be close enough.  That schematic is attached.

Alas, it is not sufficient and I need a schematic for the USB model.  In addition to gummed up pots and blown resistors (on the power for the Op Amps for the headphone for some reason), I discovered that the USB is sending left and right, but sadly both from the left channel.

The non-USB schematic that I have looks close enough (so far) to be usable in my repair of the headphone circuit. 

In my testing, I found that the headphone circuit was bad, but everything else worked, at least after spraying some of the pots and switches with Deoxit Fader lube.  [side note: I had heard about the loss of intentional weighted "drag" in the slide pots and that is true].

Once I get it off my phone, I will post a picture of the circuit board after removing two surface mount resistors (47 ohm). They were in line with the plus/minus rails going to the two preamps outputing to the headphone jack.  Something pulled a lot of current through them and I suspect that the two Op Amps (4580) are also toast (three on order now, along with several resistors and parts to make a "5th Gear Overdrive" pedal).

Phil in gorgeous Young Harris, Georgia

ps, the schematic of a different model of Behringer USB mixer might also work for my purposes.  I just need to see how the USB is driven.
Howdy all.  Attached is the PDF schematic of the Peavey PV6-USB mixer.  I am posting this as well as my journey, struggles and questions as I work to repair a broken mixer.

I have seen online comments regarding power supply for these older mixers: it is critical to note that the non-USB models require a 16 volt AC adapter, while the USB models require a 15 volt DC supply.  I will also post a picture showing the input requirements shown on the back of the mixers.

The mixer I am trying to fix had a serious power problem which blew the NCP3063 boost/buck/inverting converter surface mounted chip apart.  It was so bad that it burned the top layer of the board down to the fiberglass matting below (I think I have a picture; if so I will include it too).

My questions will start in my next post as I work with my meter to see why the mixer works but the USB does not.

Phil in gorgeous Young Harris, Georgia, USA

Got the parts, installed them in the PV8-USB and then tested the mixer.  Everything works as expected.

I did find that the USB operation had fooled me, since when I started testing, I did not see any signal going into my DAW from the mixer, but HP on the mixer allowed me to hear music playing from my DAW.  It turns out that the traffic is one-way at a time. Although it seems obvious now, if I set the switch to feed the Tape/USB into the mix or set the switch to feed the Tape/USB into the Ctrl/HP, I got the USB signal from the PC into the mixer, but no return signal. Once I unset those two switches, I got signal into my PC from the mixer.  In the schematic, I have not found any switching but it works.  I also tested one of my previously repaired PV6-USB, and the USB does work on the one that I thought was only one way.     

I went back into the board on the PV6-USB that has no USB function to see if I can repair that too.  I had to replace the +16vdc transistor (Q21) with a different model (spec'd model is obsolete) and I am not getting the +16 VDC rail to where I think it should be.  I think I will start a new thread and post the Schematic for the PV6-USB and ask questions there.

Thanks for letting me share, and for sharing so much on here. 

Phil in gorgeous Young Harris, Georgia, USA
Howdy.  I voted for Battery amp, since "Other" was not available (Looper Pedal?). 

Thanks for the diversion.

Phil in gorgeous Young Harris, Georgia
I have replaced the one open zero ohm SMD chip (jumper), three bad SMD resistors and seven of the SMD ICs (parts removed and locations circled in attached picture). 

I found two more ICs bad (circled in black, in the headphone and control room outputs).  I also found three more out-of-spec SMD resistors (4.7ohm, reading over 8 ohms each).  Two of the three 4.7 ohm resistors are spec'd for 1% tolerance, so I will get them all like that.

I expect parts to be delivered tomorrow and will try to get it done and working.

Phil in gorgeous Young Harris, Georgia, USA
Schematics and Layouts / Re: 5th Gear Overdrive v3.0
April 02, 2020, 10:55:50 PM
Thanks for the clarification. 

But, but, but... I don't know if I can afford that because that one Darlington transistor costs 45 cents each!  (Mouser, as of 4/2/2020).  lol

Of course shipping is $7.99, so I wish I had seen this yesterday (I ordered the 2nd round of parts for the Peavey mixer I am repairing), but I forgot to turn "Notify" on.  I'll see if I need more stuff once I get the known bad parts replaced.

Phil in gorgeous Young Harris, Georgia, USA
Schematics and Layouts / Re: 5th Gear Overdrive v3.0
March 29, 2020, 09:38:42 PM
Thanks for posting that. Looks cool, might try it.

Which diode is the LED and which is the 4148?

Can two general purpose NPN transistors be configured as the darlington, or does the sound depend on the characteristics of that particular transistor?

Phil in gorgeous Young Harris, Georgia, USA
Here is a picture from the repair in process.  I have removed the seven known-bad preamps using ChipQuik.  Here is a picture after removing one of the chips and cleaning with solder wick to remove the excess solder.  The chip is a 4565 in SMD form (square, 5mm per side) apparently (hopefully!) and I've got 10 on order (at less than the unit cost of $0.39 each at Mouser).

I will try to keep this thread updated as I progress.  The PV6USB models that I repaired were only broken in the power supply, so this is way out there for me.

Phil in gorgeous Young Harris, Georgia, USA