Help with Glitch
I finally got my beta Kookaburra powered up today. It surprisely came up right away and works great. But I have a strange glitch I need to debug. While the preamp seems to work great and sounds very nice, there is a periodic glitch every 10 seconds or so of static that interrupts the music. It's very periodic and won't let up. Not sure where to look as I have not bee closely following this thread.
Has their been any code or design changes since the original beta kits went out?
Any clues on what might be causing it? I'm using a cheap Cybmax DVD player with the Mauro Penasa amp. All driving some Advent 2's I got awhile back on ebay. Nice sounds, but the glitch is driving me crazy.
Thanks for any suggestions.
I'm going to try to attach a pix showing my small little chassis. All parts used were from a complete parts kit from Russ/Brian. Including the little Amveco tranny.
Tommytube
I finally got my beta Kookaburra powered up today. It surprisely came up right away and works great. But I have a strange glitch I need to debug. While the preamp seems to work great and sounds very nice, there is a periodic glitch every 10 seconds or so of static that interrupts the music. It's very periodic and won't let up. Not sure where to look as I have not bee closely following this thread.
Has their been any code or design changes since the original beta kits went out?
Any clues on what might be causing it? I'm using a cheap Cybmax DVD player with the Mauro Penasa amp. All driving some Advent 2's I got awhile back on ebay. Nice sounds, but the glitch is driving me crazy.
Thanks for any suggestions.
I'm going to try to attach a pix showing my small little chassis. All parts used were from a complete parts kit from Russ/Brian. Including the little Amveco tranny.
Tommytube
Re: Help with Glitch
Hi Tommy,
There have not been any code changes since then as far as I can remember(is it new years eve and I have a pretty good buzz on). I am thinking over your problem, but honestly my first thought is that it is something outside the pre, Try this as a test. Short the inputs and see if the 10 second glitch continues.
Happy new years!!!
I am sure we can get this thing sounding right as rain.
Cheers!!!
Russ
tommytube said:
Hi Tommy,
There have not been any code changes since then as far as I can remember(is it new years eve and I have a pretty good buzz on). I am thinking over your problem, but honestly my first thought is that it is something outside the pre, Try this as a test. Short the inputs and see if the 10 second glitch continues.
Happy new years!!! I am sure we can get this thing sounding right as rain.
Cheers!!!
Russ
Happy New Year
Grounded the preamp inputs and still detect the glitch. With a bunch of gain and amplifying just noise, it seems the signal cuts out or drops out two times quickly in a row and then 10 seconds (approx) passes before it happens again. If I turn off the preamp and leave the amp on it goes away. If I turn off the CD player or disconnect the cables and ground the conductors to the signal ground, it continues.
One thing I was wondering about is if you intended for the chassis ground on the AC plug to be used. I see that you have a bunch of circuitry grounds together, but I didn't connect that center pin on the incoming AC plug on the PC board. I ran a quick jumper from the AC signal ground (third pin on the plug), to that center pin and didn't hear a difference.
I'll try another amp tomorrow. It may be some feedback interaction between the pre and amp.
Happy New Year.
More pix of the kookaburra here:
http://www.tommytube.com/Kookaburra.htm
Grounded the preamp inputs and still detect the glitch. With a bunch of gain and amplifying just noise, it seems the signal cuts out or drops out two times quickly in a row and then 10 seconds (approx) passes before it happens again. If I turn off the preamp and leave the amp on it goes away. If I turn off the CD player or disconnect the cables and ground the conductors to the signal ground, it continues.
One thing I was wondering about is if you intended for the chassis ground on the AC plug to be used. I see that you have a bunch of circuitry grounds together, but I didn't connect that center pin on the incoming AC plug on the PC board. I ran a quick jumper from the AC signal ground (third pin on the plug), to that center pin and didn't hear a difference.
I'll try another amp tomorrow. It may be some feedback interaction between the pre and amp.
Happy New Year.
More pix of the kookaburra here:
http://www.tommytube.com/Kookaburra.htm
Hi Tommy, I must admit I am a bit stumped at your problem. I have never witnessed this type of beaviour before. One thing that comes to mind is that I put a current limiting resistor on the pop preventing relay to keep in running cool. one thing to check would be if that relay is switching on its own (it should only switch on turn on (after about a few houndredths secocond delay) and turn off (nearly immediate). If the you hear the relay clicking when it shouldn't be try replacing the resistor which feeds the relay with a jumper (you could actually just solder a temporary jumper across the resistor).
Other then the above suggestion I would really have to start focusing on the PCB itself by looking for cold joints or solder bridges. Maybe a close up shot of the bottom of the PCB? That would help me see if there might be a problem there.
Try the relay fix first.
The kooka and the MyRef are a good match, I have been using them together frequently. There is no problem using them together,
As for the mains GND you can attach that to the case, but keep it isolated from the circuit to avoid ground loops and other nasty transient issues.
Cheers!<----- black coffee
Russ
Other then the above suggestion I would really have to start focusing on the PCB itself by looking for cold joints or solder bridges. Maybe a close up shot of the bottom of the PCB? That would help me see if there might be a problem there.
Try the relay fix first.
The kooka and the MyRef are a good match, I have been using them together frequently. There is no problem using them together,
As for the mains GND you can attach that to the case, but keep it isolated from the circuit to avoid ground loops and other nasty transient issues.
Cheers!
<----- black coffeeRuss
My gremlins are still present
I swapped the preamp over to my big rig and got the same sort of periodic dropouts/distortions as before. This was into some CJ Premier 12 monoblocks. So the problem definitely followed the preamp into my main system.
I took out the PCB and did a jumper around the resistor Russ was talking about near the OMRON relay. This killed the sound completely. Not sure if I created any shorts by adding this jumper to the power plane. THere isn't a whole lot of keepout area around the pins not attached to the ground plane. Perhaps I've got a pin shorted to the ground plane and can't find it yet.
I did resolder all around the relay and the power input portion of the board and still have the problem.
I'm attaching a pix of the bottom side of the board.
BTW, I'd love a legible schematic that shows all the parts including the relay. So far all I've seen in schematics aren't very high resolution and when you zoom in on them, they break up and don't have much detail. I'm assuming your draw the schematic up with your PCB tool set.
Anyway any suggestions would be appreciated.
thanks,
Tom
I swapped the preamp over to my big rig and got the same sort of periodic dropouts/distortions as before. This was into some CJ Premier 12 monoblocks. So the problem definitely followed the preamp into my main system.
I took out the PCB and did a jumper around the resistor Russ was talking about near the OMRON relay. This killed the sound completely. Not sure if I created any shorts by adding this jumper to the power plane. THere isn't a whole lot of keepout area around the pins not attached to the ground plane. Perhaps I've got a pin shorted to the ground plane and can't find it yet.
I did resolder all around the relay and the power input portion of the board and still have the problem.
I'm attaching a pix of the bottom side of the board.
BTW, I'd love a legible schematic that shows all the parts including the relay. So far all I've seen in schematics aren't very high resolution and when you zoom in on them, they break up and don't have much detail. I'm assuming your draw the schematic up with your PCB tool set.
Anyway any suggestions would be appreciated.
thanks,
Tom
Attachments
My PGA2311 Board
Hi Russ,
I just wanted to post a photo of my PGA2311 board to show you what you have inspired. I used a pic 16F88 as a controller. Right now it's set up for push button control, but I plan on modifying the code a bit to A/D convert values from a pot, translate and send the data to the PGA2311. This will give me enough free pins on the uC to hook up an input selector board which I am working on. As you can see I have the PIC outputing the volume info to a 4 line LCD, eventually it will be displaying input info as well. The output from the PGA2311 right now just goes to a pair of jacks for testing putposes, but soon it will be connected to my OPA627/buf634 preamp.
Thanks again for the inspiration.
G.
Hi Russ,
I just wanted to post a photo of my PGA2311 board to show you what you have inspired. I used a pic 16F88 as a controller. Right now it's set up for push button control, but I plan on modifying the code a bit to A/D convert values from a pot, translate and send the data to the PGA2311. This will give me enough free pins on the uC to hook up an input selector board which I am working on. As you can see I have the PIC outputing the volume info to a 4 line LCD, eventually it will be displaying input info as well. The output from the PGA2311 right now just goes to a pair of jacks for testing putposes, but soon it will be connected to my OPA627/buf634 preamp.
Thanks again for the inspiration.
G.
Attachments
If it a cyclical issue it has to have something to do with a time constant.
ie cap charging / discharging, or something over heating / cooling.
Measure the voltage on your rails... +/ - 12 and +/- 5 and see if they fluctuate any. Also measure the AC from the trafo and see if it surges up or down.
ie cap charging / discharging, or something over heating / cooling.
Measure the voltage on your rails... +/ - 12 and +/- 5 and see if they fluctuate any. Also measure the AC from the trafo and see if it surges up or down.
I also made preamplifier module basing on PGA2310/11 from TI. PCB includes place for 2 chips, so balanced mode is available. What can I say… PGA2310 needs a good power supply (LT317/337 is OK if You like integrated one) and pre or buffer in some cases.
Features: optoisolation (analog from digital section), 2x16 display, input selector, IR pilot, encoder… Documentation is available on my www
Features: optoisolation (analog from digital section), 2x16 display, input selector, IR pilot, encoder… Documentation is available on my www
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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