rljones said:
Craig,
Last night I hooked up my APOX-2 to my dual-mono amp (separate L and R channels, just like monoblocks, but in one chassis).
I hooked up the SHIELD pin to the input GND for the right channel. The right channel was very quiet, but the left channel
had a noticeable hum. I removed this SHIELD connection, and
the hum was pretty much gone from both speakers, but there is more noise in the tweeters when I put my ear closer to the speakers. This noise was not there when I had the SHIELD pin connected.
I guess I am still confused as to properly use the SHIELD pin for my application. On my CDP, both the L and R RCA signal outputs share the same GND. On the input to each amp channel, the signal goes to the amp power supply GND via a 10R resistor.
After reading Robert's comments about connecting the signal GNDs to the 5V power supply GND to greatly reduce hum, I am
even more confused because this just ties the analog and digital
GNDs together, which I thought would cause more noise.
BTW, my +5V power supply for the APOX does not have an AC GND, just Live and Neutral on one side, and OUT+ and OUT- on the other side, which goes to the apox.
Any ideas?
Thanks for your help,
Vinnie
Robert, Vinnie,
The shield is not ment to be connected at more than one end, and as such will not contribute to anti-hum efforts (check out the other end -- there should be no connection between shield ends if you check out your XLR commercial cable)
The ground is the deal that lets you fix voltages together. This is usually (if not always) the origin of hum.
Grounding is not for the faint at heart. There should typically be one ground point ....
I am glad you got your unit unhummed, Robert.
[Digital and analog ground should be connected at some point. It does not matter if these are connected with a relatively high impedance/resistance, but they should definitely not be kept floating completely as static etc. can build up and eventually destroy things.]
Petter
The shield is not ment to be connected at more than one end, and as such will not contribute to anti-hum efforts (check out the other end -- there should be no connection between shield ends if you check out your XLR commercial cable)
The ground is the deal that lets you fix voltages together. This is usually (if not always) the origin of hum.
Grounding is not for the faint at heart. There should typically be one ground point ....
I am glad you got your unit unhummed, Robert.
[Digital and analog ground should be connected at some point. It does not matter if these are connected with a relatively high impedance/resistance, but they should definitely not be kept floating completely as static etc. can build up and eventually destroy things.]
Petter
dipchip said:
I put in the 2K current resistors that your parts list specifies. These strike me as pretty high. The board functions (at least it chatters when I turn the volume encoder) and the volume variable changes on the front panel.
I get a different 1R1 behavior when I disconect the APOX-1
Regarding the splash screen, I only have the 1R1 and the apox 1 hooked up right now. I'll be populating the 1s1's tonight, there may be something there with it not finding the input boards.
The power supply has enough chutzpa, it's a 10 amp bench supply. I'l pull my scope out now...
Sheldon
APOX-1 LED issue
I just went out to the bench and did a little probing of the APOX1 board with my scope. The 5 volt signals are there, I get the nice slow heartbeat one clearly. But no LED lighting. So the current limiting resistors are too high.
Hope this helps others too.
Sheldon
I just went out to the bench and did a little probing of the APOX1 board with my scope. The 5 volt signals are there, I get the nice slow heartbeat one clearly. But no LED lighting. So the current limiting resistors are too high.
Hope this helps others too.
Sheldon
Petter said:
Hi Petter,
There is only one SHIELD point on the APOX-2. I am using
RCA, not XLR. I don't know what you mean by
"The shield is not ment to be connected at more than one end, and as such will not contribute to anti-hum efforts (check out the other end -- there should be no connection between shield ends if you check out your XLR commercial cable)"
Based on my post above (cdp-->APOX-2-->dual-mono amp),
I don't know where to put the shield or the correct way to
do the grounding. Should the SHIELD go to the
Apox power GND? Should the L adn R (analog) signal GNDS be tied together? Should they be tied to the digital GND?
Thanks,
Vinnie
OK, I see what you mean now.
In balanced circuitry, you have the following connections:
Sig+
Sig-
Gnd
Shield (which is only connected on one end)
For single ended:
Live
Gnd (I assume you refer to this as shield)
I have not done as much work on the Apox 2 as the 1 and SHM, and have mostly looked at balanced operation. However ...
There are 2 grounds: one for right, the other for left. Hook up center pin of one channel to X1-1, the surronding ground to X1-2 etc.
On the output, hook up "center pin" to X2-1. You may hook up the ground pin to X1-2 OR X2-2. I suspect it will sound "better" on X1-2 ....
The shield does not seem to be on the schematic ..... so it is hard to say what you should do there. Craig/Dave?
Petter
BTW, consider soldering the wires in once you are happy with the layout instead of those large screw terminals.
In balanced circuitry, you have the following connections:
Sig+
Sig-
Gnd
Shield (which is only connected on one end)
For single ended:
Live
Gnd (I assume you refer to this as shield)
I have not done as much work on the Apox 2 as the 1 and SHM, and have mostly looked at balanced operation. However ...
There are 2 grounds: one for right, the other for left. Hook up center pin of one channel to X1-1, the surronding ground to X1-2 etc.
On the output, hook up "center pin" to X2-1. You may hook up the ground pin to X1-2 OR X2-2. I suspect it will sound "better" on X1-2 ....
The shield does not seem to be on the schematic ..... so it is hard to say what you should do there. Craig/Dave?
Petter
BTW, consider soldering the wires in once you are happy with the layout instead of those large screw terminals.
Sheldon,
Have you mounted the diode the right way? (not intended to sound like an insult)
Petter
Have you mounted the diode the right way? (not intended to sound like an insult)
Petter
Petter said:
Hi Petter,
The shield IS in the schmatic, on the very top above the relay layout.
Please let me know what you think.
Thanks,
Vinnie
Yes, sorry about that -- they appear to be the shields of the individual relays. I would try connecting them to a ground. Now which one is a good question. If you hook it up to the input grounds, you need to shorten the grounds between channels. This is probably not a big deal, except if you truly need to have completely separated channels (means separated power supplies etc.). In balanced operation, this all becomes a mute point of course.
It is still not quite clear to me what this ground pin is connecting to (external plane?) so I am at a loss. I thing a look at the board is required. From memory, I seem to recall this was probably left open and needs to be hooked up to something. What sounds best is another matter.
Now I see a few different things to try (for sound):
1. Leave shield open, as long as it is connected to something
2. Connect shield to digital ground (not recommended either)
3. Connect shield to one of the input grounds (single ended)
4. Connect shield to both of the input grounds (single ended).
5. Any of the above could even be done with resistors or ferrite beads.
I don't know what is best. My guess is that it has to be tried out.
Petter
It is still not quite clear to me what this ground pin is connecting to (external plane?) so I am at a loss. I thing a look at the board is required. From memory, I seem to recall this was probably left open and needs to be hooked up to something. What sounds best is another matter.
Now I see a few different things to try (for sound):
1. Leave shield open, as long as it is connected to something
2. Connect shield to digital ground (not recommended either)
3. Connect shield to one of the input grounds (single ended)
4. Connect shield to both of the input grounds (single ended).
5. Any of the above could even be done with resistors or ferrite beads.
I don't know what is best. My guess is that it has to be tried out.
Petter
Dale/Craig,
I too have a probelm with an LED on the IS1 board. I'm fairly certain it was wired correctly but the LED fails to light. I reversed it twice and still a no go. (It may be a bad LED, I'll try another; I got too busy with the hum stuff.) The board itself makes switching noises, so I'm sure it's working OK.
As for the ground wire on the APOX-2, this should be a standard correction, possibly for all of the input boards (I'm not sure how Petter laid out the APOX-SHM). The hum is probably being generated by the difference in potential of the input signal ground and the 'floating' digital ground.
____
I've now got to build up more boards. My chassis for the 6-channel surround will be a stack of three 75mm tall chassis that are screwed together. The bottom will contain display and power supplies; the middle section, 5 APOX-2 and 7 APOX-IS1 boards; and the top unit, the audio preamp circuitry. There will be 8 XLR inputs for L/R, 4 XLR inputs for C and surrounds. Power and I2C lines will go through internal holes from the bottom to upper chassis. I'll then make a front panel that will cover all 3 units making is look like a single unit from the front. (Hopefully, a side benefit of this design is fairly complete shielding for each section.)
I'll try to get some preliminary images up. The part I dislike is all of the holes I need to drill for all of the balanced inputs...
Regards, Robert
I too have a probelm with an LED on the IS1 board. I'm fairly certain it was wired correctly but the LED fails to light. I reversed it twice and still a no go. (It may be a bad LED, I'll try another; I got too busy with the hum stuff.) The board itself makes switching noises, so I'm sure it's working OK.
As for the ground wire on the APOX-2, this should be a standard correction, possibly for all of the input boards (I'm not sure how Petter laid out the APOX-SHM). The hum is probably being generated by the difference in potential of the input signal ground and the 'floating' digital ground.
____
I've now got to build up more boards. My chassis for the 6-channel surround will be a stack of three 75mm tall chassis that are screwed together. The bottom will contain display and power supplies; the middle section, 5 APOX-2 and 7 APOX-IS1 boards; and the top unit, the audio preamp circuitry. There will be 8 XLR inputs for L/R, 4 XLR inputs for C and surrounds. Power and I2C lines will go through internal holes from the bottom to upper chassis. I'll then make a front panel that will cover all 3 units making is look like a single unit from the front. (Hopefully, a side benefit of this design is fairly complete shielding for each section.)
I'll try to get some preliminary images up. The part I dislike is all of the holes I need to drill for all of the balanced inputs...
Regards, Robert
Petter said:
I have it in the right way, I've tried it both ways. I'm sure it's the 2K current limiting resistors. That's only allowing about 100 - 150 uA to the diodes. I'd need a photomultiplier tube to see the radiation coming out of that LED.
rljones-
I'm getting ready to build my 1S1's tongiht, but it sounds a lot like my current problem, which is the resistors which drive the LED's are too big.
Sheldon
LED update
OK, the 2K resistors are fine for some LED's. I can't make the two with my APOX-1 board light up on my bench. I swapped out the two with a couple from my "personal stock" and they are blinking nicely.
I think there may be some bum LED's in these kits. I'll be building my pair of 1S1's tongiht and we'll see how those LED's fare.
Sheldon
OK, the 2K resistors are fine for some LED's. I can't make the two with my APOX-1 board light up on my bench. I swapped out the two with a couple from my "personal stock" and they are blinking nicely.
I think there may be some bum LED's in these kits. I'll be building my pair of 1S1's tongiht and we'll see how those LED's fare.
Sheldon
LEDS and Display
Seems hard to believe that LEDS would be DOA.
Craig and I debated whether or not to include the LEDS/resistors in the first place. We decided that they may be an aid to debug (assuming that they are not the cause of failure). The LEDS are not required and some may argue that having them is a bad thing anyways.
If anyone has some bum leds and wants replacements, let us know. The chattering of relays and a multimeter is the better way to debug anyways.
Sheldon,
Did you enable the standby mode? If so, try disabling and then power cycle your IR1 board. Does the splash work ok?
Have you downloaded the latest software for the IR1 board? There was a problem with the initial display if standby mode is enabled.
Let me know...
Thanks,
Dale
Seems hard to believe that LEDS would be DOA.
Craig and I debated whether or not to include the LEDS/resistors in the first place. We decided that they may be an aid to debug (assuming that they are not the cause of failure). The LEDS are not required and some may argue that having them is a bad thing anyways.
If anyone has some bum leds and wants replacements, let us know. The chattering of relays and a multimeter is the better way to debug anyways.
Sheldon,
Did you enable the standby mode? If so, try disabling and then power cycle your IR1 board. Does the splash work ok?
Have you downloaded the latest software for the IR1 board? There was a problem with the initial display if standby mode is enabled.
Let me know...
Thanks,
Dale
my preliminary look at your instructions seems to have found the LED flaw. You are suggesting:
13. Place LED1 with the longer lead away from R16, as viewed from the top of the board
That makes the longer lead (which is the cathode) at a higher potential than the anode and the LED is acting like a diode. The cathode should be at ground (closer to R16) forit to light up. When I tried to switch my LED's, they wouldn't work, I've never seen a case where I could burn out an LED like that, but the ones on my apox board and the 1s1 board were toast. When put in properly, they work fine.
I'm going to go burn some new firmware into my controller board.
another error:
In my APOX1 resistor kit, your parts list shows the pass resistors (in my 10K case, 100K, 8.25K & 15K) labeled incorrectly. R13 and R1 are repeated for two different resistor values. I used the spreadsheet and schematic to straighten it out.
Thanks for the help.
Sheldon
13. Place LED1 with the longer lead away from R16, as viewed from the top of the board
That makes the longer lead (which is the cathode) at a higher potential than the anode and the LED is acting like a diode. The cathode should be at ground (closer to R16) forit to light up. When I tried to switch my LED's, they wouldn't work, I've never seen a case where I could burn out an LED like that, but the ones on my apox board and the 1s1 board were toast. When put in properly, they work fine.
I'm going to go burn some new firmware into my controller board.
another error:
In my APOX1 resistor kit, your parts list shows the pass resistors (in my 10K case, 100K, 8.25K & 15K) labeled incorrectly. R13 and R1 are repeated for two different resistor values. I used the spreadsheet and schematic to straighten it out.
Thanks for the help.
Sheldon
I think I've gotten my cathode and anode verbage wrong in the above post, but the point is the same, I think the longer leg needs to face TOWARD R16
Sheldon
Sheldon
Re: LEDS and Display
The splash screen works fine when power cycling without standby mode. However I still have the problem of no splash when first powering up with standby enabled. (it's not a big deal for my application, but something to work out I suppose)
I downloaded the latest firmware (the one on your web site) and downloaded it into the uP. I still have the same splash screen problem, the volume board now goes to zero when I put the unit in standby. but the volume is always zero when I bring it back out of standby, regardless of the setting for "last volume"
I'm making myself a nuisance with all the posts, sorry all... I hope you all find some of my pitfalls useful to avoid.
Sheldon
harvardian said:
The splash screen works fine when power cycling without standby mode. However I still have the problem of no splash when first powering up with standby enabled. (it's not a big deal for my application, but something to work out I suppose)
I downloaded the latest firmware (the one on your web site) and downloaded it into the uP. I still have the same splash screen problem, the volume board now goes to zero when I put the unit in standby. but the volume is always zero when I bring it back out of standby, regardless of the setting for "last volume"
I'm making myself a nuisance with all the posts, sorry all... I hope you all find some of my pitfalls useful to avoid.
Sheldon
Sheldon,
I think the instructions for LED placement was only for APOX-2 and IR-1, not APOX-1. I know they definitely work for the first two. Maybe next round of boards should have a polarity marking on the mask.
The anode (longer lead) is typically facing the positive power supply. With a 5V supply and a 2k resistor, the current will be about 2.5 mA which is pretty typical for an LED (5/2,000 amps). You could increase the resistor to 10k if you want a less bright LED. Reversing an LED at low voltage (with an in-line resistor) almost never ruins it; momentarily sticking one on a 9V battery will kill it instantly.
regards, robert
I think the instructions for LED placement was only for APOX-2 and IR-1, not APOX-1. I know they definitely work for the first two. Maybe next round of boards should have a polarity marking on the mask.
The anode (longer lead) is typically facing the positive power supply. With a 5V supply and a 2k resistor, the current will be about 2.5 mA which is pretty typical for an LED (5/2,000 amps). You could increase the resistor to 10k if you want a less bright LED. Reversing an LED at low voltage (with an in-line resistor) almost never ruins it; momentarily sticking one on a 9V battery will kill it instantly.
regards, robert
Re: Re: LEDS and Display
Dale, last night I downloaded the latest firmware for the IR-1
and now when I put the unit in standby, and then turn it
back on, I don't get the splash screen. The firmware that
I downloaded a few weeks ago didn't have this problem.
No big deal for now, but let me know when this is updated and
I'll give it a try. It's a real easy process to download, and only
takes a minute.
Criag,
Do you have any ideas for shield/gnding in response to a
few of my posts yesterday. I'm going to try and get to the
bottom of this once and for all tonight.
BTW, does anyone have the COTO part number for the
relays used in the apox-2? I want to take a look at the
datasheets to learn more about the shield.
Thanks!
Vinnie
stokessd said:
Dale, last night I downloaded the latest firmware for the IR-1
and now when I put the unit in standby, and then turn it
back on, I don't get the splash screen. The firmware that
I downloaded a few weeks ago didn't have this problem.
No big deal for now, but let me know when this is updated and
I'll give it a try. It's a real easy process to download, and only
takes a minute.
Criag,
Do you have any ideas for shield/gnding in response to a
few of my posts yesterday. I'm going to try and get to the
bottom of this once and for all tonight.
BTW, does anyone have the COTO part number for the
relays used in the apox-2? I want to take a look at the
datasheets to learn more about the shield.
Thanks!
Vinnie
Hi Vinnie, Sheldon,
I just looked over the software and found the mistake. I will fix and post later today.
If I have time, I will also add the IR selection to disable Sony or Philips modes.
Dale
I just looked over the software and found the mistake. I will fix and post later today.
If I have time, I will also add the IR selection to disable Sony or Philips modes.
Dale
rljones said:
I know, I've never seen a problem like that. I have three LED's from the kit that I can't make light up after having them installed backwards through the 2K resistors (they would be acting like a diode and drawing 2.15 mA of current). I even put them on my solderless breadboard with a 470 ohm resistor and a bench supply.
Sheldon
- Status
- Not open for further replies.