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Old 9th March 2013, 05:32 PM   #5001
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Quote:
Originally Posted by udailey View Post
The "schematic"/drawing I posted years ago that you show is correct. It was made for folks who have trouble with schematics. The Lightspeed is often a first project. If you rewire anything please use your thinnest wire to be kind to the pots and ldrs. Heat is bad for both and thick wires take more heat. Please make sure the ldr dots are going to negative/0V. Also make sure that the ldr long/round leads go to signal and short/flat go to power. These are often the reason for thin sound because the ldrs are at megohms.
I didn't know that drawing was yours - it's great for simpletons like me

I'm using the thinest wire I could find. I'll check the ldrs as above.

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Old 10th March 2013, 03:27 PM   #5002
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here's some more pics of the board - I hope i done this right:

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underside of board - all ldr dots go to neg/0V, long leads to signal, and shorts leads to resistors/power, i hope!

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topside of board

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sorry, not a great photo. dual pot/volume works now - it was back to front - low was high - so i reversed the wiring. still low volume output though and trimmers ineffectual for some reason.

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Old 10th March 2013, 03:53 PM   #5003
udailey is offline udailey  United States
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I dont see a problem unfortunately. Doesnt mean I didnt miss it though.
On your Lin Lout LDRs you have wires crossed. The LDRs are not directional on the resistive side. I wonder if you have a short between some wires and have all signal from that channel going directly to ground because of the short. The short would be the crossing of the wires. Have you tested both channels?
1k trimmers do make a mild change but not much. I use a 5k pot.
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Old 10th March 2013, 04:36 PM   #5004
udailey is offline udailey  United States
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Also, use your dmm. Power off the lightspeed and measure resistance across the trimmer pots. Turn them and see if it changes. Do the same on both gangs of the volume pot.
If you get varying resistance when you turn each pot then nevermind but if it stays the same or doesnt measure then you might have found your problem. If it varies then keep the lightspeed off and measure from the 5V input at the case to the positive side of the LDR and see if you have a resistance of about 100k or less. Do it on all 4. This shows that power can in fact get from point A to point B to power on your LDR. Then the same test from the negative side of the LDR to the 0V power plug. Also measure from the 5V side of the plug to the chassis to make sure you dont have some short somehow. Measure from 5V to 0V and look for a short there as well.
Some DC power supplies have the middle pin be ground and the outer casing be positive and some are the other way around. It usually shows which is which on the wallwart itself. Might want to confirm that the positive voltage is in fact coming from where you expected it to. Also sometimes those jacks LOOK like their pin goes to the center of the plug and the other pin goes to the casing of the plug and in fact its sometimes the other way around so try somehow to check both. Or, I suppose just plug it in, turn it on and confirm that positive is positive. You can do this with your DMM or just an LED and a resistor.
The other thing I was thinking is that you should turn it on and measure the LDR resistance with your multimeter. We need to know that you are somewhere in the 0-20k range or maybe even a bit higher and that this number changes as you move the volume pot. Check on all 4 LDRs. If it varies then we know the LDR works and is wired correctly.
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Last edited by udailey; 10th March 2013 at 04:39 PM.
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Old 10th March 2013, 05:02 PM   #5005
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Quote:
Originally Posted by udailey View Post
I dont see a problem unfortunately. Doesnt mean I didnt miss it though.
On your Lin Lout LDRs you have wires crossed. The LDRs are not directional on the resistive side. I wonder if you have a short between some wires and have all signal from that channel going directly to ground because of the short. The short would be the crossing of the wires. Have you tested both channels?
1k trimmers do make a mild change but not much. I use a 5k pot.
thanks. yes, i wondered about crossing the ldr wires - that's the first time i tried that. thin, weedy sound could be a problem with grounding perhaps. I'll try splitting them.
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Old 10th March 2013, 05:06 PM   #5006
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Quote:
Originally Posted by udailey View Post
Also, use your dmm. Power off the lightspeed and measure resistance across the trimmer pots. Turn them and see if it changes. Do the same on both gangs of the volume pot.
If you get varying resistance when you turn each pot then nevermind but if it stays the same or doesnt measure then you might have found your problem. If it varies then keep the lightspeed off and measure from the 5V input at the case to the positive side of the LDR and see if you have a resistance of about 100k or less. Do it on all 4. This shows that power can in fact get from point A to point B to power on your LDR. Then the same test from the negative side of the LDR to the 0V power plug. Also measure from the 5V side of the plug to the chassis to make sure you dont have some short somehow. Measure from 5V to 0V and look for a short there as well.
Some DC power supplies have the middle pin be ground and the outer casing be positive and some are the other way around. It usually shows which is which on the wallwart itself. Might want to confirm that the positive voltage is in fact coming from where you expected it to. Also sometimes those jacks LOOK like their pin goes to the center of the plug and the other pin goes to the casing of the plug and in fact its sometimes the other way around so try somehow to check both. Or, I suppose just plug it in, turn it on and confirm that positive is positive. You can do this with your DMM or just an LED and a resistor.
The other thing I was thinking is that you should turn it on and measure the LDR resistance with your multimeter. We need to know that you are somewhere in the 0-20k range or maybe even a bit higher and that this number changes as you move the volume pot. Check on all 4 LDRs. If it varies then we know the LDR works and is wired correctly.
thanks, i'll get on to that.
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Old 10th March 2013, 06:36 PM   #5007
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Quote:
Originally Posted by udailey View Post
I dont see a problem unfortunately. Doesnt mean I didnt miss it though.
On your Lin Lout LDRs you have wires crossed. The LDRs are not directional on the resistive side. I wonder if you have a short between some wires and have all signal from that channel going directly to ground because of the short. The short would be the crossing of the wires. Have you tested both channels?
1k trimmers do make a mild change but not much. I use a 5k pot.
Uriah, I think you uncovered the problem with the crossed legs. Success at last! But at the moment only the right channel - volume pot and trimmer working very well, sounds awesome. Nothing from the left channel. Guess I need to recheck my joints?

P
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Old 10th March 2013, 11:53 PM   #5008
udailey is offline udailey  United States
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On left channel with power on check LDR resistance. Does it vary with volume pot?
If resistance is huge, like megohms, then you need to see if you even have voltage getting to the LDRs on the left channel. Do put the DMM on DCV and put one lead on 0V. The other pokes around from the positive side of the LDR (should be near 2V), then the PSU side of the trimmer and the trimmer side of the 100R resistor. At least this would give you a starting point. Do this before reheating the LDRs solder joints. Reheating is last resort.
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Old 11th March 2013, 01:49 PM   #5009
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Originally Posted by udailey View Post
On left channel with power on check LDR resistance. Does it vary with volume pot?
do i measure across the short leads / LED portion?

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Old 11th March 2013, 04:21 PM   #5010
udailey is offline udailey  United States
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No. You want to measure the resistive portion. The two LDRs create a voltage divider and by dividing the voltage of the signal you increase or decrease the volume. Since you have a volume problem we can look at the resistance here and see if its directly associated with the ldrs. So use your dmm leads on the long leads of the LDR. One DMM lead on each LDR lead. Just measure one LDR at a time. I dont care what the measurements are as much as I care that they actually change when you change the volume pot.
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