Help... button lights issue

I'm trying to narrow down where the problem might be. The button lights are not lighting. This is even when I've got the knob-light board disconnected. Yes, I've checked to see that Hijack says Button illumination max.

Interesting thing. When I use my multitester to test continuity between the upper left wire of the top button LED (the place where I've soldered the knob-board activation wire) and ground, all four buttons light dimly just from the voltage from my multitester. So at least I know the LEDs are good. (Edit: This only happens when the player is plugged in.)

I get 5 DC volts testing between any point on the resistor pack (or any of the traces or test points or other nearby components it's connected to) and ground. I test about 550 ohms resistance between the common side of the resitor pack and any of the four resistor-side legs of the button LEDs. The solder points on the resistor pack and all LEDS seems fine.

Where else can I test?

Tony,
As you know... this has been a mess for me... but 550 ohms sounds really low. I'm using a 1K resistor pack per the parts list. I mean, low resistance isn't an issue but I'm wondering what is your resistor pack value? Can you check continuity between each side of the resistor pack and each leg of the LED's? This is what I did to make sure I had all of the legs on that side of the resistor pack soldered. I mean I know you're measuring from the common side, but it's best to make sure you have complete continuity along the line. Perhaps that 550 ohms is going back from ground through the LED and you're actually measuring the resistance across the LED

That's a couple things... The lighting up seems to point to a bad ground I would think. I mean, at least that is what it is in another circuit I am working on where the voltmeter triggers a ground situation and causes a switch to flip.

Oh really? That's a 1k pack?

So if I'm getting 550, that means... what... there's a bridge between two of the legs of the resistor pack?

I've tried touching up the solder joints on all the LED legs, that didn't seem to help. Not sure where else there might be a broken trace. That's a 4-layer board and things disappear inside pretty quickly.

Nasty, false, tricksy electronses.

The parts list say it's supposed to be a 1K... anything could have been installed, thoguh. What does it read as far as numbers? 103?

Can you use your voltmeter and measure across the leads of the LED? (This may not do anything... I can't remember). The voltmeter injects a small voltage to calculate the resistance. This should be enough to get a reading.

Please test on the LED side of the resistor pack with each leg to each terminal on the pack. You have to make sure there's continuity there (0 ohms). Maybe you did that and I'm not understanding you properly. If you have 5V going into the pack but do not have SOME voltage on the positive leg of the LED (which is also the terminals on the distributed side of the resistor pack) then there is a problem with the resistor pack. If you have voltage on the negative lead on the LED then there is a ground issue. Have you measured continuity from the negative leg to ground?

Can't read the numbers on the top of the resistor pack any more... but it always worked in the past so I assume it was the correct one. Measuring resistance across the LEDs reads nothing. With the player unplugged, measuring voltage across the LEDs (in one direction only of course) reads negative half a millivolt.

I have continuity between each of the legs of the resistor pack and the legs of the LEDs.

With the player plugged in, I measure 5 volts between ground and the common side of the resistor pack.

With the player plugged in, I measure 5 volts between ground and the LED side of the resistor pack.

(edit:) With the player plugged in, I measure 5 volts between ground and the resistor-pack-side leg of the top LED.

(edit:) With the player plugged in, I measure 2.75 volts between ground and the other (non-resistor-pack-side) leg of the top LED.

(edit:) There does not appear to be a short between any given leg of the resistor pack. Each of the four legs leading to each of the LEDs seems to be independent with not continuity between them. But I get continuity between the resistor pack legs and the LED legs in each of the four cases.

Quote:
Have you measured continuity from the negative leg to ground?

Which leg is the negative leg? The negative leg of what? Please tell me where to measure from, in as much descriptive detail as possible.