Strange malfunctioning LED audio peak level meter problem

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

you cant fix them, you have to scrape them off the pads and solder tiny smd leds

Ok. I'm probably going to relocate this board and run jumper wires from it to individual wired-led's mounted into the plastic housing that mounts to the cassette player's face.

My understanding is that 1 signal goes to one side (let's called it "+" side) of the 1st, 4th, 7th, and 10th led's of both top and bottom rows. Now the other side (let's call it "-" side) of the 1st led goes to the + side of 2nd led. The - side of 2nd led goes to + side of 3rd led. The - side of 3rd led goes back to the IC. This same scenario is repeated for all the groups of 3 led's. There are 4 sets of 3 led groups on each row.

Can someone recommend wired-led's? I'll need some green, amber/yellow and red. They should fit into the plastic housing.

[budm]

Re: Strange malfunctioning LED audio peak level meter problem

You can test each LED as suggested, and also use high power magnifying glass each bonding wire of the LED.
I also see strange trace layouts.
I am also surprised that exposed bonding and die last this long, but since they cannot put black blob on top like they did for the IC since they are LED, they could have put on clear sealer instead on the LED's.

[stj]

Re: Strange malfunctioning LED audio peak level meter problem

you cant fix them, you have to scrape them off the pads and solder tiny smd leds

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

Pic

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

pics

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

So I can see the microscopic wires and pads dislodged from the led's. Thanks! Now...how to reaffix them? Its insanely small.

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

Veho Discovery vms-004 usb microscope

Worked years ago on old laptop I had. Windows 10 doesn't have a driver

Read a review on amazon ao got it to work with my camera app!

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

so what computer are you using now?
i cant believe you cam a HID/cam device that wont just work in Linux or other windows versions.

the wires are bond leads made of gold and welded at each end.

Veho Discovery vms-004 usb microscope

Worked years ago on old laptop I had. Windows 10 doesn't have a driver

[stj]

Re: Strange malfunctioning LED audio peak level meter problem

so what computer are you using now?
i cant believe you cam a HID/cam device that wont just work in Linux or other windows versions.

the wires are bond leads made of gold and welded at each end.

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

well you probably need to replace the lot - so the brightness matches

i would be tempted to build a new one possibly using a chinese vu meter module as a base and making a new led board to match the original spacings.

Thanks. The more I look at it, the micro sized led's would be beyond my capabilities. Still looking for an old windows 7 pc to use my microscope. Lol

From what I can see with limited magnification it appears that there are tiny single strand wires coming off of the leds!!

[stj]

Re: Strange malfunctioning LED audio peak level meter problem

well you probably need to replace the lot - so the brightness matches

i would be tempted to build a new one possibly using a chinese vu meter module as a base and making a new led board to match the original spacings.

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

The led's are the size of a grain of salt. I touched a couple and they went out too. I'm going to have to find an old computer running windows 7 so I can use the only usb microscope I have (Veho Discovery VMS004).

[stj]

Re: Strange malfunctioning LED audio peak level meter problem

you can use the testpoints either with another led or a multimeter on diode-test

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

Cover came off easily after I used a razor blade to slice the white plastic tabs off the back.

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

Did you try flexing the board while power up with signal so you can see flexing will cause the LED's to come and go?
https://www.badcaps.net/forum/attach...3&d=1597194394
Those white plastic dots look to holding the LED assembly to make contact with the PCB.

I tried flexing it. No joy.

[budm]

Re: Strange malfunctioning LED audio peak level meter problem

https://www.badcaps.net/forum/attach...1&d=1597194394
I wonder what you will see if you look straight from the side view.

[redwire]

Re: Strange malfunctioning LED audio peak level meter problem

What I have done when desperate to repair vintage gear is VERY CAREFULLY remove the LED diffuser assembly to access the naked LED's on the PC board. This means cutting/remelting or removing the six plastic pins and pulling off the LED diffuser straight up. If you slide it sideways it will kill all LED's by shearing off the bonding wires. I expect raw LED dies on the PC board with a tiny bonding wire.
You could also just carefully peel off the diffuser overlay to see what's inside.

I would solder in 0603 LED's to replace the defective ones.

edit: to get troubleshoot kind of displays to work in the shop we used freeze spray drops on an LED. I think they get a bad connection to the die, the bonding wire doesn't quite work.

[budm]

Re: Strange malfunctioning LED audio peak level meter problem

Did you try flexing the board while power up with signal so you can see flexing will cause the LED's to come and go?
https://www.badcaps.net/forum/attach...3&d=1597194394
Those white plastic dots look to holding the LED assembly to make contact with the PCB.

[JimBanville]

Re: Strange malfunctioning LED audio peak level meter problem

Yep, one of those encapsulated (Black blob) IC on PCB.
It looks like the LED's pins are mated to the PCB using pressure to make contact with the PCB pads.
If you flex the board you may see the LED come and go.

So what do u think I should do next? IC problem? Dead LED's? Bad led connections?

[budm]

Re: Strange malfunctioning LED audio peak level meter problem

Yep, one of those encapsulated (Black blob) IC on PCB.
It looks like the LED's pins are mated to the PCB using pressure to make contact with the PCB pads.
If you flex the board you may see the LED come and go.