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Dash LEDs
Using resources here on the ROC I finally got around to LED back lighting for dash switches, etc.
There's nothing much to add to what others have discussed here, but there was a particular issue with the HVAC control center seems worthy of mentioning.
First, removing the control module from the dash panel is the only way to facilitate installing polarity conscience LEDs. Once the module is freed from the dash panel, getting the LEDs properly oriented in their sockets is fairly easy.
Second, the T4 designs I’ve seen – which is fairly limited – all seem to be constructed the same way: “chip” LEDs (probably) SMT placed on the emitter side with solder pads on the fixture side. Of the few I’ve inspected closely, the circuit wafer is NOT physically attached to the T4 housing. This construction technique relegates soldered joints and lead wires to perform both electrical and mechanical duties - holding the populated wafer in place. While not uncommon, that is certainly not a preferred assembly technique – BUT – we are talking about pretty cheap parts here, so as cost of assembly technique, this is understandable.
The reason this is important to know is: the wafer spins off the fixture very easily. Even when being very cautious.
Emitter side of the wafer:
![Yellow]()
Fixture side:
![Circle]()
The fixture itself:
![Circle Auto part]()
After popping the head off two, I decided the opening on the HVAC circuit card was a tad to narrow to accommodate dropping the wafers on these particular T4's into the opening, so out comes the mini rat tail file.
![Electronics Technology Electronic component Electronic device Electrical network]()
A couple of light passes created a smooth drop in opening. With all T4’s in place and properly oriented, the dash went back together.
About an hour after reassembly, I notice the fan speed control switches were not illuminating. Crud. It’ll hafta wait til next time the dash comes off. And so it did this last weekend.
Here’s what I found:
![Light Automotive lighting Headlamp Lighting Incandescent light bulb]()
![Door handle Photography Metal Bicycle part Macro photography]()
As you can see, the + & - leads came in contact with each other. Seems as though this should have popped the supply fuse, but it didn't. The resistor burned until it opened completely. I'm pretty sure this happened as I was working to find the right balance of filing just enough and experimenting with fit. Even with care placing and removing the fixture into the opening, the wafer ended up getting twisted - it was VERY easy to spin these things in the housing. So whatever you do, be careful!
If you find yourself with this issue, a few more notes that might prove helpful: I clamped the shop vac hose close by while filing just to keep debris from dropping into the opposite side of the circuit card. And, although there's plenty of room for this kind of work, be mindful of depth when passing the file into/out of the opening.
Using resources here on the ROC I finally got around to LED back lighting for dash switches, etc.
There's nothing much to add to what others have discussed here, but there was a particular issue with the HVAC control center seems worthy of mentioning.
First, removing the control module from the dash panel is the only way to facilitate installing polarity conscience LEDs. Once the module is freed from the dash panel, getting the LEDs properly oriented in their sockets is fairly easy.
Second, the T4 designs I’ve seen – which is fairly limited – all seem to be constructed the same way: “chip” LEDs (probably) SMT placed on the emitter side with solder pads on the fixture side. Of the few I’ve inspected closely, the circuit wafer is NOT physically attached to the T4 housing. This construction technique relegates soldered joints and lead wires to perform both electrical and mechanical duties - holding the populated wafer in place. While not uncommon, that is certainly not a preferred assembly technique – BUT – we are talking about pretty cheap parts here, so as cost of assembly technique, this is understandable.
The reason this is important to know is: the wafer spins off the fixture very easily. Even when being very cautious.
Emitter side of the wafer:
Fixture side:
The fixture itself:
After popping the head off two, I decided the opening on the HVAC circuit card was a tad to narrow to accommodate dropping the wafers on these particular T4's into the opening, so out comes the mini rat tail file.
A couple of light passes created a smooth drop in opening. With all T4’s in place and properly oriented, the dash went back together.
About an hour after reassembly, I notice the fan speed control switches were not illuminating. Crud. It’ll hafta wait til next time the dash comes off. And so it did this last weekend.
Here’s what I found:
As you can see, the + & - leads came in contact with each other. Seems as though this should have popped the supply fuse, but it didn't. The resistor burned until it opened completely. I'm pretty sure this happened as I was working to find the right balance of filing just enough and experimenting with fit. Even with care placing and removing the fixture into the opening, the wafer ended up getting twisted - it was VERY easy to spin these things in the housing. So whatever you do, be careful!
If you find yourself with this issue, a few more notes that might prove helpful: I clamped the shop vac hose close by while filing just to keep debris from dropping into the opposite side of the circuit card. And, although there's plenty of room for this kind of work, be mindful of depth when passing the file into/out of the opening.
