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Troyota
New member
Username: Troyota
Post Number: 1
Registered: 4-2004
| | Posted on Saturday, May 13, 2006 - 11:21 pm: | 
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hello, i have a euro 3900 with a bad display. it used to just have 2 led bars out on the display. now they all have quit working. when i first noticed the problem i could wiggle the channel selector knob and it would work again, now it is just blank. i had the radio apart last night and checked for cold solder joints, i touched all the ones where the display board connected to main board with my iron but it didnt fix it.
does this sound like a led display problem? do you think i could just replace the display and fix it? just want some insight before i go replacing stuff, if so i may buy the blue display for this radio. thanks |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 670
Registered: 11-2002
| | Posted on Sunday, May 14, 2006 - 1:19 am: |
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Yes you can buy blue.
I assume that radio is built like just about every other radio sold here at Copper or anywhere else in the world.
So I believe you problem is a wire. On the back of that channel selector board there is a plug if I'm not mistaken. There is about 10 or 12 little wires on it. Start by clipping out the wire ties that hold most of those wires in that area off the wires. Then start with one wire and wiggle it all around. Then move on the next wire and wiggle it about. Now you're actually doing the hokey pokey...oh sorry.
I've ran into this problem a dozen times. Not the hokey pokey but the dead channel display. And every time but one it's been wire related. So start there first cause it's easier to replace one little wire than it is to replace a channel display and it still not work.
Now if you find the wire and fix the problem, then you can do the hokey pokey. But don't do it real long or big, cause you'll want to save some pokey for when you change to blue LEDs.
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Troyota
New member
Username: Troyota
Post Number: 2
Registered: 4-2004
| | Posted on Sunday, May 14, 2006 - 10:27 am: |
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thanks for the quick reply therealporkchop. i tried the wire wiggling thing this morning, with no luck. i wiggled on both ends the plug end and the board end, not even a glimmer. i tried everything except the hokey pokey, but i couldnt remember which foot to start with my left or right. any more ideas??
thanks |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 675
Registered: 11-2002
| | Posted on Sunday, May 14, 2006 - 3:51 pm: |
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Well the hokey pokey usually makes everything better..ha-ha.
I would make sure it wasn't a wiring problem first. I'd check all the wires in that section. Sometimes you really need to yank on them to find the one that's broken.
If that isn't the problem, then I'd lean toward a burnt out section on the display itself. There is a possibility that a diode or resistor down stream from that section is open. But if you have another display to try or if you plan the color swap anyway, it's fairly easy to do.
Remove the radio covers, top and bottom. Remove all the knobs on the radio. Remove the bezel (4 screws) Remove the last two screws that holds the front section of the radio to the chassis. Beside the channel selector there are two screws, remove them. Unplug the channel selector. There are probably 3 wires left connected to it, soldered. The black is a ground, the yellow and brown are for the transmit/recieve light. Unsolder them as well. Remember where you took them off. If you switch them around, the LED will light up backwards, nothing will blow. Check it before you put the whole thing back together.
With the channel switch on the bench, the top section of the display can easily be removed with a desoldering iron. The bottom you'll have to use desolder braid, or it's easier that way anyway. When you get it broke loose, you can pry it out from the front side. Put the new/test display in and resolder it. MAKE SURE YOU DON'T SHORT ANY OUT AND THAT YOU MAKE GOOD CLEAN CONTACT ON THEM. Also make sure the two boards are soldered together well. Plug it back it and solder the wires back on the for the transmit/receive LED. Make sure nothing is touching the chassis or shorted against something a plug the radio back in and switch it on. If all the display is lit up, unplug it and put it all back together.
Now is a good time to clean the faceplate and knobs if they are dirty. If you have the red lens, if you can find blue plastic you can use it to make the new lens. If not, you'll have to go clear. You can use just about anything, but I like to use broken or spare parts bin drawers. Cut it down to about the size you need with any X-acto hobby knife, file to fight the slot for the lens in the bezel. Once it's a nice clean tight fit, you can take a solering iron and carefully run it around the edge, sealing the clear lens to the bezel. This way it won't fall out when you touch it or are trying to clean it. The same can be done with blue plastic or whatever you decide to use.
Put it all back together and hook it up again and make sure it's still working.
Now if it's not a burnt LED section, then it's gotta be a bad diode/resistor I would think. If yo u have a spare radio with the same type channel selector I'd try that. If that one doesn't work right either, then I'd start hunting the problem on the main PCB. |
Troyota
New member
Username: Troyota
Post Number: 3
Registered: 4-2004
| | Posted on Sunday, May 14, 2006 - 4:00 pm: |
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ok guys i have just replaced the led readout with another display from an old radio i had laying around. still no readout. all traces seem to be fine and solder joints also. so my problem must be in the circuit somewhere. please help if you can, before i do the hokey pokey on this radio. cant decide which foot to put in the radio first, left or right. thanks my friends |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 679
Registered: 11-2002
| | Posted on Sunday, May 14, 2006 - 9:58 pm: |
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OK, well first off put your feet back on the floor and off this radio.
We'll assume you've used a working LED. With that said, since it still doesn't work, then the problem is somewhere else. And I want to lean towards a wire somewhere.
First thing to do is find a pin-out for that LED display. You can find them about anywhere, it'll show you which pin(s) make which section light up. Then trace back on the channel selector board from that pin and start checking the diodes/resistors/capacitors etc. Until you make it to the plug. Now if all is well on the channel selector PCB, then you know the problem is in the radio or it's wiring.
I still lean toward the wiring. Following the pin-out to the plug, trace that wire. Even replace the wire if possible to rule it out. Then you'll have to start tracing that once it hits the PCB. Or does it go into the channel board? I'm not real familiar with that radio. And off the top of my head I can't remember whether or not those wires run to the main PCB or a channel board.
That is what I'd do if it were in front of me. Other than that, it's hard to say exactly which part and where it's at that is bad. |
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