TRX-1: TRX-1 Screen Issuse

[HamsterWOZ]

Hi, I have a Whistler TRX-1 and the screen on the unit appears to fade away while using the unit, on both batteries and on USB power.
The radio still functions as I can remote control it from my computer and the backlight on the screen is still on, the screen seems to lose all contrast.
If I unplug the unit and wait for a while and then plug it back in the screen turns back on like normal and then starts slowly fading away till the contrast on the screen is completely gone.

I've tried reapplying the firmware for the CPU and DSP boards and reformatting the SD card along with re-copying over the config to it.

Wondered if anyone else has had this issues and can help?

Apologies in advanced if I've posted this in the wrong place. First time using this forum

 

[tvengr]

Bad SD cards can cause all kinds of strange problems. I would start with replacing the SD card to eliminate that possibility. If you are still losing the display after replacing the SD card, it sounds like an electronic problem. Bad electrolytic capacitors can change value with temperature and could cause a fading problem like that. How old is your TRX-1. A bad solder connection or leakage in capacitors or solid state components can set up a time constant that causes the display to gradually fade. When you turn off the scanner, the time constant will be reset.

 

[HamsterWOZ]

Not sure how old my TRX-1 is, as I am not the original owner, however the device was basically brand new in the box with all the protective wrapping over it when I got it a few days ago.
I was about to try changing the SD card, however I have powered it on for the first time since last night and I have no contrast on the screen straight away so I suspect that it must have a electrical problem or something wrong with the screen...

 

[tvengr]

Did you try adjusting the contrast on the General Settings page of EZ Scan? I would still replace the SD card to eliminate that as a possible problem. If that works, it is a quick, easy, and cheap solution. I had a friend with a Uniden BCD536HP that appeared to be totally dead. No display, no backlight, no indication it was turned on. Replacing the SD card brought it back to life. The SD card controls everything in the scanner, including the contrast.

 

[HamsterWOZ]

Yeah, contrast is set to 15 in EZ Scan, I've managed to get the screen to come back on by re-seating the DSP board, not sure why but if I re-seat this board the screen comes back at the set contrast.
I've got a different SD Card and programmed it with EZ Scan, so I am just waiting to see if fades away again.

 

[CycleSycho]

Yeah, contrast is set to 15 in EZ Scan, I've managed to get the screen to come back on by re-seating the DSP board, not sure why but if I re-seat this board the screen comes back at the set contrast.
I've got a different SD Card and programmed it with EZ Scan, so I am just waiting to see if fades away again.

.


Sounds like an oxidized pin or connection, these are probably the easiest to fix if true. Good luck!


.

 

[HamsterWOZ]

Sadly, it's still fading away, I have reseating the board a few time, so I would of thought the oxidation would of gone away by now, however the radio still functions without the DSP board attached, so I'm not really sure at this point, though I think it defiantly a electrical issues with either the logic board or the LCD.
The only thing I can think and maybe it a coincident is reseating the boards is discharging something or removing some kind of residual capacitance from the board. But I'm not really sure, I wish I was a electrical engineer
Not sure if this radio is becoming a lost cause, at least with my skills set.

 

[pyeman99]

Sadly, it's still fading away, I have reseating the board a few time, so I would of thought the oxidation would of gone away by now, however the radio still functions without the DSP board attached, so I'm not really sure at this point, though I think it defiantly a electrical issues with either the logic board or the LCD.
The only thing I can think and maybe it a coincident is reseating the boards is discharging something or removing some kind of residual capacitance from the board. But I'm not really sure, I wish I was a electrical engineer
Not sure if this radio is becoming a lost cause, at least with my skills set.

Can you adjust the contrast level when it first starts up. I had same problem with my TRX2, the previous owner had set the contrast to maximum.

 

[HamsterWOZ]

Can you adjust the contrast level when it first starts up. I had same problem with my TRX2, the previous owner had set the contrast to maximum.

Yeah, I can change the contrast when the unit initial comes on, mine it set to 15, however after about an hour of use (sometime less) the screen will begin to fade away till the text is no longer viewable on the screen, changing any of the contrast controls remotely once the screen gets to this point doesn't seem to affect anything on the screen.

 

[HamsterWOZ]

I've tried a few cables they all didn't seem to make a difference, same with the more powerful power brick, sadly they all didn't make a difference.
I think it defiantly a electrical problem with the logic board but it probably outside my range of skills.

 

[Ubbe]

It's usually a negative voltage that goes to the contrast pin of a LCD display. That negative voltage comes from voltage converter that hacks the positive DC voltage into a high frequency, something like 10Khz, signal that feeds a capacitor in series and then to diodes that rectify the negative pulses and clean the voltage with an electrolyte capacitor.

It's usually the capacitor that starts to leak and then not giving enough negative voltage to increase the contrast. Electrolyte capacitors can be designed to smooth out 50Hz or designed to handle higher frequencies and if going cheap, the 50Hz versions, they can use the wrong type of capacitor that have a higher risk of failing.

/Ubbe