Dim Spectra display.....

[N0ZPK]

Hello All, i got a 450 Moto Spectra that the display goes dim while in operation. the rest of the light stay on except the display. If I turn it off then on again i get a error code of 01/9X, (X=1,2,3 ect... i cannot see it) What could be the problem here?.. Thanks,, n0zpk.....

[larryepage]

Hard to diagnose this one for sure without having the radio to look at, but this has all the elements of leaky or otherwise failed electrolytic capacitors on the display board or on the command board. Look for areas on the circuit board where electrolyte has leaked from the caps.

If that has happened, it is important to correct it quickly, since the electrolyte is corrosive and will eventually destroy components as well as the traces on the circuit boards.

[Will]

As Larry says, look for discoloration arround the large caps on the display/control head board. Sometimes there is a black discoloration on the traces where the electrolite has eaten the trace under the solder mask, the green coating. I have seen Spectras with very wacky problems with corrisive electrolite under the componets .. very hard to repair... But Spectras is what I do! (repair).

I have some of the new caps, not the leaky /\/\ ones, from a aftermarket source that are working very well in my repairs.

As Larry said, time to change the caps. Be VERY carefull, these are surface mounted componets and the pads are easally distroyed.

I'll be glad to fix them for for BatBoard members at a very reasonable rate.

[VE3TUH]

I would sure try the caps first, but your display itself may just be worn out, you would need a new display to correct. It could also be a voltage issue in the display driver circuit.

Randy

[hvfcadmin]

On this subject, i have 2 HLN6283A A7 control heads one of them has the dim display problem. I swapped the heads around to see if it was a software thing but the problem follows the control head. To give and idea of what it looks like, one radio set to full brightness, the other looks like it is set to medium.

did some measurements.

Good display ~ 33.68v
??? Display ~ 31.05v

Would a ~2.5v difference be that critical. I belive these to be the supply voltages for the VFD driver. Does any one know if the VFD voltage can be adjusted via hardware or is the timming controlled through the uC. I'm waiting for my service manual to come in so i'll be able to supply pin numbers for locations of my test. Basically if you look at the rear of the control head, it is pin 2 from the left on the VFD. Caps have allready been replaced, no change.

[Will]

The brightness is controled by the display driver IC and is time/pulse width variable. The voltage stays the same.
DO NOT try to 'probe' arround in the switching supply circuit per the book, they blow up easaly.

Check the filiment voltage first, if ok, the pulses on the anodes.

VFD might just be weak.... they do that over the years.