I recently acquired a BC780XLT which was working just fine and looks like new (the prior owner, a friend, upgraded to a newer unit). With a 40 meter inverted v antenna connected to the 780, I was able to receive local weather broadcasts loud and clear. No other signals were heard as I scanned various frequencies. The backlight was bright, the characters on the screen were readable and clear, and the audio was booming in at half volume with the built-in speaker.
Due to my need to finance other radio interests, I sold and shipped the 780 (packed very well) to a buyer in Arkansas. After unpacking and inspection, buyer fired it up but something was damaged or loosened up during shipping because buyer reported the backlight was out, characters were very faint, and audio was weak and distorted. I had the buyer ship it back to me. The pack (medium flat rate priority box) had taken quite a hit in a corner on the trip to Arkansas but the packing absorbed some of the shock and kept any visible damage from occurring to the 780.
After my visual inspection of the exterior, I plugged it in. Unfortunately, the buyer’s report was accurate in nearly all respects. Specifically, when turning the unit on, the backlight flashes (medium intensity) for a second and goes dark. Characters on the display were not readable (although they were there). I was able to receive my local weather station but the audio level is much lower than noted above (with vol control at max) and there is moderate distortion in the audio.
In looking in the RR archives, I found posts* with some fixes for the dim display, distorted or no audio, and no backlight. (*3057035, 360267, and 239745)
I took the covers off the unit. Everything inside the unit looks like new. Nothing appears loose or damaged. I pulled the two ribbon cables to the display board and cleaned both ends on each cable with Pro Gold and reseated them. Fired up the 780...no change.
Next step is to remove the front plastic cover to get a look at the front of the display board and find the physical locations of the resistor, capacitor and zener discussed in the referenced posts...and to check the voltages on the various pins. Since all was well prior to the apparent rough ride, it seems the problems would be generated from something damaged by the shocks during shipping as opposed to a component failure (especially a resistor, cap or zener).
In order to separate the display board from the front plastic panel, I see 4 Philips head screws that pass through the PCB with threads headed towards the front panel. I have already removed the nuts holding the volume/squelch and VFO controls so the front panel assy is loose. Anything else to remove before the front panel will come off?
Is there a service manual on the web that would show voltages on the various connector pins?
Any and all assistance will be greatly appreciated.
Chris W7JPG
Due to my need to finance other radio interests, I sold and shipped the 780 (packed very well) to a buyer in Arkansas. After unpacking and inspection, buyer fired it up but something was damaged or loosened up during shipping because buyer reported the backlight was out, characters were very faint, and audio was weak and distorted. I had the buyer ship it back to me. The pack (medium flat rate priority box) had taken quite a hit in a corner on the trip to Arkansas but the packing absorbed some of the shock and kept any visible damage from occurring to the 780.
After my visual inspection of the exterior, I plugged it in. Unfortunately, the buyer’s report was accurate in nearly all respects. Specifically, when turning the unit on, the backlight flashes (medium intensity) for a second and goes dark. Characters on the display were not readable (although they were there). I was able to receive my local weather station but the audio level is much lower than noted above (with vol control at max) and there is moderate distortion in the audio.
In looking in the RR archives, I found posts* with some fixes for the dim display, distorted or no audio, and no backlight. (*3057035, 360267, and 239745)
I took the covers off the unit. Everything inside the unit looks like new. Nothing appears loose or damaged. I pulled the two ribbon cables to the display board and cleaned both ends on each cable with Pro Gold and reseated them. Fired up the 780...no change.
Next step is to remove the front plastic cover to get a look at the front of the display board and find the physical locations of the resistor, capacitor and zener discussed in the referenced posts...and to check the voltages on the various pins. Since all was well prior to the apparent rough ride, it seems the problems would be generated from something damaged by the shocks during shipping as opposed to a component failure (especially a resistor, cap or zener).
In order to separate the display board from the front plastic panel, I see 4 Philips head screws that pass through the PCB with threads headed towards the front panel. I have already removed the nuts holding the volume/squelch and VFO controls so the front panel assy is loose. Anything else to remove before the front panel will come off?
Is there a service manual on the web that would show voltages on the various connector pins?
Any and all assistance will be greatly appreciated.
Chris W7JPG
