Bearcat BC855XLT Looses it's Memory Occasionally

John-

I have a Radio Shack HTX-10 transceiver with that problem. When disconnected from any power source, memory contents were maintained by the charge on a 220 Microfarad capacitor. Over a month, memory contents were lost due to leakage.

I installed a 3.6 Volt Lithium battery, isolated by a 1N4004 diode, across the capacitor. This approach may work for you if the operating memory voltage is higher than 3.6 Volts.

Last time I checked, memory contents were still good after ten years!

Fred

Have you tried bending the pins to stop the memory becoming loose?

Hi Fred and others,

I forgot to mention that I was unable to identify the "unique capacitor" by visual examination of the circuit board. I do not see any "out of the ordinary" capacitors.

John

How long is a great while? There's a low leakage electrolytic capacitor that will hold a charge to keep the memory alive for about 3 days maximum according to the user manual.

Same here. Some user manuals, but no service manuals.

It's a low leakage type, probably one of these:

You'll probably need to find the capacitor in question and measure the operating voltage. Try turning OFF the scanner and measure the voltage across all the likely culprits (large value electrolytics). Anything with voltage when it's off is a possibility. You might also check the minimum voltage needed to keep the memory alive. Then, add a battery with a reverse protection diode to prevent the radio from charging the battery.

Sorry, but it's the best I can do.

They are usually .47F to 1F and are normally short and squat.

To follow up on this problem, I sent John copies of the schematics from the BC855XLT service manual I have. Hopefully, he will be able to fix his prob lem with the channel memory. As a side note, my late mom had this same mode l scanner and it exhibited the same problems as John is having. So it would appear this problem was happening to other BC855XLT scanners too.