I picked up a PRO-668 from a seller on Amazon complete with box and all accessories. The SIMM looks like it had been formatted so I didn’t have the OEM software but easy to get off the web. Anyway, I loaded brand new NiMH batteries making sure the switch was set to the same in the battery compartment and everything was working fine except I noticed that the battery indicator was only showing about half charge. I checked the batteries and they were fine. I figured something had to be wrong so I took it to the work bench and found out that even when the scanner was off the battery drain was around 280 mA! I opened it up and didn’t notice anything unusual. I knew something had to be getting warm so feeling around on the circuit boards I noticed a warm spot on the underside next to the speaker. It was had to see so I had to pull the board out and noticed a rather large surface mount cap had turned into a piece of charcoal and it was the culprit for sure – very warm to the touch. It appears that this cap is connected directly across the battery terminals. There is no indication what the value is but I suspect it to be an electrolytic. I can only surmise that someone installed some batteries incorrectly which caused the cap to fail. Diode protection probably saved the rest of the scanner. Unfortunately the cap turned into a big resistor that was pulling current from the batteries. I removed the cap and left it off. I don’t see any need for it since USB power is very well regulated.
There was an additional problem I had to deal with. When I took the boards apart there were several quick connects – a large multi-connector and two power connectors. One of the power connectors was missing the ground pin – there was probably enough ground connectivity with the other connectors that it didn’t interfere with the scanner but I wanted to fix that problem. I removed what was left of the old connectors and just solder wire connections.
There was another issue that I thought might be a problem. The keypad used a flat flex connector that inserted into a socket on the board. When I removed it to work on the scanner there was small bits of white plastic all over the place. It looks like very bad quality stuff and I was afraid that it might cause some continuity issues. I cleaned it up the best I could and so far no problems.
Once it was back together I measured the vitals again and got:
2 mA – scanner off
7 mA – scanner on and idle
200 mA – scanner in search mode
230 mA – scanner locked on station and receiving
I also measured the charge circuit: 8 volts @ 45 mA. This may take a long time to charge completed discharged batteries so I would use a dedicated charger for NiMH batteries. When the switch is in alkaline position no charge is applied.
Anyway I wanted to point this out in case anyone else is noticing poor battery performance on their Pro-668.
I hope this helps.
John
There was an additional problem I had to deal with. When I took the boards apart there were several quick connects – a large multi-connector and two power connectors. One of the power connectors was missing the ground pin – there was probably enough ground connectivity with the other connectors that it didn’t interfere with the scanner but I wanted to fix that problem. I removed what was left of the old connectors and just solder wire connections.
There was another issue that I thought might be a problem. The keypad used a flat flex connector that inserted into a socket on the board. When I removed it to work on the scanner there was small bits of white plastic all over the place. It looks like very bad quality stuff and I was afraid that it might cause some continuity issues. I cleaned it up the best I could and so far no problems.
Once it was back together I measured the vitals again and got:
2 mA – scanner off
7 mA – scanner on and idle
200 mA – scanner in search mode
230 mA – scanner locked on station and receiving
I also measured the charge circuit: 8 volts @ 45 mA. This may take a long time to charge completed discharged batteries so I would use a dedicated charger for NiMH batteries. When the switch is in alkaline position no charge is applied.
Anyway I wanted to point this out in case anyone else is noticing poor battery performance on their Pro-668.
I hope this helps.
John