Batboard

Ok, I have done everything I can think of, I have cleaned all contacts, resoldered the battery connections, checked all grounding springs, and yet, on a new battery (any and all) fully charged, I get a low battery double beep on TX.

What could cause this, and yes I have used other batteries and confirmed voltage / amps from the batts and used them on other radios no problem....

What else should I check, Im actually stumped.

any ideas?

I'm not too familiar with the GP300 RSS yet, but I recall that other RSS packages I've worked with have let you set the 'threshold' when the radio will start to bug you about a low battery. Maybe (if the settings is there at all for a GP300?) it's cranked up to an insane value?

Could probably be a ton of other things too, but I'll leave those for someone with more experience than I have.

Have you checked the butterfly clips that are soldered on the edges of the PCB to make sure that 1.) all seven of them are still there and 2.) that the solder is good where the clips are soldered to the PCB, and further that the area where the clips make contact with the chassis is clean and that the plating is not worn off?
Obviously, something in the battery supply circuit is dropping a lot of voltage under the relatively high current load(~2.1 amps) on transmit. And if yours is an older unit that's been used roughly, the grounding clips (or lack of them) are a common problem. Anything that causes the voltage that the uP senses on the PCB to fall below the low batt threshold displayed in the RSS will bring in the low batt alarm, usually on transmit when current demand of the electronics is the highest, and it doesn't reset itself until the radio is switched off and then on again.

yay, thanks al, you helped me on this one, I bet its the two missing butterfly clips.

It's a late 1995 radio and I cleaned all contact areas and replaced the two missing butterflys and its still doing it.

...... the rss has the same setting for low voltage indicator as my other gp300's.

Resolder the power contacts on the on switch /volume pot.
These often go loose due to the poor design
As a test just solder acreoss the contacts and see if the problem goes away as it could be an off/switch on the way out. ( fairly common problem)

Bruce, thanks for that info as well, That was the first thing I tried after changing all batteries and checking the uP.

Just for the pure amusement of myself, I tried a 89% depleted and normally reporting BEEPBEEP battery on this gp....

It doesnt say its almost dead..... Something is backwards here.... A almost dead acts as full (report wise not funtionability), where a new full battery reports almost dead.....

Looks like I got a parts donor radio here.

Hi, Check pin 53 of the micro.That is the battery sense line. There should be 2.5 to 3 volts there. I'm suspecting it is zero or close to it. Look on the solder side between the shield and the bottom of the radio. Look for a 180k and 100k ohm resistor. They may have cracked.

HTH
Sean

Pin 53 has 2.61v
both resistors in good shape, I replaced them per your post and same issue.

I am just going to part it out I guess.

Darn!

Only other thing I can think of is under radio wide configuration (from main menu, F4, F2), there is a field "Low Battery Thr". I checked one codeplug and it had "166" as a value.

GL
Sean

i Checked my low battery thermosistor setting and its the same as my other gp300s...... I cant figure it out unless a IC has an internal fail....

Did you perform your check on the uP pin 51 under transmit conditions, and use the uP ground as the reference for your measurement?

yes I did, everything checks out that I can test. I give up, I have a spare gp300 board ill swap em out and use the parts off it when/if needed on others. maybe the vco died.