GP-300 charger schematic/board diagram

[kc0cdg]

I have a couple of GP-300 chargers that someone hooked up to a power supply backwards and it looks like they blew some kind of transistor. I can't tell what the component is and am looking for a schematic/board diagram to identify the part. Can anyone help? Thanks.

Brad Ziegler, KC0CDG

[Will]

As far as I know there was no schematic/board diagram information published for either GP300 charger. The 'transistor' at the back edge of the board is a 5 volt regulator for the uP.

There was a replacement circuit board, but probably no longer available.

There is four versions, two Rapid, and two slow chargers. Used on GP300, GP350, and P110 radios.

[Satelite]

Hello:
PM me your email address and i will scan the GP300 schematics and the component bd layout and the order parts numbers as motorola knows them from my M manual .
I have them for the 6 bay rapid chgr and the rapis smart chgr.
Satelite

[Satelite]

Hello :
I have already had two wanting the schematics /parts list /
bd layout / exploded parts picture for the GP300/P110/P1225/GP350 radios.
It is the 6 charger list but the charger inside it is the same as the 1 hr rapid charger so it will work for both.
I do but did not scan it have it for the 16 hr rapid charger.
If anyone else wants the rapid charger scans + Please speak up soon as i was fortunate enough to have them still on the computer and will eventualy delete them.
Thank you Satelite

[kc0cdg]

The board diagrams that Satellite sent over did not match my circuit board.

Here's what the board looks like that I have:


Specifically, I'm trying to identify the circled component:


Anyone have any ideas?

Brad Ziegler

[W8RW]

Brad,

That component you have circled looks like a diode to me. If it were a transistor or voltage regulator all three pins would have separate connections.

I cannot tell from the photo, but if this diode is connected across the input power connector, then its purpose is to protect the rest of the charger from reverse voltage. It looks like it gave its life for this purpose. I can see from the picture that one side is connected to the + input.

If what I say is true, put an ohmmeter across this diode (without the transformer plugged into the charger). If it shows a low resistance or short with the red and black leads in either position, you can take it out and see if the charger still works. Be careful not to hook the voltage up backwards because there is no more protection diode.

[kc0cdg]

That component actually has three leads, which made me think it was a transistor. Reexamining it, two of the leads appears it could be a protection diode, because two of the lead are electrically connected on the left side. I'll check it out later and report what I come up with.... Thanks for the tip.....

[Satelite]

Hello:
Just an educated qeuss.
I think its component # VR106.
VR106 = Diode / Motorola part#4811058B05
Satelite

[Will]

KC0CDG,

The charger you have shown is what we call the original Rapid charger. Could be a overvoltage clamping diode, hence the VR designation.

Satellite,

Could you email me copies of the charger schematics you have. Thank you.

[Satelite]

Hello Will:
Yes i can and will email you the schematics.
lease pm me your email address.
And a thank you to kc0cdg for putting them all in one so i could easily email them all at once.
Satelite.

[Banditt27]

Hi,

Does anyone happen to still have the schematics for this charger kickin around?
Have one im trying to convert over to NiMh...

Thanks in advance!

[Tom in D.C.]

You are wasting your time. The standard NiCd charger will charge a
NiMH battery just fine and there's no need to change anything. You
should be able to get at least a 90% charge on the NiMH with the
standard charger. What will NOT work on the standard charger is a
Lithium Ion battery -- that's an entirely different animal with a basic
cell that's rated at 3.6 volts.

[Banditt27]

Hey Tom in D.C.,

Thanks for the reply.

I would assume that there would be a temp correction for the thermistor needed to stop the rapid charge cycle and not overheat the NiMH battery packs from rapid charge. I dont actually have the new packs yet... but should in a couple of days...

There have been various posts regarding conversion to NiMH from NiCD and most reference that the moto chargers will not transfer over to trickle without a mod....

I suppose i have yet to verify for myself, however a schematic would be helpful in understanding the circuit and in case of component failure.

Have you tried this b4 by any chance?

[Tom in D.C.]

Tonight I charged a GTX/GP300 NiMH battery on a Motorola HTN9042A
Intellicharger. Started with a red light and eventually went to green, so
I think it works fine on this type of battery with no mods needed. I've
never seen a schematic for any of the GP chargers, either manual or
automatic, though they probably do exist somewhere. Problem is that
the board is obviously so cheap that Motorola wanted everyone to just
toss the bad units and buy new ones, 'way back when they were a
popular item, that is.

Regards,

[Banditt27]

Thanks for the info Tom. Much appreciated. Ill try them out on my HTN9748A when the batts get here.