Mongoose 450 / Rebel TX500 Schematics

[wcsd106]

Anyone have schematics on the Mongoose 450 / Rebel TX500 / Blackhawk 120 (Same radio)

PC Board Number is: jpmxx0222-a

Picked up two of these little gems on Ebay last week for $15 each. One works perfectly, the other one receives but does not transmit. Been going back and forth between the working one and the non-working checking voltages. The only reference I've found so far is a block diagram over at the tricky cb site.

Found a difference in voltage on Q18 (RF Amp) but without a schematic or a voltage chart, I'm working blind.

I guess the good thing is I can hear myself on a nearby radio, but am showing no wattage out... gotta be something small, blown cap, diode, transistor, etc somewhere in that transmit chain.

Thanks in advance for any help.

 

[wcsd106]

bump... op:

 

[Mongoose]

I have been trying to find a MONGOOSE radio for years, for obvious reasons. Damn, somebody beat me to it.

 

[MisterFatty]

I have been trying to find a MONGOOSE radio for years, for obvious reasons. Damn, somebody beat me to it.

Can't help on the schematic, but there are 2 mongoose radios on Ebay from the same seller for $15 each, both have problems, but its cheap enough..

 

[wcsd106]

Hello,

thanks for the replies.. at least I know people are looking at this.

I've been doing a little more research, and have found the company in charge of importing this radio. I have sent them an email and am hoping to acquire the service manual and schematic. If I even had the owners manual, it had a schematic in it.

I've been going back and forth between the working and non-working radio checking voltages and seeing if I can find something out of place.

I have noticed that on the troubled radio when I key the microphone, the internal meter on the radio starts to jump up then drops back to zero... This leads me to think of something bleeding to ground on TX.

I can hear myself on a nearby radio, but the signal is scratchy and low. I noticed tonight while checking TX voltages on a few transistors that if I have the DVM lead touching any point in the transmit section the signal becomes very strong on the nearby radio and sounds perfect.

I guess I can rule out anything in the PLL or Mixer sections as the signal is being processed and is coming out dead on frequency.. gotta be something in that power circuit.

This is where a scope would come in very handy, I know... Maybe after Christmas I'll try to find one. I used to have a nice Tek 465 when I ran a shop, but when I closed the doors to pursue my new career, I sold off the great majority of my inventory and higher-end test equipment. Hindsight is 20/20 they say...

 

[Mongoose]

Well I finally got a Mongoose 450 from Ebay for $10.01, no transmit but it gives something to play with . Bidding on another but with the silver face.

 

[ravenstar]

mongoose reply

got my mongoose 450 cb in spring 1996, in grants New Mexico
I followed the instructions for tuning the antenna to the letter, meaning i got knowledgeable help and had great service just with the 40 channel range, can not tell more about bout the upper and lower channel usage mainly because I did not have access to any 1 who has that channel capacity,,
and did get some compliments on well it sounded at the receiving end.
later I put this in my personal pick up truck and did not tune the antenna as strictly as before and it did stop working after awhile.
Left it at a cb shop in Canyon ville OR. he fixed it and said it works great all channels.. if I remember correctly he said he peak tuned it to 7 watts or something like that 40 channel range ,,,
I am very pleased with it and glad i have it, it's one of those life time keeper things.... Lesson learned,, TUNE THAT ANTENNA to the vehicle..

I also have a Uniden pc 78 elite, I got that just because of the orange color at nite, just like seeing a campfire with that orange glow. Had lots of compliments on the output sound as well