Where to find a BC300 Service Manual?

[Astrogoth13]

I have looked and had no luck. Ideas?

 

[UPMan]

I find the schematics, but no s/m.

 

[pro92b]

I don't believe there was ever a service manual released for the BC300. In the attached letter from 1981 I requested a service manual from Electra and they said it was not available. The schematic they did send is the one that you can now find on the web. At the end of 1983 I tried again to get a service manual but only the schematic was available from Electra. Not long after that Uniden bought Electra's scanner business.

 

[ipfd320]

I Found Scematics also here----http://w5jgv.com/downloads/Bearcat/Bearcat%20BC300%20Schematic.pdf

A Couple of Tech Tips Here----http://w5jgv.com/downloads/Bearcat/Bearcat%20BC300%20Repair%20Tips.txt

As for anything Else..I Searched a Bit and Found Nothing Worth Wild---You Did Not Mention Why You Need the Manual---That Could Help a Bit

 

[Astrogoth13]

Thanks for the help everyone. I got this 300 in great condition but I am sure it needs a mass cap' replacement and, if possible, an alignment. Hence the service manual..

Oh well, I will adapt.

 

[Astrogoth13]

"For part alignment see XD529-02."

Sure! Where is that located?? And while I'm moaning where on the board is C98 located? Roughly.

 

[Astrogoth13]

Okay, for future reference I found C98. With the case apart and the buttons facing you, to the left of midline you will notice a medium sized transformer. Immediately above the transformer are two medium sized electrolytic cap's. The one on the left is C98, clearly marked. But. My C98 is a clearly marked 100uF 35V! The solder appears to be untouched and as old as the others near it. I will still put a 45uF 35Volt cap in its place. My display is very dim.

 

[jonwienke]

My C98 is a clearly marked 100uF 35V! The solder appears to be untouched and as old as the others near it. I will still put a 45uF 35Volt cap in its place. My display is very dim.

Bad idea. Unless you are ABSOLUTELY sure the original part was wrong, the uF ratings of the original and replacement parts should match exactly, and the replacement part's voltage rating should be equal to or greater than that of the original.

 

[Astrogoth13]

I am sure. I could not be more sure. Still, I don't understand why Electra put that value in there.

 

[jonwienke]

I would trust the markings on the factory original part over a schematic.

 

[Astrogoth13]

The marking on the schematic and the ones on the board agree. That IS C98. Who knows.

 

[Astrogoth13]

Okay, replaced 4 cap's. The display is still too dim, but the radio works. So I went looking and found an unsoldered part. Fixed it. Wiggled the ribbon cable where it plugs in, very carefully. Tightened all the inner case screws for a better ground. Straightened a few parts. Reassembled the case and everything but the display works better. The Ham button and the Hold button now work. The banks all work. But there is now a 60 cycle hum to wake the dead. And the display is still too dim. Tomorrow.

 

[Ubbe]

If you replaced a 100uF filter cap with a 45uF I would assume that would be the result.
Filter caps should always be replaced with the same or bigger values in both uF and voltage.

/Ubbe

 

[Astrogoth13]

I did it in stages. First that cap. Then I tested it. Nope. No hum. No change at all in fact. And larger filter caps are okay. Better in fact.

 

[jonwienke]

But there is now a 60 cycle hum to wake the dead.

Nope. No hum.

So which is it???

 

[Astrogoth13]

So which is it???

Whatever dude.



It's a new day. Today I looked and found two more bad solder joints. Tested the repairs.... No improvement. Loud hum still mostly covering voices on the radio. It needs a complete capacitor replacement job and frankly this scanner, as nice as it looks, isn't worth all that work. As I went along fixing things I was also making other old parts fail. Frustrating. So, this BC-300 will sit on a shelf and remind me of my teen years. Hope all this helps future BC-300 owners.


I still wonder how this thing ever made it out of the factory. It couldn't have worked well with so many open circuits. Time didn't do THAT.

 

[VK3RX]

Try operating it on DC. The problem is most likely in the PSU and all those caps should be replaced, but its worth trying.

Agree re the build quality. Not quite as bad as some Grief-kits I've seen, but -

 

[Astrogoth13]

Try operating it on DC. The problem is most likely in the PSU and all those caps should be replaced, but its worth trying.

Agree re the build quality. Not quite as bad as some Grief-kits I've seen, but -

Good idea, I'll try it! Thanks.