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Therealporkchop
Member
Username: Therealporkchop
Post Number: 51
Registered: 11-2002
| | Posted on Wednesday, August 18, 2004 - 6:21 pm: | 
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I've looked before I ask this, and I hope I haven't overlooked my answer. I have a Mirage 44, it's an older radio. The echo/mic control board is the old style, that is, it doesn't have SMC's. The radio will key up, atleast the transmit light changes from receive to transmit. The problem is there is no audio, no audio in the PA circuit. I have another radio on my bench and it receives the key up, but that's it. I can touch the mic board and hear a hum from the Mirage and I can lay my hand on the solder side of the main pcb and I can hear a hum. I assume this means my audio chip is working. I just have no sound. It will dead key, but when you talk into the mic, there is no sound, modulation or anything. I've changed the driver and the final, still nothing. Can a tech help me with this please? I'd appreciate it alot. |
Tech548
Moderator
Username: Tech548
Post Number: 243
Registered: 5-2004
| | Posted on Wednesday, August 18, 2004 - 9:49 pm: |
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Therealporkchop
Just for the heck of it (if you haven't done so already) try a different mic!
Jeff. |
Therealporkchop
Member
Username: Therealporkchop
Post Number: 52
Registered: 11-2002
| | Posted on Thursday, August 19, 2004 - 10:28 pm: |
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Thanks, but I have. Several different ones, several different times. Any other suggestion? I'd really like to fix this radio if possible. |
Tech548
Moderator
Username: Tech548
Post Number: 249
Registered: 5-2004
| | Posted on Thursday, August 19, 2004 - 11:05 pm: |
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Therealporkchop
If you have the schematic for your radio, I would start at the mic-plug and work in from there. This just may end up being something simple such as a shorted transistor or a wire broke off the board or mic-gain control.
Jeff |
Therealporkchop
Member
Username: Therealporkchop
Post Number: 53
Registered: 11-2002
| | Posted on Sunday, September 05, 2004 - 7:19 pm: |
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That would be a great ideal. Where could I get a schematic...that is my problem. I know not where to find any. |
Tech548
Moderator
Username: Tech548
Post Number: 281
Registered: 5-2004
| | Posted on Tuesday, September 07, 2004 - 12:55 am: |
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Therealporkchop
Try here....
Gary Bedell
2957 Ponderosa Drive
Concord, CA. 94520
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I'm sorry to say but I don't have his phone number anymore. Perhaps someone here on the forum can help you out with that.
Jeff
Tech548 |
Therealporkchop
Intermediate Member
Username: Therealporkchop
Post Number: 113
Registered: 11-2002
| | Posted on Monday, December 27, 2004 - 11:27 am: |
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It's been awhile since I've messed with this radio, but here is something else that has been brought to my attention. Looking at a O'scope, there isn't any carrier at all. You key the radio and nothing changes on the scope. There isn't any audio in the talkback either. Could it be possible that I have a bad driver/final even though I replaced them? Could I use a 2sc2078 from an old Cobra just to try? The radio receives fine and I have audio there, just nothing on transmit or talkback. |
Therealporkchop
Intermediate Member
Username: Therealporkchop
Post Number: 187
Registered: 11-2002
| | Posted on Sunday, April 24, 2005 - 1:49 am: |
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Well, I've been working of this dag-on radio for a long time now. I'm slow for sure, but guess what...I FIXED IT FINALLY!!!!
Incase anyone else has this problem, this is what to check first off. First check your driver and final. I replaced my driver and final with new pieces.
Once the final was replaced the audio returned but still no swing. I had carrier, but no swing. A quick check of the 2sb754 transistor, it was bad. Replaced this with the bigger and better 2sb817. Swing returned and now this radio works fine again.
I didn't think that the 2sb754 was my problem, nor did I think it could cause such problems.
But now if you have this problem, this is most likely the cure....thanks to everyone that tried to help out.
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