| Author |
Message |
    
Therealporkchop
| | Posted on Monday, September 01, 2003 - 2:39 pm: | 
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I was given a Palomar 225 mobile amp. When I got it, it would keep blowing fuses. The small diode beside the hot wire was blown. A 1N4004 diode, I assume to be used for a protection circuit. I replaced it and now the amp will stay on without blowing the fuse. The only problem is I have no power output. When you key you don't get anything. I can't find anything about this amp. Can you please point me into the direction I need to go to find my problem? It is a new amp, and some guy hooked it up backwards. Hot to ground and ground to hot.
Thanks |
Tech671
| | Posted on Tuesday, September 02, 2003 - 4:46 am: |
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Replace the power transistors (1446)x2 |
Kc0gxz
| | Posted on Tuesday, September 02, 2003 - 3:29 am: |
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Therealporkchop
When you key the mic, can you hear the relays in the Palomar trip? If not, put your fingers on the relay and see if you can feel the relay click.
One of two things may be wrong. The small transistor that keys the relay may have shorted out and/or the relay itself may also be trashed since it experienced a polarity inversion. These are just a couple of possibilities. There's more.
Jeff, kc0gxz. |
Therealporkchop
| | Posted on Saturday, September 06, 2003 - 4:53 pm: |
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If I switch the preamp on, I hear the relay come on. I know there are two off them. When I key though, I don't hear anything or feel anything. Wonder which transistor is the keying one? It's really hard to get the stuff to unsolder. I just clipped the diode I replaced. It was easier than trying to remove it from the other side. I'll check it out though.
Thanks alot!! |
Adshar64
| | Posted on Sunday, September 07, 2003 - 5:02 am: |
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Hey Therealporkchop, just sent you a circuit diagram
cheers adshar64 |
Therealporkchop
| | Posted on Sunday, September 14, 2003 - 3:57 pm: |
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Thanks for the diagram, but I have no idea what to do with it. I can't read a circuit diagram.
I now have the amp keying. I don't really know what I did to get it to work. It will only key about a watt and talk about two. I changed the output transistors in it, but that didn't fix anything. I really want to fix this amp, but I am at a stand still now.
Thanks |
Therealporkchop
Junior Member
Username: Therealporkchop
Post Number: 27
Registered: 11-2002
| | Posted on Tuesday, March 30, 2004 - 6:37 pm: |
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Thanks Tech671. I re-replaced the transistors, and the amp is working great now. I have another Palomar, a 250 and it's a real pain. Wouldn't key up at first, now it keys and the relay clicks (replaced keying transistors 2N2222a), but no output on this either. One resistor gets real hot and burned the •••• outta me today. I've checked every resistor in it, replaced almost all of them (mostly because I wanted to) and replaced every diode in it. The two 1n5401 diodes I haven't replaced. Still no power out. I need a schematic...
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Kc0gxz
Advanced Member
Username: Kc0gxz
Post Number: 694
Registered: 3-2003
| | Posted on Tuesday, March 30, 2004 - 11:25 pm: |
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Therealporkchop
Possibly you may need to replace the RF power transistors in that one also.
I hope you're not paying a lot for these burnt-up RF amplifiers.
Jeff, kc0gxz. |
Therealporkchop
Junior Member
Username: Therealporkchop
Post Number: 39
Registered: 11-2002
| | Posted on Tuesday, June 08, 2004 - 10:13 pm: |
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No, it's junk somebody gave me. Just something to kill time and have a reason to get outta the house. That 250 is still sitting though, I don't know what to do to it. I'm thinking of taking a hammer to it. |
