guzzik
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Ham Jumbo 2.................................??
Now I am flumoxed guys................Rig works ok other than the audio keeps "dropping out", example, switch on, perfect audio from speaker, key mic.......VERY low audio from speaker, switch rig of and back on, perfect audio, turn volume up, audio drops of again same thing happens when on earphones/Ext Spkr........Leave radio switched on and in comes the audio, key mic, audio goes low again....... I have as a matter of course changed the rather ancient AF Gain control and checked as many joints as I can reach without major surgery. Any clues gentle people?
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4/Jan/2011, 4:19 pm
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madmark1
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Re: Ham Jumbo 2.................................??
What chassis is in that Jumbo, is it the PTBM125 chassis ?
Mark
--- http://www.youtube.com/MrMadjones
http://gw0wvl.weebly.com/
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4/Jan/2011, 5:54 pm
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scottydog61
Registered: 11-2010
Location: Sunderland
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Re: Ham Jumbo 2.................................??
Cant say for sure but sounds like the power transformer may be getting a bit past its sell by quite common on the Jumbo apparantly
--- 26FB036
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Scotty
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http://www.sunderlandusedoil.co.uk/
TTI 1100 cb/10meter
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4/Jan/2011, 6:01 pm
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YT2095
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Registered: 12-2010
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Re: Ham Jumbo 2.................................??
possibly part of the RX/TX switch-over circuitry, but 1`st it`s Usually best to elliminate the Simple things, have you checked the PTT switch in the Mic itself?
does it happen when you use a wire to short the correct pins on the Mic socket of the set itself?
I would normally do these things as a matter course before I even lifted a screwdriver.
have you tried the PA setting as well?
--- I`m also on Twitter as "YT2095" ;)
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4/Jan/2011, 7:11 pm
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guzzik
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Re: Ham Jumbo 2.................................??
Changed mics, shorted pins, tightened screws washed board in dettol, used stiff wire brush.............Oxy-acetylene torch and a lump hammer and bolster chisel as recomended by all good screwdriver experts.............
Nah, I haven't a clue what is breaking down, spray with switch cleaner, perfect.......then it goes low audio, spray with switch cleaner again, nothing happens, stays on low audio.
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4/Jan/2011, 7:45 pm
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guzzik
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Re: Ham Jumbo 2.................................??
quote: madmark1 wrote:
What chassis is in that Jumbo, is it the PTBM125 chassis ?
Mark
Hi Mark, nope it be the PTMB 121D4X, the same as the High Gain 5 etc.
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4/Jan/2011, 7:48 pm
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guzzik
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Re: Ham Jumbo 2.................................??
I now think the squelch control is shot.............More on this exciting saga tomorrow...............(rolls eyes heaven wards!)
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4/Jan/2011, 9:58 pm
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guzzik
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Re: Ham Jumbo 2.................................??
No, it is not the squelch..........Bugger........It is really weird, switch on, it works, touch the AF gain control, audio goes quiet.............
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5/Jan/2011, 1:20 pm
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guzzik
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Re: Ham Jumbo 2.................................??
quote: scottydog61 wrote:
Cant say for sure but sounds like the power transformer may be getting a bit past its sell by quite common on the Jumbo apparantly
Nope, have the rig on external power pack now, still doing the same
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5/Jan/2011, 1:36 pm
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madmark1
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Re: Ham Jumbo 2.................................??
the thing is, its a complicated piece of radio gear, and as such for most fault finding, other than the usual faults that just spring out at you.
Have you checked for bad solder joints or faulty tracks, if i remember the radio has tracks on both sides of the board..... although its a while since ive worked on one.
your going to have to do some voltage checks, and have some test gear to fault find, and just work your way along the various voltage and rf paths.
To test that the audio amp is fully working, and not breaking down at all, its possible to put a test tone into the input of the amp and listen to the output, this will tell you if its the audio amp. while doing this flex the circuit board a bit to see/listen to what happens if anything.
you will have to get your deer stalker on and do a bit of detective work.
Mark
--- http://www.youtube.com/MrMadjones
http://gw0wvl.weebly.com/
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5/Jan/2011, 6:12 pm
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