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guzzik Profile
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Freebander

Registered: 08-2010
Posts: 38
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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?
4/Jan/2011, 4:19 pm Link to this post Send Email to guzzik   Send PM to guzzik Blog
 
madmark1 Profile
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Accomplished DX-er

Registered: 10-2009
Location: Abertillery
Posts: 454
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Re: Ham Jumbo 2.................................??


What chassis is in that Jumbo, is it the PTBM125 chassis ?


Mark

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4/Jan/2011, 5:54 pm Link to this post Send Email to madmark1   Send PM to madmark1 Blog
 
scottydog61 Profile
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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 emoticon

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YT2095 Profile
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Freebander

Registered: 12-2010
Location: the Black Country
Posts: 188
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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?


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I`m also on Twitter as "YT2095" ;)
4/Jan/2011, 7:11 pm Link to this post Send Email to YT2095   Send PM to YT2095 Blog
 
guzzik Profile
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Freebander

Registered: 08-2010
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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.............emoticon

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.
4/Jan/2011, 7:45 pm Link to this post Send Email to guzzik   Send PM to guzzik Blog
 
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Freebander

Registered: 08-2010
Posts: 38
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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.
4/Jan/2011, 7:48 pm Link to this post Send Email to guzzik   Send PM to guzzik Blog
 
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Freebander

Registered: 08-2010
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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!)
4/Jan/2011, 9:58 pm Link to this post Send Email to guzzik   Send PM to guzzik Blog
 
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Freebander

Registered: 08-2010
Posts: 38
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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.............
5/Jan/2011, 1:20 pm Link to this post Send Email to guzzik   Send PM to guzzik Blog
 
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Freebander

Registered: 08-2010
Posts: 38
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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 emoticon



Nope, have the rig on external power pack now, still doing the sameemoticon
5/Jan/2011, 1:36 pm Link to this post Send Email to guzzik   Send PM to guzzik Blog
 
madmark1 Profile
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Accomplished DX-er

Registered: 10-2009
Location: Abertillery
Posts: 454
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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

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http://gw0wvl.weebly.com/
5/Jan/2011, 6:12 pm Link to this post Send Email to madmark1   Send PM to madmark1 Blog
 


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