[ICOM] 751A Won't Transmit

[Gary P. Fiber]

Have him take a look at the Transmit 8 volt line that might be the 
trouble. for some reason its not getting to where its supposed to be 
while attempting to transmit.
Also:


      Knowledge Base Article 5BA9425945

Issue
No TX output from my 751 in all modes. Problem is traced to no output at 
J8 connector on the RF unit.

Resolution
There is a bad Q14 transistor amplifier on RF unit. Replace Q14 
transistor. There may be other problems on the RF unit. Check the DC 
voltages at D47 diode.

Category
Amateur : HF : 751


      Knowledge Base Article 5BA9554454

Issue
No TX output at all in RTTY or CW modes from my 751/751A. SSB and AM are OK.

Resolution
There is a bad carrier generator crystal on the main unit. Replace X1 
crystal.

Category
Amateur : HF : 751

Hope some of this helps.

Gary K8IZ

EP Swynar wrote:
> Good Day All.
>
> This is an absolute long shot, I know, but without my technical supplement here beside me, all I can do is quote my buddy...
>
> My 751A suddenly, & without warning, refused to transmit awhile back. It receives A-OK, but the instant you hit the transmitting key / microphone, the RF power output needle will swing upward for a nanosecond, & that's all...no RF output in any mode...
>
> My friend, who does consumer electronics repair for a business, says that he has traced the problem to a 9-MHz crystal oscillator board that suddenly stops oscillating when the rig is put into transmit mode. He says the crystal & all the voltages appear to be normal & functioning, except when transmitting --- then it just stops working.
>
> Has anyone else ever encountered this problem...? I researched my old QST magazines & located the review for the 751, & apparently the one under review did the same thing --- wouldn't transmit, but no reason given beyond it being due to a "...bad resistor".
>
> Like I said initially, it's a L-O-N-G shot...! 
>
> Any & all feedback appreciated...thanks!
>
> ~73~ Eddy VE3CUI - VE3XZ
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