Standard Horizon HX750E fault diagnosis

[Colin123]

I have a Standard Horizon HX750E that has shown reliable service mover the years. It seems to have a problem but I can't find any indication in the manual or Google what's wrong. Can enyone help please?

- the display looks "normal" and key presses make the speaker beep
- that battery voltage is showing 8.0v
- on turning on the channel number flashes
- pressing the PTT makes it bleep and the tx power indcation disappears
- turning the SQL to zero does not get the usual "hash" noise
- all other functions appear to work normally

Is it something obvious or time for a new radio?

[willk]

Sounds like a bad power supply. 8v and no TX is the pointer. Test with a direct feed to the battery or bus board. The copper in the power supply leads is likely rotten and black. Pare back to shiney or replace.