Cobra 2000 No voltage at Test points 7 and 8

[Handy Andy]

I'd start to feel around, by and starting at the Pre-driver down to Driver and Final, feel the FOIL side of the board, for heat, a hot spot means there may be something JUST AFTER (down stream - next component or stage) that is causing the stage ahead of it, to kick into overdrive, this usually indicates a failed component or parts in the area at least need to be looked into.

 

[Low_Boy]

I am staying out of this one and may have missed this but are you running the internal power supply? I would also try this using the external power supply and see what happens. Back to you Andy

 

[Brian G]

I am staying out of this one and may have missed this but are you running the internal power supply? I would also try this using the external power supply and see what happens. Back to you Andy

No I run it off an external supply.

 

[Brian G]

I'd start to feel around, by and starting at the Pre-driver down to Driver and Final, feel the FOIL side of the board, for heat, a hot spot means there may be something JUST AFTER (down stream - next component or stage) that is causing the stage ahead of it, to kick into overdrive, this usually indicates a failed component or parts in the area at least need to be looked into.

L44 gets very warm or hot. If I move it at all it will cool down again. Couldn’t find that anywhere else.

 

[nomadradio]

L44 doesn't have the brown-glue rot, does it? I have seen that part destroyed by corrosion.

73

 

[Brian G]

Soooo once again there is no bias at the driver or final. Voltages all check out fine so i assume there must be a bad part up to or prior to the driver?

I replaced c157 , 200 ,214, and r209. The driver also checks out fine. And I believe D50 is ok too. What else could be fault? The only thing is maybe there’s still an issue between L44 and the driver—probably around L44 most likely? Is there a way to safely check current flow in that area or how else can I be sure that isn’t the problem area since voltages do check out fine there?

So my conclusion is that L44 is bad. It’s pretty beat up has a lot of that old glue on it and seems to be a source of problems. If that’s the case I’m screwed because I don’t have another one unless someone knows what could be used as a substitute I could buy? It seems like such a cruddy part design. So fragile.