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Hi all,
I have a fairly old 7500. The power cable was shorting. I fixed it and the unit worked fine for a while. Now it blows the fuse every time I turn it on. I checked the big black surface mount cap at the plug recepticle, and it is fine.
What do you think is the problem?
Have you tried a different power cord?
I have not tried a different cord but I have hooked it up to a 12V bench power supply (+12V alligator clip to switch solderball and ground to radar shroud. It turned on for about 10sec and then excess current shut supply down. So do not think it is the power cord. By the way, just to ensure I do not have any of the wires twisted, do you know the order of the wires in the RJ12 connector?Quote:
Originally Posted by davekr
Sorry I do not, I would do yourself a favor and go to radio shack and try one or walmart for that matter. If it happens again you know it's the unit. I hope that's not the case.
I will do that this weekend. If it is the unit, a guy at work said it might be one or more of the transistors but he did not know if they are PNP or NPN or what type they may be. Any clues?Quote:
Originally Posted by davekr
No something like that you will need to send it for service. Or go to best buy and buy one and put yours in the box and take out the new one and then tell them it's defective. :twisted: :twisted:
Hold on a sec...This power cord doesnt have an inline fuse? That should be blowing long before that bench supply shuts down. About how much power is the unit drawing?
Well the fuse in the cord is a 2 Amp fuse so that would indicate that your unit has a serious failure, something is completely shorted to ground. Check the input filter tantalum caps, those are yellow on my 7500, but I know that those can be black as well. There should be a large one marked 226 near to the plug. Tantalums will short quickly if a reverse voltage is placed across those and with your "shorting power cable" experience, that would be something to check. I you have an ohmmeter measure across those caps, maybe you'll get lucky.Quote:
Originally Posted by tbob
Why don't you go and just get another power cord and try it? :roll:
Tried it and it still blew fuse. The bench power supply was seeing over 3 AMPS. I will try test the caps.Quote:
Originally Posted by davekr
Thnaks