TK-790H not powering ON

[ffmedic14]

Hey Guys,

Looking for a little help; was just issued a TK-790H for the FD that I volunteer for. It is replacing a TK-730H (we are going narrowband). The problem is, I can't seem to get the radio to power ON. It does have the full-featured remote head. I have tried several times w/o sucess; I can hear the relays in the chassis click when the power button is pressed but no display. The radio WAS working when it was removed from an engine.............any ideas??? Thanks!!

 

[jim202]

By any chance is the radio looking for a +12 volts for an ignition sense input on the accessory connector?

Many of those radios get programmed for ignition sense and are looking for the +12 volts input to turn
the radio on. If you have a new radio out of the box, there is a good chance that is your problem. Once
you get it on, you can probably go in and shut that ignition sense off if you don't want it.

Jim

Hey Guys,

Looking for a little help; was just issued a TK-790H for the FD that I volunteer for. It is replacing a TK-730H (we are going narrowband). The problem is, I can't seem to get the radio to power ON. It does have the full-featured remote head. I have tried several times w/o sucess; I can hear the relays in the chassis click when the power button is pressed but no display. The radio WAS working when it was removed from an engine.............any ideas??? Thanks!!

 

[code3cowboy]

Was the radio turned off prior to being pulled from the engine?

 

[ffmedic14]

Not sure if the radio was turned "off" prior to being removed from the engine. I did not remove it. As for the igniton sense; which pinout do I need to apply +12V to?? There was only the constant power leads & grounds when I received the radio....Any help would be great!!! Thanks!

 

[DPapay]

Pin 1 on the control heads accessory connector is ignition. Ignition option is enabled by moving a soldered jumper within the chassis.

 

[ffmedic14]

Thanks very much for all the help guys!! Unfortunately, I finally gave up and took the radio to a local shop & they found that the internal fuse had blown. $5 replacement and now we are good to go. I didn't realize that these had an internal fuse...anyone able to give me a little more insight?? Is this something that i may be able to replace in the future, god forbid it blows again??

 

[Luis_R]

Thanks very much for all the help guys!! Unfortunately, I finally gave up and took the radio to a local shop & they found that the internal fuse had blown. $5 replacement and now we are good to go. I didn't realize that these had an internal fuse...anyone able to give me a little more insight?? Is this something that i may be able to replace in the future, god forbid it blows again??

If you are skilled in soldering and desoldering on surface mount equipment, it's a piece of cake. The fuse is on the front of the controller board ( fuse F502 ). Look at the attachment.

 

[code3cowboy]

They frequently blow when someone decides to jump start something with the radio plugged in and turned on. I see this happen at least once per month.

It was my next suggestion after trying the ignition lead.

 

[ffmedic14]

Awesome!! Thanks very much guys.

 

[ffmedic14]

Anyone know what the igniton sense lead should be fused at?? The fuse (internal) I think says 1.8A and I have the lead currently fused at 3A. The main power lead is fused at 30A. Just looking for confirmation. Thanks very much in advance.

 

[ramal121]

The KCT-18 ignition sense cable comes pre-loaded with a 3 amp fuse. Looks like you are good to go all the way around....

 

[ffmedic14]

Cool, thanks!!! Now, any idea why the internal fuse would keep blowing??? When I first was issued the radio it was already blown. (Came out of a piece of fire apparatus) I had it replaced and life was good. Installed in my truck and fused appropriately on both the power leads & ignition lead. Radio worked fine for several months and then just shut off. (No, I did not jump the truck or anything like that) I tested everything and then removed the chassis and discovered that the damn internal fuse had blown again!!! Any insight as to what may have happened??? The radio had been in an engine for several years wired the same way and NEVER had an issue............

 

[code3cowboy]

Where is your power coming from? Could there have been a voltage spike? Where is the body of the radio mounted? Could you have spilled something that shorted the radio? Where are you getting the ignition feed from? Did you use the right type and rating of fuse?

 

[ffmedic14]

Power is directly from the battery and fused at 30A, the chassis is mounted directly to the back wall of my pickup behind the rear seat. No chance of spillage. Ignition feed is from an open circuit in the fuse panel and fused at 3A (mini ATC fuse). As for a voltage spike, not sure.......................what would typically cause that??

 

[code3cowboy]

Starting the vehicle is the most frequent, followed by jump starting.
Have you gone over the boards and checked to see nothing is arcing?
Are any of your wires loose?

Im really thinking about this issue and thumbing through the TSBs and service manuals.