TK-790H Display went out.

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trcostan
Posts: 1
Joined: Mon Feb 02, 2009 6:05 pm

TK-790H Display went out.

Post by trcostan »

I plugged in my programming cable and poof went the display lcd and back light, the radio still seems to come on but it cant be controlled or keyed. all I can think it is shorted out the v+ or their was some sort of ground loop. So I have two questions.

1. Anyone had a similar exp? If so what did it fry? I traced several of the surface mount components to see of one was messed up in the head and no luck this brings me to? Two.

2. I need a schematic for the 790h.

Thanks.

Tyler.
va3wxm
Posts: 14
Joined: Tue Nov 29, 2005 10:02 am
Location: Toronto, Canada

Re: TK-790H Display went out.

Post by va3wxm »

Sounds like something may have shorted out. There is a chip(?) fuse for the +v supplied to the head. It is located on the main board near where the drawer-to-head pigtail is.

I found a PDF of the 790 service manual on Google. If you can't find it let me know and I'll see if I can dig it up and e-mail it to you.

I did the same thing to an 890 once. From then on I always power down the radio before hooking up the programming cable!
KF6OWC
Posts: 33
Joined: Tue Mar 18, 2008 8:43 pm

Re: TK-790H Display went out.

Post by KF6OWC »

I have had this problem before, actually i have a radio sitting on the bench right now with the similar problem. You can order the fuse from kenwood around 4 bucks a piece little SMD thing goes on the controll board. or you can solder leads to a round type fuse, use a 1.5 amp fuse and solder the leads to the pads where the SMD goes. I Have done this before and it worked fine, just be careful not to heat the pads up too much. I also had a head go out, burnt trace behind the power button. Fixed that but it think that what ever burnt the trace also took out the LCD driver. I tried the a new LCD but no luck. I sent it off, not worth the time wasted trying to figure it out. I recomend using a round type fuse and fixing it that way. good luck.
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