Good ol' fashing kick fixes problem

[mzeitlin3348]

Good ol' fashion kick fixes problem

I have a Kenwood KT-815 which I received free as part of another purchase. I turned it on and it worked (not that surprisingly).

It has the electronic locking mechanism whereby tuning close to a station automatically centers the tuning.

But I notice an interesting problem. The tuning signal strength would often times be weak despite a good antennae. Frustrated, I banged on it with my hand - tap - tap. And lo and behold, the signal strength jumped to full (5 out of 5 on the signal meter) and the sound clear as a bell. I tapped it again and it fell back to 3 out of 5 with a raspy sound. Tap tap again, back to full strength.

Knowing nothing else - any ideas on where to look. I suspect a loose connection somewhere, but where to consider first? Could it be a discrete component (transistor).

The tapping works best right on the tuning knob - and I don't have to tap hard or anything (I don't have to rattle the whole case) - just thump thump with my hand.

It would be great if it's trivial.

 

[onepixel]

ooh...you have the Midas touch. Could you come over and slap some of my stuff around?! Just kidding.

It's most likey a loose connection. Try opening her up and take a peek with a pen light. Just like CSI. Your eye will focus on the beam. Just methodically scan all the soldered connections. Also make sure all the wire connectors are snug.

Cheers

 

[Lefty]

Might also be a case of the tuning capacitor needing a good cleaning

Lefty

 

[Soundthought]

I like to call that a "love tap".

 

[OvenMaster]

A "love tap" with a screwdriver handle fixed my Yamaha's intermittent right channel. Gotta get the relay cover off to clean the contacts, but this worked in a pinch.
Tom

 

[mzeitlin3348]

How do you clean the tuning capacitor? I read that if you don't clean it correctly it can really screw up your tuning!

I'll do a search here to see if this has been covered.

 

[kcollins4]

mz,
Some high pressure air is best. Just blow the dust out. The main thing is to avoid ever getting a residue of any kind in there.

 

[Lefty]

How do you clean the tuning capacitor? I read that if you don't clean it correctly it can really screw up your tuning!

I'll do a search here to see if this has been covered.

Well I've had good luck just applying deoxit at both end bearings. I just manually applied via a soaked Q-tip, don't go spraying in this area. Anyway worked the tuning knob back and forth and that did the trick for me. My symptom was nosiy weak receaption only on the lower 25% of the FM scale.

Lefty

 

[mzeitlin3348]

Here's a picture

http://i57.photobucket.com/albums/g230/mjz_3348/kt-815.jpg

I opened up the case. The inside is surprisingly clean.

I took air cleaner and 'sprayed' the tuning cap - and instant results. The signal jumped from poor to strong but then back to poor again. The air didn't permanently change anything, but it must have put air pressure on something.

So I started tapping gently on the screws and the one pointed to in the picture (yellow arrow - not great focus unfortunately) caused instant changes, I was able to get a strong signal when I tapped that one screw. Tap again and poor signal. I tapped on it a few times and the signal became more stable, but I wonder what it does. It has a plastic insulator between the screw and the copper connection. Don't know where it goes after that.

What are these screws? (4 of them/ am/fm?).

The system is stable right now, but I don't know for how long.

Any ideas? (can I turn this screw?)

 

[EchoWars]

Beats me...FM front ends work on magic as far as I'm concerned. :stupid:

See if you can't get Punker X's attention and opinion, but if you haven't tried some DeOxit on the grounding reeds (if it has them) and the end bearings you might be missing an easy fix.

 

[mzeitlin3348]

End bearings? Why would they have anyting to do with this?

(are they in the electrical path?)

 

[Punker X]

The part you are tapping on is a trim cap for a tuned LC tank. Its probably loose. These should be adjusted for peak RF signal and lowest audio distortion at or near 106Mhz. Yours could be maladjusted, or turned out. The screw just squeeze to plated closer together, the plastic acts as the dielectric. When you tap it you are moving the plates closer together, which lead me to believe that it is out of alignment.

You can probably get it working by just adjusting that cap at 106. To get the most from your tuner I would suggest a professional aligment. Would try adjusting anything else with out some knowledge and test equipment.

X

 

[mzeitlin3348]

Thanks Punker X !!! Problem solved.

I adjusted the screw as you described (it was quite loose) - not much I might add, and sure enough - presto. The signal jumped from 3 on the scale to almost 5-pegged. I backed out the screw and it fell back - I went back and forth until the signal was maxed and centered on where the screw ties in best.

Rock solid now across the whole band. I have a decent tuner now.

I noticed, however, that the screw is still quite loose in order to get the max signal. I suspect that in the moves over the years, it probably backed out a bit.

Should I put some 'nail polish' across the screw to anchor it?

This tuner is no where near as good as my KT-9900 or more receivers 9600,7600, but it does have that neat automatic locking feature.

Thanks again!!

 

[Punker X]

No I wouldn't put anything on that screw to hold it in. It will affect the adjustment and or make cap usless.

X