Amp

[Dale W]

This is a Nakamichi 730 receiver, very sweet piece with some cool functions. Almost all the front panel controls are heat sensitive !!!! you can depress them with anything you like and they will not react. olny the heat from your finger will work.Power button,funtion controls,tape monitor,station preset, etc. Manual controls are volume preset balance, bass, treble, tuning threshold and fine tuning knobs.

very nice fm receiver, it has stereo mode, dolby fm and hi blend.

Here in lye's my problem: some of the heat sensitive controls are sticking and not responding to my touch. I sent this amp away 8 years ago for the same problem, it was gone for 2 months and came back with a healthy bill attached. This sucker weighs 50lbs and i have to send it 1000km away to have it repaired $$$$$$.

Does anyone know what i would use to clean the contacts inside, aparently this is all that needs to be done.

[sunnysal]

that's a receiver...how does it sound? tony

[Dale W]

This little piece sounds great , you would'nt believe it. I hooked it into my k-horns and man they really danced. I have not had this apart yet and don't know what kind of out put stage it has but it sure is HEAVY . The sound is very clean and crisp. Nak makes some good stuff like the pa-7 and pa-5. I don't even know how old it is, maybe someone else might know.

[sunnysal]

I have a 70's technics cassette recorder that also has heat sensitive switches. I used plain old rat shack contact/tuner cleaner spray on them and they improved somewhat, they still tend to be somewhat finicky however. Tony

[lynnm]

Hi Dale

Got your email - Thanks! The invitation goes both ways I'm in the High River phone book.

With regard to cleaning those switches the question is whether the problem is with the sensors themselves or with the glass or plastic in front of them. Rather than using contact cleaner I would be inclined slightly moisten a soft cloth or tissue with water and gently wipe the surface of each of the sensors and the glass or plastic behind which they sit.

Do Not Use Windex or similar ammonia based cleaners as they can degrade plastics and cause clouding which in addition to spoiling the appearance of the unit would likely impair the cover's capacity for heat transfer. If you find the need to use something to cut through the accumulated dirt then I suggest a weak solution of water with a little dishwashing liquid - nothing stronger.

[Dale W]

If we look at the middle row of switchs, these are the ones in question. They are steel or chrome plated something. I don't know what physical principal they work on, you don't have to depress them. All you have to do is touch one or even hold your finger 1 mm away and they will activate.

Change in electricial signature due to heat from finger ????? I don't know, just guessing here. IF i ramble on any more i'm going to make myself appear ignorant. I do not have a manual for this unit yet.

[chickey]

These may be capacitive voltage sensors (I have these on my Lightstar amps). Typically, there is a control inside the unit that allows the sensitivity of the touchplate to be adjusted. If you have a service manual for the unit, you could probably locate the control mechanism. It was a simple 1/4 turn of a screwdriver once I found mine.

Not sure if this helps, but it may shed some light on the problem.

Colin

[lynnm]

I suspect that cleaning those switches will not clear up the problem. That type of switch is known as a proximity switch. An unstable field is generated which is detected by a receiving element. So long as that field is unchanged the switch remains closed or open as the case may be. Bringing a finger into close proximity causes a shift in the frequency of the field. This results in the circuit changing the operating state and opening or closing the switch. This type of switching scheme is frequently used for elevators etc.

An interesting application of a similar technology is to be found in the theremin which is described here:

http://www.theremin-saw.com/theremin.htm#how

[Dale W]

Well i'm not sure if thats good news or not !! I think i'll try taking it apart and see whats up inside and if i can't figure out the problem than away she goes. Hate to get rid of this girl , such a nice fm unit.

[artto]

I have to agree with some of the previous posts that cleaning may not be the answer. On the other hand, if it is, you will want to try Caig Laboratories "ProGold G5". This stuff works great. Use it on ALL connections/connectors! Big improvement in the sound. Almost like hard wiring everything.

http://www.caig.com/

Side Note: I had been in the early stages of renovating my listening room & giving everything a "tune-up". A new audiophile friend was over for a first time listening session. Hardly any of the connections anywhere in the system had been disconnected & cleaned in many years. After about a half hour of listening he mentions that sound from the right side of the system (K-horn L&R, Belle center) sounded "smoother, more open & detailed for some reason". Guess what!? The right side speaker was the only component in the system that had every one of its non-soldered connections cleaned with this stuff. This was a truely blind test, so this stuff obviously works.