Nakamichi Reciever 2 problems

[katanassn]

I have a nakamichi reciever 2, which seems to cut out at a certain not to high volume.

I opened it up and it was full of dust, everything was coated.

Could this be causing the problem with the cutting out?

Hoe best to clean the amp out? Vacum cleaner and a soft brush?

Or would compressed canister air be better?

Cheers

[anatech]

Hi katanassn,
Compressed air and a soft 1" paint brush by far. That's how I do it. 75 lbs of air pressure gets most of the dust out.

What is the resistance of your speakers? These may have been good to 6 ohms minimum. I can't remember.

-Chris

[XEAGLEKEEPER]

Sounds like a dirty volume control also. Clean switches and controls after dedusting. Use deox-it for best results.

[anatech]

Hi XEAGLEKEEPER,
No mention of volume control crackle when rotating the control.

In keeping with normal diagnostic procedure (for me), play music at a normal, non-cutting out level. Slowly operate the controls one by one and note any noise / crackling you hear.

-Chris

[XEAGLEKEEPER]

which seems to cut out at a certain not to high volume.



Anatech this above statement would lead me to at least check out the volume control (very dirty or possibly broken) and after you blow 75 psi you are bound to get dust inside the controls so as a follow up I would clean the controls, I mean if the circuit board is covered with dust - cleaning the switches and controls would be a "no brainer".

[anatech]

Hi XEAGLEKEEPER,
Respectfully, I'll disagree with you there. The last thing you should do is clean a control that doesn't require cleaning. Especially if there may be loose dust inside that will turn into a sticky, messy mat. If the control does require cleaning, the simple tests I outlined will point that out. So we should wait for katanassn to post his findings.

I used to be an authorized warranty centre for Nakamichi and many other brands. This model was just out of warranty when I sold the shop, so I didn't see any of these. But I do own a TA-2 which is even older. Controls are now an issue & I'll be stripping it soon.

One question for katanassn, is the relay cutting out and coming back in?

-Chris

[XEAGLEKEEPER]

A vaccuum and a soft brush would work. Just be real careful and don't exert to much pressure on components. If you use compressed air don't forget eye and hearing protection this would be best done outside.Beyond a good cleaning you might want to start looking for a service manual, just in case.

[katanassn]

Originally posted by anatech


One question for katanassn, is the relay cutting out and coming back in?

-Chris

Welll i cleaned it out with a soft brush and canned air. It was full of dust and hair.

Yep the relay cuts in and out, prior to cleaning but the volume didn't crackle.

Haven't tested it yet as I've been really busy.

[anatech]

Hi katanassn,
Okay, that means your protection circuit is being triggered. An open emitter resistor or emitter-base junction on an output can cause this. The set would sound fine at lower levels as the driver as doing all the work.

At this point I would hook the unit up to a dummy load, feed a sine wave in and look at the waveforms in the output section. It's also possible that the filtering cap in the protection network has gone open.

-Chris

[Original Burnedfingers]

Chris,

This reminds me of an amp I worked on a while back. It would pass a sine wave to full power but the protection circuit would cut out under slightly loud music.