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Problem with Nakamichi BX-300

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Posted on December 13, 2010 at 11:16:48
Tadlo
Audiophile

Posts: 1925
Location: midwest
Joined: March 8, 2003
 My Nakamichi BX-300 cassette deck has a distortion problem. Mechanically the deck is working well, but it produces distortion on playback. About a year ago it started making occasional momentary static-like sounds. They would last a second or so when the deck was still cool and would go away after being in use for a while. This problem gradually got worse. Last week I made a recording on the BX-300 that sounds good when played back on my other deck, but is distorted when played on the BX-300. The distortion is barely noticeable when the output level on the deck is low, but increases with increased level. With the output level full up the distortion is extreme.

Has anyone here encountered this kind of problem before? Does it sound like an easy fix or difficult and expensive? Any advice would be appreciated.

 

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RE: Problem with Nakamichi BX-300, posted on December 13, 2010 at 11:28:21
Marantzguy
Industry Professional

Posts: 2848
Location: Berkeley, CA
Joined: June 21, 2002
 Hi, Tadlo:

There was a period in the production of Nakamichi decks where they used some orange capacitors which failed. Their failure affected many aspects of functionality and might possibly be directly responsible for the type of distortion you may be experiencing.

Richard Links
Berkeley, CA

 

RE: Problem with Nakamichi BX-300, posted on December 13, 2010 at 14:47:40
Tadlo
Audiophile

Posts: 1925
Location: midwest
Joined: March 8, 2003
 Thanks. I've heard about "orange cap disease" but I didn't know what the symptoms are or whether my problem could be caused by it.

 

RE: Problem with Nakamichi BX-300, posted on December 13, 2010 at 16:15:28
Marantzguy
Industry Professional

Posts: 2848
Location: Berkeley, CA
Joined: June 21, 2002
 Hi, Tadlo:

Your problem must be tackled by a professional tech who can trace the circuitry and determine the exact cause. Otherwise, get yourself a bag of new capacitors and start repopulating the circuit board where you see the orange crappy ones.

Personally, I would not spend a nickel on repairs, unless you absolutely are in love with the deck, and would just try to find another to replace it with. Service fees these days are pretty scary and as a result, I see all manner of great (mostly non-working) audio gear being dumped onto varous recycling places and thrift shops.

As a matter of fact, I have a little wall of Nak decks downstairs for this very reason.

Need spare parts for a Nak 480? No problem!

Richard Links
Berkeley, CA

 

RE: Problem with Nakamichi BX-300, posted on December 13, 2010 at 16:34:05
Tadlo
Audiophile

Posts: 1925
Location: midwest
Joined: March 8, 2003
 That is pretty much what I figured. I have several other working decks, including a pristine DR-3 and a CR-1a. The BX-300 is the only 3 head Nak I have, so I hate to see it go, but I can get by without it.

 

I just put my 682ZX into the..., posted on December 14, 2010 at 12:52:46
docw
Audiophile

Posts: 8115
Location: So. California
Joined: July 23, 2004
 Willy Herrman hospital (in No CA). Took her there myself when visiting for the holiday.

You might contact him. Don't know how it will come out, but many folks here feel he's reliable.

 

RE: Problem with Nakamichi BX-300, posted on December 15, 2010 at 00:39:41
tapetech
Industry Professional

Posts: 24
Joined: November 10, 2009
 The defect orange caps are mainly in the bias oscillator, so I don't think it's your problem since your distortion is not recorded on the tape.

My guess is that you have defect output muting transistors. Q108 and Q208. They are 2SC2878. Just cut them out or remove with soldering iron. The deck will work fine without them (just a minor turn-on and off pop will occur)

Let me know if that fixes the distortion.

Tim

 

RE: Problem with Nakamichi BX-300, posted on December 15, 2010 at 07:40:59
Tadlo
Audiophile

Posts: 1925
Location: midwest
Joined: March 8, 2003
 Thanks, that sounds hopeful. I looked inside and there is a lot of stuff in there. Can you give me an idea of where to find the transistors in question and what they look like. Should I get at them from the bottom or top?

 

RE: Problem with Nakamichi BX-300, posted on December 15, 2010 at 10:00:41
tapetech
Industry Professional

Posts: 24
Joined: November 10, 2009
 Yes, there is a good possibility those transistors are defective. If you are looking at the front panel, the transistors are both at the rear, center of the mother board (the large, main circuit board). Board label says: Q108 and Q208. Just cut them out from the top. Or, if you know how to de-solder parts, do that from the bottom. The transistors are black, match-head size and have 3 legs. If you cut them out, make sure the remaining legs do not touch each other.

The BX-300 is a very nice deck and definitely worth repair.

Tim

 

It worked!, posted on December 15, 2010 at 11:31:28
Tadlo
Audiophile

Posts: 1925
Location: midwest
Joined: March 8, 2003
 You were right and removal of those transistors fixed the problem. It does now make a brutal noise when I turn it on. That's no problem as long as I remember to turn it on before the amp is on and selected to 'tape.' Thank you very much. I am really glad that I asked for help here before disposing of the deck.

 

RE: It worked!, posted on December 15, 2010 at 12:41:46
tapetech
Industry Professional

Posts: 24
Joined: November 10, 2009
 Thats good news! Would have been a shame to trash such a nice deck with such a simple defect. Yes, without the muting transistors you will get power on/off pops.

If you know how to solder, you could always buy 2 new muting transistors and install them. MCM Electronics sells them (p/n is 2SC2878). Or buy the transistors and have a friend or local repair shop install them. The service manual is available free on HiFiEngine.com, BTW.

Or, just make sure your main volume control is off when powering up the deck.

 

RE: It worked!, posted on December 15, 2010 at 15:34:48
Tadlo
Audiophile

Posts: 1925
Location: midwest
Joined: March 8, 2003
 Thanks, I may get around to that sometime. But honestly, I'm not sure it's worth the trouble. I've built Dynakits before and installed crossover caps in speakers, but I am a little intimidated by the smallness of these guys, and I cut the old ones out so the wire stubs are still there and might be hard to dig out.

 

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