UPDATE: Nakamichi BX-300 Repair - NEW Problem
 

Hello Everyone:

Here is an update on my Nakamichi BX-300. This is the same tape deck
that has flickering
digits in its counter and keeps resetting its counter back to "0000"
AND keeps
putting itself back into PLAY mode - even when there is no tape in the
machine.

I have solved a couple of problems but caused another.

First of all, I have narrowed it down to IC701 on the counter PC
board. This IC
chip (microprocessor) apparently was faulty.

In the Nakamichi service manual, this chip is listed as LM6416E-106

I found an LM6416E at an online parts source that caters to repair
techs. There was no suffix of any kind
after the "E". It is just a "regular" LM6416E. I thought this IC was
the same
as the faulty one in the BX-300, but it's not.

FIRST THE GOOD NEWS: After I installed the new LM6416E chip, the deck
no longer
has flickering numbers in the counter and the deck no longer puts
itself into
PLAY mode, so I'm happy about that....

NOW THE BAD NEWS: THE COUNTER NO LONGER WORKS.

Instead of "0000" when you first turn the deck on, you see "88_
_" (the
underlines represent the two missing digits).

When you press PLAY the counter DOES NOT change.

When you press REW or FF, the counter briefly shows this:
"8_8_" ...and then
changes to this: "8_ _8" ...and DOES NOT change.

Unless someone has any ideas, I am either going to have to find a
parts deck to
get the proper LM6416E-106 chip, or I am going to have to live without
the counter.

I really wouldn't bother with this deck as I have other Naks that are
much
nicer, but this BX-300 has great sentimental value because it was my
very first
piece of Nak equipment.

DOES ANYONE HAVE ANY IDEAS HOW I CAN CORRECT THE PROBLEM - OR DOES
ANYONE HAVE
ANY SPARE NAKAMICHI IC CHIPS?

THE CHIP THAT CAME OUT OF MY BX-300 HAS THESE MARKINGS ON IT: 106
B-6368A 4F2

Thanks in advance to all who can help me with this!

UPDATE: Nakamichi BX-300 Repair - NEW Problem
 

Naive response...

Is it possible that the -106 version (if that, indeed, is what the number
represents) has custom ROM that handles the counter? This is unlikely, but
who knows?

There's also the possibility that, in making repairs, you damaged something
related to counter operation.

UPDATE: Nakamichi BX-300 Repair - NEW Problem
 

William:

Not a naive response at all! It turns out that the -106 version does
seem to be a customized version of the LM6416E chip. I did some online
searching, and a couple of electronics wholesalers list part number
LM6416E-106 with manufacturer listed as Nakamichi. So either
Nakamichi manufactured the chip themselves, or the more likely
scenario is that this chip was custom manufactured for Nakamichi.
Aaargh!

On May 27, 12:21 pm, "William Sommerwerck"
wrote:
Naive response...

Is it possible that the -106 version (if that, indeed, is what the number
represents) has custom ROM that handles the counter? This is unlikely, but
who knows?

There's also the possibility that, in making repairs, you damaged something
related to counter operation.

UPDATE: Nakamichi BX-300 Repair - NEW Problem
 

EADGBE wrote:
William:

Not a naive response at all! It turns out that the -106 version does
seem to be a customized version of the LM6416E chip. I did some online
searching, and a couple of electronics wholesalers list part number
LM6416E-106 with manufacturer listed as Nakamichi. So either
Nakamichi manufactured the chip themselves, or the more likely
scenario is that this chip was custom manufactured for Nakamichi.
Aaargh!

On May 27, 12:21 pm, "William Sommerwerck"
wrote:

Naive response...

Is it possible that the -106 version (if that, indeed, is what the number
represents) has custom ROM that handles the counter? This is unlikely, but
who knows?

There's also the possibility that, in making repairs, you damaged something
related to counter operation.



The LM6413 is just a general purpose 4 bit microprocessor with on board
ram and rom (PDF's are on line). Without the onboard rom programmed, its
totally stupid with no directions to follow. Unless you find the -106
version which has the rom preprogrammed, you would need the firmware and
a programmer to program a blank LM6413 (if that's even possible).

http://www.datasheetarchive.com/pdf/...datasheet.html


Before you changed the chip, did you check for proper power supply rail
voltage, ripple, and that any filter caps were not defective?



Bob

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UPDATE: Nakamichi BX-300 Repair - NEW Problem
 

Bob:

Thanks for your very informative response. It explained a lot!

Yes, I did thoroughly check all power supply voltages, both at the
power supply circuit and at the IC itself. I checked DC voltage and
AC ripple. All numbers were stable and well within spec. Didn't
check any filter capacitors, though.

On May 27, 2:04 pm, Bob Urz wrote:

The LM6413 is just a general purpose 4 bit microprocessor with on board
ram and rom (PDF's are on line). Without the onboard rom programmed, its
totally stupid with no directions to follow. Unless you find the -106
version which has the rom preprogrammed, you would need the firmware and
a programmer to program a blank LM6413 (if that's even possible).

http://www.datasheetarchive.com/pdf/...6416-datasheet...

Before you changed the chip, did you check for proper power supply rail
voltage, ripple, and that any filter caps were not defective?

Bob

UPDATE: Nakamichi BX-300 Repair - NEW Problem
 

"EADGBE"

Not a naive response at all! It turns out that the -106 version does
seem to be a customized version of the LM6416E chip. I did some online
searching, and a couple of electronics wholesalers list part number
LM6416E-106 with manufacturer listed as Nakamichi. So either
Nakamichi manufactured the chip themselves, or the more likely
scenario is that this chip was custom manufactured for Nakamichi.
Aaargh!



** The LM6416 is a programmable micro-computer - aka a microcontroller.

Equipment makers purchase them as "blanks" and then program them with the
code needed to do the task in a particular product. The code is invariably
kept secret - so only the equipment maker can supply spare ones.

If the supply of spares dries up or the maker goes out of business like Naka
did, there is no way to get a replacement.




....... Phil

UPDATE: Nakamichi BX-300 Repair - NEW Problem
 

I thought as much, Phil. Thanks!

It's funny...I went and Googled "LM6416E-106" and there are TONS of
these sitting around. Unfortunately, they are all in Hong Kong, it
seems! I can get them for $10-$20 apiece plus shipping to the USA,
which brings the price up to 50 or 60 bucks.

I think I'll just wait and get a friend's Nak parts donor deck. His
deck has a digital counter in it as well, very likely powered by the
same IC. And even if it isn't, I'm sure there is something in there I
can use at another time.

UPDATE: Nakamichi BX-300 Repair - NEW Problem
 

"EADGBE" wrote in message
ups.com...

I thought as much, Phil. Thanks!

It's funny...I went and Googled "LM6416E-106" and there are TONS of
these sitting around. Unfortunately, they are all in Hong Kong, it
seems! I can get them for $10-$20 apiece plus shipping to the USA,
which brings the price up to 50 or 60 bucks.

**Good luck with that. Last timne I tried to get some oddball parts, I was
presented with some company in China who ONLY wanted payment via Western
Union (there's a scam right there), or they wanted minimum orders totalling
US$300.00 - $500.00.


I think I'll just wait and get a friend's Nak parts donor deck. His
deck has a digital counter in it as well, very likely powered by the
same IC. And even if it isn't, I'm sure there is something in there I
can use at another time.

**Depends on the deck.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

UPDATE: Nakamichi BX-300 Repair - NEW Problem
 

"EADGBE" wrote in message
ups.com...

I thought as much, Phil. Thanks!

It's funny...I went and Googled "LM6416E-106" and there are TONS of
these sitting around. Unfortunately, they are all in Hong Kong, it
seems! I can get them for $10-$20 apiece plus shipping to the USA,
which brings the price up to 50 or 60 bucks.

**Good luck with that. Last time I tried to get some oddball parts, I was
presented with some company in China who ONLY wanted payment via Western
Union (there's a scam right there), or they wanted minimum orders totalling
US$300.00 - $500.00.


I think I'll just wait and get a friend's Nak parts donor deck. His
deck has a digital counter in it as well, very likely powered by the
same IC. And even if it isn't, I'm sure there is something in there I
can use at another time.

**Depends on the deck.


--
Trevor Wilson
www.rageaudio.com.au




--
Posted via a free Usenet account from http://www.teranews.com

UPDATE: Nakamichi BX-300 Repair - NEW Problem
 

On May 27, 1:34 pm, EADGBE wrote:
Bob:

Thanks for your very informative response. It explained a lot!

Yes, I did thoroughly check all power supply voltages, both at the
power supply circuit and at the IC itself. I checked DC voltage and
AC ripple. All numbers were stable and well within spec. Didn't
check any filter capacitors, though.

On May 27, 2:04 pm, Bob Urz wrote:





The LM6413 is just a general purpose 4 bit microprocessor with on board
ram and rom (PDF's are on line). Without the onboard rom programmed, its
totally stupid with no directions to follow. Unless you find the -106
version which has the rom preprogrammed, you would need the firmware and
a programmer to program a blank LM6413 (if that's even possible).

http://www.datasheetarchive.com/pdf/...6416-datasheet...

Before you changed the chip, did you check for proper power supply rail
voltage, ripple, and that any filter caps were not defective?

Bob- Hide quoted text -

- Show quoted text -

If I were you, I would put the original chip back in with the correct
programming, then check ALL the input pins for glitches, especilly the
ones that sense the tape movement, how does that part work, is there
an optical sensor or what, check the logic signals from these sensors,
maybe try a 0.1uF cap to ground on each one to remove any glitches,
the switches might be dirty causing the software based counter to
misbehave if it was not designed to have some debouncing feature...

Mark