Hi,

I have a Matrix auto chromatic tuner-to tune instruments-model
SR-4000.

A while back I killed it by-accidentally, I swear!-plugging in a
power cord which was set to a few volts too high (12v instead of 9v)
backwards (reversed polarity).

I would like to fix it. I would like to diagnose the problem and if
I'm lucky repair it (I assume it's a dead component that needs to be
replaced.)

While I am no electronics expert, I am also not a novice. I have
repaired computer hardware (and built a few parts of my own), and even
our home's wiring (although that's really just dangerous, not complex.)

I've got a digital multimeter, variable power supply, all kinds of
wires, alligator clips, etc, hopefully pretty much any tools I might
need. I've also got a large box full of electronic part potpourri that
I got from various places including a supplier a long time ago and from
various electronic devices I've cannibalized.

I have scanned the circuit board and they can be found he
http://img378.imageshack.us/img378/4...erfrontbo8.png
http://img230.imageshack.us/img230/8...nerbackag3.png

I've tried running a couple of small tests, but I don't really know how
to test something like this. For example, I'm not certain how to test
if a transistor is good (I've got an idea but I'd rather hear from
experienced people), or a quick connectivity test reveals nothing
useful since pretty much everything seems to be connected to everything
else, and testing for power returns all kinds of variable voltages that
tell me nothing.

Does anyone have any tips or advice (or maybe a complete walkthrough?)
on how to test and repair this?


Thanks a lot!

--
Alec S.

Alec S. wrote:
Hi,

I have a Matrix auto chromatic tuner-to tune instruments-model
SR-4000.

A while back I killed it by-accidentally, I swear!-plugging in a
power cord which was set to a few volts too high (12v instead of 9v)
backwards (reversed polarity).

I would like to fix it. I would like to diagnose the problem and if
I'm lucky repair it (I assume it's a dead component that needs to be
replaced.)

While I am no electronics expert, I am also not a novice. I have
repaired computer hardware (and built a few parts of my own), and even
our home's wiring (although that's really just dangerous, not complex.)

I've got a digital multimeter, variable power supply, all kinds of
wires, alligator clips, etc, hopefully pretty much any tools I might
need. I've also got a large box full of electronic part potpourri that
I got from various places including a supplier a long time ago and from
various electronic devices I've cannibalized.

I have scanned the circuit board and they can be found he
http://img378.imageshack.us/img378/4...erfrontbo8.png
http://img230.imageshack.us/img230/8...nerbackag3.png

I've tried running a couple of small tests, but I don't really know how
to test something like this. For example, I'm not certain how to test
if a transistor is good (I've got an idea but I'd rather hear from
experienced people), or a quick connectivity test reveals nothing
useful since pretty much everything seems to be connected to everything
else, and testing for power returns all kinds of variable voltages that
tell me nothing.

Does anyone have any tips or advice (or maybe a complete walkthrough?)
on how to test and repair this?


Thanks a lot!



It doesn't look like there's any regulator or protective circuitry on
the power input, I wouldn't be surprised if the reverse polarity killed
the microcontroller or whatever that large Intel chip is.

It's a frequency identifier. How can I test it? Is it replaceable or
even worth it?

James Sweet wrote:
Alec S. wrote:
Hi,

I have a Matrix auto chromatic tuner-to tune instruments-model
SR-4000.

A while back I killed it by-accidentally, I swear!-plugging in a
power cord which was set to a few volts too high (12v instead of 9v)
backwards (reversed polarity).

I would like to fix it. I would like to diagnose the problem and if
I'm lucky repair it (I assume it's a dead component that needs to be
replaced.)

While I am no electronics expert, I am also not a novice. I have
repaired computer hardware (and built a few parts of my own), and even
our home's wiring (although that's really just dangerous, not complex.)

I've got a digital multimeter, variable power supply, all kinds of
wires, alligator clips, etc, hopefully pretty much any tools I might
need. I've also got a large box full of electronic part potpourri that
I got from various places including a supplier a long time ago and from
various electronic devices I've cannibalized.

I have scanned the circuit board and they can be found he
http://img378.imageshack.us/img378/4...erfrontbo8.png
http://img230.imageshack.us/img230/8...nerbackag3.png

I've tried running a couple of small tests, but I don't really know how
to test something like this. For example, I'm not certain how to test
if a transistor is good (I've got an idea but I'd rather hear from
experienced people), or a quick connectivity test reveals nothing
useful since pretty much everything seems to be connected to everything
else, and testing for power returns all kinds of variable voltages that
tell me nothing.

Does anyone have any tips or advice (or maybe a complete walkthrough?)
on how to test and repair this?


Thanks a lot!



It doesn't look like there's any regulator or protective circuitry on
the power input, I wouldn't be surprised if the reverse polarity killed
the microcontroller or whatever that large Intel chip is.

"Alec S." wrote in message
oups.com...
It's a frequency identifier. How can I test it? Is it replaceable or
even worth it?

www.findchips.com

Dave wrote:
"Alec S." wrote in message
oups.com...

It's a frequency identifier. How can I test it? Is it replaceable or
even worth it?


www.findchips.com




That sounds like one of those useless chip brokers that hooks all the
searches. Great if you need to buy 5,000 of them but pointless to the
average person.


What's the symptom of the device? Is it completely dead? Can you trace
the power circuit?

"James Sweet" wrote in message
news3jNg.2909$xr.847@trnddc03...
Dave wrote:
What's the symptom of the device? Is it completely dead? Can you trace
the power circuit?

Yes, it's completely dead (the switch does nothing now). I'm not sure
how to trace it.

--
Alec S.
news/alec-synetech/cjb/net

"James Sweet" wrote in message
news3jNg.2909$xr.847@trnddc03...

www.findchips.com


That sounds like one of those useless chip brokers that hooks all the
searches. Great if you need to buy 5,000 of them but pointless to the
average person.

Gee, maybe next time you can look at the site before you make some
dickheaded un-informed comment about it.

It's consumer-oriented. Yes, it has hooks to search engines in online parts
catalogs of all the major distributors. Would YOU rather search them all
individually?

Alec S. wrote in message
oups.com...
Hi,

I have a Matrix auto chromatic tuner-to tune instruments-model
SR-4000.

A while back I killed it by-accidentally, I swear!-plugging in a
power cord which was set to a few volts too high (12v instead of 9v)
backwards (reversed polarity).

I would like to fix it. I would like to diagnose the problem and if
I'm lucky repair it (I assume it's a dead component that needs to be
replaced.)

While I am no electronics expert, I am also not a novice. I have
repaired computer hardware (and built a few parts of my own), and even
our home's wiring (although that's really just dangerous, not complex.)

I've got a digital multimeter, variable power supply, all kinds of
wires, alligator clips, etc, hopefully pretty much any tools I might
need. I've also got a large box full of electronic part potpourri that
I got from various places including a supplier a long time ago and from
various electronic devices I've cannibalized.

I have scanned the circuit board and they can be found he
http://img378.imageshack.us/img378/4...erfrontbo8.png
http://img230.imageshack.us/img230/8...nerbackag3.png

I've tried running a couple of small tests, but I don't really know how
to test something like this. For example, I'm not certain how to test
if a transistor is good (I've got an idea but I'd rather hear from
experienced people), or a quick connectivity test reveals nothing
useful since pretty much everything seems to be connected to everything
else, and testing for power returns all kinds of variable voltages that
tell me nothing.

Does anyone have any tips or advice (or maybe a complete walkthrough?)
on how to test and repair this?


Thanks a lot!

--
Alec S.


from my file
http://www.divdev.fsnet.co.uk/repair2.htm

Matrix SR 4000 auto chromatic guitar tuner, 1993?
Owner had connected an external 9V ps reversed
and knocked out the 78L05 as no reverse protection.
Replaced V Reg and cut trace to switch to put
a small 150mA diode in line
I was intrigued by another 3 pin TO92 device marked
8054
HN
3C31
Presumably working order - just wondered what it did.
Probably 8054HN not 8054 datecode , by Seiko,
activation voltage 3.8V to 4.2V, battery monitor.
One line is connected to INVERSE READ of the 80C51 micro
, I didn't trace any other lines.
Seems odd having this sophistication to hold
the micro from erroneous but not fatal operation
but no diode protection against battery or ext ps reversal,
especially in a product destined for musos.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Thanks for the reply, I see you've worked on two of them. It doesn't
say whether or not you managed to fix the one that is similar to my
case. I don't suppose you remember how it turned out?-it won't be 15
years ago, but it might be up to 13. :-|


N Cook wrote:
from my file
http://www.divdev.fsnet.co.uk/repair2.htm

Matrix SR 4000 auto chromatic guitar tuner, 1993?
Owner had connected an external 9V ps reversed
and knocked out the 78L05 as no reverse protection.
Replaced V Reg and cut trace to switch to put
a small 150mA diode in line
I was intrigued by another 3 pin TO92 device marked
8054
HN
3C31
Presumably working order - just wondered what it did.
Probably 8054HN not 8054 datecode , by Seiko,
activation voltage 3.8V to 4.2V, battery monitor.
One line is connected to INVERSE READ of the 80C51 micro
, I didn't trace any other lines.
Seems odd having this sophistication to hold
the micro from erroneous but not fatal operation
but no diode protection against battery or ext ps reversal,
especially in a product destined for musos.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Hi!

It's a frequency identifier. How can I test it? Is it replaceable or
even worth it?

It's actually an 80C51 microcontroller. If it is fried, you'll not only have
to replace it, but also the code that was programmed into it. Finding
another 80(C)51 isn't going to be so bad. It's getting the code that makes
it run that will be the hard part. You'd almost have to find another example
of a working unit and try to get the code out of it somehow.

Have you tried the manufacturer to see if they would repair it?

William

William R. Walsh wrote:
It's a frequency identifier. How can I test it? Is it replaceable or
even worth it?

It's actually an 80C51 microcontroller. If it is fried, you'll not only have
to replace it, but also the code that was programmed into it. Finding
another 80(C)51 isn't going to be so bad. It's getting the code that makes
it run that will be the hard part. You'd almost have to find another example
of a working unit and try to get the code out of it somehow.

The code is to identify an input frequency. It's an instrument tuner,
so the code is pretty important.

Have you tried the manufacturer to see if they would repair it?

No, it's really old and would probably cost much, much more to have
professionally repaired than to buy a new one. Part of why I want to
repair it myself (besides that I'd rather not spend money I don't have)
is to do an electronics project since I haven't done one in a while.
Also, I feel awful that I wasted a perfectly good thing, and would like
to alleviate that feeling.

--
Alec S.

No, it's really old and would probably cost much, much more to have
professionally repaired than to buy a new one. Part of why I want to
repair it myself (besides that I'd rather not spend money I don't have)
is to do an electronics project since I haven't done one in a while.
Also, I feel awful that I wasted a perfectly good thing, and would like
to alleviate that feeling.


If the chip is bad you could probably write some code for an AVR or PIC
to accomplish the same thing, it can't be too terribly complex.

Alec S. wrote:
Hi,

I have a Matrix auto chromatic tuner-to tune instruments-model
SR-4000.

A while back I killed it by-accidentally, I swear!-plugging in a
power cord which was set to a few volts too high (12v instead of 9v)
backwards (reversed polarity).

I would like to fix it. I would like to diagnose the problem and if
I'm lucky repair it (I assume it's a dead component that needs to be
replaced.)

While I am no electronics expert, I am also not a novice. I have
repaired computer hardware (and built a few parts of my own), and
even
our home's wiring (although that's really just dangerous, not
complex.)

I've got a digital multimeter, variable power supply, all kinds of
wires, alligator clips, etc, hopefully pretty much any tools I might
need. I've also got a large box full of electronic part potpourri
that
I got from various places including a supplier a long time ago and
from
various electronic devices I've cannibalized.

I have scanned the circuit board and they can be found he
http://img378.imageshack.us/img378/4...erfrontbo8.png
http://img230.imageshack.us/img230/8...nerbackag3.png

I've tried running a couple of small tests, but I don't really know
how
to test something like this. For example, I'm not certain how to
test
if a transistor is good (I've got an idea but I'd rather hear from
experienced people), or a quick connectivity test reveals nothing
useful since pretty much everything seems to be connected to
everything
else, and testing for power returns all kinds of variable voltages
that
tell me nothing.

Does anyone have any tips or advice (or maybe a complete
walkthrough?)
on how to test and repair this?


Thanks a lot!

--
Alec S.

1: The 80C51 is a pre-programmed microcontroller. Tektronix used bugs
like this in the 1730/1/5 scopes. The point is they didn't set any of
the protection features so I read out the program from a working unit,
programmed it into an 8751 (actually 8752 but the concept is the same)
and brought the other scope back to life. The two-fold hitch is you
need a programmer and a working chip AND the protection bits NOT set.

2: Someone else noted a 78L05 regulator that may have failed. There
certainly is some sort of regulator as the 8051 family is 5 volts and
will let the magic smoke out with 9 volts. There might be a protection
diode on the power input to protect just this mode. If that failed, an
ohm meter on the power input would read nearly 0.

My bet is the processor is still OK and repairing the regulator(s) will
bring it back.

GG

wrote:
My bet is the processor is still OK and repairing the regulator(s) will
bring it back.


That's what I'm hoping. Can you advise me on how to test the
regulator(s)? (I'm not even sure which one it is.)

Thanks.

--
Alec S.

In article .com, "Alec
S." wrote:

wrote:
My bet is the processor is still OK and repairing the regulator(s) will
bring it back.


That's what I'm hoping. Can you advise me on how to test the
regulator(s)? (I'm not even sure which one it is.)

Alec-

I don't see one leaping out at me in your photo. As I recall, the 78L05
is about the size of a small plastic transistor.

Find the 80C51 data to see which are the power pins, and trace the plus
lead to see what feeds it. Similarly, trace the power connector pins to
see where they go. They should meet at the 78L05.

Fred

Fred McKenzie wrote:

That's what I'm hoping. Can you advise me on how to test the
regulator(s)? (I'm not even sure which one it is.)

Alec-

I don't see one leaping out at me in your photo. As I recall, the 78L05
is about the size of a small plastic transistor.

Find the 80C51 data to see which are the power pins, and trace the plus
lead to see what feeds it. Similarly, trace the power connector pins to
see where they go. They should meet at the 78L05.

Look at:
http://img378.imageshack.us/img378/4...erfrontbo8.png

The upper right corner, above the jack, left to the 2 electrolytic
capacitors, there is one transistor-like (TO-92 case) component. it's
exactly where the positive lead (as seen in the solder-side photo of the
unit) coming from the DC jack ends.

Replace it, it's cheap and it's toast anyway, if you reversed the polarity.

Matti

Matti Adolfsen wrote:
Fred McKenzie wrote:
My bet is the processor is still OK and repairing the regulator(s) will
bring it back.

That's what I'm hoping. Can you advise me on how to test the
regulator(s)? (I'm not even sure which one it is.)

I don't see one leaping out at me in your photo. As I recall, the 78L05
is about the size of a small plastic transistor.

You're right, it's too dark and receded to see. I've bent the two
components back a bit and scanned it closer:

http://img53.imageshack.us/img53/766...sistorsuz9.gif

The one to the left is marked "8054 HN 3C31". The one to the right is
marked "S78L 05ACZ 326"

I don't know how to test if the 78L05 is good or not. If it is bad,
I'm guessing that an electronics or surplus store would have them
right?


Find the 80C51 data to see which are the power pins, and trace the plus
lead to see what feeds it. Similarly, trace the power connector pins to
see where they go. They should meet at the 78L05.

I've checked the datasheet for the pinout:

http://img245.imageshack.us/img245/2033/pinoutuh0.gif

If you mean the VCC, it is connected on the component side and goes all
the way around to connect to the 78L05 (on the Input pin).


Look at:
http://img378.imageshack.us/img378/4...erfrontbo8.png

The upper right corner, above the jack, left to the 2 electrolytic
capacitors, there is one transistor-like (TO-92 case) component. it's
exactly where the positive lead (as seen in the solder-side photo of the
unit) coming from the DC jack ends.

There's also another component between the two capacitors. You can see
it in the close up picture above. Is that the one you mean? The one
on the left is an "8054 HN 3C31" which an Internet search brings up
almost nothing for, except the brief in which N Cook mentioned above,
stating that it was "intriguing".


--
Alec S.

In article . com, "Alec
S." wrote:

Matti Adolfsen wrote:

The one to the left is marked "8054 HN 3C31". The one to the right is
marked "S78L 05ACZ 326"

I don't know how to test if the 78L05 is good or not. If it is bad,
I'm guessing that an electronics or surplus store would have them
right?

Alec-

In your situation, substitution may be the best way to test the 78L05.
Otherwise you can search the web for a connection circuit. Then remove it
from the circuit, apply a voltage to the input through a current-limiting
resistor and measure the output. Be sure to note its orientation on the
PCB before removing it!

It should be easy to find. An electronics shop that carries the NTE
series of replacement semiconductors is likely to have one. Otherwise
search the web for places like Digikey and Mouser. The trick will be to
find a place that will sell you just one (or two for a spare), without a
huge minimum order charge.

Fred