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HELP - Please Identify These Two Parts....................

  • Thread starter Reinhard Zwirner
  • Start date
E

EADGBE

I have a "rainy afternoon project" that has got me puzzled.

I have an old Pioneer cassette deck that I am restoring.

The capstan motor worked for a short while, then it stopped.

The casing of the motor felt VERY warm, so I knew something was
amiss.

(One of the voltage regulators in the deck's main power supply became
EXTREMELY hot whenever the capstan motor was connected, which was
another clue).

Suspecting a short in the capstan motor, I took the motor apart.

Take a look at what I found when I examined the motor's internal
voltage regulator circuit board...

http://i240.photobucket.com/albums/ff58/eadgbe123/SCORCHED.jpg

The motor's voltage regulator had burned itself up. Look at how
scorched the circuit board is!

I have a replacement regulator, but I want to make sure that all is
well inside this circuit before installing the replacement. (Yes, I
KNOW that I could simply get another motor, but remember, I am
tinkering for the sake of tinkering!)

So I have been checking all of the other components in this circuit,
to verify their health.

The one component that has me puzzled is the small black "diode"
indicated at the bottom of the photo.

There is no mark on this component other than the yellow stripe you
see.

I cannot get any type of reading on this component when I use my
multimeter -- I get nothing using my diode check function (forward or
reverse bias), no continuity, no resistance reading. It must be
faulty, I am assuming.

The other component that has me puzzled is the olive green "resistor"
just above the larger blue electrolytic capacitor. I get a steady
resistance reading of .5 ohms on this component.

I am going to disconnect at least one leg of each of these two
"mystery components" and take further readings, but I'm not used to
getting such odd readings right off the bat on these two components.

Can anyone provide any clues as to what these components are?

BY THE WAY, the motor is fed a steady voltage of 12.5 volts DC, with
no AC voltage ripple present. I have verified this.

Thanks In Advance.....
 
N

N_Cook

EADGBE said:
I have a "rainy afternoon project" that has got me puzzled.

I have an old Pioneer cassette deck that I am restoring.

The capstan motor worked for a short while, then it stopped.

The casing of the motor felt VERY warm, so I knew something was
amiss.

(One of the voltage regulators in the deck's main power supply became
EXTREMELY hot whenever the capstan motor was connected, which was
another clue).

Suspecting a short in the capstan motor, I took the motor apart.

Take a look at what I found when I examined the motor's internal
voltage regulator circuit board...

http://i240.photobucket.com/albums/ff58/eadgbe123/SCORCHED.jpg

The motor's voltage regulator had burned itself up. Look at how
scorched the circuit board is!

I have a replacement regulator, but I want to make sure that all is
well inside this circuit before installing the replacement. (Yes, I
KNOW that I could simply get another motor, but remember, I am
tinkering for the sake of tinkering!)

So I have been checking all of the other components in this circuit,
to verify their health.

The one component that has me puzzled is the small black "diode"
indicated at the bottom of the photo.

There is no mark on this component other than the yellow stripe you
see.

I cannot get any type of reading on this component when I use my
multimeter -- I get nothing using my diode check function (forward or
reverse bias), no continuity, no resistance reading. It must be
faulty, I am assuming.

The other component that has me puzzled is the olive green "resistor"
just above the larger blue electrolytic capacitor. I get a steady
resistance reading of .5 ohms on this component.

I am going to disconnect at least one leg of each of these two
"mystery components" and take further readings, but I'm not used to
getting such odd readings right off the bat on these two components.

Can anyone provide any clues as to what these components are?

BY THE WAY, the motor is fed a steady voltage of 12.5 volts DC, with
no AC voltage ripple present. I have verified this.

Thanks In Advance.....
Click to expand...

Is the diode oriented to soak up back emfs from the motor ?
The green thing is an inductor
 
J

Jamie

EADGBE said:
I have a "rainy afternoon project" that has got me puzzled.

I have an old Pioneer cassette deck that I am restoring.

The capstan motor worked for a short while, then it stopped.

The casing of the motor felt VERY warm, so I knew something was
amiss.

(One of the voltage regulators in the deck's main power supply became
EXTREMELY hot whenever the capstan motor was connected, which was
another clue).

Suspecting a short in the capstan motor, I took the motor apart.

Take a look at what I found when I examined the motor's internal
voltage regulator circuit board...

http://i240.photobucket.com/albums/ff58/eadgbe123/SCORCHED.jpg

The motor's voltage regulator had burned itself up. Look at how
scorched the circuit board is!

I have a replacement regulator, but I want to make sure that all is
well inside this circuit before installing the replacement. (Yes, I
KNOW that I could simply get another motor, but remember, I am
tinkering for the sake of tinkering!)

So I have been checking all of the other components in this circuit,
to verify their health.

The one component that has me puzzled is the small black "diode"
indicated at the bottom of the photo.

There is no mark on this component other than the yellow stripe you
see.

I cannot get any type of reading on this component when I use my
multimeter -- I get nothing using my diode check function (forward or
reverse bias), no continuity, no resistance reading. It must be
faulty, I am assuming.

The other component that has me puzzled is the olive green "resistor"
just above the larger blue electrolytic capacitor. I get a steady
resistance reading of .5 ohms on this component.

I am going to disconnect at least one leg of each of these two
"mystery components" and take further readings, but I'm not used to
getting such odd readings right off the bat on these two components.

Can anyone provide any clues as to what these components are?

BY THE WAY, the motor is fed a steady voltage of 12.5 volts DC, with
no AC voltage ripple present. I have verified this.

Thanks In Advance.....
Click to expand...
Well, I guess you now know why the reg burt up.
that diode is suppose to go across the motor leads to suppress back
EMF which can damage components..
It would be a simply low current SI diode.


http://webpages.charter.net/jamie_5"
 
E

EADGBE

The anode of the diode is attached directly to three of the resistors
as shown.

I have tried to re-create the circuit board traces on the other side.

The cathode connects to what N_Cook has described as an inductor.

Take a look at this photo:

http://i240.photobucket.com/albums/ff58/eadgbe123/DIODE.jpg

Thanks to everyone for your help so far.

Any chance of finding a replacement for this diode?
 
F

Franc Zabkar

Actually, I'll do just a bit better.

Here are ALL of the circuit board traces, done as best as I can. Let
me know if the traces aren't clear enough:

http://i240.photobucket.com/albums/ff58/eadgbe123/CIRCUIT.jpg

By the way, the AN6601 laid flat against the circuit board, with the
label side DOWN.
Click to expand...

My vrt databook lists the TDA1151 and TDA1152 as equivalents for the
AN6610.

Here is a datasheet and application circuits for the TDA1151:
http://www.datasheetarchive.com/pdf-datasheets/Datasheets-32/DSA-633666.pdf

This is an equivalent NTE part:
http://www.nteinc.com/specs/7000to7099/pdf/nte7089.pdf

BTW, I think there is an error in your circuit diagram. AFAICT, there
is no DC current path from the IC's output pin and the negative
terminal of the motor.

As for the motor, I would clean out any carbon dust from between the
commutator segments.

- Franc Zabkar
 
E

EADGBE

I should point something out that I haven't mentioned before...

There are two slots in the circuit board.

One of them is just above the smaller black electrolytic capacitor,
and the other slot is just below the larger blue electrolytic
capacitor.

You can see the traces going to these slots and appearing to "stop
dead".

These slots are where the motor contacts are soldered.
 
F

Franc Zabkar

...

Which themselves are listed as "obsolete, discontinued, or hard-to-find".
IMHO, doesn't seem worth the effort for an 87-cent motor. YMMV
Click to expand...

I can buy the AN6610 here in Australia for AU$2.75.

- Franc Zabkar
 
K

Kevin McMurtrie

Richard Crowley said:
"EADGBE" wrote ...

Depending on what the actual diagram looks like,
it is quite possibly a simple, generic silicon diode
like a 1N4001 (power rectifier) or maybe even a
popular signal diode like a 1N4148, etc. These
are both very common parts that likely cost only
a few cents in production quantities.
Click to expand...

I believe it takes at least two transistors. It's a positive feedback
system to compensate for losses in the motor, creating a virtual perfect
motor that doesn't change speeds under load. And that brings about the
second problem...

The circuit has only one pot so it's not going to work on a worn motor.
The loss compensation is a fixed resistor so it's only good for a motor
in perfect condition.
 
T

Tim Schwartz

Hello,

Don't forget the motor itself

Only one person mentioned in passing that you should check the actual
motor. This is really critical. It is common for the motor itself to
be drawing WAY too much current because of brush dust contamination and
maybe a seized bearing.

Try powering the motor directly (no board) off a 6 volt or so power
supply with an amp meter in the line. Unloaded I'd think it should draw
well under 100mA in current. The motor being in trouble is what
probably caused the IC to run way to hot to begin with.

Regards,
Tim Schwartz
Bristol Electronics
 
E

EADGBE

Richard:

Per your request, I have taken a photo of the back of the circuit
board.

http://i240.photobucket.com/albums/ff58/eadgbe123/CIRCUIT_3.jpg

I have numbered all of the connections so that no one will get
"lost".

They are as follows:

1 - speed control pot connections
2 - 43k resistor
3 - 332 ohm(?) resistor (orange/orange/red?/black/brown)
4 - 421M ohm(?) resistor (yellow/red/orange?/blue/green?)
5 - inductor (olive "resistor" shaped part)
6a - negative lead of 10uF/25v electrolytic
6b - positive lead of 10uF/25v electrolytic
7a - negative lead of 3.3uF/25v electrolytic
7b - positive lead of 3.3uF/25v electrolytic
8 - pink "resistor" (red/red/brown/grey/black)
9 - 22 ohm green resistor (red/red/black/silver)
10a - cathode of black diode (yellow stripe is closest to this
connection)
10b - anode of black diode

The positive and negative power connections are also indicated.

SOME QUICK ADDITIONAL COMMENTS, based on comments I have received so
far....

REMINDER: I know that I could easily get another motor. I AM SIMPLY
TINKERING FOR THE SAKE OF TINKERING, and it's a good opportunity to
learn a bit about this circuit. That's all!

Someone said that they found a substitute for AN6610, but that is NOT
the part number. The burned part says "AN6601". It is made by
Matsushita (Panasonic). I do indeed have an exact replacement for
this part in hand. I found it online at a supplier specializing in
obsolete semiconductors.

I have tested the motor by running 9 volts directly into it. The
motor runs smoothly and quietly. I will take a current reading, just
to see what I find. But the motor appears to be OK.

I am currently going on the assumption that AN6601 failed on its own
and/or because of the fault of the diode.
 
F

Franc Zabkar

...

OK, then that would mean paying AU$2.75 to repair a motor
that likely isn't worth half that. Not to mention that without
knowing why the original blew, the OP has an excellent chance
of blowing up the replacement instantly. That doesn't make
sense up here in the Northern Hemisphere. Perhaps things
look different from your perspective. :)
Click to expand...

I just realised the OP's IC is an AN6601, whereas I've been looking
for an AN6610. <smacks forehead>

Anyway, if the motor is an odd type, or if the pulley is difficult to
remove, then it may make sense to try to repair the PCB. I remember
having to do this one time, although I had to make my own PCB, using a
different IC, and mounted externally. My effort wasn't wasted, though,
as I treated it as a learning experience.

BTW, over here audio motors typically cost AU$8.65, which is still
cheap.

- Franc Zabkar
 
F

Franc Zabkar

I believe it takes at least two transistors. It's a positive feedback
system to compensate for losses in the motor, creating a virtual perfect
motor that doesn't change speeds under load. And that brings about the
second problem...

The circuit has only one pot so it's not going to work on a worn motor.
The loss compensation is a fixed resistor so it's only good for a motor
in perfect condition.
Click to expand...

My understanding is that a real motor can be represented as a perfect
motor with a small series resistance. To maintain a constant speed
under all load conditions, one needs to add an external series
resistor of equal value and then add the voltage drop across this
resistor to the motor voltage.


o---- Rloss ----- perfect motor -----o o--- Rext ---o
|<--- voltage at motor terminals --->| |<-- loss -->|

Here is a circuit I found in "303 Circuits" by Micro-Tech/Elektor
Electronics.

|-------------------------|
| |
| |\ |
| | \ |
|---|- \ | Vm -> Im
| \ -----|--- R3 ---|----o o--- MOTOR ---o GND
V1 o--- R1 ---|---|+ / |
| | / |
| |/ |
| |
|------ R2 ----|

Vm = V1 + Im x [(R2/R1) x R3]

Effectively you have a voltage source with a negative output
resistance of R3 x (R2/R1).

- Franc Zabkar
 
F

Franc Zabkar

Richard:

Per your request, I have taken a photo of the back of the circuit
board.

http://i240.photobucket.com/albums/ff58/eadgbe123/CIRCUIT_3.jpg

I have numbered all of the connections so that no one will get
"lost".

They are as follows:

1 - speed control pot connections
2 - 43k resistor
3 - 332 ohm(?) resistor (orange/orange/red?/black/brown)
4 - 421M ohm(?) resistor (yellow/red/orange?/blue/green?)
5 - inductor (olive "resistor" shaped part)
6a - negative lead of 10uF/25v electrolytic
6b - positive lead of 10uF/25v electrolytic
7a - negative lead of 3.3uF/25v electrolytic
7b - positive lead of 3.3uF/25v electrolytic
8 - pink "resistor" (red/red/brown/grey/black)
9 - 22 ohm green resistor (red/red/black/silver)
10a - cathode of black diode (yellow stripe is closest to this
connection)
10b - anode of black diode

The positive and negative power connections are also indicated.

SOME QUICK ADDITIONAL COMMENTS, based on comments I have received so
far....

REMINDER: I know that I could easily get another motor. I AM SIMPLY
TINKERING FOR THE SAKE OF TINKERING, and it's a good opportunity to
learn a bit about this circuit. That's all!

Someone said that they found a substitute for AN6610, but that is NOT
the part number.
Click to expand...

Sorry, my mistake.
The burned part says "AN6601". It is made by
Matsushita (Panasonic). I do indeed have an exact replacement for
this part in hand. I found it online at a supplier specializing in
obsolete semiconductors.

I have tested the motor by running 9 volts directly into it. The
motor runs smoothly and quietly. I will take a current reading, just
to see what I find. But the motor appears to be OK.

I am currently going on the assumption that AN6601 failed on its own
and/or because of the fault of the diode.
Click to expand...

This is how I see your circuit:

+ o--------|-----|-----|---------|
12V | | | ___|___
| | | | |
| | | R4 R2 43K
+_|_ | | |_____|
C6 ___ | | | D10
10uF | | | |-------|>|--- L5 --|-----|
25V | | | | | |
| R8 Motor R3 3K3 +_|_ |
| 220R| | | C7 ___ |
| | | |-> VR1 5K 3.3uF | |
| | | |----| 25V | |
| |_____|_________|___________________| |
| | |
| | voltage |
| | feedback |
| AN6601 --------------------------------|
| |
0V 22uH | |
- o-- L9 --|-----------|

AFAICT, the AN6601 IC senses the motor voltage via the potential
divider consisting of VR1, R2, R3, and R4. I suspect that if this
voltage begins to increase, then D10 conducts, causing the voltage at
the AN6601's control pin to rise with respect to its supply pin, thus
turning off the AN6601 and reducing the motor current.

- Franc Zabkar
 
E

Eeyore

EADGBE said:
I have a "rainy afternoon project" that has got me puzzled.

I have an old Pioneer cassette deck that I am restoring.

The capstan motor worked for a short while, then it stopped.

The casing of the motor felt VERY warm, so I knew something was
amiss.

(One of the voltage regulators in the deck's main power supply became
EXTREMELY hot whenever the capstan motor was connected, which was
another clue).

Suspecting a short in the capstan motor, I took the motor apart.

Take a look at what I found when I examined the motor's internal
voltage regulator circuit board...

http://i240.photobucket.com/albums/ff58/eadgbe123/SCORCHED.jpg

The motor's voltage regulator had burned itself up. Look at how
scorched the circuit board is!

I have a replacement regulator, but I want to make sure that all is
well inside this circuit before installing the replacement. (Yes, I
KNOW that I could simply get another motor, but remember, I am
tinkering for the sake of tinkering!)

So I have been checking all of the other components in this circuit,
to verify their health.

The one component that has me puzzled is the small black "diode"
indicated at the bottom of the photo.

There is no mark on this component other than the yellow stripe you
see.

I cannot get any type of reading on this component when I use my
multimeter -- I get nothing using my diode check function (forward or
reverse bias), no continuity, no resistance reading. It must be
faulty, I am assuming.
Click to expand...

Then you're somewhat stuffed without a schematic I'm afraid. Unless you
can reverse engineer the circuit ! I've just been through a similar
problem myself where the parts list had everything on it except RESISTOR
values ! what IDIOT was responsible for that I hate to think.

For any AUDIO people listening, that company was MIDAS btw. I've been in
contact with them for about 2 weeks now about it and all they did was to
re-send the same list in a different file size with the resistor values
STILL missing.

The other component that has me puzzled is the olive green "resistor"
just above the larger blue electrolytic capacitor. I get a steady
resistance reading of .5 ohms on this component.
Click to expand...

Plausible. Low value Rs aren't always marked conventionally. Most likely a
current sense R.

Graham
 
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