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

EADGBE schrieb:

Obviously, you've forgotten the red connection:

HTH

Reinhard

Reply to
Reinhard Zwirner
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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...

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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.....

Reply to
EADGBE

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

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

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.

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Reply to
Jamie

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:

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Thanks to everyone for your help so far.

Any chance of finding a replacement for this diode?

Reply to
EADGBE

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:

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

Reply to
EADGBE

WHere does the motor winding itself attach? I'm guessing that the pins on the 'bottom' of the image are teh power input, right?

Reply to
PeterD

So are you saying that the resistance is "infinite" regardless of how you try to measure it? If that is the case, then it is likely "blown". Dunno how critical it is without the full schematic diagram.

If it IS blown, then you should likely discover WHY before replacing it or the replacement may blow instantly as well.

Do you have some reason to believe that it is not just a

0.5 ohm resistor? Again, hard to guess without the full schematic diagram.
Reply to
Richard Crowley

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.

Reply to
Richard Crowley

That is good, but you don't indicate which nodes connect to the motor, and which are the power input (+ and -). Without that critical info, it won;t be easy to make much sense out of the circuit.

Are you SURE you have a replacement for this IC? Panasonic lists it as an "application specific circuit" (i.e. a custom-made chip, not a generic part). And it says that it is "obsolete" (i.e. not made anymore). Also there is no indication that it is a "regulator", or that it has any replacement.

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Furthermore, the original was so burned up (as shown by your excellent photo), that I would be reluctant to just replace it without determining WHAT caused the original to burn. I don't remember that you revealed anything about the motor itself (impedances?, windings?, brushes? mechanical rotation? etc.)

Reply to
Richard Crowley

On Sun, 5 Oct 2008 17:48:53 -0700 (PDT), EADGBE put finger to keyboard and composed:

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

Here is a datasheet and application circuits for the TDA1151:

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This is an equivalent NTE part:

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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

--
Please remove one \'i\' from my address when replying by email.
Reply to
Franc Zabkar

OK, here is the circuit again, this time with positive and negative power inputs labeled....

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Reply to
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.

Reply to
EADGBE

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

Reply to
Richard Crowley

Then it appears that you didn't trace the circuit properly.

According to your green lines, the only path from the upper motor node is through the adjustable resistor at the top (highly unlikely for such a high impedance as 5000 ohms) or through the black electrolytic capacitor (electrically impossible).

How about just posting a photo of the BACK of the board instead of trying to interpret it?

There IS a direct path from the +power input to the lower motor node, which seems consistent with the motor speed regulator IC circuit.

Did you say that you *have* a replacement for the semiconductor in hand, or that you had simply identified it?

Reply to
Richard Crowley

On Sun, 5 Oct 2008 20:56:11 -0700, "Richard Crowley" put finger to keyboard and composed:

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

- Franc Zabkar

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Please remove one \'i\' from my address when replying by email.
Reply to
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. :-)

Reply to
Richard Crowley

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.

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Google is a pro-spamming service.  I will not see your reply if you use Google.
Reply to
Kevin McMurtrie

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

EADGBE wrote:

Reply to
Tim Schwartz

Richard:

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

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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.

Reply to
EADGBE

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