TA7317P output protection

[John Smith]

Has anyone encountered fake TA7317P devices?

I've just replaced one in an Electro Voice 81PMX powered mixer but the
output relay still doesn't turn on.
Meter readings after replacement made no sense but an oscilloscope showed
high frequency oscillation at pin 6 of the replacement device which I
presume were confusing the meter.

Before anyone asks, the unit works perfectly when pin 6 is connected to
ground to turn the relay on and the output is only mV away from ground with
no signal.

The schematic of the unit I'm trying to repair can be found by googling
ElectroVoice-61_81PMX pwrmix.pdf
And the TA7317P data sheet can be similarly found.

Before I replaced the chip I checked the voltage at all pins as follows.

1. -0.7
2. 0.7
3. 0.1
4. 0
5. -0.8
6. 76.5
7. 0
8. 0.6
9. 3.2

I concluded that The 0.7V at pin 2 must be coming from within the chip
because there is near 0V at the other end of the series resistor on that
pin.

After replacing the TA7317P, meter readings show only 1.8 V at pin 9. There
is high (higher than my old 20MHz oscilloscope can show) frequency
oscillation at pin 6.

So I think that either the replacement TA7317P is duff or fake.

I'm going to fit some socket strip when I take the replacement out again.

I have three more TA7317P from the same source (I bought four).

I think I'll test the remaining devices with a power supply, a series
resistor to pin 9 and pin 4 grounded, and see what is on pin 9. Unless
anyone can suggests other tests to confirm whether or not the replacement
parts I bought really are TA7317P.

Thanks for any suggestions.

old guy

[N_Cook]

John Smith <inv...@invalid.invalid> wrote in message
news:ji9ot1$8j8$1...@dont-email.me...

I was wrestling with a similar function C1237HA / uPC1237HA recently, as
falsely holding off the relays, replaced associated caps, replaced the
device , still the same

[Tim Schwartz]

Good Morning,

I've usually seen these IC's in NAD receivers. I've certainly had
issues with both the capacitors and resistors going bad, even though
they seem to measure OK in circuit. I'm going from my memory (bad idea)
but 150K, 180K, 220K 15K, 18K and 22K stick in my mind.

Best of luck,
Tim Schwartz
Bristol Electronics

[N_Cook]

John Smith <inv...@invalid.invalid> wrote in message
news:ji9ot1$8j8$1...@dont-email.me...

For a Panasonic SA313 use of TA7317P, p1 to p9
-.7,0,0,0,-.7,1.3,0,1.3,3.1 V dc

[Franc Zabkar]

On Fri, 24 Feb 2012 23:43:18 -0500, "John Smith"
<inv...@invalid.invalid> put finger to keyboard and composed:

>The schematic of the unit I'm trying to repair can be found by googling ...

It would have been nice for you to have made it easy for us ...

>ElectroVoice-61_81PMX pwrmix.pdf

http://www.eserviceinfo.com/download.php?fileid=46360
http://elektrotanya.com/electro-voice_61_81pmx_sm.pdf/download.html

>And the TA7317P data sheet can be similarly found.

http://www.portes.cz/data/integrovane_obvody/TA7317P.pdf

>Before I replaced the chip I checked the voltage at all pins as follows.
>
>1. -0.7
>2. 0.7
>3. 0.1
>4. 0
>5. -0.8
>6. 76.5
>7. 0
>8. 0.6
>9. 3.2
>
>I concluded that The 0.7V at pin 2 must be coming from within the chip
>because there is near 0V at the other end of the series resistor on that
>pin.
>
>After replacing the TA7317P, meter readings show only 1.8 V at pin 9.

AISI, the maximum voltage at this point would be equivalent to the
voltage drop across 4 forward biased diodes. Simlarly, the voltage
drop at pin 5 should be equal to a single forward biased diode.

If the voltage drop is taken to be 0.8V, then this is consistent with
both measurements.

What voltage do you see at pin 5 of the replacement? Do pins 1,2,3 and
7 of the replacement part now show the expected voltages?

Does pin 9's series resistor (R372) measure correctly (22K)?

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

[Franc Zabkar]

On Fri, 24 Feb 2012 23:43:18 -0500, "John Smith"
<inv...@invalid.invalid> put finger to keyboard and composed:

>Before I replaced the chip I checked the voltage at all pins as follows.
>

>6. 76.5
>9. 3.2

AISI, the voltage across R372 (22K) must be 73.3V.

Therefore its power dissipation would be ...

73.3 ^ 2 / 22K = 244mW

However, the parts list rates it for 1/5W.

[John Smith]

"Franc Zabkar" <fza...@iinternode.on.net> wrote in message
news:40lik7pl2h78il7vj...@4ax.com...

> On Fri, 24 Feb 2012 23:43:18 -0500, "John Smith"
> <inv...@invalid.invalid> put finger to keyboard and composed:
>
>>Before I replaced the chip I checked the voltage at all pins as follows.
>>
>>6. 76.5
>>9. 3.2
>
> AISI, the voltage across R372 (22K) must be 73.3V.
>
> Therefore its power dissipation would be ...
>
> 73.3 ^ 2 / 22K = 244mW
>
> However, the parts list rates it for 1/5W.

Thanks but this is one of the first things I checked before replacing the
device.
R372 does measure 22K.
I actually cut one of its legs to test it out of circuit because it's a pain
to get the board off the heatsink (all output FETs have to be unsoldered) I
then soldered its leg together again.

I spotted another potential design error.
Compare the TA7317 Vcc max with what I measured. This only affects pin 6.

I'll find out more when I get back to it on Monday.

old guy

[John Smith]

"Franc Zabkar" <fza...@iinternode.on.net> wrote in message

news:7mhik7hqigipphcj9...@4ax.com...

> On Fri, 24 Feb 2012 23:43:18 -0500, "John Smith"
> <inv...@invalid.invalid> put finger to keyboard and composed:
>
>>The schematic of the unit I'm trying to repair can be found by googling
>>...
>
> It would have been nice for you to have made it easy for us ...

Sorry, I didn't think a quick cut & paste into Google was hard.

I'll be able to answer your other questions on Monday.

old guy

>
...

[John Smith]

"N_Cook" <div...@tcp.co.uk> wrote in message
news:jibeen$f6o$1...@dont-email.me...

> John Smith <inv...@invalid.invalid> wrote in message
> news:ji9ot1$8j8$1...@dont-email.me...
>> Has anyone encountered fake TA7317P devices?
>>

...

>
> For a Panasonic SA313 use of TA7317P, p1 to p9
> -.7,0,0,0,-.7,1.3,0,1.3,3.1 V dc

Useful information. Thanks.

>
>

[Mark Zacharias]

"John Smith" <inv...@invalid.invalid> wrote in message
news:ji9ot1$8j8$1...@dont-email.me...

At a glance, 0.6 volts at pin 8 is wrong - capacitor C312 should charge up
through R364.

If it is held low, the thing will never turn on. The voltage at pin 9 looks
like may be low - R372 could be way high in value.

Mark Z.

[Franc Zabkar]

On Sat, 25 Feb 2012 19:00:43 -0500, "John Smith"

<inv...@invalid.invalid> put finger to keyboard and composed:

>"Franc Zabkar" <fza...@iinternode.on.net> wrote in message
>news:7mhik7hqigipphcj9...@4ax.com...
>> On Fri, 24 Feb 2012 23:43:18 -0500, "John Smith"
>> <inv...@invalid.invalid> put finger to keyboard and composed:
>>
>>>The schematic of the unit I'm trying to repair can be found by googling
>>>...
>>
>> It would have been nice for you to have made it easy for us ...
>
>Sorry, I didn't think a quick cut & paste into Google was hard.

No harder than a quick cut & paste into a newsreader ...

BTW, I notice that the voltage rating of the filter capacitors (C401 /
C402) on the amp's positive and negative supplies is 80V. Are you sure
the AC mains voltage selector is in the correct position?

[John Smith]

"Mark Zacharias" <mark_za...@labolgcbs.net> wrote in message
news:4f4a3d8f$0$10360$4c5e...@fastusenet.org...

> "John Smith" <inv...@invalid.invalid> wrote in message
> news:ji9ot1$8j8$1...@dont-email.me...
>> Has anyone encountered fake TA7317P devices?

....

>>
>> Thanks for any suggestions.
>>
>> old guy
>>
>
> At a glance, 0.6 volts at pin 8 is wrong - capacitor C312 should charge up
> through R364.

I'll check R364/C312 tomorrow.
R362 measured 22K out of circuit. I might replace it anyway.

[John Smith]

"Franc Zabkar" <fza...@iinternode.on.net> wrote in message

news:a14lk75flul8glf0j...@4ax.com...

I'll check it on Monday. I'm in a 115V 60Hz area.

[Franc Zabkar]

On Sun, 26 Feb 2012 08:11:41 -0600, "Mark Zacharias"
<mark_za...@labolgcbs.net> put finger to keyboard and composed:

>At a glance, 0.6 volts at pin 8 is wrong - capacitor C312 should charge up
>through R364.
>
>If it is held low, the thing will never turn on.

AISI, pin #8 should go low if either pin #1 or pin #7 are high, or if
either pin #2 or pin #3 are outside the range of -0.7V to +0.7V.

If there is a fault condition, one or more of Q6, Q18, and Q19 will be
on. This means that Q10 will be off and Q11 will be on. This in turn
means that Q12 and Q13 will be off and the relay will be open.

[John Smith]

It took me a little longer than expected to get back to this but here's the
story so far.

The mains voltage selector is set correctly for the area I'm working in. So
+75V and -75V rails seem to be correct.

I removed the replacement TA7317P and fitted socket strip.

With no chip fitted R372 = 21.6K and R364 = 220K.

All other resistance checks made sense and no adjacent socket pins are
shoreted together.

I then connected pin 6 to pin 4 of the socket to turn the relay on and also
connected four 1N4148 dioded in series from pin 9 to pin 4 of the socket.

With the power on, here are the voltage readings I now get. Note that no
chip is fitted, just the diodes mentioned above.

1. -15V
2. 8.8mV
3. 0.17V
4. 0V
5. -75V
6. 0V
7. 0V
8. 2.67V
9. 2.7V

The voltage on C314 is varying between -42 and -49V, presumably due to
ripple. I'll scope it tomorrow. The voltage at pin 1 of the socket is also
varying a bit too.

Thanks for any further suggestions.

My next move will be to test the remaining TA7317P I bought, with a 22K
resistor to pin 9 and pin 4 grounded with no other pins connected and see
what I get on pin 9.

Old guy

[Franc Zabkar]

On Thu, 1 Mar 2012 14:30:32 -0500, "John Smith"
<inv...@invalid.invalid> put finger to keyboard and composed:

>The mains voltage selector is set correctly for the area I'm working in. So
>+75V and -75V rails seem to be correct.

That means that quite a few components are operating close to spec or
slightly in excess of spec.

>I removed the replacement TA7317P and fitted socket strip.

>With the power on, here are the voltage readings I now get. Note that no
>chip is fitted, just the diodes mentioned above.
>
>1. -15V
>2. 8.8mV
>3. 0.17V
>4. 0V
>5. -75V
>6. 0V
>7. 0V
>8. 2.67V
>9. 2.7V
>
>The voltage on C314 is varying between -42 and -49V, presumably due to
>ripple. I'll scope it tomorrow. The voltage at pin 1 of the socket is also
>varying a bit too.

I'd change the capacitor, but I don't believe that level of ripple
would be enough to influence the circuit.

AISI, pin #1 senses the current in the 0.33 ohm load sharing/sensing
resistors R33, R34, R35, and R36. It would require about 2A to turn on
Q324. Q325 would then turn on after a delay determined by C311 and
R357, sending pin #1 of the TA7317P high and causing the relay to
open.

>My next move will be to test the remaining TA7317P I bought, with a 22K
>resistor to pin 9 and pin 4 grounded with no other pins connected and see
>what I get on pin 9.

I suspect that your replacement parts may have a string of 3 diodes on
pin #9. If the voltage at pin #5 is -0.6V, then this would tend to
confirm it.

I notice that the datasheet identifies each diode as a Q rather than a
D, so I suspect that the original part uses diode-connected
transistors rather than actual diodes. Perhaps your replacement part
uses the latter?

[Franc Zabkar]

On Fri, 24 Feb 2012 23:43:18 -0500, "John Smith"

<inv...@invalid.invalid> put finger to keyboard and composed:

>Has anyone encountered fake TA7317P devices?

>Before I replaced the chip I checked the voltage at all pins as follows.
>
>1. -0.7
>2. 0.7
>3. 0.1
>4. 0
>5. -0.8
>6. 76.5
>7. 0
>8. 0.6
>9. 3.2
>
>I concluded that The 0.7V at pin 2 must be coming from within the chip
>because there is near 0V at the other end of the series resistor on that
>pin.
>
>After replacing the TA7317P, meter readings show only 1.8 V at pin 9.

I believe pin #3 is being used to provide thermal overload protection.
That said, I can't see how it could possibly work, even with the
"correct" supply voltage at pin #9.

Here is the relevant section of the circuit:

pin #3
o
|
pin #9 o-|-- R366, 15K -- TH301 --|-- R367, 3K --o pin #4, Ground
| |
|-- R365, 180K ----------|


TH301 is an NTC thermistor, Panasonic p/n ERT-D2FHL503S:
http://www.panasonic.com/industrial/components/pdf/arg0000ce2.pdf

It's resistance at 25C is 50K.

AISI, in order for the thermal overload to activate, pin #3 would have
to exceed 0.6V (the B-E voltage of Q15 in the datasheet). However,
even if we allow the resistance of TH301 to fall to 0, then the
voltage at pin #3 is still only 0.57V, assuming a voltage of 3.2V at
pin #9. At 1.8V, the voltage at pin #3 would be only 0.32V.

C316, R371 and R374 appear to provide a dethump delay at switch-on.

[John Smith]

"Franc Zabkar" <fza...@iinternode.on.net> wrote in message

news:ebk0l75aaimkfva8a...@4ax.com...

> On Fri, 24 Feb 2012 23:43:18 -0500, "John Smith"
> <inv...@invalid.invalid> put finger to keyboard and composed:
>

....

>
> I believe pin #3 is being used to provide thermal overload protection.
> That said, I can't see how it could possibly work, even with the
> "correct" supply voltage at pin #9.
>
> Here is the relevant section of the circuit:
>
> pin #3
> o
> |
> pin #9 o-|-- R366, 15K -- TH301 --|-- R367, 3K --o pin #4, Ground
> | |
> |-- R365, 180K ----------|
>
>
> TH301 is an NTC thermistor, Panasonic p/n ERT-D2FHL503S:
> http://www.panasonic.com/industrial/components/pdf/arg0000ce2.pdf
>
> It's resistance at 25C is 50K.
>
> AISI, in order for the thermal overload to activate, pin #3 would have
> to exceed 0.6V (the B-E voltage of Q15 in the datasheet). However,
> even if we allow the resistance of TH301 to fall to 0, then the
> voltage at pin #3 is still only 0.57V, assuming a voltage of 3.2V at
> pin #9. At 1.8V, the voltage at pin #3 would be only 0.32V.
>
> C316, R371 and R374 appear to provide a dethump delay at switch-on.

Thanks Franc

I haven't checked your analysis but in my time as a circuit designer (not
saying how many years or what I worked on) I encountered many situations
where pleasing management was the most important thing.

So a thermal overload test may have been done on one unit and it may well
have passed.
And then it may have been assumed that...

The unit has a very big heat sink, actually I don't recall many that were
bigger.
So I'm not too concerned if thermal overload doesn't work.
No one is going to be injured by a FET going pop, well except the speaker if
the relay doesn't turn off, so my risk assessment is that it doesn't matter
as long as I can get the relay to turn on when the output isn't stuck at a
rail.

If I can't do that then I won't get paid for the repair :(

Old guy

[Franc Zabkar]

On Fri, 2 Mar 2012 00:52:36 -0500, "John Smith"

<inv...@invalid.invalid> put finger to keyboard and composed:

>The unit has a very big heat sink, actually I don't recall many that were
>bigger.
>So I'm not too concerned if thermal overload doesn't work.
>No one is going to be injured by a FET going pop, well except the speaker if
>the relay doesn't turn off, so my risk assessment is that it doesn't matter
>as long as I can get the relay to turn on when the output isn't stuck at a
>rail.

I pointed it out because it looked wrong. In fact the design seems to
have too many oddities.

That said, the 4 protection inputs look OK to me, so there does appear
to be a problem with the IC.

There is one thing you might like to try. The TA7317P datasheet
specifies a maximum current of 5mA into pin #9. The circuit as it
stands draws about 3mA through R372. Perhaps you could add a 47K
resistor in parallel with R372. If the voltage on pin #9 rises, then
this would point to an internal regulation problem.

[John Smith]

Thanks Franc,

Here are the results of todays experiments.

I took another of the TA7317P I bought and carefully bent most pins so that
when I put it in the socket only pins 4,5 and 9 are in the socket.

Here's what I get:

Socket pin V, Chip pin V.

1 -16.5, -1.04
2 0.01, -1.98
3 0.01, -0.66
4 0, 0
5 -2.39 -2.39
6 76.6 -2.38
7 0, -1.29
8 0.3 0.122
9 0.3 0.3

Something tells me that this can't be a TA7317P despite its markings.

Maybe the manufacturer got it reversed in the package.
I think it should be safe to try one backwards.

Old guy

[John Smith]

Well wadda you know.

I straightened the pins and put it in backwards.

At power on there was a click and the readings now are.

1. 0.23
2. 0.32
3. 0.64
4. 0
5. 0.82
6. 3.7
7. 2.57
8. 1.44
9. 3.35

For socket pins 1 - 9. The device is definitely in backwards.

I rechecked pin 5. It's +0.82 not -0.82, strange.

Pins 7 and 8 seem strange too.

Perhaps it's still not really a TA7317P

Old guy

[Franc Zabkar]

On Fri, 2 Mar 2012 15:30:36 -0500, "John Smith"

<inv...@invalid.invalid> put finger to keyboard and composed:

>Socket pin V, Chip pin V.
>
>1 -16.5, -1.04
>2 0.01, -1.98
>3 0.01, -0.66
>4 0, 0
>5 -2.39 -2.39
>6 76.6 -2.38
>7 0, -1.29
>8 0.3 0.122
>9 0.3 0.3
>
>Something tells me that this can't be a TA7317P despite its markings.

It sure looks that way. That said, I can't see any economic incentive
to counterfeit a part that I can buy for AU$2.75 in single quantities.

Maybe you should bite the bullet and buy it as a spare part from
Panasonic or Yamaha?

BTW, the more I examine the circuit, the more errors and anomalies I
find. For example, AFAICS there is a 50V capacitor (C409) in the 40V
phantom power supply that would be operating at 49V. I have a feeling
that the correct HV supplies should be +/-55V, not 75V.

There is also a PNP transistor (Q405) in the -15V supply that is drawn
as an NPN, and a 2SD transistor (Q401) in the 40V supply is listed as
a 2SC in the parts list.

My overall impression is that it's a shoddy product.

[Franc Zabkar]

On Fri, 2 Mar 2012 16:42:59 -0500, "John Smith"

<inv...@invalid.invalid> put finger to keyboard and composed:

Maybe the chip was damaged by your first attempt?

I think pin #8 is probably OK. AFAICS, Q7 (diode) and Q10 should both
contribute around 0.6V when the relay is closed.

I would think that pin#6 should be a lot closer to 0V.

I also don't understand why the voltage on pin #3 is so high.

[Franc Zabkar]

On Fri, 2 Mar 2012 16:42:59 -0500, "John Smith"

<inv...@invalid.invalid> put finger to keyboard and composed:

>I straightened the pins and put it in backwards.
>
>At power on there was a click and the readings now are.
>
>1. 0.23
>2. 0.32
>3. 0.64
>4. 0
>5. 0.82
>6. 3.7
>7. 2.57
>8. 1.44
>9. 3.35

When the IC was installed backwards, pins 4 and 6, and pins 3 and 7,
would have been swapped. This means that the +75V supply would have
been applied to the IC's ground pin via the relay coil. The IC's pin
#7 would have been grounded via a 3K resistor (R367). This means that
Q19's base-emitter junction would have been reverse biased by the +75V
supply, thereby destroying it. Your measurements would suggest that
Q19's B-E junction is now open, which would be consistent with the
expected damage.

Furthermore, the reading at pin #5 (Q20) would suggest that its
connection to the IC's ground (pin #4) has been opened. AFAICS, this
is also to be expected.

[Franc Zabkar]

On Sat, 03 Mar 2012 10:00:29 +1100, Franc Zabkar
<fza...@iinternode.on.net> put finger to keyboard and composed:

>When the IC was installed backwards, pins 4 and 6, and pins 3 and 7,
>would have been swapped.

If you are wary about the polarity of your ICs, I would use a 9V
battery and a 1.8K series resistor to test the IC. I would connect the
battery's negative terminal to pin #5. This pin is consistent,
irrespective of polarity. I would then connect the battery's positive
terminal, via the resistor, to pins 1 and 9 in turn. I expect that you
should see approximately 1.4V at pin #1 and 3.2V at pin #9.

[John Smith]

"Franc Zabkar" <fza...@iinternode.on.net> wrote in message

news:r0g2l7t502i5uit57...@4ax.com...

> On Fri, 2 Mar 2012 16:42:59 -0500, "John Smith"
> <inv...@invalid.invalid> put finger to keyboard and composed:
>
>>Well wadda you know.
>>
>>I straightened the pins and put it in backwards.
>>
>>At power on there was a click and the readings now are.
>>
>>1. 0.23
>>2. 0.32
>>3. 0.64
>>4. 0
>>5. 0.82
>>6. 3.7
>>7. 2.57
>>8. 1.44
>>9. 3.35
>>
>>For socket pins 1 - 9. The device is definitely in backwards.
>>
>>I rechecked pin 5. It's +0.82 not -0.82, strange.
>>
>>Pins 7 and 8 seem strange too.
>>
>>Perhaps it's still not really a TA7317P
>>
>>Old guy
>
> Maybe the chip was damaged by your first attempt?

I have two more unused parts.
I'll try another unused one in backwards on Monday.

>
> I think pin #8 is probably OK. AFAICS, Q7 (diode) and Q10 should both
> contribute around 0.6V when the relay is closed.
>
> I would think that pin#6 should be a lot closer to 0V.

Yes I noticed that.

>
> I also don't understand why the voltage on pin #3 is so high.

I don't either.

I do agree it's a shoddy product but I won't get my pocket money if I can't
fix it.

Old guy

[John Smith]

"Franc Zabkar" <fza...@iinternode.on.net> wrote in message

news:bgk2l7pcj2ok930pv...@4ax.com...

> On Sat, 03 Mar 2012 10:00:29 +1100, Franc Zabkar
> <fza...@iinternode.on.net> put finger to keyboard and composed:
>
>>When the IC was installed backwards, pins 4 and 6, and pins 3 and 7,
>>would have been swapped.
>
> If you are wary about the polarity of your ICs, I would use a 9V
> battery and a 1.8K series resistor to test the IC. I would connect the
> battery's negative terminal to pin #5. This pin is consistent,
> irrespective of polarity. I would then connect the battery's positive
> terminal, via the resistor, to pins 1 and 9 in turn. I expect that you
> should see approximately 1.4V at pin #1 and 3.2V at pin #9.

Thanks Franc, I'll take your advice and do that on Monday with the two
unused parts I have.

Old guy

[Franc Zabkar]

On Fri, 2 Mar 2012 18:52:18 -0500, "John Smith"
<inv...@invalid.invalid> put finger to keyboard and composed:

>"Franc Zabkar" <fza...@iinternode.on.net> wrote in message
>news:bgk2l7pcj2ok930pv...@4ax.com...
>> On Sat, 03 Mar 2012 10:00:29 +1100, Franc Zabkar
>> <fza...@iinternode.on.net> put finger to keyboard and composed:
>>
>>>When the IC was installed backwards, pins 4 and 6, and pins 3 and 7,
>>>would have been swapped.
>>
>> If you are wary about the polarity of your ICs, I would use a 9V
>> battery and a 1.8K series resistor to test the IC. I would connect the
>> battery's negative terminal to pin #5. This pin is consistent,
>> irrespective of polarity. I would then connect the battery's positive
>> terminal, via the resistor, to pins 1 and 9 in turn. I expect that you
>> should see approximately 1.4V at pin #1 and 3.2V at pin #9.
>
>Thanks Franc, I'll take your advice and do that on Monday with the two
>unused parts I have.

I should have said that the above voltages would be with respect to
pin #4. Add about 0.8V when measuring with respect to pin #5.

BTW, I suspect that the 3K resistor on pin #3 would now be open. That
would explain the higher than expected voltage on pin #3.

[N_Cook]

John Smith <inv...@invalid.invalid> wrote in message

news:jirern$6tj$1...@dont-email.me...

Are you using the left hand side of the printing as your index for pin "1"
or the chamfer or notch in the body ?

[John Smith]

"N_Cook" <div...@tcp.co.uk> wrote in message

news:jisl7s$ebo$1...@dont-email.me...

> John Smith <inv...@invalid.invalid> wrote in message
> news:jirern$6tj$1...@dont-email.me...
>> Well wadda you know.
>>

...

>>
>
> Are you using the left hand side of the printing as your index for pin "1"
> or the chamfer or notch in the body ?

Both are at the same end.
I even googled up a drawing of SIP9 to make certain that the chamfer end
should be pin 1.

It's not a Toshiba one but it looks just like the one on this page I found
with google images.
Watch out for link wrap.

http://www.donberg.ie/catalogue/semiconductors/semiconductors_t-tc/ta_7317.html

>
>

[N_Cook]

John Smith <inv...@invalid.invalid> wrote in message

news:jitcps$ks$1...@dont-email.me...

I looked in my tub of salvaged and sorted on 731.... and did not find one ,
surprisingly ( a Matshusta AN7317 9 pinner but dual amp , not protector . I
could have done some "diode" tests.
Its just no the sort of thing to pirate , there are other TA73** devices of
9 pin SIL so perhaps a cock-up in the labelling section. Now removing 3055
marking off TO3s and marking them 2N3773 or whatever , would be the actions
of a pirater

[josephkk]

On Sat, 03 Mar 2012 08:45:51 +1100, Franc Zabkar
<fza...@iinternode.on.net> wrote:

>On Fri, 2 Mar 2012 15:30:36 -0500, "John Smith"
><inv...@invalid.invalid> put finger to keyboard and composed:
>
>>Socket pin V, Chip pin V.
>>
>>1 -16.5, -1.04
>>2 0.01, -1.98
>>3 0.01, -0.66
>>4 0, 0
>>5 -2.39 -2.39
>>6 76.6 -2.38
>>7 0, -1.29
>>8 0.3 0.122
>>9 0.3 0.3
>>
>>Something tells me that this can't be a TA7317P despite its markings.
>
>It sure looks that way. That said, I can't see any economic incentive
>to counterfeit a part that I can buy for AU$2.75 in single quantities.
>
>Maybe you should bite the bullet and buy it as a spare part from
>Panasonic or Yamaha?
>
>BTW, the more I examine the circuit, the more errors and anomalies I
>find. For example, AFAICS there is a 50V capacitor (C409) in the 40V
>phantom power supply that would be operating at 49V. I have a feeling
>that the correct HV supplies should be +/-55V, not 75V.

It begins to sound like somebody "hot rodded" the amplifier. And did a
shoddy job of it.

[John Smith]

"Franc Zabkar" <fza...@iinternode.on.net> wrote in message

news:4383l7dmffp7hv631...@4ax.com...

None of the resistors look distressed and R367 measures 2.85K with no chip
fitted.

I was going to try the battery test but first I used a resistance meter
between pin 4 and pins 2 and 3. I was expecting these two pins to look the
same but they didn't no matter which pin I assumed to be pin 1.

With nothing to lose I fitted an unused chip backwards.

At power on there was a click and:

1. 0.22V
2. 0.32V
3. 0.6V
4. 0V
5. 0.82V
6. 3.49V
7. 2.38V
8. 1.35V
9. 3.16V

R366 (15K) has 2.53V at the thermistor end.

R369 is 28mV at the end not connected to the chip.

My next move was to connect a 100K resistor between the rail end of R372 and
pin2.
This took pin 2 up to 3.11V but the relay didn't turn off.

My conclusion is that whatever I bought in SIP9 packages marked TA7317P
can't be TA7317P

This could have happened accidentally, the manufacturer may have packaged
the wrong device.

There is no doubt that the devices are marked TA7317P but I happened to
accidentaly type TA7137P into Google today and found that this is also SIP9.

I think the only thing I can do to make progress is to get more TA7317P from
a different source and perhaps tell the vendor that I don't think they
supplied TA7317P despite the markings.

Old guy.

[Franc Zabkar]

On Mon, 5 Mar 2012 18:44:57 -0500, "John Smith"

<inv...@invalid.invalid> put finger to keyboard and composed:

>I was going to try the battery test but first I used a resistance meter
>between pin 4 and pins 2 and 3. I was expecting these two pins to look the
>same but they didn't no matter which pin I assumed to be pin 1.

Nice idea.

>With nothing to lose I fitted an unused chip backwards.
>
>At power on there was a click and:
>
>1. 0.22V
>2. 0.32V
>3. 0.6V
>4. 0V
>5. 0.82V
>6. 3.49V
>7. 2.38V
>8. 1.35V
>9. 3.16V
>
>R366 (15K) has 2.53V at the thermistor end.

That means that the current through R366 is ...

(3.16V - 2.53V) / 15K = 42uA

The current through R367 is ...

0.6V / 2.85K = 210uA

The current through R365 is ...

(3.16V - 0.6V) / 180K = 14uA

Therefore pin 3 of the IC must be sourcing 154uA (= 210 - 42 - 14).
This is inconsistent with the equivalent circuit in the IC datasheet.

Also, the fact that pin #5 is at a higher potential than ground would
suggest that the IC has an internal open circuit between pin #4 and
Q20.

Assuming capacitor C316 is not leaking, then pin #7 of the IC must be
sourcing 72uA (= 2.38V / 33K). This is also inconsistent with the
equivalent circuit.

>R369 is 28mV at the end not connected to the chip.
>
>My next move was to connect a 100K resistor between the rail end of R372 and
>pin2.
>This took pin 2 up to 3.11V but the relay didn't turn off.
>
>My conclusion is that whatever I bought in SIP9 packages marked TA7317P
>can't be TA7317P

It sure seems that way. :-(