[sdiy] SSM2164 last time buys

Tue Mar 1 18:38:20 CET 2011

Or they may be more open to disclose the nasties...

-----Original Message-----
From: Neil Johnson [mailto:neil.johnson97 at ntlworld.com] 
Sent: Tuesday, March 01, 2011 1:07 AM
To: Barry Klein
Cc: Synth DIY
Subject: Re: [sdiy] SSM2164 last time buys

Given that AD are EOLing it I'd suggest contacting CoolAudio as they
will more likely have a vested interest in supporting future designs.

Neil

2011/3/1 Barry Klein <Barry.L.Klein at wdc.com>:
> Did anyone try calling Analog Devices tech support and asking about this?
>
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Tim Ressel
> Sent: Monday, February 28, 2011 4:42 PM
> To: Oscar Salas; Synth DIY
> Subject: Re: [sdiy] SSM2164 last time buys
>
> Excellent work Oscar! This will be a relief to many I'm sure. The only
> question
> I have is does the current limiting resistor affect normal operation?
>
> --TimR
>
>
>
> ----- Original Message ----
> From: Oscar Salas <osaiber at yahoo.es>
> To: Synth DIY <synth-diy at dropmix.xs4all.nl>; Scott Juskiw
> <maillist at tellun.com>
> Sent: Mon, February 28, 2011 4:10:30 PM
> Subject: Re: [sdiy] SSM2164 last time buys
>
> Hello, I was thinking about it and I did again the tests.
> I thought that it is about current and remembered that I did the test with
a
>
> very little power supply that I have for the breadboard.
>
> So, like in the past test, I put side by side a V1264 and a SSM2164
without
> connect the negative rail for two minutes connected, this time, to a big
> power
> supply HBB15 1.5A.
> Both died.
>
> So it is current, and the solution could be as easy as put a series
limiting
>
> resistor in the positive supply.
>
>
> I did tests with another V2164:
> Data-sheet says that supply current is 6mA as typical and 8mA as a maximum
> in
> class AB operation. I wanted worst case for make the test and measured a
> maximum
> of 10.8mA on positive supply with following settings:
> class A operation
> for all four VCAs:
> signal input= V+ (+15V)
> control voltage input= V- (-15V)
>
> OK with those settings I started putting a 1K5 resistor in series with the
> positive supply. With the negative rail connected(normal) I read 8.8mA and
> without connect the negative I read 9mA. The best thing is that the chip
> doesn't
> die, nor goes hot!
>
> Further I did several measurements reducing the value of the resistor, for
> example with a 510Ω resistor I read 10.6mA (normal) and 25mA without
connect
> the
> negative rail. And the chip doesn't go hot!
>
> The Chip starts going hot (measured by touching) with resistor=56Ω,
without
> connect the negative rail you can read 115mA.
> And dies with resistor=2Ω you can read more than 500mA and then falls to
> 0mA.
>
> Ok, take my measurements as a orientation, think for-example that those
> chips
> had been used for several test.
>
>
> As a summary I would say:
>
> A) With a resistor in series with the positive supply the chip is
protected
> restricting the current. I would say that a value about 510Ω or 1K would
do
> the
> job.
>
> Question: There is any inconvenient in use a resistor? could it affect the
> performance of the VCAs
>
> B) I didn't test it but another solution would be a resettable fuse but in
> this
> case stay within 10mA or 50mA per chip. Maybe better one fuse per chip.
>
>
>
> Best Regards,
>
> Oscar.
> --- On Sun, 2/27/11, Scott Juskiw <maillist at tellun.com> wrote:
>
>> From: Scott Juskiw <maillist at tellun.com>
>> Subject: Re: [sdiy] SSM2164 last time buys
>> To: "Synth DIY" <synth-diy at dropmix.xs4all.nl>
>> Date: Sunday, February 27, 2011, 7:49 PM
>> I've had similar experiences with
>> CoolAudio v2164 where it overheated a lot (and very quickly)
>> when my negative supply was accidentally disconnected. BUt
>> in my case, those chips are now worthless. Considering that
>> some power supplies have been known to have one rail lock up
>> on startup, this is a bad thing for anyone trying to use
>> these chips in a module.
>>
>> Is there a simple way to test for this "lack of negative
>> supply" condition and disconnect the positive rail
>> automatically before the chip becomes toast?
>>
>> On 2011-02-27, at 9:31 AM, Oscar Salas wrote:
>>
>> > Hello,
>> >
>> > Regarding the SSM2164 I would like report my
>> experience with the coolaudio v2164.
>> >
>> > Time ago 3 quad VCAs of my system died. (They are Mike
>> Irwin linearized  so 6 chips) I didn't understand
>> why. I read somewhere that the 2164 dies when the negative
>> rail faults and forget it. Just replace them. I thought that
>> maybe I shorted accidentally the negative rail with that
>> result.
>> > More recently another quad VCA, this time with new PCB
>> layout, also did die. Just replaced the chips and now is
>> working.
>> >
>> > Well, I wanted to know why. I bought a pair of
>> original ssm2164 and I did several tests. For example, I
>> placed in a breadboard, side by side, a V2164 and a SSM2164
>> without connect the negative rail for more than five
>> minutes. Neither of both did die.
>> > The only thing that I can report is that the V2164
>> went so much hot than the original SSM2164. I don't have a
>> thermometer and temperatures were sensed with the finger :).
>> The diference was very clear. The SSM2164 was hot but you
>> could stay touching the chip. The V2164 you could not stay
>> touching it nor one second, was really burning.
>> >
>> > I didn't found why the V2164 of my system died, nor
>> if they were original SSM2164 they had died.
>> > What I found was a difference within them.
>> >
>> > Other similar experiences?
>> >
>> > Hoping that my English is understandable :) Best
>> regards,
>> > Oscar.
>>
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