[sdiy] SSM2164 last time buys

Tue Mar 1 01:51:52 CET 2011

Hey Tim thanks, 
Yes I have the same question, it would be great the solution just with one resistor. If not the other solution would be the resettable fuse. Lets see more opinions!

--- On Tue, 3/1/11, Tim Ressel <madhun2001 at yahoo.com> wrote:

> From: Tim Ressel <madhun2001 at yahoo.com>
> Subject: Re: [sdiy] SSM2164 last time buys
> To: "Oscar Salas" <osaiber at yahoo.es>, "Synth DIY" <synth-diy at dropmix.xs4all.nl>
> Date: Tuesday, March 1, 2011, 2:41 AM
> 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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