RE: AD561JN DAC compatibility

From: Bill Karkula <sociableone_at_gmail.com>
Date: Sat Dec 01 2012 - 12:16:03 EST

I'm thinking "parameter shift" due to the age of the devices (r's or c's on
the die have changed significantly enough to cause issues). Back in the
early 80's process control was not anywhere like it is today. SEM photos of
laser-trimming looked like bombing devastation and opened the top
passivation layer. Also, that part is over 30 years old and of dubious
handling over that entire time (possible ESD damage?).

Plastic packages did exert more pressure on the die from the molding process
versus ceramic packaging and caused parameter shift after bonding and
molding but that was taken into consideration as part of the manufacturing
process. However it may have more longer term effects than ceramic
packaging due to that pressure, especially for analog parts. Going from my
faulty memory, back in the day the useful life target for commercial
semiconductors was around ten years. It amazes me that 30 years later a
majority of these parts are still humming given the (in relative terms)
imperfect technology used to produce them. Although there are some parts
that I see now commonly failing due to age and we can all probably make a
good list based upon our own experiences by part number and manufacturer.
Logic parts by Signetics would be at the top of my list.

I have experienced the parameter shift phenomenon with Asteroids boards
using AM6012s where the image was shifted either a little too far vertically
or horizontally and had to parallel a 200K potentiometer with the zero
offset 10K resistors at either R81/R82 (for x direction shift) or R82/83(for
Y direction shift) to adjust / compensate. I have done this for several
boards and they have worked fine for years afterwards.

I have not investigated if an AD561 with the issue you have seen can be
compensated by an external component value change. Would be interesting to
see if it was possible.

Bill

-----Original Message-----
From: owner-vectorlist@vectorlist.org
[mailto:owner-vectorlist@vectorlist.org] On Behalf Of Ian Eure
Sent: Friday, November 30, 2012 6:56 PM
To: vectorlist@vectorlist.org
Subject: Re: VECTOR: AD561JN DAC compatibility

The one that was there originally was 8101. The defective replacement 561J
is 8146. The JN is 9623.

On Nov 30, 2012, at 5:19 AM, Bill Karkula <sociableone@gmail.com> wrote:

> What is are the date codes for the two devices? I'm curious to know
> if they are young or NOS.
>
> Bill
>
> -----Original Message-----
> From: owner-vectorlist@vectorlist.org
> [mailto:owner-vectorlist@vectorlist.org] On Behalf Of Ian Eure
> Sent: Friday, November 30, 2012 12:14 AM
> To: vectorlist@vectorlist.org
> Subject: Re: VECTOR: AD561JN DAC compatibility
>
> Following up on this, I got around to swapping the bad DAC on this
> Asteroids board. Here it is running the AD561JN on the X circuit:
>
> http://i.imgur.com/4bA9x.jpg
>
> I believe this is perfectly acceptable. I also purchased an AD561J to
> compare against, but unfortunately it appears to be defective, with
> instability on the far right edge of the image:
> http://i.imgur.com/q8LH0.jpg
>
> The only thing I note with the JN vs. 561J is that the JN seems to
> output a somewhat smaller image, though it is correctable with the X
> trimmer pot, and could be due to differences from one production run to
another.
>
> On Oct 30, 2012, at 7:37 AM, Ian Eure wrote:
>
>> Interesting. Well, I found a source for some cheap AD561JN chips, and
>> I
> have a PCB that needs a new X DAC.
>>
>> I bought one of each, so I'm going to socket the bad location on this
> board and try both.
>>
>> On Oct 30, 2012, at 1:32 AM, Andrew Welburn <andy@andysarcade.net> wrote:
>>
>>> Yes, however i have found thet the plastic versions can be a little
> 'noisier' ie, adding spikes to vectors. This might have just been the
> particular one or two that i have seen, but i've had to replace
> plastic ones with cermaic to fix problems before.
>>>
>>> Andrew Welburn
>>> http://www.andys-arcade.com
>>>
>>> On 30/10/2012 05:47, Ian Eure wrote:
>>>> Has anyone used an AD561JN in a vector board successfully? I poked
> around the datasheet, and it looks like the only difference is that JN
> uses a plastic housing instead of the ceramic used by the JD chips.
> They're rated the same in every other regard, so I assume they will
> work the same, but I thought I'd ask to see if anyone has done it.
> ----------------------------------------------------------------------
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Received on Sat Dec 1 12:16:22 2012

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