1541 Assy# 250442

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1541 Assy# 250442

silverdr-2
Do we have correct schematics for this 1541 board?

It uses 74LS123 in place of DM9602 but all the schematics I found refer to the 9602 mulitvibrator, which - as Ruud noticed here:

http://www.baltissen.org/newhtm/1541a.htm

seems not to be a drop-in replacement. Also I found that:

http://www.zimmers.net/anonftp/pub/cbm/schematics/drives/new/1541/boards.txt

says: "1541A2   250446-01   A 74LS123 replaces the 9602 at UD4" but all 250442 I have are already equipped with '123


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Re: 1541 Assy# 250442

William Levak

I have the schematic for 250442.  UD4 is a 9602. Sams Photofact says to
use a NTE9602 or ECG9602.


On Mon, 21 Nov 2016, [hidden email] wrote:

> Do we have correct schematics for this 1541 board?
>
> It uses 74LS123 in place of DM9602 but all the schematics I found refer to the 9602 mulitvibrator, which - as Ruud noticed here:
>
> http://www.baltissen.org/newhtm/1541a.htm
>
> seems not to be a drop-in replacement. Also I found that:
>
> http://www.zimmers.net/anonftp/pub/cbm/schematics/drives/new/1541/boards.txt
>
> says: "1541A2   250446-01   A 74LS123 replaces the 9602 at UD4" but all 250442 I have are already equipped with '123
>
>
> --
> SD!
>
>
>       Message was sent through the cbm-hackers mailing list
>
>

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Re: 1541 Assy# 250442

silverdr-2
Hi William,

I think it was you who wrote the boards.txt file?

> On 2016-11-22, at 06:35, William Levak <[hidden email]> wrote:
>
> I have the schematic for 250442.  UD4 is a 9602.

Unfortunately that's not the case:

https://dl.dropboxusercontent.com/u/58002657/cbm/1541/ASSY250442.jpg

so it should be corrected.

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Re: 1541 Assy# 250442

William Levak

The information was taken from:
   1540/1541 Technical manual  990445
   1540/1541 Service Manual 314002-01
   1541/1541-II Service Manual 314862-01
   Sams Computerfacts CD4 VIC-1541, 1541

They contain the following disclaimer:
   The information is made available solely on an as is basis, and the
   entire risk as to quality and accuracy is with the user.

I have no control over the content of Commodore's manuals or the Sams
Computerfacts.  If you have better information, you should post it so we
all will have access to it.

On Tue, 22 Nov 2016, [hidden email] wrote:

> Hi William,
>
> I think it was you who wrote the boards.txt file?
>
>> On 2016-11-22, at 06:35, William Levak <[hidden email]> wrote:
>>
>> I have the schematic for 250442.  UD4 is a 9602.
>
> Unfortunately that's not the case:
>
> https://dl.dropboxusercontent.com/u/58002657/cbm/1541/ASSY250442.jpg
>
> so it should be corrected.
>
> --
> SD!
>
>
>       Message was sent through the cbm-hackers mailing list
>

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Re: 1541 Assy# 250442

silverdr-2

> On 2016-11-22, at 16:30, William Levak <[hidden email]> wrote:
>
>
> The information was taken from:
>  1540/1541 Technical manual  990445
>  1540/1541 Service Manual 314002-01
>  1541/1541-II Service Manual 314862-01
>  Sams Computerfacts CD4 VIC-1541, 1541
>
> They contain the following disclaimer:
>  The information is made available solely on an as is basis, and the
>  entire risk as to quality and accuracy is with the user.

I understand.

>
> I have no control over the content of Commodore's manuals or the Sams Computerfacts.  If you have better information, you should post it so we all will have access to it.

William, but (besides looking for 250442 schematics) that's what I am doing. Please take no offence. I simply thought that since (I believe so, based on the metadata of the boards.txt file) you created that file, you may want to update it with the seemingly more correct information I posted.

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Re: 1541 Assy# 250442

William Levak
On Tue, 22 Nov 2016, [hidden email] wrote:

>
>> On 2016-11-22, at 16:30, William Levak <[hidden email]> wrote:
>>
>>
>> The information was taken from:
>>  1540/1541 Technical manual  990445
>>  1540/1541 Service Manual 314002-01
>>  1541/1541-II Service Manual 314862-01
>>  Sams Computerfacts CD4 VIC-1541, 1541
>>
>> They contain the following disclaimer:
>>  The information is made available solely on an as is basis, and the
>>  entire risk as to quality and accuracy is with the user.
>
> I understand.
>
>>
>> I have no control over the content of Commodore's manuals or the Sams Computerfacts.  If you have better information, you should post it so we all will have access to it.
>
> William, but (besides looking for 250442 schematics) that's what I am doing. Please take no offence. I simply thought that since (I believe so, based on the metadata of the boards.txt file) you created that file, you may want to update it with the seemingly more correct information I posted.

Looking at the schmatic, I find a note that it is good for 250442 and
250446 with the following changes:

      Component    250442      250446
         UD4        9602       74LS123
         R12        22K          15K
         C31        33pF      Eliminated

It appears that the same PCB was used for two different assemblies.


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smf
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Re: 1541 Assy# 250442

smf
On 24/11/2016 05:10, William Levak wrote:
> Looking at the schmatic, I find a note that it is good for 250442 and
> 250446 with the following changes:
>
>      Component    250442      250446
>         UD4        9602       74LS123
>         R12        22K          15K
>         C31        33pF      Eliminated
>
> It appears that the same PCB was used for two different assemblies.

Do you know if there is any board rework required to convert a 250442 to
a 250446? If so then this may have been reworked in the factory to use
up existing pcb's (or some time later during a repair). It would be
strange to change the ASSY number for a component change, but people
(especially commodore people) do strange things.


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Re: 1541 Assy# 250442

silverdr-2
In reply to this post by William Levak

> On 2016-11-24, at 06:10, William Levak <[hidden email]> wrote:
>
> Looking at the schmatic, I find a note that it is good for 250442 and 250446 with the following changes:
>
>     Component    250442      250446
>        UD4        9602       74LS123
>        R12        22K          15K
>        C31        33pF      Eliminated
>
> It appears that the same PCB was used for two different assemblies.

The problem is that 9602 and LS123 seem NOT to be pin compatible and I haven't noticed any patches on any of the 250442s I happen to have.

Maybe the note means that the schematic is valid /also/ for 250442 and 250446 with the mentioned changes? Which file is the schematic in question? Could you share it?

--
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Re: 1541 Assy# 250442

silverdr-2
In reply to this post by smf

> On 2016-11-24, at 11:28, smf <[hidden email]> wrote:
>
> On 24/11/2016 05:10, William Levak wrote:
>> Looking at the schmatic, I find a note that it is good for 250442 and 250446 with the following changes:
>>
>>     Component    250442      250446
>>        UD4        9602       74LS123
>>        R12        22K          15K
>>        C31        33pF      Eliminated
>>
>> It appears that the same PCB was used for two different assemblies.
>
> Do you know if there is any board rework required to convert a 250442 to a 250446? If so then this may have been reworked in the factory to use up existing pcb's (or some time later during a repair). It would be strange to change the ASSY number for a component change, but people (especially commodore people) do strange things.

I would expect the rework to be needed around the 74LS123 but nothing like that is visible on any of the 250442 boards I examined.

--
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Re: 1541 Assy# 250442

William Levak
In reply to this post by silverdr-2
On Thu, 24 Nov 2016, [hidden email] wrote:

>
>> On 2016-11-24, at 06:10, William Levak <[hidden email]> wrote:
>>
>> Looking at the schmatic, I find a note that it is good for 250442 and 250446 with the following changes:
>>
>>     Component    250442      250446
>>        UD4        9602       74LS123
>>        R12        22K          15K
>>        C31        33pF      Eliminated
>>
>> It appears that the same PCB was used for two different assemblies.
>
> The problem is that 9602 and LS123 seem NOT to be pin compatible and I haven't noticed any patches on any of the 250442s I happen to have.
>
> Maybe the note means that the schematic is valid /also/ for 250442 and 250446 with the mentioned changes? Which file is the schematic in question? Could you share it?


The schematic is 251748.

The image you have posted has R12 as 15K and C31 is not present, so your
board corresponds to the description of 250446.

I also notice that the image shows a paper label with an entirely
different number on it.



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Re: 1541 Assy# 250442

William Levak
In reply to this post by smf
On Thu, 24 Nov 2016, smf wrote:

> On 24/11/2016 05:10, William Levak wrote:
>> Looking at the schmatic, I find a note that it is good for 250442 and
>> 250446 with the following changes:
>>
>>      Component    250442      250446
>>         UD4        9602       74LS123
>>         R12        22K          15K
>>         C31        33pF      Eliminated
>>
>> It appears that the same PCB was used for two different assemblies.
>
> Do you know if there is any board rework required to convert a 250442 to a
> 250446? If so then this may have been reworked in the factory to use up
> existing pcb's (or some time later during a repair). It would be strange to
> change the ASSY number for a component change, but people (especially
> commodore people) do strange things.

I don't have any information on that.


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Re: 1541 Assy# 250442

Gerrit Heitsch
On 11/30/2016 04:06 PM, William Levak wrote:

> On Thu, 24 Nov 2016, smf wrote:
>
>> On 24/11/2016 05:10, William Levak wrote:
>>> Looking at the schmatic, I find a note that it is good for 250442 and
>>> 250446 with the following changes:
>>>
>>>      Component    250442      250446
>>>         UD4        9602       74LS123
>>>         R12        22K          15K
>>>         C31        33pF      Eliminated
>>>
>>> It appears that the same PCB was used for two different assemblies.
>>
>> Do you know if there is any board rework required to convert a 250442
>> to a 250446?

I do have two ASSY 250442, one with a 9602 und one with a 74LS123. The
differences mentioned above fit the visible differences. There are
photographs available by email.

  Gerrit



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Re: 1541 Assy# 250442

William Levak
In reply to this post by William Levak
On Wed, 30 Nov 2016, William Levak wrote:

> On Thu, 24 Nov 2016, [hidden email] wrote:
>
>>
>>> On 2016-11-24, at 06:10, William Levak <[hidden email]> wrote:
>>>
>>> Looking at the schmatic, I find a note that it is good for 250442 and
>>> 250446 with the following changes:
>>>
>>>     Component    250442      250446
>>>        UD4        9602       74LS123
>>>        R12        22K          15K
>>>        C31        33pF      Eliminated
>>>
>>> It appears that the same PCB was used for two different assemblies.
>>
>> The problem is that 9602 and LS123 seem NOT to be pin compatible and I
>> haven't noticed any patches on any of the 250442s I happen to have.
>>
>> Maybe the note means that the schematic is valid /also/ for 250442 and
>> 250446 with the mentioned changes? Which file is the schematic in question?
>> Could you share it?
>
>
> The schematic is 251748.
>
> The image you have posted has R12 as 15K and C31 is not present, so your
> board corresponds to the description of 250446.
>
> I also notice that the image shows a paper label with an entirely different
> number on it.

I have opened up 3 1541s. the numbers on the circuit boards do not match
any numbers on my list of versions.  However, the numbers on my
list of versions do match the part numbers on Commodore's relacement parts
lists.

It appears that Commodore used two different munbering systems.  In
determining which version you have, you should use the descriptions of
the board and not the number on the circuit board.

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