1541-II Is it supposed to look like this inside?

Flemming

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Today i had a look inside my 1541-II and i find something funny looking on the most bottom PCB. Don't know if it's a hack/mod or if it's suppose to look like this. Does your 1541-II drives look like this too?

IMG_20150424_132511.jpg
 

Bryce

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It looks a bit like the write protection mod. Have any other parts been added to the bottom of the PCB? Is the track to pin 6 of the 74LS14 cut, or any other tracks on the PCB cut?

Bryce.
 

MC1173

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Yeah...looks like a mod.

I checked a Rev.5 and a Rev.6 and neither have that.
 

demolition

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I have had at least 6 1541-II drives here and they all had that exact modification. Thus I am fairly certain it is a factory mod, but not sure what it is for.
 

Flemming

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No other parts seems to be added, and no tracks seems to be cut. I will test to see if i can actually write to a write-protected disk, just to be sure.

I'll check which revision it is. back in a sec.... :)
 
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demolition

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Pin 8 on U7 is the main clock output. The gate array (251828) comes in three flavors, where -01 and -03 have 40 pins and -02 have 42 pins. You can see the PCB has holes for 42 pins so I am guessing the board was designed for the -02 version, but they made a fix so they could use the 40 pin -03 version in the same board.
The connection can be seen on this schematic going to pin 21 on the gate array:
http://www.zimmers.net/anonftp/pub/cbm/schematics/drives/new/1541/1541-II.gif

Edit: So this is clearly not a write protect mod.
 
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Flemming

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Pin 8 on U7 is the main clock output. The gate array (251828) comes in three flavors, where -01 and -03 have 40 pins and -02 have 42 pins. You can see the PCB has holes for 42 pins so I am guessing the board was designed for the -02 version, but they made a fix so they could use the 40 pin -03 version in the same board.
The connection can be seen on this schematic going to pin 21 on the gate array:
http://www.zimmers.net/anonftp/pub/cbm/schematics/drives/new/1541/1541-II.gif

Edit: So this is clearly not a write protect mod.

Thank you very much for looking into this! This is good stuff. i never would have found out by myself.

So my 1541-II is quite normal it seems. Suits me just fine :)
 

TheCorfiot

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This is one of those wonderful Commodore factody mods, nothing to worry about.
Have you seen the factory mods on a C128 mobo lol.

:)
 
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