Advice desired about construction of Rotten Snow 61e/f Missing Module board for rc2014

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Richard Deane

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Sep 22, 2021, 6:46:39 PMSep 22
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I seek advice from someone less confused than I.

I am about to solder up a "Rotten Snow" (Karl - z80.no) 61f missing module pcb and came across the errata shown below. I have no doc specifically for 61f, it all relates to 61e. Since Karl has suspended sales for a while, I got the pcb design from his group post and had it made up by jlcpcb in hk.

My problem is that the silk screen for 61e shows + on the leds for the top pin. The errata says there are errors so I read the errata as the +ve should be on the bottom pin, however my conclusion looking at the board conductors is that the bottom led pins should be -ve, e.g. The RX bottom pin goes to gnd on the ftdi connector so must be negative. This implies the errata is either wrong or that it is a correction for a previous unmentioned board and that 61e boards are correct. My 61f board looks identical (or very similar) to the 61e picture on the z80.no site.

Has anyone built and tested a board to confirm the led polarity?

Regards
Richard


The following is from z80.no
ERRATA


There are errors on the silk screen. The plus sign on RX and TX LEDs is in the wrong position, + (5V) is in the lower position. I have also changed my mind regarding the resistor values for R8 and R9, I have changed them to 330ohm.

PauldB

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Sep 23, 2021, 11:42:03 AMSep 23
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Hi Richard,

Regarding the orientation of the LEDs, a simple solution is to build up the board, just leaving out the LEDs. Then put the board in a slot on your computer and before powering up, put the LEDs loosely in the board with the polarity you think is correct and turn on the power. If one or more LEDs do not light up, just pull it out, turn it 180 degrees and insert it again. You cannot damage an LED if the polarity is wrong; it just won't conduct (assuming of course the presence of a series resistor ;) ).

Paul 

Karl Albert Brokstad

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Sep 23, 2021, 12:06:02 PMSep 23
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Here is the assembly guide for #61f
Karl

61f MissingModule.pdf

Richard Deane

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Sep 23, 2021, 1:02:07 PMSep 23
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Thanks Paul, I had already formulated that option, but hopefully not needed as Karl has published the instructions for board revision 61F, and I expect it to all work smoothly.

I have to choose which colour of leds to use, this usually seems to be a personal choice, and brightness seems a personal choice too. ( I have a Z80-MBC2 board where one led will dazzle a driver at 200m :). 

Richard



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PauldB

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Sep 23, 2021, 1:31:48 PMSep 23
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On Thursday, 23 September 2021 at 19:02:07 UTC+2 rwd...@gmail.com wrote:

I have to choose which colour of leds to use, this usually seems to be a personal choice, and brightness seems a personal choice too. ( I have a Z80-MBC2 board where one led will dazzle a driver at 200m :). 

Sounds familiar. When using LEDs as simple indicator lights I usually end up increasing the value of the series resistor; sometimes quite a lot. When I built Steven's SC131 I experimented with the LED resistors until I got about the same brightness from the 3 LEDs (red, green and orange). I ended up with 1K for the green and 10K(!) for the red and orange.

Fabio must have a well-lighted workshop as I also found the LEDs on my Z80-MBC2 much too bright. There I switched both resistors and LED colors to my liking (nice kit though :)).

Paul
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