Re: [N8VEM-S100:2631] S-100 Bus Extender V2 and reversed Q1 transistor

John and Vince, thank you both for your time and precious help.
I have now fit everything on my extender board, except R14, R15 and the female connector on top (I'll solder that when I'll actually be ready to test another board). Q1 is a PN2907A, positioned in the same way specified by the silkscreen and schematics.

If I have some luck on my side, this weekend I'll be able to give power to the board and start calibrating the resistors (and try the LS14). The calibration won't be conclusive I guess, as I have no other complete board to check "true" logic signals, but I can start with bare Vcc and GND and see if the led behave as they should.

Today I finished cleaning up my S-100 box and wiring a new fan in it (I had to remove all the passive components on the main power line, as they all were for 110VAC, which is not used here in Italy), by the end of the week I should have enough time to cut a piece of wood to make a proper stand for my switching power supplies, wire them to the mains and the backplane and finally power the box for the very first time. The extender and the 6502 (which now has all the passive components soldered, and all the active ones waiting for assembly) board are to follow.

On Tuesday, March 4, 2014 1:45:50 AM UTC+1, monahanz wrote:

Fabio, I switched the transistor around and went back to the 6.8K/390 ohms resistors. The LOW led is now on when no connection and while most S100 signals see to work I find for example the clock line (pin 49) is not showing anything. Clearly the trigger point is now off. I’m am bogged down with other things right now, just wanted you to be aware. Let me know if you get a fix, perhaps a LS14 on U3.
John

From: n8ve...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Fabio Battaglia
Sent: Monday, March 3, 2014 3:05 PM
To: n8ve...@googlegroups.com
Subject: RE: [N8VEM-S100:2631] S-100 Bus Extender V2 and reversed Q1 transistor

Thanks John!
I'm left with fitting the power supply in my S100 box and then I'll be able to test the extender board (well, the logic probe part at least). I'll try to fine tune the resistors and see which results I'll get, and then I will report back.
Bye!
Fabio
On Mar 3, 2014 11:54 PM, "John Monahan" <mon...@vitasoft.org> wrote:
I think you are correct Fabio, thanks for pointing that out. The schematic at the bottom of the page is the way it should be.
If you have time perhaps you could fine tune the values for R14 and R15 and let us know. Perhaps temporally using two pots.

BTW, as best I can keep up, the “most current” schematic (at the bottom of each page) on all the S100Computers.com pages are the ones to use.
There are various schematic links to prototypes (+/- errors) in the pages for these boards as we fine tune the layouts and go through various versions.
Unless you wish to follow progress/the evolution of these boards (e.g. the 80386 board for example), always use the .pdf’s at the bottom of the page.

John

From: n8ve...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Fabio Battaglia
Sent: Monday, March 3, 2014 2:31 PM
To: n8ve...@googlegroups.com
Subject: [N8VEM-S100:2629] S-100 Bus Extender V2 and reversed Q1 transistor

Hello everyone,
I almost finished building my S-100 bus extender, the first board that will go into my S-100 system to help me debug future boards.
I'm left with only one piece to install: the Q1 PNP transistor, which is leaving me some doubts.
The extender board page (http://www.s100computers.com/My%20System%20Pages/Extender%20Board/Extender%20Board.htm) states that there is an error in the schematics and that Q1 is reversed. It's not clear to me if this is a problem of the V1 board/schematics only or if this is present in V2 too.

Adding to my confusion is that I see three schematics in the page:
1) Schematics of the V1 version (http://www.s100computers.com/My%20System%20Pages/Extender%20Board/Printing%20S100_Bus%20Extender-sch%20(FINAL%20V1).pdf) which i suppose has the reversing error.
2) A picture of what i think is the V1 version schematics, with a correction drawn in red (http://www.s100computers.com/My%20System%20Pages/Extender%20Board/Extender%20Board%20V3b%20Schematic.jpg)
3) The V2 schematics (http://www.s100computers.com/My%20System%20Pages/Extender%20Board/Printing%20S100_Bus%20Extender-sch%20(V2-1-FINAL).pdf), which has the transistor in the same position as the picture of point 2.

If the schematics of V2 are correct Q1 should have the collector tied to GND, and with my PN2907A (http://www.mouser.com/ds/2/149/PN2907A-191970.pdf) this means the transistor would actually be oriented the same way shown on the silkscreen, but in the very first picture of the extender board page i see the opposite: the transistor is still reversed on V2 card.

Anyone can shed some light on the matter?

Thanks,
Fabio
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