[N8VEM: 20119] N8VEM SBC v.2, Tantalums vs. electrolytics...

[John O'Brien]

soooo, i downloaded the XLS parts list file, and used the product numbers
therein to order the components for my SBC....
C24-C28 are listed as Jameco Part No. 545609, so i ordered those....
of course every photo i've seen of the board and looking at the board
itself, the solder pads are marked for the electrolytic's polarity....
can i use these tantalum caps or am i going to have to place another order
and wait another week? ;)

http://n8vem-sbc.pbworks.com/w/file/39085368/N8VEM%20SBC%20V2%20Parts%20List%20clean.xls
1 N8VEM C24 1.0 uF C1V5 545609
can the tantalums be substituted for the electrolytics?
have a lot of soldering to do before this thing is finished, but i'd like
to get it done this weekend :/
(soldering between the naptimes and bedtimes of three toddlers...)

[Wayne Warthen]

These are the charge pump caps for the RS-232 line driver. Tantalum is
fine as long as the value is correct. Like electrolytic, tantalum also has
polarity, so be sure to mount them in the proper orientation.

--Wayne

Post by John O'Brien
soooo, i downloaded the XLS parts list file, and used the product numbers
therein to order the components for my SBC....
C24-C28 are listed as Jameco Part No. 545609, so i ordered those....
of course every photo i've seen of the board and looking at the board
itself, the solder pads are marked for the electrolytic's polarity....
can i use these tantalum caps or am i going to have to place another order
and wait another week? ;)
http://n8vem-sbc.pbworks.com/w/file/39085368/N8VEM%20SBC%20V2%20Parts%20List%20clean.xls
1 N8VEM C24 1.0 uF C1V5 545609
can the tantalums be substituted for the electrolytics?
have a lot of soldering to do before this thing is finished, but i'd like
to get it done this weekend :/
(soldering between the naptimes and bedtimes of three toddlers...)

[John O'Brien]

Post by Wayne Warthen
These are the charge pump caps for the RS-232 line driver. Tantalum is
fine as long as the value is correct. Like electrolytic, tantalum also has
polarity, so be sure to mount them in the proper orientation.
--Wayne

thanks for the headsup, will hopefully be posting a screen cap by
monday....

[John O'Brien]

<Loading Image...>

<Loading Image...>
It's Alive!
had a few tense moments... inserted all the ICs, machined sockets are a
P.I.T.A.
connected my USB-Serial adapter, fired up PuTTY, applied power from a
regulated breadboard power supply (jumpered through the bus connector)
and...
no smoke! but no welcome screen...
nothing.....
i put pins in place of D1 so i can wire an LED later.... so i jumper an LED
to the pins.... i've got power...

used a logic probe to test for power at the ICs, good
hooked up my o-scope to check the clock signals, good
ditch the breadboard PSU, hotwire a spare ATX supply...... still nothing....
hook up my XP pc (that i use for programming EPROMs) because it has a
serial port... power up... nothing....

hrmm..... maybe if i hit the "reset" button on the damned board.... BINGO!

so i feel like an idiot, but i'm going to blame the three kids and a
chronic lack of sleep for missing the obvious....

currently running with the Prolific USB-Serial and breadboard PSU
my multimeter has 3 ranges, 2mA, 200mA, and 10A, at the 10A setting,
without D1 hooked up the SBCv2 draws 0.41A

in case anyone was curious....

[Max Scane]

Hi John,

Congratulations! Well done! Getting your first SBC up and going is quite a
feat.

The reset issue might be caused by not having any backup power connected to
the DS1210. There was some discussion about this a while back. From
memory the DS1210 blocks the first couple of operations to the RAM to
indicate the backup battery is low in volts.

You can either connect a battery to BT1 or remove the DS1210 and jumper
pins 1 to 6.

Cheers!

Max

Post by John O'Brien
<https://lh3.googleusercontent.com/-XXn78jYHp9E/Vfzpgeo83oI/AAAAAAAAR3o/fc1KRAp3R84/s1600/20150919_001843.jpg>
<https://lh3.googleusercontent.com/-AyNpR-6cuXA/Vfzl6ISP8rI/AAAAAAAAR3c/fNykIDSmalE/s1600/Capture.JPG>
It's Alive!
had a few tense moments... inserted all the ICs, machined sockets are a
P.I.T.A.
connected my USB-Serial adapter, fired up PuTTY, applied power from a
regulated breadboard power supply (jumpered through the bus connector)
and...
no smoke! but no welcome screen...
nothing.....
i put pins in place of D1 so i can wire an LED later.... so i jumper an
LED to the pins.... i've got power...
used a logic probe to test for power at the ICs, good
hooked up my o-scope to check the clock signals, good
ditch the breadboard PSU, hotwire a spare ATX supply...... still nothing....
hook up my XP pc (that i use for programming EPROMs) because it has a
serial port... power up... nothing....
hrmm..... maybe if i hit the "reset" button on the damned board.... BINGO!
so i feel like an idiot, but i'm going to blame the three kids and a
chronic lack of sleep for missing the obvious....
currently running with the Prolific USB-Serial and breadboard PSU
my multimeter has 3 ranges, 2mA, 200mA, and 10A, at the 10A setting,
without D1 hooked up the SBCv2 draws 0.41A
in case anyone was curious....
--
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