11 Oct
2015
11 Oct
'15
8:01 p.m.
On 10/11/15 6:19 PM, Josh Dersch wrote:
On Sun, Oct 11, 2015 at 12:07 PM, Brent Hilpert
<hilpert at cs.ubc.ca
<mailto:hilpert at cs.ubc.ca>> wrote:
On 2015-Oct-10, at 8:44 PM, Josh Dersch wrote:
. . .
Note that the "+13V" supply must also be present, and it's
generated and referenced on the Mains side of everything.
In summary, for the relay to activate:
1) The Mains is rectified and filtered to produce Mains
+300V via bridge LNS-CR1 and caps LNS-C1,C2.
2) MOB-D1,D2,R1,R2 form a voltage divider / balancing
network to produce Mains +150VDC.
They also balance the voltage across the Mains filter
caps (LNS-C1,C2) when in 220VAC mode.
** 3) Mains +150V is regulated via MOB-R3, BIB-Q6, BIB-C4,
BIB-D11 to produce Mains +13V, referenced
from MOB-D2 feeding ("START-UP DRIVE") the base of BIB-Q6.
16V zener BIB-D12 additionally clamps this level.
4) Mains +13V supplies 555 oscillator BIB-E2, LM393
comparator BIB-E3b and associated circuitry. These form a SMPSU
with MOB-T1.
5) The output from MOB-T1 is half-wave rectified in both
polarities to produce BIB +12V (MOB-D6,C3) and BIB -15V
(MOB-R4,R5,R6,D4,C2,D5).
6) BIB +12V produces BIB +5V via regulator BIB-E1.
7) BIB-E3a forms a voltage level sensor with reference
zener BIB-D13 and voltage divider BIB-R3,R4,R27 that must detect
an adequate level on
the Mains +300V to turn on the relay via BIB-Q11,
BIB-E5, BIB-E4a.
LNS = Line Supply section PDF.146
MOB = Motherboard PDF.162
BIB = Bias & Interface Board PDF.166-168
** There appears to be something inconsistent in the schematic
here in that the base of BIB-Q6 is fed by +10V from MOB-D2, which
would leave the Mains +13V at more like +8V.
Am I missing something? - is there anywhere in that doc that
explicitly declares the association between the 2-dozen
connectors, for example, that Line Supply P1 & P2 connect to
Motherboard J5 & J4, and that Bias and Interface Board J1 & J2
connect to Motherboard J7 & J6?
Awesome, thanks for the detailed writeup. Things make sense, or at
least more sense.
I went to take a look at the +13V supply and of *course* once I did
things started working, mysteriously. The relay clicks over and I get
+13V and it looks like the bias voltages are present as well. All I
did was tack on a wire to the 10/L header pins on the bias/interface
board (+13V)...
So that's... good, but I have no idea what the actual problem is/was.
Going to clean the connectors and look for cold solder joints (again
:)) just to rule that out. I'll get a dummy load hooked up and see if
anything happens when I throw the front panel switch.
Thanks again, all.
- Josh
Re-inspection revealed no cold solder joints, but I reflowed the
backplane connector pins on the Bias/Interface board pins L and 10
anyway. I reassembled everything in the chassis, hooked up a dummy load
and everything came up fine. Reinstalled the CPU boardset + terminator
and I get the Console chevron prompt after a couple of seconds and the
built-in diagnostic tests pass. So, success, of a sort. I feel like I
cheated somehow :). We'll see if it keeps working...
Now to figure out mass storage; I have an SMD controller and a drive --
let's find out if either of them work :).
Thanks again for the analysis and advice, I'm slowly figuring things out
but I think I really need to sit down one of these days and really study
power supply electronics.
- Josh