24 Mar
2018
24 Mar
'18
1:47 p.m.
After a recent power cut and a series of glitches as the power was
restored, one of my Indys suffered a PSU failure. It's a Sony APS-81
171W unit, SGI P/N 060-0008-001. I've found half a dozen damaged parts,
and I've identified a 150R 1W metal film resistor (R135), two trannies
(Q105, a 2SC4304 and Q106, a 2SC2785) and a couple of small diodes. One
of them (D116) appears to be a 6.2b2 (6.2V 1/2W) zener.
The other one I'm not sure about. On the PCB it's labelled D113, and
it's adjacent to the 2SC2785. It's very small, with a green band at the
cathode end, and the legend "4B" in green - photos at
https://www.flickr.com/photos/pnt103/albums/72157667056183978
Oddly, another Sony PSU I looked at had a diode there that looked
identical except it's marked "4A".
I have an idea what it might be but if anyone actually knows what family
or type/value this is, I'd be grateful for any insight.
--
Pete
Pete Turnbull
24 Mar
24 Mar
2:23 p.m.
4BSOD-123F MM1Z2V2SemtechZener diode
http://www.s-manuals.com/smd/4b
On Sat, Mar 24, 2018 at 4:47 PM, Pete Turnbull via cctalk
<cctalk at classiccmp.org> wrote:
After a recent power cut and a series of glitches as
the power was
restored, one of my Indys suffered a PSU failure. It's a Sony APS-81 171W
unit, SGI P/N 060-0008-001. I've found half a dozen damaged parts, and I've
identified a 150R 1W metal film resistor (R135), two trannies (Q105, a
2SC4304 and Q106, a 2SC2785) and a couple of small diodes. One of them
(D116) appears to be a 6.2b2 (6.2V 1/2W) zener.
The other one I'm not sure about. On the PCB it's labelled D113, and
it's adjacent to the 2SC2785. It's very small, with a green band at the
cathode end, and the legend "4B" in green - photos at
https://www.flickr.com/photos/pnt103/albums/72157667056183978
Oddly, another Sony PSU I looked at had a diode there that looked
identical except it's marked "4A".
I have an idea what it might be but if anyone actually knows what family
or type/value this is, I'd be grateful for any insight.
--
Pete
Pete Turnbull
26 Mar
26 Mar
8:08 a.m.
4B would be a 2.2V zener; 4A would be a 2.0V zener, so that?s odd indeed...
Camiel
On 3/24/18, 9:47 PM, "cctech on behalf of Pete Turnbull via cctech"
<cctech-bounces at classiccmp.org on behalf of cctech at classiccmp.org> wrote:
After a recent power cut and a series of glitches as the power was
restored, one of my Indys suffered a PSU failure. It's a Sony APS-81
171W unit, SGI P/N 060-0008-001. I've found half a dozen damaged parts,
and I've identified a 150R 1W metal film resistor (R135), two trannies
(Q105, a 2SC4304 and Q106, a 2SC2785) and a couple of small diodes. One
of them (D116) appears to be a 6.2b2 (6.2V 1/2W) zener.
The other one I'm not sure about. On the PCB it's labelled D113, and
it's adjacent to the 2SC2785. It's very small, with a green band at the
cathode end, and the legend "4B" in green - photos at
https://www.flickr.com/photos/pnt103/albums/72157667056183978
Oddly, another Sony PSU I looked at had a diode there that looked
identical except it's marked "4A".
I have an idea what it might be but if anyone actually knows what family
or type/value this is, I'd be grateful for any insight.
--
Pete
Pete Turnbull
9:07 a.m.
On 26/03/2018 16:08, Camiel Vanderhoeven wrote:
4B would be a 2.2V zener; 4A would be a 2.0V zener, so
that?s odd indeed...
That's the idea I had...
Except it's not a zener, or at least not anything like those. I took
one out of another (working) supply, and I can tell it has a forward
voltage of 0.2V, so it's presumably a Schottky diode of some sort. I
can also tell it's not a low-voltage zener; the reverse breakdown
voltage is more than 35V (the highest my bench supply goes up to).
I'm hoping I don't have to breadboard a 1kV supply and find a lot of
multi-megohm resistors to try and estimate the breakdown voltage - and
then guess at the forward current rating.
On 3/24/18, 9:47 PM, "cctech on behalf of Pete
Turnbull via cctech" <cctech-bounces at classiccmp.org on behalf of cctech at
classiccmp.org> wrote:
After a recent power cut and a series of glitches as the power was
restored, one of my Indys suffered a PSU failure. It's a Sony APS-81
171W unit, SGI P/N 060-0008-001. I've found half a dozen damaged parts,
and I've identified a 150R 1W metal film resistor (R135), two trannies
(Q105, a 2SC4304 and Q106, a 2SC2785) and a couple of small diodes. One
of them (D116) appears to be a 6.2b2 (6.2V 1/2W) zener.
The other one I'm not sure about. On the PCB it's labelled D113, and
it's adjacent to the 2SC2785. It's very small, with a green band at the
cathode end, and the legend "4B" in green - photos at
https://www.flickr.com/photos/pnt103/albums/72157667056183978
Oddly, another Sony PSU I looked at had a diode there that looked
identical except it's marked "4A".
I have an idea what it might be but if anyone actually knows what family
or type/value this is, I'd be grateful for any insight.
--
Pete
Pete Turnbull
9:51 a.m.
On 26/03/2018 17:39, ethan at 757.org wrote:
If only! That question has been asked many times on SGI forums like
nekochan, for the Sony PSU (like this one) and also the Nidec. No-one
has ever claimed to have seen one, and the chances are Sony wouldn't
ever have released them.
I have thought about tracing out the relevant area of the circuit, but
it would take a while as the components are fairly densely packed, and
I've got several other tasks on the agenda.
--
Pete
Pete Turnbull
I'm hoping
I don't have to breadboard a 1kV supply and find a lot of
multi-megohm resistors to try and estimate the breakdown voltage - and
then guess at the forward current rating.
Is it possible to get the schematics? 
10:12 a.m.
If only! That question has been asked many times on
SGI forums like
nekochan, for the Sony PSU (like this one) and also the Nidec. No-one has
ever claimed to have seen one, and the chances are Sony wouldn't ever have
released them.
Yea I was looking for the Nidec one for the Indigo, as mine constantly
spits out a power lost error on the console of my R4000. IIRC Nidec said
no, but Sony might be different. I think there is a private system that
Sony repair shops can access that has schematics online.
I have thought about tracing out the relevant area of
the circuit, but it
would take a while as the components are fairly densely packed, and I've got
several other tasks on the agenda.
I can imagine that would take a ton of time. And the parts list still
wouldn't be official.
--
: Ethan O'Toole
8 Apr
8 Apr
9:51 a.m.
On 26/03/2018 17:07, Pete Turnbull via cctalk wrote:
Except it's not a zener, or at least not anything
like those [ones
Camiel and Bob suggested]. I took one out of another (working)
supply, and I can tell it has a forward voltage of 0.2V, so it's
presumably a Schottky diode of some sort. I can also tell it's not a
low-voltage zener; the reverse breakdown voltage is more than 35V
(the highest my bench supply goes up to).
So I dug out my Avo 8, set to the 50?A range, hooked a matching diode
from another Indy PSU up to a 300VDC supply via a
couple of 1Mohm
resistors and a 2Mohm pot as a voltage divider. I found that as I
wound
the pot up from zero volts, the reverse leakage current rose abruptly
from 2-3?A to a few tens of ?A at about 59V across the
diode, and the
voltage across it dropped a little as I wound the pot up further.
So I think it's a Schottky rectifier diode, with a PIV rating probably
between 50V and 60V. Of course I have no idea what the current rating
might be, and I can't think of a simple safe way to work that out.
Any comments?
--
Pete
Pete Turnbull
2211
days inactive
2226
days old
7 comments
4 participants
participants (4)
-
bobsmithofd＠gmail.com -
camiel.vanderhoeven＠vmssoftware.com -
ethan＠757.org -
pete＠dunnington.plus.com