8590/9590 PSU

90 PSU Pinouts
90 PSU Models
Remove Model 90 PSU
Open 90 PSU
Myth of "Weak 90 PSU" Debunked!
Testing the 90 PSU
Planar Power Contact Oxidation
Cleaning Your Contacts (for the PSU, not your eyes!)

90 PSU Pinouts
Check the voltages with connectors P1 and P2 plugged into the system board.
-Lead Pin   +Lead Pin   V dc Minimum   V dc Maximum
   1 (P1)    2-7 (P1)     + 4.8            + 5.25 
   1 (P1)    8,9 (P1)     +11.5            +12.6 
   2 (P2)    1   (P2)     -11.5            -12.6
    B        D            + 4.8            + 5.25
    B        A            +11.5            +12.6

Conductor Functions
Black    -12v
Blue     +12v
Red      +5v
Orange   Power Good?
Yellow   POR Power On Request
White    On/Off

   There are two systems fans: one in the power supply, and a second fan on the base. If the power supply fan does not work, replace the power supply. If the second fan does not work, replace it. 


Power Supply Models
   There are at least two different PS for the 90- I have heard rumors of a 150W PS. 

Rich Wolos said 
   The earlier ones had a sticker DC output of 5v, 28a.  Otherwise same. The earlier ones were stamped REV B, newer ones  REV C. 5v, 30a. Must have been around 1990, we got some that are "old sticker 28amps" with "old leads" that have new part number on taped on, FRU 92F0088, covering up FRU 64F4114, but they forgot to change the REV, still B. 
  You could start the old ones (yellow/black short leads and plugs) by grounding the white wire to the CASE.
   The new ones, with long red/black wires, don't work that way. Seems you have to ground the white wire to a black wire. Guess the case is not connected to ground in newer units.

64F4114 194 watts (from Jan 92 HMM) 
Yellow/Black power leads like on the 95s 
+ 5v  28A 
+12v   5A 
-12v   0.35A

92F0088 215 watts (from 96 HMM) 
 Red/Black/Blue power leads. 
 + 5v   30A 
 +12v    5A 
 -12v    0.35A 


Remove Model 90 PSU

   Unscrew the captive screw on the power-supply support leg. Pull the top of the support away from the PSU and continue rotating it forward until the support is free of the bottom clips on the PSU. Now pull the support towards the rear of the system until the front tip can be pulled from the drive shelf.
   Now unscrew the three standard screws from the PSU. Unplug the planar power supply sockets from the board and pull the PSU out.

Opening the 9590 PSU 
  You need a T-15 security TORX. There are three screws on the inner side (towards the complex), two on the outer side (towards the case) and one long screw on the front (towards the floppy).
   The PSU I opened had the same type of construction as that of the 8595 PSUs. The heatsinks are thin (about 1/16ths to 3/16ths) but for a 215W PSU they are quite acceptable.


Little Big 90
    > I'm worried about heat during extended sessions.  There are no drives in the case sucking power and no bulky SCSI cable, but that still doesn't resolve the fact that the 90 really wasn't meant to take a Pentium. 

From Al Savage
    You know, I've heard this before and I admit that I just don't get it. I've been running, for over a year, two 8590-OLFs with P66 complexes, 24x7: one running OS/2 Lan Server over W4 FP13, plus the text mode Seti client, plus ftpserver by Peter Moylan, two internal HDDs and a CDROM, and several external SCSI devices, and EVERY slot filled;  theother running W4 FP13 and Apace/2 plus the Seti client, one HDD & CDROM. 
   The Seti clients make sure that processor utilization is always at 100%, so the CPUs are running as hot as they can ever will.  The P60 & P66 run a lot hotter than the P75/P90/P100 etc (13 watts, IIRC), and I can put my hand on the heat sink and not get burned. Hell, my AMDs run hotter.  No baffle, the front case fan moves about twice the air that any of the clone cases do.  The CPU's heat  sink is still directly in the airflow. 
    I *do* keep the case vacuumed out, though.  I take the covers off  every six months and Kirby the guts.  Dust builds up rapidly, and is an excellent insulator.  Both units are on a 3.1VA (BIG!) UPS. My opinion is that cooling is not a problem on the 8590.  I have not had to replace the PS. I keep a "spare", preconfigured identical 8590 as backup (just swap in HDD & go), but I've never used it. 
   Ed. With either a 194 or 215W PSU, the 90 compares favorably with the 9577 PSU, which was 194W. But nobody complains about the "weak" 9577 PSU, do they?


Testing the 90 PSU
Peter Wendt sez:
   The most important point is that the "testing the power-supply" topic extends only on testing the thing as "one box" and *not* open it. You should leave that to trained experts, because it bears some risks - from which sudden death is the most evil (can spoil the whole day - and more). This sort of "shocking experience" should be left out. 
   The easiest way to test the power-supply if it is still working at all is to open the case, look at the right side under the power-supply, locate the 2 plugs from the power supply to the systemboard and carefully unplug them by simply pulling them out. It might be a bit difficult to get them back this way - but if the power-supply is broken you will have to remove it nyways when you get another one, so we can leave that at the moment. 
      Now: once you got the two plugs pulled out - look at them. The one "P1" marked connector has 2 blue, 6 red and 1 black cables ... that's the lesser important one at that point. The second "P2" marked is the one we need to look at closer. Do the following: re-attach the machine to the AC, then use a piece of wire or a bended paperclip and connect the white wire with one of the neighboring black ones. 
   No danger - the highest voltage on that side of the power-supply is +12VDC. the white line is "+5V sense voltage" and the black one is GND. As long as the white wire isn't attached to GND the other voltages are 0 VDC (power supply de-activated) so there is no risk of accidently shorting any voltage at all. 
   In case the connection is good and the power-supply itself is functional the power-supply fan should come up - and most likely the machines' harddisks as well, which are directly attached to the power-supply with 4-wire DC-cables. If the power-supply comes up the problem sits somewhere else: 
- broken connection between ON/OFF switch and board (low - voltage) 
- broken systemboard 
- defective complex (but at least the green power-LED should light up then) 
   In case nothing happens apart from a faint "click" inside the power-supply ... now ... get familiar with the idea of getting a spare from somewhere. It often pays trying to get an entire working machine rather than only a power-supply. 
   Mod. 8590 without harddisks and memory often sold for some 30 - 40 bucks ... some ask 40$ for the power-supply alone. The 9590s may cost some more - the power-supplies however are identical as far as I know. The main difference between an 8590 and a 9590 is the 1.44MB FDD on the 8590 and that some versions come with only a 512K XGA-1 on the planar. Everything else (processorboard, memory, power-supply, harddisks) can be interchanged among the models. 
   A high pitch whistle indicates the PSU will not pass this test and is broken. Usually these power-supplies are pretty reliable - some of them suffer on "long term problems" with dust contamination and related overheating. In case there were an over-current condition (overload on +5V / +12V lines) it should come up in the above-mentioned test - if that malfunction is not caused by the harddisks. Try detaching the 4-pin power-plugs from the harddisk(s) and retry ... if the malfunction persists even with nothing attached to the power-supply it is definitely broken. 
   To fix these kind of "switching power supplies" you need some more equipment than only a multimeter, a pair of scissors and a roll of duct-tape. Parts inside these supplied are directly connected to mains AC and converted into DC impulses of hazardous voltages and frequencies ... so I would not even recommend trying to open the box if you do not exactly know what you are doing. In case of doubt: leave it as it is. There are a few "power-supply gurus" out which may be able to repair the unit - but they are hard to find. 

Planar Power Supply Contacts
Peter said:
   This machine is also known for burning the contacts on the systemboard where the power supply connectors go to. They have some problem with too small contact surfaces, the printboard-style contacts oxydate and the current drawn let them get hot. After some time the area around the contacts gets brownish and the machine looses contact and don't work anymore. This *can* be fixed in many cases with re-soldering the contact surfaces with a thin layer of soldering tin or with liquid silver - as used for rear window defoggers on cars. The inside of the power supply plugs however needs to be cleaned with a good TV tuner cleaner spray to remove the oxydation.

Cleaning Planar and Plugs
Rick Ekblaw had way too much time on his hands:
   There's not an easy way to check the power supply connections, but there is a simple way to clean off oxidation and re-establish a good connection from the power supply to the planar, as follows:

(1) Remove the power supply from the case. Look HERE.  First, remove the power connections from any internal devices (hard drives, CD-ROMs, etc), remove the sheet metal "bracket" between the power supply and the drive cage, then remove the screws in the back. "Flop" the power supply 180 degrees from left to right to make it easier to access the planar power connectors, and then remove the connectors.

(2) At this point, you can easily look at the planar and power supply connections, and they'll probably look OK.  Don't be fooled.  Take a small piece of ScotchBrite (that green plastic scrubby stuff that is frequently used to scrub pots and pans) and LIGHTLY buff the planar solder pads to make them nice and shiny.  Buff the power supply connector fingers with an emory board - again, just a light touch is needed, rub each finger two or three times.

(3) Slide the power supply connectors on the motherboard pads, then remove the power supply connectors again.  Do each of the pads show marks where the power supply connector fingers dug into the solder pads?  If not, you need to re-tension the fingers that did not make a mark.

(4) Once all the fingers make marks, re-install the power supply and power connections to your devices.  Power up and enjoy reliable 9590 power for several more years.

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