Can a Power Supply for an IBM 5170 be repaired if damaged by shipping carrier?

[Dave Farquhar]

I do have a spare IBM XT 150 W power supply. My concern is what was shown in minuszerodegrees website a necessity for AT machines needing 192 W to handle IBM hardware. However, since this is a clone of an AT, do I need that much power or wattage?

While 150 watts is on the low side for a 386, a 386 PC with 4 MB of RAM, a simple video card, and modern-ish IDE storage would probably be fine, especially if it's just a temporary arrangement until the repaired 200W unit comes back.

 

[alejack12001]

While 150 watts is on the low side for a 386, a 386 PC with 4 MB of RAM, a simple video card, and modern-ish IDE storage would probably be fine, especially if it's just a temporary arrangement until the repaired 200W unit comes back.

What about a 286 with 640 KB and MFM hard drive? I have that in the wings since the 386 has that Dallas RT clock embedded in the motherboard and requires removal and repair.

 

[Dave Farquhar]

What about a 286 with 640 KB and MFM hard drive? I have that in the wings since the 386 has that Dallas RT clock embedded in the motherboard and requires removal and repair.

I would think it would be OK, especially if it's a later 286 board with a chipset rather than discrete parts like the 5170 had. Though if it were me, I'd probably go with an IDE drive or better yet, compact flash, until I could get a 200W power supply. Then I'd copy the data over to the MFM drive and go MFM at that point.

I had a 12 MHz baby AT clone board in my 5170 case until I was able to acquire a 5170 board to swap in, but I never did measure its power consumption.

 

[Scrawner]

Thanks for the suggestion. I don't know if the power supply is an IBM. Frankly, I don't think it is; I think it is a rebuilt power supply. Can you tell from my pictures?View attachment 1271567View attachment 1271566

Just to chime in here - this is the same TRW-095-1005-01 Power Supply I have in my IBM 5170 which was built in 1985 and I've owned since ~1990. Mine has "8502" where yours has "8514", this appears to be the build week. Just happened to pull it out of the closet this week to start restoring. I last turned it on about 10 years ago, but feeling it's time to replace caps before testing fate. I just ran into the same issue with the rivets.

 

[alejack12001]

The power supply in question was sent back to the of the computer who is going to check it out. To be honest, I doubt if I see that supply ever again.

So I took the initiative to acquire an AT (IBM 5170) clone power supply from a vendor on eBay that has a peculiar connection with regard to the Power Good pin (P8.1). As seen from the pictures below,, IMG_5234a.jpg, the P8.1 is directly coupled to the P8.2 or +5-volt supply. I thought the purpose of the power good was to signal the power supply to show that the 386 motherboard was receiving enough power. The supply doesn’t seem to be powering my 386 motherboard, and I just wanted to know if this connection between P8.1 and P8.2 was having a negative effect on the board preventing the motherboard from powering on?

The other pictures are the power supply and a picture of the supply apparently working with a motherboard made by eBay seller testing conducted on the supply using a digital volt meter. Of course, I don’t know when this picture was made. It could be 1 year ago. Apparently the power supply is made by a Taiwan company called KPI.

Could the 386 motherboard have a grounding issue? The motherboard is connected to the case via screws to the case. The tested power supply is connected to a motherboard that isn't in a case. Should I isolate the motherboard from the case?

 

[alejack12001]

Just a note here the computer above means computer eBay seller. I couldn't correct the error after 10 min.

 

[alejack12001]

I did substitute an unbranded 286 motherboard for the 386 motherboard that I have been writing about in earlier posts and the results were the same. Neither one of the two motherboards will power up with the written power supply earlier. I am trying to find out more about this motherboard. The 5 pin connector is shown in the picture below between the resistor and memory bank 0 or 1. The picture also shows two sets of 4-pin connections and a 2-pin connector. I don't have a clue as to what those are but I suspect one pair is the speaker. I don't have much or any information on this board. It's a 286 motherboard with 10-MHz clock and 640-KB RAM with Award BIOS. There are Chips and Technologies large scale IC's as well. Also the board included a co-processor. There are multiple jumpers on the board again as with the acquired power supply the seller demonstrated that the board worked before selling, but, as I said earlier I don't know when the pictures were made. As with the earlier testing of the power supply picture, the motherboard testing was made outside of the case, again I wonder if it is a grounding issue? I am completely baffled by this problem. The entire motherboard is shown in the picture Unbranded 286 Motherboard.jpg. Question the keylock on the IBM 5170 uses a switch to power off the keyboard and prevent someone from opening the case when the barrel switch is turned to the off position. I looked into the keylock and found a lever with a push button switch attached. I am asking if open meaning the lock is open that the switch is normally open and conversely closed if the switch is off or closed. Is that correct?

 

[alejack12001]

I found the motherboard in Stason.org under Informtech International, Inc. Stason has a couple errors on their listing, however, it is an exact match to the board shown in the earlier post as Unbranded 286 Motherboard.

 

[modem7]

The supply doesn’t seem to be powering my 386 motherboard, and I just wanted to know if this connection between P8.1 and P8.2 was having a negative effect on the board preventing the motherboard from powering on?

It could very well be causing a problem.

Some technical information is at [here]. At the flick on the power switch, POWER GOOD is at a TTL LOW level, holding the motherboard, which includes the CPU, in a reset state. Later, the PSU takes POWER GOOD to HIGH, releasing the reset. The CPU needs that delay (needs to be held in a reset state for a minimum period) - see note 1 at the bottom of aforementioned web page.

Your P8-1 to P8-2 connection would mean that the CPU is not being reset. Maybe the POWER GOOD output failed on the PSU, and the P8-1 to P8-2 connection was a bad repair attempt.

Question the keylock on the IBM 5170 uses a switch to power off the keyboard ...

No. For the IBM 5170, the situation is illustrated at [here]. Via pin P17 on the motherboard's keyboard controller chip, the power-on self test (POST) in the IBM motherboard BIOS will see that the switch is in the ON position, and as a result, the POST will display, "302-System Unit Keylock is Locked".

I am asking if open meaning the lock is open that the switch is normally open and conversely closed if the switch is off or closed. Is that correct?

There is no international standard.

 

[Malc]

Maybe the POWER GOOD output failed on the PSU, and the P8-1 to P8-2 connection was a bad repair attempt.

Agreed, A bodge to fake the PG signal, Not a good thing to do.

 

[alejack12001]

It could very well be causing a problem.

Some technical information is at [here]. At the flick on the power switch, POWER GOOD is at a TTL LOW level, holding the motherboard, which includes the CPU, in a reset state. Later, the PSU takes POWER GOOD to HIGH, releasing the reset. The CPU needs that delay (needs to be held in a reset state for a minimum period) - see note 1 at the bottom of aforementioned web page.

Your P8-1 to P8-2 connection would mean that the CPU is not being reset. Maybe the POWER GOOD output failed on the PSU, and the P8-1 to P8-2 connection was a bad repair attempt.


No. For the IBM 5170, the situation is illustrated at [here]. Via pin P17 on the motherboard's keyboard controller chip, the power-on self test (POST) in the IBM motherboard BIOS will see that the switch is in the ON position, and as a result, the POST will display, "302-System Unit Keylock is Locked".


There is no international standard.

Yes, Thank you both. After reading your minuszerodegrees page, I think I need to remove that coupling from P8.2 to P8.1 so that the reset can be initiated.

The power supply that originated with the orinial acquired IBM 5170 was a Chinese model that I believe was a substitute by the original owner of the 5170 machine. In my initial post, that power supply, which came with the 5170, was damaged along with the frame and case cover as if the seller or the shipper damaged the box either before or during shipment. Never-the-less, I returned the supply to the seller for a replacement, however, I know I'll never see the replacement.

The power supply written and being discussed here is one I got off eBay with the coupling to the high connection between the P8.1 and P8.2. The power supply must have been used to power some motherboard that didn't follow the reset setting shown in the minuszerodegrees page and therefore was rendered as shown. I plugged it in thinking it was going to work when of course it didn't.

I sort of goofed the Key Lock on the 5170 case by taking off the face plate to discover what the momentary switch did in terms of its role to the keyboard. However the minuszerodegrees page shows what it's role is relative to the keyboard. In dismantling the key lock, I don't remember where case lock lever, pressure spring, momentary switch and some U shaped metal plate reassemble once all together. I have been searching for a rear view of the key lock on the 5170 to avail.. Do any of you know where t can find how these pieces look when reassembled. Thanks.

 

[modem7]

The power supply written and being discussed here is one I got off eBay with the coupling to the high connection between the P8.1 and P8.2. The power supply must have been used to power some motherboard that didn't follow the reset setting shown in the minuszerodegrees page and therefore was rendered as shown.

If a motherboard has its own reset circuitry, i.e. ignores the POWER GOOD signal, nothing needs to be done to the power supply.

There exists the possibility that the PSU is faulty, in that at some point in the past, the POWER GOOD signal stopped behaving as expected. If so, the owner may have erroneously concluded that since POWER GOOD is normally at a TTL HIGH level, that a fix was simply to tie POWER GOOD to +5V. If the PSU could not be properly repaired, the fix shown at [here] should have been used as a workaround.

I sort of goofed the Key Lock on the 5170 case by taking off the face plate to discover what the momentary switch did in terms of its role to the keyboard. However the minuszerodegrees page shows what it's role is relative to the keyboard. In dismantling the key lock, I don't remember where case lock lever, pressure spring, momentary switch and some U shaped metal plate reassemble once all together. I have been searching for a rear view of the key lock on the 5170 to avail.. Do any of you know where t can find how these pieces look when reassembled. Thanks.

Does [this] help? Shown in unlocked position.

 

[alejack12001]

If a motherboard has its own reset circuitry, i.e. ignores the POWER GOOD signal, nothing needs to be done to the power supply.

There exists the possibility that the PSU is faulty, in that at some point in the past, the POWER GOOD signal stopped behaving as expected. If so, the owner may have erroneously concluded that since POWER GOOD is normally at a TTL HIGH level, that a fix was simply to tie POWER GOOD to +5V. If the PSU could not be properly repaired, the fix shown at [here] should have been used as a workaround.


Does [this] help? Shown in unlocked position.

Yes, the picture of the key lock was greatly appreciated. Thank you.

The attached is Stason's layout of the current motherboard. I have highlighted in a darker yellow the current settings while a lighter yellow are settings that I think I'd like to have, like 1-MB of RAM and 0-wait state. The green were settings that were inherently not correct and needed to be changed. The J8 is a 2-prong pin set near the RAM while the J1 is a 3-prong pin set near the co-processor and SW2/4 setting is incorrect as there isn't a SW2 on the drawing or board. It's SW1/4. The P2 is the Turbo switch/LED. There are 4-prongs there and figuring out which is which will be an another issue.

 

[alejack12001]

As a followup to all that has been posted regarding this IBM 5170; I have been able to get an IBM motherboard as shown in the picture below. I have but one question regarding this motherboard. I can see from minuszerodegreeqs website that the motherboard is a type 3 with 8-MHz clock and 512-KB RAM. I am trying to determine whether the motherboard is a model 319 or 339. The model makes a difference as the type of keyboard for 319 is 84-key keyboard and the 339 is 101-key keyboard. I have an 101-key keyboard but not the 84-key keyboard.

 

[jafir]

I use a 101 key model M keyboard from the PS/2 era on my 5170 with a type 1 motherboard without issues, or at least without issues that I’m aware of.

 

[Malc]

The 11/15/85 IBM 5170 BIOS as used in the Type 3 Motherboard has support for the 101 key keyboard

 

[alejack12001]

This is good to know that BIOS was the key to setting up the keyboard for the certain IBM Motherboards. Thanks for the information.

 

[modem7]

I am trying to determine whether the motherboard is a model 319 or 339.

Note that 'model' is a designation that IBM used for the computer. For example, '5170 Model 68'. For the IBM 5170, the model information can be found on the barcode at the rear of the computer. I see '099' on the barcode of the 5170 that is presently out on my dining table.

Types 1, 2, and 3, are the correct way to refer to the IBM 5170's motherboard. (And IBM also used those motherboards in computers other than the IBM 5170.)

 

[alejack12001]

Note that 'model' is a designation that IBM used for the computer. For example, '5170 Model 68'. For the IBM 5170, the model information can be found on the barcode at the rear of the computer. I see '099' on the barcode of the 5170 that is presently out on my dining table.

Types 1, 2, and 3, are the correct way to refer to the IBM 5170's motherboard. (And IBM also used those motherboards in computers other than the IBM 5170.)

The IBM 5170 that I have does in fact have the barcode, however, I doubt if the code matches what was found internal to the machine when received. The motherboard that was housed in the case was a 386DX, with 4-MB RAM. It's a DTK ROM board with a small description found on Stason.org.. It doesn't work because of an soldered Dallas RT clock, which appears to be dead. Getting that clock off the board is a real challenge both with the surrounding components and keyboard chip in proximity. In addition, my hands tremor a lot.

I direct you to the posted picture of the motherboard above. I believe that the physical board is a type 1 with 8-MHz, 286 processor, and 512-kB RAM except for the ROM, which displays the following boot screen picture and acquired from the seller who was demonstrating that the machine would boot. It's obvious that the IBM ROM was replaced or overwritten by the previous owner. Right now, I am unsure what would be the correct direction to correct the ROM's to put them back to the IBM format when the motherboard was built. I am looking for suggestions.

 

[modem7]

I direct you to the posted picture of the motherboard above. I believe that the physical board is a type 1 with 8-MHz, 286 processor, and 512-kB RAM except for the ROM, which displays the following boot screen picture and acquired from the seller who was demonstrating that the machine would boot.

Your "type 1" is obviously a typo; you correctly identified the pictured motherboard as a type 3 in post #34.
(FRU-6489922 = type 3).

I see that the photo in post #34 is that of a yet-to-sell eBay item, item 266650606293.

It's obvious that the IBM ROM was replaced or overwritten by the previous owner. Right now, I am unsure what would be the correct direction to correct the ROM's to put them back to the IBM format when the motherboard was built. I am looking for suggestions.

Per [here], the type 3 motherboard was supplied with a 11/15/85 dated BIOS.

Option #1: Find somewhere, a set of original IBM ROM's of the 11/15/85 BIOS. Per [here], IBM used various IBM part numbers for the 11/15/85 BIOS dated BIOS.

Option #2: Have someone program you a set of EPROM's containing the 11/15/85 BIOS dated BIOS. Some people/companies that can do that are listed at [here]. Images for the EPROM's are at [here]. Per [here], for an 8 MHz 5170 motherboard, EPROM's with an access time of 190 ns, or faster, are required. As for EPROM type, use 27256 or 27C256, or per [here], the Winbond W27E257.