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mdo IBM 5170 (Type 3)

Introduction

A lucky find! I bought a used but not complete IBM AT 5170 unit on ebay a few days ago. Yesterday (19.10.2021) it was delivered.

The hard drive is missing, but that was known to me, the controller WD 1003-WA2 is included (not tested yet). But the most important thing, the motherboard works flawlessly. Otherwise, the YD-DATA YD-380 (1.2MB) and Toshiba ND-356 (1.44MB) are also included (both not tested yet), but they look good except for the stained bezel.

The power supply basically works as well. It only smells a bit. This could be due to age and dirt or scorched but still functional components inside. The power supply I have to look separately and also open it!

When I consider what all the individual parts would cost on eBay, the purchase was a bargain! I still have enough hard disks (ST-225/238/277/251) in stock but unfortunately no Seagate ST-4038.

According to Roman Ondrejka - Vintage PC Collector (IBM PC 5170 512kB System Board #4) I have a model 319/339, type 3 motherboard with small differences. The motherboard is not green (RAL 6035), but lighter (RAL 6025) and the back is brown-orange (RAL 8023). The RAL values are only rough estimates on my part! Furthermore the IC U83 is socketed and not soldered.

The motherboard still has the original BIOS (11/15/85, U27=62X0820, U47=62X0821).

IBM 5170 type 3
IBM 5170 model 319/339, type 3, p/n 62X0670

Versions

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Basically, IBM released three different motherboard versions of the 5170.

In addition, there were several sub-models.

Models 68 and 99 / August 1984:

Model 239 / October 1985:

Models 319 and 339 / April 1986:

Further details and information about the IBM 5170 can be found in the official „IBM Announcement Letters“, see below.

Configuration

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Restoration & Repair

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Motherboard

As mentioned at the beginning, the motherboard is in perfect condition. It doesn't need any repairs at the moment; let's see when the first tantalum resistor burns down!

Battery

The 6V battery is missing. In the IBM AT 5170 a special 6V battery of IBM part number 8286121 is built-in. Of course, nowadays you can not buy this battery. An external case for four 1.5V batteries of type AAA Micro LR03 is easy to buy in an electronics store (Internet) and off you go.

Cabinet

The upper cabinet has become really clean again and especially the front panel is like new. Unfortunately, the metal gray cabinet has several small spots of flash rust. Spray paint I have in the basement but this is a thing to do outside in nice weather, so I have to wait a little.

Floppy Disk Drives

YD-DATA, YD-380 (1.2MB)

The following paragraph originally refers to the YD-580 (360KB), but in my experience the same applies to the YD-380 (1.2MB) drive.

My experience with the YD-580 is that the white nylon cone does not lock an inserted floppy exactly in the centre; the cone ages and becomes brittle. As a result, the diskette is almost impossible to read/write. So far I have been able to solve this problem by carefully moving the locking lever up and down several times. With this movement, I could then centre the floppy disk as usual. This problem is also described in the VCFED forum, see below.

Otherwise, I just had to blow the drive through properly with compressed air and oil it a bit, because the stepper hooked a bit. The front bezel also looks good again after cleaning. Since the coloring of the back of the front bezel is exactly the same as the front, I didn't have to bleach anything either. The locking knob can be removed very easily by loosening an Allen screw.

YD-DATA YD-380, 1.2 MByte
YD-DATA YD-380, 1.2 MByte

The YD-380 can read/write 1.2MB and 360KB floppy disks, but you should use the drive with 360KB disks only to read NOT write! Why? See here.

YD-DATA YD-380, 1.2 MByte
YD-DATA YD-380, 1.2 MByte
YD-DATA YD-380, 1.2 MByte
YD-DATA YD-380, 1.2 MByte
YD-DATA YD-380, 1.2 MByte
YD-DATA YD-380, 1.2 MByte

Toshiba, ND-356 (1.44MB)

The floppy is a 3.5" drive from Toshiba (ND-356), which is installed in a drive box. I forgot to mention that both floppies have drive rails on the sides that you can just slide into the case.

Of course, I also cleaned the ND-356. It works perfectly again.

Floppy disks (YD-DATA YD-380, Toshiba ND-356)
Floppy disks (YD-DATA YD-380, Toshiba ND-356)

The different coloring or bleaching is visible, of course, but that's just retro computing.

Update 10/22/2021: The ND-356 doesn't work quite so flawlessly after all. It sometimes has reading difficulties. Maybe the track position is not perfect, then it can come to problems with foreign disks. I have replaced it with a TEAC FD235; I have never had problems with these.

Hard Disk Drive & Controller

As already mentioned, the hard drive is missing, but this was known to me when I bought this IBM 5170 unit. According to Roman Ondrejka - Vintage PC Collector this must be a Seagate ST-4038 with 30 MByte.

Currently I am using an original IBM WD25, type 13 hard disk with 20 MByte. This also has the full height and a wonderful black front panel with the IBM logo.

The hard disk and floppy controller is a WD1003-WA2 (MFM). This works perfectly but it is not original. But that doesn't matter, because I still have exactly this controller (IBM PC AT Fixed Disk and Floppy Drive Adapter 2nd generation, 69X3948) in reserve.

Floppy disks (YD-DATA YD-380, Toshiba ND-356)
IBM PC AT Fixed Disk and Floppy Drive Adapter 2nd generation, 69X3948

Both controllers are fully compatible, you can easily replace them. The hard disk does not need to be „low level“ reformatted. But unfortunately this controller only supports a maximum interleave of 3:1. The better WD1003-MM2 and WD1006-MM2, on the other hand, support 1:1. Well then!

Power Supply Unit - PSU

I am currently using my test power supply, as I am not quite sure about the original power supply. Yes, it works, but it smells a bit. It is still very dusty and needs to be cleaned. A replacement power supply is ordered though.

Unfortunately, the fan is riveted and can't be replaced easily.

Update 25.10.2021

The power supply is completely disassembled and cleaned from dust and dirt. It was not as complicated as I first thought. The capacitors still look good on the outside but still ... I think I will replace almost all of them though. That's a nice task for the winter.

Power supply unit disassembled
Power supply unit disassembled

Done

For the sake of clarity, I have removed all cables.

IBM 5170 type 3
IBM 5170 model 319/339, type 3, p/n 62X0670

In the end I decided to use my today modded Gotek (OLED, speaker) with FlashFloppy 3.29 after all. As USB I use a very short stick. This only protrudes max. 7 mm and you can't bend it off by accident.

IBM 5170 type 3
IBM 5170 model 319/339, type 3, p/n 62X0670

BIOS

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As you can see on the first picture, this motherboard has the original BIOS (U27, 62X0820 / U47, 82X0821 / dated "11/15/85").

I don't like to use the original BIOS, because you have to re-enter all settings in a very complicated way, if the battery was disconnected. My favorite BIOS for the IBM AT 5170 is the following BIOS from AMI.

The two ROM's (U27 & U47) are basically of type 27256 (32K). But you can also use 27C256 EPROM's or Winbond W27E257 EEPROM's. I use the W27E257-12 with my GALEP-5; quick and easy to burn/erase.

AMI

I use the AMI BIOS (12/15/89), because you can access the SETUP very easily. The BIOS is Y2K capable.

In addition to the actual SETUP, there is also a DIAGNOSTICS screen. Here you can, among other things, perform a low-level format for the MFM hard disk; with AUTO INTERLEAVE DETECTION.

286-BIOS (c)1989 American Megatrends Inc
286-BIOS (c)1989 American Megatrends Inc / DIAGNOSTICS

The following picture is only an example picture. In fact, the combination WD25 with 69X3948 controller can be operated with an interleave of 2:1 (232,9 KB/sec). Whether the WD1003-WA2 can also do this, I do not know!

286-BIOS (c)1989 American Megatrends Inc
286-BIOS (c)1989 American Megatrends Inc / DIAGNOSTICS

Documents

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Downloads

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