Only RAW image for ST225 from a Philips P3500 TurboDOS system

[ich.c...@gmail.com]

Hi,

I got  the ST225 from a P3500 system.  As last year  a P3800 was identified  for the mfm-emu I hoped that Philips did use identical hd controllers but this isn't the case.

As I got only a raw image with the actual software I need help to make an emu file as that's out of my knowledge

Starting the ST225 I got smoke and just switched of the power.  I removed the circuit board but didn't see what was smoking as I switched off to fast.  I then replaced the board with a spare one and hoped that there were identical CRC's used as the boards are different versions.

Starting again I got a RAW image but no appropriate controller was found in analyse mode.

The P3800 was read with following conf:

--sectors 17,0 --heads 7 --cylinders 1166 --header_crc 0x0,0x1021,16,0 --data_crc  0x0,0xa00805,32,5 --format MacBottom --sector_length 512 --retries 50,4 --drive 1 

As for the P3500 nothing was found I'll try a second read today with the original circuit board as I found a bad capacitor and snapped it off. It will be replaced later.  Maybe that the firmware of the original board must be used to read the hard disk.

All I have collected for the P3500 can be found there:

https://electrickery.nl/comp/divcomp/doc/  please scroll down to Philips P3500 / P3800 computer systems

I will get a picture from the P3800 hard disk controller next time  and will get the rom dump from the controller below next if needed.

 

[David Gesswein]

On Tue, Sep 19, 2023 at 05:17:22AM -0700, ich.c...@gmail.com wrote:
> Hi,
> I got the ST225 from a P3500 system. As last year a P3800 was

> controllers but this isn't the case.
> As I got only a raw image with the actual software I need help to make an
> emu file as that's out of my knowledge
>

mfm_util can make an emulator image from the raw image. Just specify
cylinders and heads without --ana.

> Starting the ST225 I got smoke and just switched of the power. I removed
> the circuit board but didn't see what was smoking as I switched off to
> fast. I then replaced the board with a spare one and hoped that there were
> identical CRC's used as the boards are different versions.
>
> Starting again I got a RAW image but no appropriate controller was found in
> analyse mode.
>

> As for the P3500 nothing was found I'll try a second read today with the
> original circuit board as I found a bad capacitor and snapped it off. It
> will be replaced later. Maybe that the firmware of the original board must
> be used to read the hard disk.
>
> All I have collected for the P3500 can be found there:
> https://electrickery.nl/comp/divcomp/doc/ please scroll down to Philips
> P3500 / P3800 computer systems
>

Is the raw image on the site? I didn't see it. If you want me to take a look
put it up on the site or use my upload
http://www.pdp8online.com/upload/abuploadab.html

[MFM Discuss]

d...@pdp8online.com schrieb am Dienstag, 19. September 2023 um 14:29:36 UTC+2:

On Tue, Sep 19, 2023 at 05:17:22AM -0700, ich.c...@gmail.com wrote:
> Hi,
> I got the ST225 from a P3500 system. As last year a P3800 was
> controllers but this isn't the case.
> As I got only a raw image with the actual software I need help to make an
> emu file as that's out of my knowledge
>
mfm_util can make an emulator image from the raw image. Just specify
cylinders and heads without --ana.

 

ah yes,  I have not the P3500 system here but thanks to remember me.

 

 

>
Is the raw image on the site? I didn't see it. If you want me to take a look
put it up on the site or use my upload
http://www.pdp8online.com/upload/abuploadab.html

Thanks for the offer,  I made just in the moment an upload named harddisk.zip 

Greetings

Fritz

[David Gesswein]

I took a look. The data from the drive is no good. You can try putting
the original board back and see if it works any better. If not you would
need to try a microstepper to see if the problem is the heads are no longer
aligned with the tracks.

http://www.pdp8online.com/mfm/microstep/index.shtml

The picture I found online the stepper seems to be a normal one and not the
5 phase.

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[ich.c...@gmail.com]

There where 2 capacitors bad and I replaced them.

Sadly after repair  the board wasn't able to read anything so the next step will be micro step with the replacement board  - but I have to learn about.

[ich.c...@gmail.com]

ich.c...@gmail.com schrieb am Mittwoch, 20. September 2023 um 16:38:21 UTC+2:

There where 2 capacitors bad and I replaced them.

Sadly after repair  the board wasn't able to read anything so the next step will be micro step with the replacement board  - but I have to learn about.

>

I found a bad R27 = 39Ohm with has 0Ohm. As it's for the stepper motors there may be more bad parts. (If I see it right)

 

[ich.c...@gmail.com]

With the R27 I got in the false direction. It has 0,39Ohm and is for the spindle motor - not the stepper.

I'm a mechanic not an electrician :-)   that was my experience and will see if I can get  any local help .

[Steve Mastrianni]

More likely you are measuring across a semiconductor, a diode or a transistor junction. Switch the leads of your meter. A 2watt resistor won’t short. Measure the transistor junctions, there are probably dozens of videos that can show you how. In general it’s difficult to measure components in-circuit and get a reliable reading. I’m surprised you found bad caps of those type, they are usually fairly reliable. Based on a quick glance I’d lean toward one of the transistors, especially if there’s an emitter-follower somewhere.

--Steve

Dr. Steve Mastrianni

Sent from my iPhone

On Sep 20, 2023, at 4:03 PM, ich.c...@gmail.com <ich.c...@gmail.com> wrote:



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