AtariFox STFM service blog

Blogs & guides and tales of woo by forum members.
Post Reply
Steve
Posts: 2056
Joined: Fri Sep 15, 2017 11:49 am

AtariFox STFM service blog

Post by Steve »

Hi, this STFM is having issues where the floppy stops working when the ASCI HDD is enabled. User had trouble doing the DMA resistor mod and worried the floppy controller might be dead.

Motherboard: C070789-001 REV.D1

I can see where the client had trouble
IMG_20200830_173532.jpg
IMG_20200830_173532.jpg (297.19 KiB) Viewed 3418 times
As I'm not sure whether the WD chip works, I'll fit a socket with the pullup resistor (I could have installed it underneath too I guess)
IMG_20200830_184749.jpg
IMG_20200830_184749.jpg (283.06 KiB) Viewed 3418 times
Nice and clean, checked traces, all good.
IMG_20200830_184931.jpg
IMG_20200830_184931.jpg (449.49 KiB) Viewed 3418 times
Socket fitted ready for WD chip.
IMG_20200830_185950.jpg
IMG_20200830_185950.jpg (451.08 KiB) Viewed 3418 times
Chips ahoy!
IMG_20200830_190452.jpg
IMG_20200830_190452.jpg (380.67 KiB) Viewed 3418 times
A marpet ram upgrade is installed and had those red tweaser connectors, I removed them and soldered the ram bypass for better connection.
IMG_20200830_191017.jpg
IMG_20200830_191017.jpg (460.76 KiB) Viewed 3418 times
tzok
Posts: 311
Joined: Sat Dec 30, 2017 2:27 pm

Re: AtariFox STFM service blog

Post by tzok »

Steve wrote: Sun Aug 30, 2020 7:27 pm Ouch, looks like that big CAP on the PSU is about to go POP!
I may assure you that it is completely fine! The plastic insert on the top has that hemispherical shape. I had the same, decided to replace it. But when removed, it measured perfectly fine (ESR, leakage, and capacity). I have removed the plastic wrapping, and discovered that this is only a protective insert, not the capacitor's can.
User avatar
exxos
Site Admin
Site Admin
Posts: 18962
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: AtariFox STFM service blog

Post by exxos »

Just to clarify, Heat from the cap can warp the plastic top, but its not a definitive indication that the cap is perfectly OK. Also as I keep saying, ESR meters can give you indication of a caps values, but even tested OK , it still cannot be assumed the cap is healthy. Such meters can lie to you!
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Steve
Posts: 2056
Joined: Fri Sep 15, 2017 11:49 am

Re: AtariFox STFM service blog

Post by Steve »

Cheers tzok I did not know this :)
Steve
Posts: 2056
Joined: Fri Sep 15, 2017 11:49 am

Re: AtariFox STFM service blog

Post by Steve »

After doing these fixes the floppy drive still says 'Drive error data could be corrupted' when loading programs.

I then have done these:

Floppy 1k resistor 5v pullups
IMG_20200831_143913.jpg
IMG_20200831_143913.jpg (384.51 KiB) Viewed 3320 times
Data/address bus 2.2k sips
IMG_20200831_160623.jpg
IMG_20200831_160623.jpg (552.17 KiB) Viewed 3320 times
Steve
Posts: 2056
Joined: Fri Sep 15, 2017 11:49 am

Re: AtariFox STFM service blog

Post by Steve »

Still when loading programs from floppy, I see 'Drive error data could be corrupted'

I have also: cleaned floppy heads & tried known good floppy drive

Next I am thinking either: Ram test and/or PSU test.
User avatar
exxos
Site Admin
Site Admin
Posts: 18962
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: AtariFox STFM service blog

Post by exxos »

It may simply be because of the long cables on the marpet. They cause all sorts of screwy problems. Changing the bus resistors may solve it, but last motherboard I had here, I gave up with it. So you might have to try removing marpet to see if it solves the problem.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Steve
Posts: 2056
Joined: Fri Sep 15, 2017 11:49 am

Re: AtariFox STFM service blog

Post by Steve »

Good idea, cheers.
User avatar
AtariFox
Posts: 80
Joined: Wed Aug 07, 2019 6:13 pm

Re: AtariFox STFM service blog

Post by AtariFox »

Hi there! Thanks for working on my atari.

It never had any actual issues reading or writing floppies even with the marpet plugged in and working when i got it. i did run extended memory tests on it when i first got it and it had no errors.

So the floppy works again without the megafile connected?

it sat mostly in the cupboard for a year or so till i managed to get the parts for the megafile @icky sent me. Though the ASCI Cabie may be damaged, i don't know, since i think icky said it was cut in half at some point. ?

But yeah, when i finally finished and installed the Megafile it would give the floppy cannot be read/data corrupted? issue. But when the megafile was unplugged it would work just fine.

At least it did before i messed up the soldering and i dunno if i burnt out that c68 resistor it's supposed to go to by the larger chip above it with too much heat.

has the megafile been tried on another Atari? Since due to the issue, i was never able to initialise the disk or anything.
Steve
Posts: 2056
Joined: Fri Sep 15, 2017 11:49 am

Re: AtariFox STFM service blog

Post by Steve »

To be honest I haven't had a reason to check the megafile yet, as the ST itself has issues. I'll check out that capacitor.
Post Reply

Return to “MEMBER BLOGS”