Atari 1040STfm in ICU awaiting your cure

[atarifanboi]

I was just thinking the same thing. A friend of mine once got a nasty shock by accidentally touching the exposed heat sinks of a 1040 STfm with just a brush of the wrist. You are probably better off building a cable to connect a standard PC desktop power supply to the ST motherboard in order to test it and the floppy drive.

 

Good luck and remember to check, re-check, and check again that the correct wires are going to the board before connecting and turning on power.

As RodLightning says, IF you decide to go ahead and use an alternate power supply, don't just double check, triple or even quadruple check before you power any thing on.

 

It's not paranoia, it's safety.

Edited April 17, 2016 by atarifanboi

[atarifanboi]

BTW, have you tried emailing me the image file yet?

Edited April 17, 2016 by atarifanboi

[Agussy]

I did my "Splice-in" idea with external 12v 1.25A and they measured correctly as working, but my Atari still is not doing anything (In fact now, it doesn't even make the clicking noise - Also, I "think" this is new: The light in the middle right (below 1040ST) comes on with power, then dims way, way down quickly - My Reds were both measuring 4.95v before so, I can't believe if needs 5v that 4.95v would cause problems - I press down all the Chips (carefully) before I did any of this - I thought for sure the Splice-in would've worked....wah!

 

I did however get my Steem to PC up and running Master Tracks Pro, but the MIDI in/out to USB cable, while working, is jumbling up the output data to my instruments - e.g., my Multi-Channel Tone Generator notes gets stuck, but some data works great (Drum mach. on CH. 16, for instance)....still trying to fix this = it's probably an internal Steem setting I need to reset correctly, I guess? I saw some kind of MIDI "Volume" slider in the Steem MIDI section; maybe it's in there?

[RodLightning]

With the power issues, make sure the "splice-in" can supply enough current to drive the ST motherboard, I don't have exact specs on hand. I can venture a guess that it should be 5 volts dc at 2 to 3 amps and around 1 amp 12 volts dc. AT or ATX desktop pc power supplies are a good choice for use as bench testers because they provide clean and well regulated output and are generally rated higher than anything the Atari ST will require.

[Agussy]

Hi Rod, all I know is that when I powered on the Atari, the Blue wire requiring 12v 0.9A (according to the Atari specs I found) WAS being supplied 12v 1.25A (which I understand it only siphons off 0.9A) and it still was not working - All of my measurements were done With the all of the Atari's components connected, powered up and running

[RodLightning]

Well, it's possible the power supply might not be what's wrong. The only way to be sure is to try a 'known good' Atari PSU or take a pc power supply, as mentioned, and make the proper connections. The original behavior your ST had would suggest that the floppy drive is not being seen at startup. Troubleshooting would be as follows:

 

Check power supply, both 5 and 12 volt lines

Check integrity of power cable running to floppy drive.

Check the floppy drive data ribbon cable and connection points for damage, bent pins, etc..

 

After that, you begin to look at the motherboard for faults, which is another level of difficulty. First in line there would probably be the floppy controller chip.

[Agussy]

On the PS both were 4.95v (which I think should be enough), but the Blue wire Did come up as 10.75v, that's why I thought for sure was the problem - the P-cable and ribbon and pins look great - I put in two floppy drives that I know work and while the green front light was on, it did nothing else - maybe it's a component on the MB, but I don't know how each are identified - for now, just going with virtual STeem and Master Tracks Pro Music Studio on PC where currently, using a Midi in/out to USB cable that's brand new, I'm having a Midi Piano "Chords" reading problem - Single notes are fine = Electronics: Yea!

[atarifanboi]

Hi Rod, all I know is that when I powered on the Atari, the Blue wire requiring 12v 0.9A (according to the Atari specs I found) WAS being supplied 12v 1.25A (which I understand it only siphons off 0.9A) and it still was not working - All of my measurements were done With the all of the Atari's components connected, powered up and running

If you are going to splice in another PSU, a PC power supply would be good, but If you are still using the ST power supply for 5v, you may be onto a loser. Best bet, unless I've misread, would be to use one PSU for everything, in other words, both 5v and 12v.

 

It could be the whole ST psu is knackered, and the 5v line is bad too, just be damn careful when you are rigging everything up, so you don't get a nasty shock!

[Agussy]

Thanks, but I've tested the two 5v DC (which came in at 4.95v each - close enough, I assume?) so, since they Were working, me adding in the 12v separately (which also measured correctly at 12v) should have worked, although, it didn't - If all 3 measured correctly when they were 120v AC powered-up, I can't figure out why that's not the fix? At the moment, I'm still stuck on getting STeem to make Master Track Pro's MIDI to come in accurately - MIDI kinda half works, as is...Maybe I'll look into Hatari instead

[RodLightning]

Agussy,

 

Other obvious things to check are the floppy physical connections to computer. Does the power supply line to floppy have 5v and 12v? Is the floppy drive data cable oriented correctly? Non-Atari oem floppy drives need you to flip the cable upside down. The drive select also needs to be 'DS0'. PC drives are set to 'DS1' by default and many models don't have an easy way to switch the select to zero. Finding a working replacement floppy drive unit can be a challenge. Many of the high density drives will not work correctly in a ST even with the right drive select and with data cable plugged in properly. We really need a list of compatible tested / working drive models, similar to the one for VGA monitors for use with ST resolutions.

 

These issues may or may not apply to your particular case. I am just throwing some ideas out there for possible troubleshooting.

 

If you are happy with emulation, and can find a workable solution for using MIDI, you may be better off in the long run going that route. Emulation takes care of all the headaches from keeping old hardware running as there is nothing to wear out. I like Hatari, but no idea about the state of MIDI emulation at present.

[atarifanboi]

Agussy, I'm going to be away for a few days, when I get back I have some 'Project Time' booked with my other half to allow me to catch up on mods I've been trying to do for weeks.

 

This means I need to take my STE apart again to get at some components below the PSU. When I do, I'll get some voltage readings under load and post them here, might help.

[Agussy]

Thanks Rod - The 12v "bypass" adapter I added in did provide 12v, but while the FD clicking went away, it did nothing else - I did flip over the Cable = no change - I don't know how to chg to DS0 - Since my PS Did put out 10.75v (but needed 12v) so, I can't imagine the problem being anything other than that, but it must be somewhere deeper inside the unit(?) I downloaded Hatari and at present trying to see if that will work for me...I need more Hatari-study time

[Agussy]

And Thank you Atarifanboi for all your help, too!

[atarifanboi]

And Thank you Atarifanboi for all your help, too!

You're welcome. Back from my trip a day early, long story.......

Hoping to get some retro time in tomorrow, so should be able to check my on load voltages.

[atarifanboi]

Agussy, just checked and the on load, i.e. ST powered on and running, voltages are 5.02v and 11.96v

[Agussy]

Thanks for posting Atarifanboi - I will check mine next chance I get and post'em

[Agussy]

Hey Atarifanboi - And heeere they are: With my unit fully powered up, (110v plus my 12v DC "PS Bypass Blue pin) I read the two Red wires (specs say each should be 5v) and they did measure that (actually 4.94v each but close enuf, right?) So, that trio of wires are getting what they require (I think I already mentioned the PS intact measurements were 4.94v x 2 + 10.75v <-- That's why I'm puzzled my 12v bypass didn't work?!) - btw, Do you know what the Floppy's 4-Pin Power Plug Voltages are, by chance? - I've been searching, with no luck so far, and I'd like to measure those, as well - Onward and upward!

[RodLightning]

On a 3.5in floppy drive unit, RED wire is +5 volts DC, YELLOW wire is +12 volts DC.

The two black center wires are ground.

[atarifanboi]

Agussy, RodLightning is correct, however I believe Atari uses blue instead of yellow for 12v, the same as on the power supply. It could be that the Atari PSU is providing the correct voltages(the 12v rail does seem low), but not enough power, so by just bypassing the 12v side, you still might not have what you need, so you may need to bypass both 5v and 12v. All previous safety warnings apply.

[atarifanboi]

A quick look, and it looks like the Atari PSU is 5v and 3a, so if the 5v side is not delvering that, then splicing in 12v @ 1a may not work at all, because the 5v side is below par.

 

if you Google "atari st atx" there are some good articles that may help you out, and there are PSU alternatives such as PicoPSU, or one of Chris Swinson's brand new devices here: http://www.exxoshost.co.uk/atari/last/store.htm

[Faucon_2001]

Hi,

I have replaced my STE power supply by a pico PSU, and it works great. So may be an option if you want a cheap solution.

Beware that checking voltage is not enough, amperage and stability under load are key, and difficult to see only with a multimeter. I bet for dried electrolytic caps.

 

Regarding floppy not working, I got a similar issue with clicking non working drive. There are electrolytic caps too in the floppy drive, and the one to control head move may be dead. Open your drive and you should see the head moving back and forth, like vibrating.

As I had a spare floppy, I just replaced it, but if I remember forum reading it could be fixed. Look for small electrolytic caps close to the motors power supply.

[atarifanboi]

Hi,

I have replaced my STE power supply by a pico PSU, and it works great. So may be an option if you want a cheap solution.

Beware that checking voltage is not enough, amperage and stability under load are key, and difficult to see only with a multimeter. I bet for dried electrolytic caps.

 

Regarding floppy not working, I got a similar issue with clicking non working drive. There are electrolytic caps too in the floppy drive, and the one to control head move may be dead. Open your drive and you should see the head moving back and forth, like vibrating.

As I had a spare floppy, I just replaced it, but if I remember forum reading it could be fixed. Look for small electrolytic caps close to the motors power supply.

Agussy, this is a very good point, as far as the PSU goes I have replaced all of the caps in mine (Even though it was working), Exxos does cap kits here, though I would suggest you speak to him first to see if a US cap kit is possible. It's about 30 minutes work all told. His store is here: http://www.exxoshost.co.uk/atari/last/store.htm

 

PicoPSUs are a good option, but require a bit more modding, but definitely a way to go. Also, is there anybody who can loan you a PSU just to test out that your mainboard is ok?

Edited May 9, 2016 by atarifanboi

[Agussy]

Thanks Everyone for all the info - I agree!

Hey Atarifanboi,

I do Not have access to a working unit to test anything - Sounds like you (and many others) thinks that it is a simple matter of just replacing the power supply? - Surely the PS AND the Floppy didn't break at the same time?! Also, I guess if I measure the Floppy PS wires (yes, mine are Red & Blue), it is still getting it's juice from the main PS anyway so, probably wouldn't tell me much and that was causing the clicking - Thanks for PS link, too - If I can ever just get the STeem emulator's Midi working, I'd be a happy person at the campsite!

[atarifanboi]

Thanks Everyone for all the info - I agree!

Hey Atarifanboi,

I do Not have access to a working unit to test anything - Sounds like you (and many others) thinks that it is a simple matter of just replacing the power supply? - Surely the PS AND the Floppy didn't break at the same time?! Also, I guess if I measure the Floppy PS wires (yes, mine are Red & Blue), it is still getting it's juice from the main PS anyway so, probably wouldn't tell me much and that was causing the clicking - Thanks for PS link, too - If I can ever just get the STeem emulator's Midi working, I'd be a happy person at the campsite!

If the original PSU is unstable (Could be 25 or more years old), you may get the voltage as reading ok, but the current may be insufficient, and the problem with the floppy is just a symptom of lack of current from the PSU.

 

For example, the PSU is rated for 3A at 5V, which works out to 15Watts. If the PSU is still delivering 5v, but only 2A, that means 10Watts, so probably not enough power.

 

To measure power, you need to put a meter inline, which is a little difficult as you need to have it plugged into a suitable load i.e. an Atari ST in order to check this.

[Agussy]

AFB - With the unit powered up, if I measure 12v, 5v & 5v, would I still not know the Amps at that point? or might my Actual readings of 12v, 4.95v & 4.95v indicate that it's a little low on amps? - I assume a more professional multi-meter does measure amps? (I have a Radio Shack Digital M-M with DC, AC, resistance and continuity)