new PSUs in my Falcon causes video output to fail

Problems with your machine in general.
kodak80
Posts: 34
Joined: Sat Oct 21, 2017 1:14 am
Location: Brisbane, Australia

new PSUs in my Falcon causes video output to fail

Post by kodak80 » Sun Apr 08, 2018 5:57 am

OK, I have two brand new PSUs. An Exxos PSU and a Centurion Technologies PSU. When I install these in place of my original PSU, the video ouput no longer works!

Both new PSUs cause similar issues with the video output on my Falcon. The Exxos PSU when installed, caused hundreds of white dots on the screen "like stars in the night sky". The Centurion Technologies PSU sent the video output beyond the range of the LCD I normally use on the Falcon. When I connected another LCD used on ny STE, the video output from the Falcon was lots of green dots randomly on the screen (see image below).

The original PSU has been recapped with an Exxos kit and when the original PSU is installed, the Falcon works fine. When I tested the original PSU not under load, I only see 7v on the 12v line. Both new PSUs show 12v on the 12v line (not under load). I know I should check these whilst under load but have not done this yet.

I am looking for guidance on what could be wrong given that two new PSUs are causing a similar issue with teh video output in my Falcon?

At least the original PSU works fine but it would be good to understand why the new PSUs cause the video issue?

Here is the screen with the Centurion Technologies PSU powering my Falcon:
IMG_1187.JPG
IMG_1187.JPG (412.39 KiB) Viewed 444 times
Atari Falcon 030 | Atari 1040 STE | Atari 1040 STFM | Atari 1040 STF | Kryoflux & Supercard Pro Flux boards
Admin of Atari ST Review Magazine Archive: http://www.ataristreview.com

User avatar
exxos
Site Admin
Posts: 2541
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: new PSUs in my Falcon causes video output to fail

Post by exxos » Sun Apr 08, 2018 9:29 am

If you put a floppy in the drive does it appear to still boot up?
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

kodak80
Posts: 34
Joined: Sat Oct 21, 2017 1:14 am
Location: Brisbane, Australia

Re: new PSUs in my Falcon causes video output to fail

Post by kodak80 » Sun Apr 08, 2018 10:44 am

No, it does not attempt to boot from floppy when the video is as per the picture.

I have now stripped the Falcon down to do some testing.

I unplugged the HDD to force it to boot from my Gotek floppy and in doing this the system booted and the video output worked! I tried plugging the HDD back in and the video output went back to the green dots. So I unplugged the HDD thinking this was the issue but the green dots remained on next power on. So then I thought it might be NVRAM related which is why I removed the shielding. It gave me the opportunity to replace the socketed Dallas chip with my Exxos RTC module.

As I have the Centurion PSU ready, I have been testing with this PSU. Interestingly, I have found that pressing the reset switch sorts out the video output after powering on! This works until I power the Falcon off and then have to repeat pressing the reset switch to get the video working.
Atari Falcon 030 | Atari 1040 STE | Atari 1040 STFM | Atari 1040 STF | Kryoflux & Supercard Pro Flux boards
Admin of Atari ST Review Magazine Archive: http://www.ataristreview.com

User avatar
exxos
Site Admin
Posts: 2541
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: new PSUs in my Falcon causes video output to fail

Post by exxos » Sun Apr 08, 2018 10:50 am

Replaced the big cap next to videl ?

Clock buffer patch installed ?
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

kodak80
Posts: 34
Joined: Sat Oct 21, 2017 1:14 am
Location: Brisbane, Australia

Re: new PSUs in my Falcon causes video output to fail

Post by kodak80 » Sun Apr 08, 2018 10:59 am

Capacitor next to videl, no, probably not been replaced. Not by me and the previous owner had not replaced the NVRAM so I would bet it is the original capactior.

Clock patch - yes, I believe so:
IMG_1191.jpg
IMG_1191.jpg (342.21 KiB) Viewed 421 times
Atari Falcon 030 | Atari 1040 STE | Atari 1040 STFM | Atari 1040 STF | Kryoflux & Supercard Pro Flux boards
Admin of Atari ST Review Magazine Archive: http://www.ataristreview.com

User avatar
exxos
Site Admin
Posts: 2541
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: new PSUs in my Falcon causes video output to fail

Post by exxos » Sun Apr 08, 2018 12:36 pm

What I suspect is that the newer PSUs output a slightly higher voltage causing the ringing on the clock lines to be greater and cause the issues you are seeing.

You could pull all the 5V wires from the PSU and re-connect one via 2x 1n5400 diodes to drop the voltage (just as a test). Or try some 47R resistors in series with those wires which go to the motherboard from the clock patch.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

kodak80
Posts: 34
Joined: Sat Oct 21, 2017 1:14 am
Location: Brisbane, Australia

RESOLVED: new PSUs in my Falcon causes video output to fail

Post by kodak80 » Tue Apr 17, 2018 12:47 pm

We tried the new PSU in another Falcon and it worked fine. The issue was only with my Falcon. We added a 22uf capacitor to increase the reset delay after powering on and this has resolved my issue with the new PSU. Video now works 100% each boot so issue is resolved. Just posting in case anyone else gets a similar issue.
IMG_1209.JPG
IMG_1209.JPG (601.43 KiB) Viewed 337 times
Atari Falcon 030 | Atari 1040 STE | Atari 1040 STFM | Atari 1040 STF | Kryoflux & Supercard Pro Flux boards
Admin of Atari ST Review Magazine Archive: http://www.ataristreview.com

User avatar
exxos
Site Admin
Posts: 2541
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: new PSUs in my Falcon causes video output to fail

Post by exxos » Tue Apr 17, 2018 1:33 pm

Thanks for letting us know!

Out of interest, how long does actually take after turn on for the video to appear ? My 2 Falcons it takes three or four seconds before it comes out of reset..
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

kodak80
Posts: 34
Joined: Sat Oct 21, 2017 1:14 am
Location: Brisbane, Australia

Re: new PSUs in my Falcon causes video output to fail

Post by kodak80 » Mon May 07, 2018 7:43 am

OK. the added 22uf capacitor on the reset circuit did not solve my problem so I am back to troubleshooting this with my Exxos PSU. I went to do some timings on the boot and the issue was back!

I have obtained another original Falcon PSU and this works without issue in my Falcon. Something to do with the new PSUs as both the Centurion Technolgies PSU and Exxos PSU give the same result of no video output until I press the reset switch.

A mate here has also purchased and installed an Exxos PSU for his Falcon and he has the same issue where no video/boot until the reset switch is pressed. I had more or less given up with this issue but now there are two of us, I will dig deeper to try and resolve this. Luckily, one of the local Atari group here is an electrician and so he is helping me with the troubleshooting and also has a Falcon.

We tried tweaking the 5v rail on the Centurion PSU as it had this feature but changing it did not help.

I guess given the age of the Falcon's and the modifications made at the factory and afterwards makes troubleshooting interesting.

I will update here when we get some testing under way.

Cheers
Atari Falcon 030 | Atari 1040 STE | Atari 1040 STFM | Atari 1040 STF | Kryoflux & Supercard Pro Flux boards
Admin of Atari ST Review Magazine Archive: http://www.ataristreview.com

User avatar
exxos
Site Admin
Posts: 2541
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: new PSUs in my Falcon causes video output to fail

Post by exxos » Mon May 07, 2018 11:11 am

kodak80 wrote:
Mon May 07, 2018 7:43 am
OK. the added 22uf capacitor on the reset circuit did not solve my problem so I am back to troubleshooting this with my Exxos PSU. I went to do some timings on the boot and the issue was back!

I have obtained another original Falcon PSU and this works without issue in my Falcon. Something to do with the new PSUs as both the Centurion Technolgies PSU and Exxos PSU give the same result of no video output until I press the reset switch.
Does this all the Falcon have the same clock patch?
I would still suggest the same, a place something like 33R resistors in series with each of the clock patch wires..

Also what RTC is installed in the second machine ?
I would make sure you have the capacitor stated in another thread.. Later RTC boards I added them but I cannot remember which one you have all if you did the mod.. viewtopic.php?f=10&t=37#p2479
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

Post Reply