Recapping a Falcon PSU with an Exxos kit

Various other hardware solutions.
Post Reply
User avatar
Badwolf
Posts: 2228
Joined: Tue Nov 19, 2019 12:09 pm

Recapping a Falcon PSU with an Exxos kit

Post by Badwolf »

I'm hoping to record video of my attempts to resuscitate the Falcon motherboard I bought off Asci.

As a bit of a forerunner to that and a tech experiment in what works from an audio-visual point of view, I've put together a short* video of me recapping my Falcon PSU.



Conclusion so far is that the second camera isn't good enough and the audio is marginal, but let me know what you think.

I assume changing through-hole electrolytic capacitors is old hat to most guys on here, but I hope it might be useful to anyone who is a bit nervous about getting the soldering iron out or working with mains voltages.

Drama ensues when it turns out I'm short a capacitor & I get to see more filth than an adult movie producer.

Cheers,

BW

* Not at all short.
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
User avatar
exxos
Site Admin
Site Admin
Posts: 23488
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Recapping a Falcon PSU with an Exxos kit

Post by exxos »

Badwolf wrote: Tue Jun 15, 2021 10:15 pm Drama ensues when it turns out I'm short a capacitor & I get to see more filth than an adult movie producer.
Great video. Sorry you short of a cap.. will send one out.. I've checked the other kits and the 680 is in those, so not sure why that bag got missed :(

What the electronics load you have there btw ?


Odd you're not seeing any spikes. Are you limiting bandwidth or anything on your scope ?

falc5a-min.png
falc5a-min.png (7.44 KiB) Viewed 3396 times

That is why I suggest people recap as those spikes will eventually kill stuff.. Mostly seems to be the Videl, which is "first in line" ...
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.
User avatar
Badwolf
Posts: 2228
Joined: Tue Nov 19, 2019 12:09 pm

Re: Recapping a Falcon PSU with an Exxos kit

Post by Badwolf »

exxos wrote: Tue Jun 15, 2021 11:10 pm
Badwolf wrote: Tue Jun 15, 2021 10:15 pm Drama ensues when it turns out I'm short a capacitor & I get to see more filth than an adult movie producer.
Great video. Sorry you short of a cap.. will send one out.. I've checked the other kits and the 680 is in those, so not sure why that bag got missed :(
Ah, that's kind, thanks. I wasn't going to raise it as an issue as I'd had the box sitting on my shelf for months and was my fault for not checking it earlier. :cheers:
What the electronics load you have there btw ?
It's the Dave Jones design from EEVblog 102.

Screenshot 2021-06-16 at 09.38.48.png
Screenshot 2021-06-16 at 09.38.48.png (140.73 KiB) Viewed 3367 times
Odd you're not seeing any spikes. Are you limiting bandwidth or anything on your scope ?

That is why I suggest people recap as those spikes will eventually kill stuff.. Mostly seems to be the Videl, which is "first in line" ...
No filtering turned on, but I was at one volt per division. You're down at 10mV per div. I never wound it in that close. I could re-run the freshly capped version with the resolution cranked up to see how that looks.

Ta,

BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
User avatar
Badwolf
Posts: 2228
Joined: Tue Nov 19, 2019 12:09 pm

Re: Recapping a Falcon PSU with an Exxos kit

Post by Badwolf »

Thanks @exxos! A Spanky new 680uF/25V cap arrived in the post this morning.

When I get this fitted I'll run a few more of those scope tests and see how things look now. :-)

Cheers, :thanksyellow:

BW.
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
User avatar
Badwolf
Posts: 2228
Joined: Tue Nov 19, 2019 12:09 pm

Re: Recapping a Falcon PSU with an Exxos kit

Post by Badwolf »

I finally got around to fitting the missing capacitor and doing some better measurements.

Turns out my shed is noisier than your average teenager on a bus!

DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
User avatar
exxos
Site Admin
Site Admin
Posts: 23488
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Recapping a Falcon PSU with an Exxos kit

Post by exxos »

Badwolf wrote: Fri Aug 27, 2021 11:36 pm I finally got around to fitting the missing capacitor and doing some better measurements.

Turns out my shed is noisier than your average teenager on a bus!
You can turn on the bandwidth limit to like 1mhz or something. The PSU switches no where near that. It helps no end to filter background noise out. LED lighting and other switch mode close to the scope can cause problems, you pretty much have to turn everything off in the room in fact .

When I developed my PSUs I had a 400hz spike which drove me nuts for ages. Turns out, it was coming from the fan I was using to cool the load resistors with :lol: :roll:

You can also use the vmin vmax under the measure menu to automatically tell you the figures..

Also you didn't seem to mention ripple either. You need to get down to 50mv / div and fiddle with the time / div until you see a sine wave, which is the ripple. I've probably got images of it on my site somewhere.
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.
User avatar
Badwolf
Posts: 2228
Joined: Tue Nov 19, 2019 12:09 pm

Re: Recapping a Falcon PSU with an Exxos kit

Post by Badwolf »

exxos wrote: Sat Aug 28, 2021 12:53 am Also you didn't seem to mention ripple either. You need to get down to 50mv / div and fiddle with the time / div until you see a sine wave, which is the ripple. I've probably got images of it on my site somewhere.
Yeah, I had considered the noise so overwhelming that it wasn’t worth pursuing. Also, since finding my ‘before’ figures were so corrupted by the bloody voltmeter employed as a current indicator there was no meaningful comparison, so I concentrated on characterising anything dangerous or weak.

The problems of doing this the first time. ;)

Ta for the replacement cap!

BW
DFB1 Open source 50MHz 030 and TT-RAM accelerator for the Falcon
DSTB1 Open source 16Mhz 68k and AltRAM accelerator for the ST
Smalliermouse ST-optimised USB mouse adapter based on SmallyMouse2
FrontBench The Frontier: Elite 2 intro as a benchmark
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Re: Recapping a Falcon PSU with an Exxos kit

Post by Steve »

Hey BW just noticed we have the same scope, did you do the free upgrade to 100mhz? :)
Post Reply

Return to “HARDWARE ESSENTIALS”