These are the power supplies I have in my MegaST computers (3 of 4) I have never seen these listed or tested.
The large Cap on this one is a 220ohm 200v. I can find a Panasonic 105deg good size FR series (digikey does not list esr) at this rating - very common.
Do I - or should I up the value on this one for a recap? Some of the smaller ones were a little dodgy.. this one looks great. The PSU was dead though, no fuse blown - but it had been removed not working. I get values or continuity through all tested caps and resistors, I have not tested with power or load yet.
James
Mitsumi 68-4242a
Re: Mitsumi 68-4242a
What model number does it say on the sticker underneath the metal stand the board screws into?
You should be able to find PSU schematics on https://docs.dev-docs.org/ after that.
You should be able to find PSU schematics on https://docs.dev-docs.org/ after that.
Re: Mitsumi 68-4242a
Kinda looks like some revision of a SR98 to me, but not seen that exact version before.. The SR151 is totally different.
https://www.exxosforum.co.uk/atari/last/psu/index.htm
Looks like the SR98 was 68-4237?
Looks like they must have moved to a smaller opto.. then had to move the trimmer the other side of the heatsink to keep it away from the HV side. So maybe they couldn't get that older opto anymore and had to change to a alternative part towards the end of the production runs.
https://www.exxosforum.co.uk/atari/last/psu/index.htm
Looks like the SR98 was 68-4237?
Looks like they must have moved to a smaller opto.. then had to move the trimmer the other side of the heatsink to keep it away from the HV side. So maybe they couldn't get that older opto anymore and had to change to a alternative part towards the end of the production runs.
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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.
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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.
- Cosmic Puppet
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Re: Mitsumi 68-4242a
SNAP! I have the exact power supply on my STFM.
US Atari 520 STFM (C070523-001 REV.D1) , Exxos PSU, 4MB Marpet Upgrade, Exxos 6 Chip TOS 1.04 USA, EmuTOS 20211020, Ultrasatan, PP Driver, Original Floppy Disk Drive, NEC Multisync EA193Mi Monitor, Star LC-10c Printer, iMP C100110-001 DMA.
Re: Mitsumi 68-4242a
What is the model number on the bottom ?
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.
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.
Re: Mitsumi 68-4242a
Nothing not a sticker anything on any of the trays.DoG wrote: ↑Sat Nov 30, 2019 3:41 pm What model number does it say on the sticker underneath the metal stand the board screws into?
You should be able to find PSU schematics on https://docs.dev-docs.org/ after that.
So what about the question of upping the value of the hivolt cap.. 220ohm 200v?? should I up that?
I have a megaST where the PO replaced it with a meanwell.. I am going to keep that in.. as its 50w and I am putting in a PAK68/3 and they suggest getting up to 50w to have all the EXTRAS.
James
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Re: Mitsumi 68-4242a
I'd be tempted to go fo a Meanwell, at the price they are a steal and if you're going to add the PAK then you can be pretty sure it'll be more than up to the job.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: Mitsumi 68-4242a
US Atari 520 STFM (C070523-001 REV.D1) , Exxos PSU, 4MB Marpet Upgrade, Exxos 6 Chip TOS 1.04 USA, EmuTOS 20211020, Ultrasatan, PP Driver, Original Floppy Disk Drive, NEC Multisync EA193Mi Monitor, Star LC-10c Printer, iMP C100110-001 DMA.
Re: Mitsumi 68-4242a
Odd theres no sticker on bottom with a proper part number though, I'm just going to call is "SR98 REV1" and there, problem solved
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.
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.
Re: Mitsumi 68-4242a
Another MegaST2 and another 68-4242a. A batch that came out of the factory with this one and went to Canada I guess.
James
James