WHAT PSU CAPACITORS SHOULD I USE ?

Repairs & upgrades.
User avatar
exxos
Site Admin
Site Admin
Posts: 24239
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

WHAT PSU CAPACITORS SHOULD I USE ?

Post by exxos »

This is a question I get asked almost daily...

Before I explain some things, please considering buy the capacitors kits from my webstore if I sell a suitable kit. I have spent a great deal of time & money over the past 5 years alone, working and diagnosing PSU issues and finding solutions. While I may make a small profit on the capacitors I sell, this is considered as a donation to myself for all the work I have done. It really isn't fair on myself to spend a lot of time helping people find capacitors for their SR98 etc just to save a few ££'s on the parts which I already sell.

I do not document (and don't really keep) part numbers for myself or my website in general anymore. Simply due to every time I research 100's of capacitors, 6 months later they are no longer stocked, or discontinued. I have had to change the rectifiers in my kits several times due to them becoming obsolete in one respect or another. Updating my site with constantly changing parts would turn into a full time job, and I just don't have the time to keep on top of it. Normally I bulk buy capacitors in 200-500 packs because of this.

Of course I do not sell everything so here is what you have to do..

Generally I recommend the Panasonic FR series for all the general values. Often around 1,000-4,700uF. They are good ESR values and I personally use them on my own built PSU's.

Much higher uF values, I tend to look towards EPCOS. I use 10,000uF EPOCS in my PSU's as they are a good price and offer better ESR ratings then most other brands, including Panasonic. Of course there is no use paying £10 for a capacitor if a £3 one is similar or better rating from another manufacture. So it isn't "cast in stone" that I only use FR series for everything, because I don't.

Similar with the higher voltage capacitors, Once one is found with the physical dimensions, there often isn't much choice left. Generally the ESR values for high voltage caps isn't great anyway. Though each datasheet has to be looked at to see which is the best.

Often choosing one capacitor can take a few hours of work. So if anyone wants to find their own capacitors then heres what to do...

First of all, if we need a 4,700uf capacitor then do a search on a site like farnell. Select the value, dimensions, voltage rating, pin pitch from the parametrics table. Click search and you will probably have around 200 results.

The un-educated people (sorry!) will often just go for the cheapest one which will fit. But that is a pretty dumb thing to do. While in general capacitors are good, there are some I have seen which are so bad, they are likely worse than the 30 year old caps in the PSU already! I really do not understand why such bad caps are on the market , but they are. Sometimes they are not so cheap either!

Take a look at the datasheets. Look for ESR / ripple current/amps/ohms . If the manufacture doesn't list this information. Then that manufacture is either stupid, or their capacitors are not worth buying. In which case, avoid whatever series of capacitor and brand you are looking at.

Take the Panasonic FR for example...EEUFR1C472

It is worth noting that the physical dimensions of the capacitor also affect its ESR ratings. It is not totally dependant on its value or voltage!
fr.PNG
fr.PNG (89.38 KiB) Viewed 5379 times
Highlighted below is the same value and voltage capacitor, but note one is a "L" version. L=Long version where it will be slightly taller than the non-L version.
fr2.PNG
fr2.PNG (147.22 KiB) Viewed 5378 times
We can see the L version is 35mm high and 12.5mm wide, offering 3750mA.
The non-L version is 25mm high, 16mm wide, offering 3820mA.

It is important to make sure you order the physically correct dimensions to fit the space you have. If you have a little space to fit a wider or taller capacitors, and its a better spec, then I would be included to use it. Though in my example above the difference isn't huge, but on some capacitor values it can be. If there is a better spec part and its only a fraction more expensive, then I would buy it. If its double the price or more for
a small gain in spec, then I probably wouldn't go with it. Though this is based on myself having to order 200+ capacitors so I have to keep my outlay costs reasonable.

A example of a similar capacitor by Multicomp..
mc.PNG
mc.PNG (92.73 KiB) Viewed 5378 times
We have 1960mA, whereas the Panasonic was almost double that. Of course the Panasonic is about 20pence more expensive (about 40p Multicomp, 60p Panasonic) . Both capacitors would work fine in this example. Though I will always go for the higher spec parts. If I am going to the trouble of changing parts, I want to fit the best ones I can find.

These are just some example of what to look for with choosing capacitors. Its also why I am reluctant to get involved with deep conversations about choosing capacitors simple because looking through 100's of datasheets (per capacitor!) can take several hours and I don't have time to look through them all to "suggest" a capacitor to everyone, sorry!

I will say its not that difficult to look through the datasheets. Just avoid capacitors ranges which do not list any proper ratings. Often while Panasonic (maybe even rubycon, epcos etc) are pushing towards 4,000mA on the 4,7000 value, manufactures who do not list the proper ratings, do so for a reason, normally because they suck! A few years ago when I started this research there was capacitors on the market which were around 200mA! That is pretty dire indeed. Though these capacitors are still out there!

Only buy capacitors from reputable suppliers such as farnell, mouser etc. Don't go looking on iffy auction sites for the best deals on capacitors. Just no way to know if they are genuine or a China Knock-off. Don't assume the supplier has the correct specs for the parts they are selling either, as often they don't!

I hope this will give some insight to helping people chose capacitors. Though as said before, please considering buy parts from my store. Its not fair on myself to go through all this work for people just to buy parts elsewhere.
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.
MacTech05
Posts: 69
Joined: Thu Jul 07, 2022 1:21 am
Location: USA

Re: WHAT PSU CAPACITORS SHOULD I USE ?

Post by MacTech05 »

Exxos,

I looked through the Exxos Store at the PSU repair/re-cap kits andnoticed you were clear the PSU the kits were for the UK/230 VAC power supplies. So, that being the case, since I live in the US and you do not list any PSU repair/re-cap kits for US 120 VAC PSUs, would it be possible to make a list of the equivalent components necessary to assemble an equivalent PSU repair/re-cap kit for US 110 VAC 1040 STE PSU?

If not, I can just record the specs of each cap on the PSU, as well as the equivalent replacement rectifier you include in your kits for UK/230 VAC PSUs.

Thank you.

Randy
User avatar
exxos
Site Admin
Site Admin
Posts: 24239
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: WHAT PSU CAPACITORS SHOULD I USE ?

Post by exxos »

I don't have any 110v supplies so I don't know what capacitors they use. Maybe post a image of yours then see if it differs from the one here https://exxosforum.co.uk/atari/last/psu ... tm#PSM5341

I don't know even if the PSU can simple just run on 110v or if it's a different PSU. My cap kits may work but as I have no way to verify it, I state all my kits are for 230v only.
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.
MacTech05
Posts: 69
Joined: Thu Jul 07, 2022 1:21 am
Location: USA

Re: WHAT PSU CAPACITORS SHOULD I USE ?

Post by MacTech05 »

I will do that. I have not pulled the PSU yet. But it has not been powered up in almost a week.

I have been experiencing several of the symptoms that has been blamed on the DMA chip. Your "Bad DMA" investigation indicated, the 68K processor should be replaced with the MC68HC000 8 MHz CPU and very likely replace or re-cap the PSU. It seems dealing with those two items solves most of the so-called "bad DMA" issues. So, that is what I am going to do.

I ordered the MC68HC000 8 MHz CPU from the Exxos Store this week. Once it arrives, I will install it.
Now I need to deal with the PSU. I will remove the PSU this weekend, take a photo, and post it in this topic on the Exxos Forum, as you suggested.
Have not discharged capacitors in a while, but I have done it many times on other electronics and computers. It is funny though, no matter how many time I do it, I am still a bit overly cautious when discharge any capacitor.

Thank you.

Randy
MacTech05
Posts: 69
Joined: Thu Jul 07, 2022 1:21 am
Location: USA

Re: WHAT PSU CAPACITORS SHOULD I USE ?

Post by MacTech05 »

exxos,
I removed the PSU from my 1040 STE this morning. It is a Mitsumi TCI-A7S 110V US PSU. I took a couple of photos as you suggested. One is a photo of of the PSU, the second is the same photo in which I annotated the capacitor values and the rectifier value. The Mitsumi PSU as the following:

1 - 220uF 200V (the largest one)
1 - 2200uF 16V
1 - 1000uF 16V
1 - 1000uF 10V
2 - 2200uF 10V
1 - 1uF 50V
1 - RB154 90 Rectifier

Thank you

Randy

1040 STE US PSU 2.jpg
1040 STE US PSU 2.jpg (94.35 KiB) Viewed 1166 times
1040 STE US PSU 1.jpg
1040 STE US PSU 1.jpg (79.54 KiB) Viewed 1166 times
MacTech05
Posts: 69
Joined: Thu Jul 07, 2022 1:21 am
Location: USA

Re: WHAT PSU CAPACITORS SHOULD I USE ?

Post by MacTech05 »

exxos,
The actual PSU model I removed this morning from my 1040 STE is a Mitsumi Model SR97-01. Part number: CA070059-003.
Input: AC115 / 117V 60 Hz 0.7A
Output: DC5V3A DC12V0.9A

Thank you.

Randy
User avatar
exxos
Site Admin
Site Admin
Posts: 24239
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: WHAT PSU CAPACITORS SHOULD I USE ?

Post by exxos »

Thanks. Looks like one extra low voltage cap and a higher value mains cap than on the SR98. My kits won't work. You would have to look for alternative caps yourself to fit it.
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.
MacTech05
Posts: 69
Joined: Thu Jul 07, 2022 1:21 am
Location: USA

Re: WHAT PSU CAPACITORS SHOULD I USE ?

Post by MacTech05 »

exxos,

I thought that may be the case. Can you recommend the best or at least high quality brand capacitors? Should I replace the capacitors with capacitors of the exact same value? Or should I increase the voltage value or capacitance value, or both? The component I identified as a rectifier RB154/90, well that is what was stamped on the top of it. It is a 4-lead component located around the same location that I have soon on Atari 230V PSUs used in the UK. Is that component the rectifier? That is what it looks like, to me at least.

Thank you for your help and advice.

Randy
User avatar
exxos
Site Admin
Site Admin
Posts: 24239
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: WHAT PSU CAPACITORS SHOULD I USE ?

Post by exxos »

You should be able to replace the low voltage caps with Panasonic FR series 4,700uf and 2,200uf 16v.

The rectifier and larger cap won't be so simple. The cap will need physical dimensions and pin pitch searched with the parametric search on mouser to find one which will phsically fit and be the same value. Rectifier , I don't know what to suggest as the one on yours is right on the edge of the PCB. You might be better just leaving those alone for now.

If you don't know how to use the parametric search then Dave Jones eevblog has a video on that kinda stuff. It's not something I have time to get into or write a guide for. Maybe someone else on the forum can guide you on it all if needs be. Though what I wrote in the first post is a good start.
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.
MacTech05
Posts: 69
Joined: Thu Jul 07, 2022 1:21 am
Location: USA

Re: WHAT PSU CAPACITORS SHOULD I USE ?

Post by MacTech05 »

exxos,

Thank you for your recommendations and assistance.

I found a place that offers recap kits for my specific PSU, Mitsumi Model SR97. It does not appear to include a replacement rectifier, as your kits provide. However, I did ask the brand of capacitors they source and provide in the recap kit. Tech Support told me the capacitors included in their recap kits changes with availability, but most of the capacitors the source for the recap kits are from Panasonic, Nichicon, Rubycon, and UCC. I will not know which capacitors are packaged in the recap kit I ordered until it arrives.

I will take a look at Dave Jones eevblog, as you suggested. I watched one of his videos where the designed and assembled an electronic constant load for use in testing power supplies, recommended bay David at BW's Technoshed Youtube channel.

Again, thank you.

Randy
Post Reply

Return to “PSU (power supplies)”