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Old 14 March 2018, 21:52   #41
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Originally Posted by Capeview View Post
I'm seeing people using Meanwell power supplies in there old A500 and 1200 power units. Would one of these be a better fit in place of the power supply inside the ATX PSU?
Ordinarily I would say yes, but a PPC chip and a fully loaded Mediator is approaching the limit of what the standard Meanwells that most people use can supply. A heavier one might be the way to go, such as this one for a rack mounted system,. It has a 5V primary rail with a minimum of 1A, and no minimum on the 3.3V line, but still specifies a minimum load of 1A on the 12V line so you'd still need a dummy load.

This one is better, requiring only 0.5A minimum load on the 12V line and 2A on the 5V line, which an expanded A1200 will easily meet, but that will require you to do some manual wiring up...

At the end of the day, if the PSU works with your 1260, it should work with the PPC if it has the capacity (and anything above around 60-70W should do that). Many of the industrial units like the Meanwells have the 5V line as the primary rail and also include a slight adjustment capability for compensating for connection losses etc., but if you can find a normal ATX like Indigolemon's that works with the 1260 it should be fine. Any power problems there are more likely to do with the connectors.
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Old 15 March 2018, 11:46   #42
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Daedalus, appreciate your time in looking at the various PSU's for me. Gives me a much better understanding of what I'm looking at and what it all means and what I need to look for. Thanks.

Bear with me as I wrap my head around all this, as over the last few days I've been reading a lot of stuff I never knew about, and I've never really understood the Power stuff and it's amazing what a difference these things make, but I'm gradually picking things up if a little slowly.(talking baby talk for too long I think, my brain cells have been Peppa Pigged)
Even with PC ATX PSU's I've learnt a lot since upgrading to my new PC that I never knew about.

If I'm reading you right, it's the lower the Amps on the 12v for minimum load is what I'm looking for for best use, so at the bottom end of 0.5A is good. And I'm assuming this is to stop any funny business with getting power to flow correctly?? (Probably some technical term for it. )

The 5V rail, you say is good at around 2A, is there a minimum or maximum that can affect things on this rail or the higher the better?

Obviously there does appear to be a range on the Watts as no point overloading on this, as it just won't be used, and from what I read when looking at PC hardware, was too high and it actually draws more power than is actually used and just gets wasted, but good to have some head room, so Peak power of around 135-150 seems like a good thing if I'm understanding right. Only the newer non Amiga Hardware(X5000) etc that would benefit from the more PC ATX style PSU's.

Definitely more reading needed. If there is a useful resource out there that would give me a better understanding I would happily give it a look, even if I glean a little bit of understanding from it.

Will look into the other ATX PSU's and see if I can find something closer to the above you mentioned. I don't mind rewiring, I can do that, it's when it comes to adding in Resistors in the lines I have no idea how to do, but still willing to learn if there is a good resource, unless of course it's just look it up on Youtube. lol

One last thing, what is the difference between the -5v and +5v rails and same with the 12v's. Is this just to do with something along the lines of why we have a Live and Neutral. Someway for the power to travel up and down??
And if these don't really matter when looking for a compatible PSU, just focus on the 5v and 12v Amp ratings?
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Old 15 March 2018, 13:31   #43
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Quote:
Originally Posted by Capeview View Post
Bear with me as I wrap my head around all this, as over the last few days I've been reading a lot of stuff I never knew about, and I've never really understood the Power stuff and it's amazing what a difference these things make, but I'm gradually picking things up if a little slowly.(talking baby talk for too long I think, my brain cells have been Peppa Pigged)
Haha, I hear you. I've an 8 month old at home so a decent night's sleep has become one of my major life goals at this point No bother, power supply technology and theory is actually a huge subject in its own right, most of which is thankfully hidden in modern times by well defined standards and off-the-shelf ready-made modules.

Quote:
If I'm reading you right, it's the lower the Amps on the 12v for minimum load is what I'm looking for for best use, so at the bottom end of 0.5A is good. And I'm assuming this is to stop any funny business with getting power to flow correctly?? (Probably some technical term for it. )
Yes, that's it. The A1200 by itself doesn't even use 0.5A, more like 0.1A, but 0.4A is an easier deficit to make up than 0.9, or 1.4 or whatever. And yes, a certain minimum current is required to be flowing in order for a power supply to be able to regulate itself properly. High end PSUs will refuse to turn on when the minimum load required isn't presented, but lower-spec supplies will tend to run anyway, and risk having their output voltages drift away from their intended values. Here's a little run-down of the principles involved:

- Incoming power is converted from high voltage to low voltage by a conversion circuit that chops the incoming power into very high frequency pulses (I'll leave the technicalities of that for now...) which are then fed through a transformer.
- The output pulses are smoothed by a capacitor and the voltage across that capacitor is constantly measured, and the results fed back into the power conversion circuit above.
- The conversion circuit adjusts itself to compensate for any difference by adjusting the width of the pulses it produces.

The problem comes from the design of the power control portion, which needs to have reasonable minimum and maximum pulse sizes, and therefore minimum and maximum output voltages. The wider the range, the more complicated it is to design. Drawing more current reduces the voltage present, so the pulse widths are increased to increase the voltage back to where it should be. If the pulses get too wide however, they start to join into one another and power transmission fails (amongst other issues): that's where your maximum rating comes from. If the load is too low however, the output voltage increases, and the pulses are made so short that they stop being proper pulses, and again transmission fails. The wider the range of pulse width available, the bigger the difference between maximum and minimum power output, but also the more complex and expensive the PSU design. For cost and efficiency, standard ATX PSUs will cover a range that will suit almost any known PC up to their maximum power rating, and since they're never intended to run without at least a motherboard attached, a reasonable minimum is taken as the power used by a small, modern PC. Heavier power supplies for gaming-type rigs can also make the assumption that there'll be some sort of heavy graphics card present too, which is built into the design calculations.

General purpose PSUs can avoid a minimum load by providing their own load internally, which is similar to my suggestion of using a heavy resistor. So, even when nothing is attached, they're still passing enough current for stable regulation.

Quote:
The 5V rail, you say is good at around 2A, is there a minimum or maximum that can affect things on this rail or the higher the better?
You ideally want to be using somewhere in the middle between the minimum and maximum, but in reality you should be fine anywhere in between the two. An A1200 by itself will use around 2A, and any additional hardware will increase that, so a minimum requirement of the PSU of 2A suits just fine. At the maximum end of the scale, I can't imagine any Amiga setup taking more than 10A, so once the maximum is above that you're fine.

As an expansion of my explanation above, many PSUs use a single, primary power rail which is used in the feedback loop I described above. All other output voltages are simply tapped off the transformer at a suitable proportion to the primary output. So, a 5V output will always be five-twelfths of the output on the 12V rail, so if the 12V output isn't regulating and drifts over by 20% to 14.4V, the 5V output will be 6V - not a comfortable level for the Amiga's chips. Likewise, if the 12V rail dips 10% to 10.8V, the 5V rail will be 4.5V, which is again not suitable for the Amiga's chips (though not likely to cause permanent damage). These secondary rails typically have a much lower minimum current (or none at all if they're low power). Some more elaborate PSUs include separate regulation on multiple rails, in which case you effectively have separate, independent PSUs for each rail, each with their own minimum required current.

Quote:
Obviously there does appear to be a range on the Watts as no point overloading on this, as it just won't be used, and from what I read when looking at PC hardware, was too high and it actually draws more power than is actually used and just gets wasted, but good to have some head room, so Peak power of around 135-150 seems like a good thing if I'm understanding right.
Yeah, that sounds about right. A small amount of power is wasted if you go way over, but it's not really likely to be significant - even the heaviest Amiga will use less than even a very efficient PC. The primary concern should be the stability of the output at those levels.

Quote:
Only the newer non Amiga Hardware(X5000) etc that would benefit from the more PC ATX style PSU's.
True, and even then they're on the lower end of the scale. My AmigaOne G4 only uses around 100W from what I can recall.

Quote:
Definitely more reading needed. If there is a useful resource out there that would give me a better understanding I would happily give it a look, even if I glean a little bit of understanding from it.
Hmmm, well I don't have any particular references in mind, but there's plenty of information out there, including some university material on the theory that would be well worth a look. Key things to look at are "Switched-mode power supplies", "shunt regulation" and similar topics. Many universities place their course notes online, so you should find plenty to keep you busy on the cold nights

Quote:
Will look into the other ATX PSU's and see if I can find something closer to the above you mentioned. I don't mind rewiring, I can do that, it's when it comes to adding in Resistors in the lines I have no idea how to do, but still willing to learn if there is a good resource, unless of course it's just look it up on Youtube. lol
Adding resistors is easy - just wire it across the required output. Calculating the required resistor is a little tricky, but not a problem either and I can give you a hand with that for a given minimum load.

Quote:
One last thing, what is the difference between the -5v and +5v rails and same with the 12v's. Is this just to do with something along the lines of why we have a Live and Neutral. Someway for the power to travel up and down??
Not really, no. The ground is the return path for all rails, the equivalent of neutral in mains electricity terms. The negative rails are mainly only used for analogue-type applications like audio, and occasionally serial - applications which require "symmetrical" power rails. No digital logic circuitry will use them so their current ratings are typically very low. -5V is depreciated in the latest ATX specifications, so you'll find that wire isn't even present on most new supplies. It can easily be recreated from the -12V rail if needed for something else.

Quote:
And if these don't really matter when looking for a compatible PSU, just focus on the 5v and 12v Amp ratings?
The negative rails are almost always low powered and secondary, so they generally have very low, or no minimum load requirements. So just look for the primary (which is usually the rail with the highest power output), which is typically 12V on ATX PSUs and often 5V on industrial PSUs. Then just make sure the other minimum is met as well. Having a 5V primary output is preferred, but not absolutely necessary.
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Old 15 March 2018, 14:14   #44
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Wow. Thanks Daedalus.

Who would have thought a problematic BPPC would start bringing me new knowledge, as well as a bunch of headaches. Ohh the Amiga scene, never a dull moment. lol

Really appreciate the explanation and the time to write it. Definitely take me a few reads of all this stuff to make it clear in my head.

Will have to wait until I get my 1200 boards back from Recapping to test things again, so in the meantime will drag my A500's out of there boxes and start looking over those before power on. I know they have a ram module in each, with a possibility of leaking battery as they are the original 500 mem expansion, but I know a friend was lucky with his and nothing had happened.

I'm sure they'll keep me busy, and if the 500's look good, at least something to play with in the meantime.

Once I'm back up and running with the 1200's though, I'll post my findings back in this thread and any fixes or problems that may arise.
Been speaking with Chucky and he's given me some ideas on the BPPC, so have some things to try and may even give his DiagROMs a go to see if they can find any faults.

I'm just hoping it's not a corrupt Rom or GALs or duff PPC and is just a power issue.

Can't remember if I asked though, is there any way to check my Tower PSU for faults that I can do without the 1200's installed and all it's innards?
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Old 15 March 2018, 15:10   #45
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Yeah, Chucky's DiagROMs are excellent! So handy for the low level stuff.

As for testing a PSU, well you can look at the output on an oscilloscope and see if it's excessively noisy under load, but there's little point in doing that with no load. If you had a few hard drives and fans to add a bit of load to the 5V and 12V rails (and assuming it doesn't have two separate 12V rails as is sometimes the case these days), you can connect them and force the PSU to turn on by shorting the PS_ON line to ground. PS_ON is normally a green wire near the locking clip, with a black ground wire either side of it. Remember though that you really want to put the PSU under a similar load to properly determine if it's behaving itself as things like ripple and noise can vary greatly with load.
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Old 15 March 2018, 15:30   #46
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Ok, so I need an oscilloscope or someone with one.

then probably a course on how to use it. lol

I can connect up a bunch of drives and fans I have lying around and using the Mediator cabling, connected to my Keyboard adaptor that should help power the machine on and off without any Amiga present.
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Old 17 March 2018, 18:57   #47
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better off just upgrading the psu to a new as this way you have extra amps and not overloading the original psu which will let it 1 be more efficient and run cooler and last way longer i had to mod a a3000 psu for hedeon so he could power our ppc cards i stuffed a 350w seasonic inside that little a3000 psu shell

also i have 2 bppc/bvision with 060 and ppc overclocked you dont want all that going through the amigas mobo so best to have a external power source to the accel cards etc so the amps arent pulled through the mobo
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Old 17 March 2018, 19:04   #48
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The Power is fed through a Mediator board which connects to the 1200's trapdoor expansion slot so I'm thinking the BPPC draws its power from there and not through the motherboard.

I could be wrong, so anyone else with an opinion on that would be greatly appreciated.
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Old 17 March 2018, 21:21   #49
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The mediator obviously powers the Amiga differently as it bypasses the original PWR port. The pass through connector is just that and the BPPC is connect as it would, to the A1200. Either way there is no worry of power draw through the Motherboard because the designers would of factored this, into the BPPC original concept. If anything not enough power and overheating issues would be more of a concern!

The 2 links below offer some good information for those interested in BPPC and Mediators.

The link about the Infinitiv tower is interesting to me because, I own one of those towers I bought it back in 1998 when I bought my BPPC and I installed it in that very tower. I still own that Infinitiv unit today, although it has a Blizzard 1230 MKIV in there now. They are good towers if a little fragile at times!

The reason you need a better power supply is for stable running, this is something the S*** 21w Commodore effort, cannot handle! In tower systems in particular you have more peripherals and so more power is required. (Watts and amps)

On the SX and TX they have an ATX connector which helps when you want to run later Graphics cards etc. I found this out when I relied on the AT PWR source of the earlier LT series.

http://8bitplus.co.uk/articles/amiga-blizzard-ppc/
http://8bitplus.co.uk/projects/amiga...finitiv-tower/
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Old 18 March 2018, 10:04   #50
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I have one of those Infinitiv Towers. It felt like a good idea at the time until you realise how much of a pain it was to keep it from being flimsy and the fact it was too easy to catch your BPPC when removing or installing.

It's probably also in my parents loft somewhere. Hmmm, I wonder if it has a PSU installed in it still. Will have to look.

As for my Mediator, it comes with an adaptor for the ATX PSU so you could use any PSU, it's just getting one with the correct 5v and 12v amp ratings.
My 3DFX card has one of those CDrom/HDD style power connectors so draws power from that. It's only the Sound and Network cards that take there power through the Mediator Board.
I may just use my PSU but check the Caps etc are good and if not may replace them if needed.

Not feeling all that great today, so probably repeating myself as stinking cold and cant think straight. Definitely not doing much while I feel like that.

Will update my A500 thread with what I've been doing with my modules.
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Old 19 March 2018, 18:28   #51
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Part of the issue with drawing more power through the motherboard is that there are multiple connections between the power supply and the accelerator board. Each connection drops the voltage by a small amount due to contact resistance. The amount of the drop is proportional to the current drawn, and depends on the condition of the connections. In particular, the 5-pin square PSU connections are often tarnished by age and heat and can give as much as a 0.3 or 0.4V drop. This is independent of the type of power supply - if you have an old connector on a brand new ATX supply, the voltage drop will be the same.

Boards like the Mediator power the entire system from the passthrough connector, and use newer, more capable power connectors like AT and ATX which offer far less contact resistance, and thus less dropped potential. It also helps that the power doesn't have to run through the motherboard's traces, meaning the PPC gets power much closer to its required voltage.
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Old 20 March 2018, 12:22   #52
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My 3DFX card has one of those CDrom/HDD style power connectors so draws power from that.
This was to keep power constant and possibly avoid what Daedalus was explaining. The BPPC didn't have this because Phase 5 designed it to be compatible with Commodore's supplied PSU's.

From experience I tried the BPPC in the trapdoor of an A1200 with a newish version of Commodore's 21w type PSU's. It wouldn't even run at first. Then when I did finally get it going, it would sometimes reset with Guru Meditation. After stabilising, it only ran for 10mins before freezing up.

Overheating and lack of power was definitely issues! I believe that although Phase 5 stated that the BPPC was suitable for A1200 trapdoor and standard PSU use, I disagree! By the time BPPC was available for Amiga, serious users were already taking the tower option, so most BPPC's would of seen adequate space and PSU.

I certainly chose the tower option, the infinitiv "Powered by Amiga" version.<Much rarer and desired version. This was where my first BPPC was used.

After trying the BPPC in a standard A1200, I remember thinking to myself, what an utter nightmare. Never again would I want to cram an 68040, 603e PPC in such a tight spot, using a power supply that was never really up to the task!

Amiga's in the cost saving wedge are OK, if you plan to run stock. The moment you want to go serious hardware, Towers are certainly the way to go! So many obvious reason why, more space, better looks and adequate PSU's. Not to mention everything in one place rather than all over the work top! So many times I see people struggling to cram all the modern upgrades, in that wedge!!
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Old 20 March 2018, 13:49   #53
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This was to keep power constant and possibly avoid what Daedalus was explaining. The BPPC didn't have this because Phase 5 designed it to be compatible with Commodore's supplied PSU's.

From experience I tried the BPPC in the trapdoor of an A1200 with a newish version of Commodore's 21w type PSU's. It wouldn't even run at first. Then when I did finally get it going, it would sometimes reset with Guru Meditation. After stabilising, it only ran for 10mins before freezing up.
Yep, had the same issue. Once I find the rest of my gear, I'm sure i'll either find my A500 psu or a modified psu that I used in my 1200 to get it working fine and it would run but always with the trapdoor off and machine slightly raised.

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Overheating and lack of power was definitely issues! I believe that although Phase 5 stated that the BPPC was suitable for A1200 trapdoor and standard PSU use, I disagree! By the time BPPC was available for Amiga, serious users were already taking the tower option, so most BPPC's would of seen adequate space and PSU.

I certainly chose the tower option, the infinitiv "Powered by Amiga" version.<Much rarer and desired version. This was where my first BPPC was used.
Same, not long before i bought my Plastic piece of crap tower(Thats what I call it. lol) and then the Eyetech Tower which was far easier to work with and install addons in.

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After trying the BPPC in a standard A1200, I remember thinking to myself, what an utter nightmare. Never again would I want to cram an 68040, 603e PPC in such a tight spot, using a power supply that was never really up to the task!
The 060 was just as bad but more to do with getting all those extra Libraries working. Once they had been updated near the end they were far more stable. But once it was working it was really quick on the 060, just a real lack of anything to use the PPC which was a shame.
But once I could get my Mediator and 3D card, it was a lot more fun to use as a machine with decent Hi Res workbench and at speed too.

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Amiga's in the cost saving wedge are OK, if you plan to run stock. The moment you want to go serious hardware, Towers are certainly the way to go! So many obvious reason why, more space, better looks and adequate PSU's. Not to mention everything in one place rather than all over the work top! So many times I see people struggling to cram all the modern upgrades, in that wedge!!
I do like the Wedge, but think it needs to be expanded across the Back. But it is great to see what people do with them. As long as there is enough power and Air Flow, they are easy and fun to carry around. Plus they really do look cool. lol
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Old 20 March 2018, 17:36   #54
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@Capeview, Yes the 68040 is the same, it required tons of libs to run correctly! Also what you said about the Infinitiv towers could damage the BPPC if not careful. You so got to be talking about those plastic guiding rails at the top. Like 2 big L shape monsters, just waiting to destroy a component on the BPPC, as you pull it out!

It is good to know I wasn't the only one going through the perils of BPPC ownership, back in the day!

Last edited by MigaTech; 20 March 2018 at 18:08.
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Old 20 March 2018, 18:02   #55
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@Migatech, the idea was good, but the final use was anything but. And the way the plastic bridge supports would just flop about or bend got me to thinking, POWER TOWER. lol

I always thought I'd damaged by BPPC with that tower, but I've checked it against others pictures and I can't see anything un toward, but the card still worked fine so maybe it was something else.

I Hope. lol
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Old 20 March 2018, 18:17   #56
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Infinitiv were good as a first attempt. Power Towers are just over sizes heavy monsters, yet sturdy. This is some of the reasons why, I went into fabricating customised Retro Amiga Tower systems, because anything available was either too big, ugly or flimsy! Lets not forget the disgusting beige colour either. So modern with retro wins every time!

Better PSU, lighter tower, Modern colours and looks with retro inside, including modern tech. Nothing could be more paramount than this.
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Old 20 March 2018, 18:22   #57
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Yeah, mine isn't one of those huge behemoths but the Eyetech tower which was just a little taller than yours I think, and not very heavy.

It's just over the height of the A1200 width, so enough space to fit the mediator and BPPC card in as well as other cards in the required slots, and plenty of access around the back for other stuff.
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