Amiga Power Supply Transplant - Meanwell RT-50B

[Daedalus]

That's pretty spot on, yeah. Normally 4.8-5.1V would be fine, and you're pretty much bang on the mark. Good to go

[rabidgerry]

Originally Posted by Daedalus

That's pretty spot on, yeah. Normally 4.8-5.1V would be fine, and you're pretty much bang on the mark. Good to go

£15 well spent!

Happy days! Thanks lads appreciate the advice and tips

[demolition]

I also have one PSU that I rebuilt using a Meanwell unit, however it is a version that was not designed to be adjusted so it is pretty much exactly 5.00V out and this isn't optimal since it does give me some issues.

With that PSU I see around 4.7V inside the Amiga which is okay most of the time (my A1200 doesn't have a problem with it), however my A600 doesn't like it as it causes occasional issues with the joystick/mouse reading and with my A500, the ACA500plus doesn't always boot properly (sometimes I need to reset it a few times before it boots, but when it boots it does run perfectly stable).

My Jerry+ mouse adapter also has issues with 4.7V since the uC occasionally resets, causing the mouse to get stuck for a little bit until it has restarted. This can be a matter of life and death if you're in the middle of a game of Lemming or Shuffle Puck Café for example.

[voyager_1701e]

Nice one, fits well in the case.

In the interest of safety (it would be easy to mishandle the power supply when plugged in and powered on/connected), I would put some heat shrink over the power switch spade connectors

[amiman99]

Nice job.
I just fixed my old A500 power supply with RT-65B. Fits tightly in original shell.
Works fine on my A1200 with Blizzard IV 50MHz.

[Krashan]

Originally Posted by demolition

With that PSU I see around 4.7V inside the Amiga

Shorten the cable between PSU and Amiga and/or use one with thicker wires. My PSUs have just 50 cm of shielded 4×1.0 mm² cable.

[rabidgerry]

Originally Posted by voyager_1701e

Nice one, fits well in the case.

In the interest of safety (it would be easy to mishandle the power supply when plugged in and powered on/connected), I would put some heat shrink over the power switch spade connectors

I was thinking that also. You mean where the spades connect at the on off switch?

This was really an example to show how quickly it can be done, there are a few little things I may do in the future like possible secure it down inside although it's so snug it doesn't move at all. The heat shrink is another idea and also I was thinking of using proper spade connectors on the wires at the 5 wire side because they are literally single pointed connectors right now and it would be a nice fit if they were proper spade connectors.

Originally Posted by amiman99

Nice job.
I just fixed my old A500 power supply with RT-65B. Fits tightly in original shell.
Works fine on my A1200 with Blizzard IV 50MHz.

Oh really? I didn't think I could get a RT-65B in one of those, I thought it was too long when I took a look at the spec online.

I think the RTB-50B is sufficient from everything I have read though but it's always nice to have MORE POWER



@demolition of course, you need lightening speed mouse when you're playing shufflepuck!

[Lord Aga]

Good job mate

Glad you have everything sorted out

[aeberbach]

Don't get too hung up on reading 5.00 V through a meter. When was the meter last calibrated and how good was it to begin with? It's really easy to believe a measurement that looks exact but it might not be... If your Amiga works with everything you throw at it that's the main thing.

(I also use a Mean Well with a 68030, never misses a beat.)

[rabidgerry]

Originally Posted by aeberbach

Don't get too hung up on reading 5.00 V through a meter. When was the meter last calibrated and how good was it to begin with? It's really easy to believe a measurement that looks exact but it might not be... If your Amiga works with everything you throw at it that's the main thing.

(I also use a Mean Well with a 68030, never misses a beat.)

Oh I'm not but I figured I'd follow the recommendation of those on here telling me to at least get a reading close to 5v of the floppy.

Just have to trust in the meter I have as ballpark figure really.

Originally Posted by Lord Aga

Good job mate

Glad you have everything sorted out

Me too thanks

[Lord Aga]

Originally Posted by rabidgerry

Just have to trust in the meter I have as ballpark figure really.

Or! Ooor! Hear me out
We could use ye olde stick the rail under your fingernail (hey it rhymes), and count the number of hairs that jump.
5,000 hairs - 5V on the dot. Cannot go wrong with this one

[aeberbach]

When was your arm last calibrated?!

[rabidgerry]

Originally Posted by aeberbach

When was your arm last calibrated?!

Just calibrated my arm, so how many hair on my back equates to 5v?

Not sure how long I can keep this up so you might want to hurry back with an answer!




***edit*** oops 5000 hairs you already told me! Ok need to dial it down a hair or two!

[Lord Aga]

Yup, can't go wrong
No need for traditional calibration either. Just don't shave/wax your arms lads

[rabidgerry]

Originally Posted by Lord Aga

Yup, can't go wrong
No need for traditional calibration either. Just don't shave/wax your arms lads

fantastic! That's way too much maintenance anyways! Well at least I know I have accurate readings!

[demolition]

Originally Posted by Krashan

Shorten the cable between PSU and Amiga and/or use one with thicker wires. My PSUs have just 50 cm of shielded 4×1.0 mm² cable.

Not a usable solution since I want to keep the PSU on the floor (and not the Amiga ).

I have been considering modifying the PSU to increase the voltage. Should be doable by changing a resistor in the voltage feedback path, but I haven't gotten around to look at it yet. But so far I can still use it since systems like my A1200 doesn't seem to mind the lower voltage.

Originally Posted by aeberbach

Don't get too hung up on reading 5.00 V through a meter. When was the meter last calibrated and how good was it to begin with?

Pretty sure it is quite accurate, at least within +/-0.01 V which is good enough for me.

[Daedalus]

As a rule of thumb in industry, we generally would expect multimeters to meet a tolerance of +/-(1% + 1 or 2 least significant digits, depending on the model). So for measuring 5V, I would take that as being anywhere in the range of 4.93V to 5.07V. On the other hand, in 15+ years I've never seen a multimeter fail calibration, and usually they're comfortably within their tolerances. They fail for worn out switches and connectors, or pure brute force damage, but not calibration.

Of course, the point about how good it actually is, is important too. Cheaper units (Fluke are pretty standard in industry but pretty expensive for home use) might have slightly wider tolerances, and when it comes to super cheap generic meters, all bets are off. They're usually not too bad actually, but I wouldn't trust one without at least comparing it to a known good meter or reference.

[demolition]

Originally Posted by Daedalus

Of course, the point about how good it actually is, is important too. Cheaper units (Fluke are pretty standard in industry but pretty expensive for home use) might have slightly wider tolerances, and when it comes to super cheap generic meters, all bets are off. They're usually not too bad actually, but I wouldn't trust one without at least comparing it to a known good meter or reference.

I would trust it if I have three cheap meters that all read exactly 5.00V when I measure the output voltage of a modern 5V SMPS (directly on its output pins). It is also my general experience that cheap meters are quite accurate when measuring DC voltage unless it very noisy for some reason. AC voltage measuring on the other hand is much more tricky to do correctly and the cheap ones may only be somewhat accurate with a 50-60 Hz pure sine AC so I wouldn't use them for measuring the output of AC inverters, AC motor controls, dimmers and so on.

[Daedalus]

Yeah, I'd trust that too, and I wouldn't expect them to lose their calibration either. Regular calibration checks are a regulatory requirement for quality systems, but in reality even cheap digital meters are unlikely to drift these days.

[amiman99]

Originally Posted by rabidgerry

Oh really? I didn't think I could get a RT-65B in one of those, I thought it was too long when I took a look at the spec online.

It barely fit, I had to snip plastic screw standoffs to make it fit.