Power supplies

[Divya16]

When my ingot power supply failed it output about 7.5-8.0V which fried the 256Kb chips in the memory upgrade, without any other damage to the 800XL. At that time, mid to late 80s, I just put a new 7805 regulator inline on the power cord. When I purchased a 1MB Newell upgrade for another 800XL, I built a new power supply from scratch, including a crowbar circuit, for it. At the time it had been expensive enough to replace the 8-41256 chips in the first 800XL, I wasn't taking any chances with the 1MB 800XL.

 

Some advantages of using the switching power supplies is they are light, compact, +80% efficient and generate little heat. Linear regulated power supplies are normally in the 50-60% efficiency range and can generate quite a bit of heat. The switchers also appear to be reliable, and adding an inexpensive crowbar circuit between the supply and the Atari system, while maybe not necessary, does gives peace of mind as well as over-voltage protection in case of failure.

 

I think the difference between these supplies is the output circuit - either a pass transistor or an integrated regulator. A pass transistor will tend to fail as a short from collector to emitter, where the IC will just shut down (gracefully). A shorted pass transistor will generally send more than 7 volts into your computer, a sure way to burn something or, many somethings! When the video has the black horizontal bar and loud buzz in the audio, it is (normally - also could be one diode has croaked) a failure of the filter capacitor. This will not overstress your computer since the output voltage never exceeds 5 volts. (not that your Atari will work that way...)

 

All of the Atari power supplies are analog circuits. You can use a switching supply if you like, with the same exposure vs. pass transistor or IC regulator.

 

Bob

 

 

I had a Problem with the one Labeled "The Mini". What a POS. almost as bad as the "Ingot". When "The Mini" Died, I got the Multi-Colored Screen with the "Heat Waves" going through it.

 

I had an "Ingot" as well. What an over sized Door Stop. I managed to Salvage my XL after one of those went bad on me by replacing 5 ram chips.

 

It's power supplies like These that Led me to develop My New XL/XE Power Converter. With the Used Power Supplies, It's a crap shoot whether or not you will get a bad one or one that's on the verge of going bad.

 

Unless you have included a fuse and crowbar circuit then your power supply converter could still damage a system with a regulator failure. I also think you should recommend a minimum of a 1.5A power supply instead of 1A.

 

If I were to need a new power supply I believe I would use a modern switching power supply along with the crowbar circuit I mentioned in an earlier post. I have a few +5V switching power supplies from failed routers/firewalls or other electronics devices, and they are also available at some electonic specialty stores at reasonable prices. Just plug it into the crowbar circuit, with an Atari DIN power plug on the output.

 

An example is the +5V@1.5A RPR-051A5-P5, <$15.00, available at RP Electronics. They also have a +5V@5A model, RPT25-05-P5-A2, for about $20.00 + $4 to $5 for the power cord. An advantage of these is they are 115/230V compatible.

 

I also have a couple of dual output voltage, +5V@2A/+12V@2A, switching power supplies that came with USB to IDE/SATA interfaces I purchased. These have 4-pin molex connectors to plug directly into 3.5" HDD, and could be used as a replacement power supply for a 1050/XF551 drive, bypassing the internal 7805 and 7812 regulators.

 

I bought the white XL power supply with vents that matches the rest of the Atari furniture. Does that have the high voltage protection as no one has complained about those blowing up any XL/XEs?

[+orpheuswaking]

If you have an INGOT power supply you do not have to throw it away.

 

For those having an INGOT that hasn't failed yet, I would recommend adding a fuse and a "crowbar" circuit to the output, like the one at http://www.radio-ele...age_crowbar.php shown below. The addition of this circuit would make any regulated DC power supply safer.

 

 

By using a 5.1V or 5.6V Zener diode, the SCR would trigger and blow the fuse if that voltage was exceeded, protecting the Atari system. I built a custom power supply with the fuse and SCR installed before the voltage regulator, using a 5.1V Zener diode, over 20 years ago.

 

 

 

I'm okay at soldering and following parts diagrams... however I'm not sure I understand the above diagram (circuit reading was never a strong point of mine)... can anyone help me out?

 

Also what type/size fuse to use? and where does it go?

Edited May 4, 2010 by orpheuswaking

[ApolloBoy]

I had a Problem with the one Labeled "The Mini". What a POS. almost as bad as the "Ingot". When "The Mini" Died, I got the Multi-Colored Screen with the "Heat Waves" going through it.

Wow, and to think I almost considered buying one of those. Has anyone else had a problem with these?

[+bob1200xl]

PowerOne has a crowbar, OVP-12G, that may work, if you're really serious about this. Digi-Key has them for $12. Add a 1.5amp fuse in series from the power supply you want to control and wire the crowbar after the fuse, from + to - (ground). The fuse will blow if the voltage gets too high for the computer.

 

Bob

 

>---- fuse ----- + ------> to computer

...1.5 - 2amp....|

........................|+

.....................OVP-12G

........................|-

........................|

.......................GND

 

 

 

If you have an INGOT power supply you do not have to throw it away.

 

For those having an INGOT that hasn't failed yet, I would recommend adding a fuse and a "crowbar" circuit to the output, like the one at http://www.radio-ele...age_crowbar.php shown below. The addition of this circuit would make any regulated DC power supply safer.

 

 

By using a 5.1V or 5.6V Zener diode, the SCR would trigger and blow the fuse if that voltage was exceeded, protecting the Atari system. I built a custom power supply with the fuse and SCR installed before the voltage regulator, using a 5.1V Zener diode, over 20 years ago.

 

 

 

I'm okay at soldering and following parts diagrams... however I'm not sure I understand the above diagram (circuit reading was never a strong point of mine)... can anyone help me out?

 

Also what type/size fuse to use? and where does it go?

Edited May 5, 2010 by bob1200xl

[+orpheuswaking]

PowerOne has a crowbar, OVP-12G, that may work, if you're really serious about this. Digi-Key has them for $12. Add a 1.5amp fuse in series from the power supply you want to control and wire the crowbar after the fuse, from + to - (ground). The fuse will blow if the voltage gets too high for the computer.

 

Bob

 

>---- fuse ----- + ------> to computer

...1.5 - 2amp....|

........................|+

.....................OVP-12G

........................|-

........................|

.......................GND

 

 

 

If you have an INGOT power supply you do not have to throw it away.

 

For those having an INGOT that hasn't failed yet, I would recommend adding a fuse and a "crowbar" circuit to the output, like the one at http://www.radio-ele...age_crowbar.php shown below. The addition of this circuit would make any regulated DC power supply safer.

 

 

By using a 5.1V or 5.6V Zener diode, the SCR would trigger and blow the fuse if that voltage was exceeded, protecting the Atari system. I built a custom power supply with the fuse and SCR installed before the voltage regulator, using a 5.1V Zener diode, over 20 years ago.

 

 

 

I'm okay at soldering and following parts diagrams... however I'm not sure I understand the above diagram (circuit reading was never a strong point of mine)... can anyone help me out?

 

Also what type/size fuse to use? and where does it go?

 

I'm thinking this is outside of my scope... I have a couple of the 1.5a Atari PSU's I'll just make sure I only use those on the upgraded machines.

[+orpheuswaking]

I hear that some people take small 5vdc 1.5 amp+ switching power supplies from other electronics and wire on an Atari plug... Would you still need a fuse/crowbar on that?

 

 

Something like this (this one is 5vdc 2a)

[Mathy]

Hello orpheuswaking

 

HARdwareDoc doesn't use a separate fuse on his, just a small cable (two plugs and some wire) that plugs into the switching power supply and the Atari. I trust him to know what he's doing, so I did the same. And so did Stefan Dorndorf and BigBen.

 

greetings

 

Mathy

 

[edit: ours are rated at 3 Amps]

Edited May 5, 2010 by Mathy

[BillC]

If you have an INGOT power supply you do not have to throw it away.

 

For those having an INGOT that hasn't failed yet, I would recommend adding a fuse and a "crowbar" circuit to the output, like the one at http://www.radio-ele...age_crowbar.php shown below. The addition of this circuit would make any regulated DC power supply safer.

 

 

By using a 5.1V or 5.6V Zener diode, the SCR would trigger and blow the fuse if that voltage was exceeded, protecting the Atari system. I built a custom power supply with the fuse and SCR installed before the voltage regulator, using a 5.1V Zener diode, over 20 years ago.

 

 

 

I'm okay at soldering and following parts diagrams... however I'm not sure I understand the above diagram (circuit reading was never a strong point of mine)... can anyone help me out?

 

Also what type/size fuse to use? and where does it go?

 

An SCR is a rectifier(diode) that is only active when voltage is applied to its gate. In this circuit once supply voltage exceeds the breakdown voltage of the zener diode, current through the zener/resistor causes a voltage at the gate of the SCR, causing it to create a short circuit between the supply voltage and ground. Once activated the SCR will latch and keep operating even without a signal on the gate. The capacitor is so that small momentary spikes wouldn't activate the SCR, the capacitor would have to charge enough first.

 

The size of fuse used will depend on whether it is installed before of after the regulator, a fuse installed after needs to be small enough to be below the peak current of the regulator, and large enough not to blow under normal use. If the fuse is too large and the SCR activates, rather than blowing the fuse the SCR will keep the output crow-barred at the voltage regulators current limit until something fails.

 

Maximum fuse size is less limited with a fuse installed before the regulator, if the anode of the SCR can be attached between the fuse and the regulator input. In this case when the SCR activates it is short-circuiting the input to the voltage regulator, and the peak current of the regulator isn't a factor.

 

It is not as much of an issue these days, but 20+ years ago when I first used the crowbar circuit with an Atari, the 256K and 1024K bit chips in the Atari memory upgrades were worth a fair bit, and it was much less expensive to build the crowbar than to purchase replacement RAM. $5 to $10 for the crowbar vs $50 to $60 for the RAM at that time, and the crowbar parts were easier to get.

[+orpheuswaking]

Way above my pay grade LOL... I'll stick with my big white 1.5a Atari power supply... Those are supposed to be the most reliable...

[BillC]

For those who are having difficulty visualizing how a crowbar circuit would be added to a power supply I have attached a JPG file with schematics of power supplies having the fuse before and after the voltage regulator with the crowbar circuit installed. These are simplified schematics without all the normal filtering capacitors installed.

 

As I have stated before, I started using one of these after a failed Ingot power supply killed the 256K RAM chips in a 800XL 20 to 25 years ago, as much for peace of mind as anything else.

 

The values of the resistor and capacitor are not critical, you just need the resistor to cause a voltage to activate the SCR once current flows through the SCR, and the capacitor to prevent momentary spikes from causing the same. The Radio-Electronics web page linked to my previous posts suggests values of 100 ohms for the resistor, and 0.1 microfarads being a good starting point, but not necessarily optimum, for the capacitor.

Edited May 5, 2010 by BillC

[+bob1200xl]

What you need depends on your philosophy, I expect. PowerOne is a big, professional outfit. Many of their quality supplies come with OVP built-in. And, they sell OVPs for those who think they need them in other applications. Some Atari supplies have more of a tendency to fail 'badly' than others. These are cheap, consumer products that are meant to be used on inexpensive, non-critical computers. If you are worried about your system, these are paths you can take to minimize your exposure. More like solutions than suggestions.

 

I use a white case XL power supply on my computer desk - with no OVP.

 

As for 'other' supplies, my Dell laptop at work arcs at the plug every time I plug it in, a not uncommon characteristic of this kind of switching supply. I don't know what's in the Dell that filters out these spikes but I'm not sure it's all in the power supply - might be in the laptop. These are not 5 volt supplies, of course, but you should consider that the power circuits for any device may be split between internal and external hardware.

 

Bob

 

 

 

I hear that some people take small 5vdc 1.5 amp+ switching power supplies from other electronics and wire on an Atari plug... Would you still need a fuse/crowbar on that?

 

 

Something like this (this one is 5vdc 2a)

[tjlazer]

I had one blow up back in he day.. it was the original one that came with my 800xl...made the atari do all kinds of terrific colors & designs all over the screen.. So I replaced it with the BIG black plastic PSU that has the "vents" kinda like an XL case..

 

Anywayze.. The old one didnt have any screws, so I took it apart with a hammer.. and I remember it was pumped full of greenish brown epoxy.. God knows why they would do that.. I guess they didn't want anyone knowing exactly how crappy they were building those things.

 

I remember they did something like that with DigiView for Amiga-- one of the best still frame digitizers at the time. If you tried to open it, you can only break the item.

 

Yep.. I had all 3 versions of the digiview... Just so you know, its not a frame grabber.. It's a very SLOW-scan monochrome digitizer.. You had to do three SLOW scans to get a color image.. The whole process can take several minutes. The DCTV (which came out much later) had a much faster-scan color digitizer, but it still took 10 seconds or so.. A frame grabber takes an entire image in a fraction of a second, either into it's own internal memory, or the computer's via fast DMA access over the expansion bus.. The LIVE! card (or sidecar depending on what model AMIGA you had) came out about the same time as digiview (or shortly thereafter) and was an actual frame grabber.. Of course, the price difference between the two was huge..

 

Heh I have the Digi View, DCTV and Live cards. A1000 side car, and A2000 Zorro 2 card. Been wanting to mess with them, but never tried...

[tjlazer]

I have a couple of the "white" XL-looking power supply units. They get somewhat yellowed over time so finding a real white one would be rare.

 

Just perform Retr0brite on it and it will easily look brand new. The XL cases really clean up nicely with 40 Volume Creme Developer.

[atariksi]

I have a couple of the "white" XL-looking power supply units. They get somewhat yellowed over time so finding a real white one would be rare.

 

Just perform Retr0brite on it and it will easily look brand new. The XL cases really clean up nicely with 40 Volume Creme Developer.

 

I'm not into playing with chemicals. Perhaps, if it was easily available somewhere, I would give it a shot. It doesn't look so bad though. I guess the black bricks would be better since you can't see the aging yellowing effect on the black brick type power supplies.

[Justin Payne]

I hear that some people take small 5vdc 1.5 amp+ switching power supplies from other electronics and wire on an Atari plug... Would you still need a fuse/crowbar on that?

 

product1.jpg

 

Something like this (this one is 5vdc 2a)

Oooh. This is an old thread but it seems to be the last discussion on this topic...so, I too wonder if I could just replace my old ingot with one of these cell phone chargers. It seem to me that it meets the requirements (and a bit more) so instead of trying to crack open my old ingot power supply, I could just pick up a new 7 pin DIN and hook it up to this thing. I feel like I need some sort of confirmation from someone who is knowledgeable enough to tell me I'm completely screwed in the head (an electronics expert, not a psychiatrist).

[baktra]

Oooh. This is an old thread but it seems to be the last discussion on this topic...so, I too wonder if I could just replace my old ingot with one of these cell phone chargers. It seem to me that it meets the requirements (and a bit more) so instead of trying to crack open my old ingot power supply, I could just pick up a new 7 pin DIN and hook it up to this thing. I feel like I need some sort of confirmation from someone who is knowledgeable enough to tell me I'm completely screwed in the head (an electronics expert, not a psychiatrist).

 

I am using such small power supply without any problems for years. Just avoid those that are too cheap (and probably made in PRC).

If you do not intend to save your original PSU, you can cut the cable leading from the PSU to the computer and save some DIN soldering - 1 wire to three pins.

Edited April 6, 2017 by baktra

[Roydea6]

 

I prefer is type of power supply just chop off the 4pin and insert 5v to the 5v side of 7Din connector and leave the 12v wires taped back inside Din casing.

 

Being careful about polarity and + to 2-4-6 pins and - to 1-3-5 ..

 

[Justin Payne]

 

I am using such small power supply without any problems for years. Just avoid those that are too cheap (and probably made in PRC).

If you do not intend to save your original PSU, you can cut the cable leading from the PSU to the computer and save some DIN soldering - 1 wire to three pins.

Thanks! Yea, I know I shouldn't look at the size difference but that's a BIG difference.

I do intend to keep my old supply and might, at some point, fix it so it can be used but for now I just need a quick solution and this seems to be up that alley.

[Justin Payne]

196270.jpg

 

I prefer is type of power supply just chop off the 4pin and insert 5v to the 5v side of 7Din connector and leave the 12v wires taped back inside Din casing.

 

Being careful about polarity and + to 2-4-6 pins and - to 1-3-5 ..

 

Thanks but doesn't that seem like extra work, additional bulk, and extra wires to contend with? Is there a reason you like this one better than the cell phone one that provides exactly what is required?

[Mark loves Stella]

I connected a 7pin din to a usb cable. It works on any USB port with 1 or more amps. Works on wall plug and backup batteries.

[_The Doctor__]

just be careful as some of the usb adapters limit current causing the Atari to operate under brownout conditions that can kill it over time...

[Justin Payne]

just be careful as some of the usb adapters limit current causing the Atari to operate under brownout conditions that can kill it over time...

I assume you mean when you run them off of your PC. If so, I don't intend to do that. A cool trick but unnecessary for my needs.