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Level42

Failing PSU's, what do they put out ?

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Oh and no, 78xx regualutors cannot be put in parallel and also, the track layout wouldn't put it in parallel I bet.

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The same case, and likely the same heatsink, was used for an ST power supply which has multiple output voltages.

ATARI C070099 Power Supply

post-26063-0-06208000-1508220851_thumb.jpg

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By the way that 7805 is already a CV version.....and I bet 8840 means that it was produced in week 40, 1988.

The conclusion is that it must have been replaced already one time as I can't imagine this power supply to have been made in 1988.......or later...

 

It's also a messy job, leaving the excess silicone paste like that (I'm anal, I remove any excess with some alcohol and paper towel). They also screwed it in hard because it looks like the pins were soldered first and then they screwed it tight because all three pins are bent in the same angle....the correct way is first tightening the nut and bolt and only then solder the pins. This prevents mechanical stress on the solderings.

 

Good call on the date observation! Indeed it does look like it was replaced at some point, which explains the messy paste job.

 

Got the screw out finally (which is now stripped, will need a new screw/nut hehe) .. pic, better view without the big heatsink:

post-53052-0-26120400-1508222295_thumb.jpg

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Seeing that picture makes my fingers itch.

 

I'd resolder al the parts....but that's just me....look at how those resistors and the diode on the right are mounted.....yugh.

 

Also look at the bulbs of solder at the +5V wire output ....not to mention the "soldering" on the ground wire. When I created bulbs like that during electronics school the teacher kicked me in the balls.....well not really...but almost :D

 

The wires from the transformer aren't much better. I would renew ALL solderings on this thing (meaning sucking away all the old solder and putting new on. With the wires I would cut off the old parts that have been soldered and strip back the insulation a bit so you have "fresh" copper with all strands....

 

it actually amazes me that this was built by the same company that turned out these excellent quality 600 XL PCBs........in fact...I find it hard to believe it's true....probably some Chinese subsidiary threw these things together....

 

While you're at it, and if you don't have a good ESR meter, replace that big cap with a new, GOOD quality one (Panasonic, Nichicon).

 

Man....thinking about it, send it to me and I'll rework it for you.

 

 

 

 

 

Can't promise I'll ship it back though...... :grin: :grin: :grin: :grin: :grin: :grin: :grin:

Edited by Level42
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The same case, and likely the same heatsink, was used for an ST power supply which has multiple output voltages.

ATARI C070099 Power Supply

attachicon.gifST brick PS.jpg

Yep and it's a switching power supply. Completely different beast. I don't remember external ST power supplies as I only had a 1040STfm but those used switchers and I can't imagine a linear power supply of that small size delivering the amounts of amps that a ST needs. If there is a +5V output you could actually mod it and use it. But the casing is black......which makes it a lot less desirable than the beige one that matches the XL line....IMHO.

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Come to think of it:

 

There shouldn't be any solder on the parts side of the board at all. The wires should have the insulation run right unto the PCB and the soldering should be on the solder side only. I really wonder how they did this....the entire look and feel of this PCB reminds me of Wells-Garnder arcade monitors......which is not a good thing...trust me.

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It's surprising they used locktite on the nut on the other side though...maybe it's just factory left-over.

Youngsters, what are you going to do with them?

 

They were using fingernail polish for that work

before I was born. And locktite didn't exist.

This is before the beetles just in case you are

wondering. And yeah, Elvis was king. Not that I'm

a fan.

 

Try and buy some fingernail polish that ISN'T

colored. Then endure the funny looks you get

when you finally have settled on a color that

is acceptable. You guys have not paid your

dues.

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????????

 

Yoh buddy, try to stay off the drugs before posting weird stuff.....

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Yep and it's a switching power supply. Completely different beast. I don't remember external ST power supplies as I only had a 1040STfm but those used switchers and I can't imagine a linear power supply of that small size delivering the amounts of amps that a ST needs. If there is a +5V output you could actually mod it and use it. But the casing is black......which makes it a lot less desirable than the beige one that matches the XL line....IMHO.

I have 1 of the white bricks, 2 of the black XL bricks, and 1 of the ST black bricks. I got the last with the idea of converting it to an XL supply, but never got around to it.

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Last chance tonight to work on this PSU before I fly to Portland for PRGE tomorrow! So I broke out the soldering iron and got to work. For a grand total of $5.83 after tax I had all the parts I needed to do this properly, along with replacement screw and nut set :)

 

Replaced the regulator as planned, made sure to line up the hole with the heatsink before soldering it in and cutting off the excess leads. also reflowed most of the other solder points on the back of the board, but accidentally detached the AC input when it popped out! So wasted time cleaning that, and getting it back in the hole while soldering at the same time. :)

 

Quick test on the Atari without the heatsink lasted for about 1 minute before thermal shutdown of the regulator.. OOPS! that was fast... Anywho it was super hot, but survived.

 

Proceeded to finish up by re-attaching the heatsink, apply thermal paste, screw/nut the regulator to the heatsink, and close her up. All is well!

 

Nice solid 5.17V output with computer on, 5.21V with computer off. AC watt meter shows 1.3W off, 12.0W with stock 130XE, 12.6W with Sdrive2 attached, 13W with Ultimate Cart inserted.

 

Comparing with the working (for now) Ingot i have - I didn't measure DC output but AC input is 3.2W off, 13.8W Stock 130XE, and 15.1W with Ultimate Cart. So it's a little less efficient than the Hong Kong Chelco supply.

 

Cheers, and thanks Level42 and others here for the tips to encourage me to fix rather than gut it! Hopefully it remains reliable, additional time will tell.

 

post-53052-0-21135400-1508485058_thumb.jpg post-53052-0-56369000-1508485066_thumb.jpg

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Oh man....I shouldn't have helped you and you could have gutted it my way..... ;););)

 

Good job....as said....7805s usuall die in a friendly way....which is nice :)

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On 10/10/2017 at 11:57 AM, Level42 said:

Man I'd love one of those XL styled PSU...[snip]... Is the height the same as a 600/800XL ? If so the transformer is pretty shallow...

Missed the question back then about the height. A quick non-precise measurement shows the 800XL about 6cm high, and this PSU also about 6cm.

 

Here's a couple pretty pictures. :)

XLpsuTop.thumb.jpg.90231194b369b056936c72c33e7efbb6.jpg XLpsuMeasured.thumb.jpg.320a387d5fd7f1dceb852dba52a3408d.jpg

 

Edit: and one more - side by side we can see the PSU is literally 1mm shorter than the 800XL:

XLpsuHeight.thumb.jpg.5733c76cf3a6d87aa63f1fb3fbcf0847.jpg

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Hello guys

 

Maybe it's a crazy idea, but what the heck:

 

Maybe somebody could come up with a small device that would plug between the power supply and the computer that would show if the power coming from the power supply is OK.  Maybe yellow light for "to low", green light for "OK" and red light for "to much".  And maybe coming from one multicolor LED that would change color according to the voltage.

 

Sincerely

 

Mathy

 

 

 

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5 hours ago, Mathy said:

Hello guys

 

Maybe it's a crazy idea, but what the heck:

 

Maybe somebody could come up with a small device that would plug between the power supply and the computer that would show if the power coming from the power supply is OK.  Maybe yellow light for "to low", green light for "OK" and red light for "to much".  And maybe coming from one multicolor LED that would change color according to the voltage.

 

Sincerely

 

Mathy

 

 

 

Taking it a step further the C64 Saver device disconnects the power output if it exceeds a defined voltage level. There have been different versions over the years, some restore power when the voltage drops while others require a reset.

https://www.hackup.net/2020/01/c64-saver-evolution/

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Recently gutted an ingot supply because of all the bad reviews.Was curious about the components used.It was hard work,but I found good components including a 78S05 regulator in my unit.I find it hard to believe that it would fail in a high voltage mode.Maybe not all ingots are the same?

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On 11/29/2020 at 12:28 PM, Richard Gehle said:

Recently gutted an ingot supply because of all the bad reviews.Was curious about the components used.It was hard work,but I found good components including a 78S05 regulator in my unit.I find it hard to believe that it would fail in a high voltage mode.Maybe not all ingots are the same?

The issue isn't with the 78S05 but how Atari designed the circuit.

 

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I used the transformer from the ingot to build a spare supply.Had some NOS parts and got 5 volts at the output but under load it went to 2.6.Haven’t learned how import images from the iPad, so I’ll try to describe the circuit. Since I only had plain 7805 I added a PNP 2N6109 with a 4ohm resistor between emitter and base connected to input of 7805 and collector to output. Measure 12V from bridge to ground.Input and output of reg has .1mF Mylar to Grd. Bridge output has 4700mF to Grd. Output has 470mF to Grd.

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I used the transformer from the ingot to build a spare supply.Had some NOS parts and got 5 volts at the output but under load it went to 2.6.Including hand drawn schematic.

38517D7D-C11D-4A4B-80F5-A00D629FFF27.jpeg

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5 hours ago, Richard Gehle said:

I used the transformer from the ingot to build a spare supply.Had some NOS parts and got 5 volts at the output but under load it went to 2.6.Including hand drawn schematic.

38517D7D-C11D-4A4B-80F5-A00D629FFF27.jpeg

I don't think there should be capacitors used in parallel with the rectifier diodes, capacitors block DC but do pass AC signals.

The PNP transistor and 4 ohm resistor are also not necessary if a 7805 which can provide sufficient current is used, there are also switching voltage regulators which will reduce power consumption since they don't just dissipate the extra voltage as heat. These are available in different configurations, including 78xx drop-in compatible.

 

The following variable regulator from ABRA Electronics is only CDN$3.07/US$2.79, is rated @ 2.9A with heatsink, and is designed to be configured to fixed voltage output at several common levels with minor modification. The header pads are GND/VIN/GND/VOUT with both grounds being connected, which is 78xx compatible if the first pad is left out.

https://abra-electronics.com/voltage-regulator-modules/dc-dc-step-down-converters/psm-300-mini-dc-dc-4.5-24v-to-0.8-17v-3a-adjustable-fixable-step-down-converter-module.html

Edited by BillC

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