Questions tagged [power]

Questions and problems related to powering retro equipment.

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Questions about IBM PC PSU P8 key pin and change to +5V for AT

According to the IBM PC/XT Technical Reference page 3-6, pin 2 of plug P8 is a "key." (Note that this is the pin specifically; this is separate from the keying of the shroud, which is ...
cjs's user avatar
  • 25k
1 vote
1 answer
214 views

Commodore 64c supply 9 Vac waveform specs

I found an old Commodore 64c without a box, cable, or anything else and I want to put it back to work. In order to do so, I need to turn it on to see if it works. I've already found the pinout of the ...
jack07Code's user avatar
4 votes
1 answer
121 views

What is the power adapter voltage and polarity for an Avatex 1200 modem?

My very first modem was an Avatex 1200 connected to my trusty C64. Unfortunately, the power adapter has long since been, let's say, disassociated from the hardware. I probably still have it, but the ...
Geo...'s user avatar
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5 votes
1 answer
194 views

Correct voltages and current draw for Commodore PC-1

I am fixing a Commodore PC-1 PSU for a friend and want to know if the PSU is behaving as expected. No modern PSU suggestions (e.g. Meanwell), if you don't mind! :) Question: What are the voltage ...
Nick Bolton's user avatar
21 votes
5 answers
8k views

The Cray 1 used 115 kW of power. How was that much grid power physically delivered to the unit?

We are talking power plant levels of current to power the the thing. Did it just have 2 inch lugs?
R Gi's user avatar
  • 327
2 votes
0 answers
129 views

Atari 1040 STFM power supply issue & high-pitch noise

I have an Atari 1040 STFM that's been sitting in the basement for about 30 years. It doesn't power on. The power indicator light is not illuminated and there's a high-pitch noise coming from the power ...
Chocula's user avatar
  • 121
0 votes
1 answer
152 views

What if ATX 12v P4 power connector was introduced 4 years earlier? [closed]

AT power supply handled +5 and +12 volts, +5 for ISA and processors, +12 for motors in disk drives. In 1995 486DX2 was introduced with 3.3V core, so it derived that from a simple but inefficient ...
Ivan Borsuk's user avatar
6 votes
1 answer
651 views

Maximum current a GBA Game Pak can continuously draw

The GBA (specifically model AGB-001) uses a boost converter to power the Game Pak with a stable 3.3V from its batteries. The SP and Micro models use a buck-boost regulator to generate that same 3.3V. ...
forest's user avatar
  • 2,009
1 vote
0 answers
183 views

Monochrome CRT, words are wavy and sometimes move forward and backward, what could be the issue?

Monochrome CRT characters are not stable and rather shaking or waviness in them, sometime feel like moving forward and backward. Issue is in the high voltage power supply but what could it be, do high ...
Zain ur Rehman's user avatar
29 votes
5 answers
6k views

When/why did computers come to have push-button main power switches where on and off is the same push action?

In the top answer to Why were animated screensavers used instead of a black screen on CRT monitors? the main reason was said to be that it avoids users accidentally turning off the machine, thinking ...
leftaroundabout's user avatar
4 votes
2 answers
582 views

Why do computer rooms no longer have raised floors? [closed]

As I understand it, computer rooms in the days of mainframes and minicomputers, commonly had raised floors, so that the space under the floor could be used for power cables and cool air. I'm not clear ...
rwallace's user avatar
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8 votes
2 answers
2k views

Weird power lines for S-100, why no 5V?

In answering another question here on the S-100 bus (from my admittedly less-than-perfect recall), I wonder why the bus supplied 8 and 16 volt signals, relying on the boards to regulate this down as ...
paxdiablo's user avatar
  • 4,752
29 votes
3 answers
22k views

Why do Game Boy Colors not want nickel-cadmium batteries?

This is a page from the manual for the Game Boy Color: There is no explanation as to why this is, or how this can be, but it claims that one must not use rechargeable nickel-cadmium batteries. Why is ...
Bacus's user avatar
  • 291
1 vote
2 answers
622 views

Why did the description of the Windows shutdown command imply power-off was manual even with ACPI available?

The description of the ‘Shut down’ option in earlier versions of Windows reads: Ends your session and shuts down Windows so you can safely turn off power. Why was this shown in Windows 98–XP even ...
user23482's user avatar
31 votes
2 answers
4k views

What is the Commodore 64C "France version" and why does it need a beefy resistor?

While perusing the schematics for the Commodore 64C (titled COMMODORE-64 B/NE) I came across a suspicious section of the power supply: The unregulated "9V" is connected to the completely ...
pipe's user avatar
  • 1,718
11 votes
5 answers
6k views

Can a Japanese (or US) PSU for Nintendo 64 be run with 230 V mains?

The Nintendo 64 uses a proprietary PSU that takes mains voltage input and outputs 3.3 V and 12 V DC. PSU's from regions where mains voltage is 230 V (such as the EU) were sold as 230 V input while ...
Jan's user avatar
  • 315
3 votes
0 answers
195 views

PC AT power supply not providing correct voltage

I'm refurbishing a Pentium 120 PC with an AT power supply. It seems to work, at least nothing pops or smokes, but there's a slight problem with voltages, particularly on the motherboard connectors. ...
Tamás Polgár's user avatar
5 votes
2 answers
494 views

Can I power a Windows 95-era AT PC with an ATX PSU, like this?

Is this the correct way to make the adapter? Will the "15A 120V AC ONLY" switch damage anything? The switch is illuminated. (glows when off)
user21987's user avatar
12 votes
2 answers
2k views

How did the Altair ensure that the −5 V supply was the first connected and last disconnected?

The Wikipedia page for the Intel 8080 processor describes pin 11 as The −5 V power supply. This must be the first power source connected and the last disconnected, otherwise the processor will be ...
DrSheldon's user avatar
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5 votes
1 answer
836 views

Could a BBC Micro power supply be replaced with USB power?

According to this video the BBC Micro's power supply provided a 5 Volt supply to the motherboard. Could a BBC Micro have it's internal power supply replaced with a USB power connector?
billpg's user avatar
  • 153
2 votes
2 answers
327 views

Which computer used the greatest number of DC supply voltages?

The original IBM PC supplied several voltages: +5 V, −5 V, +12 V, and −12 V. Which computer supplied the most DC voltages? To facilitate the comparison, let's agree on some uniform criteria for what ...
DrSheldon's user avatar
  • 15.9k
2 votes
1 answer
298 views

Did the RTC in certain cartridges get power over the GBA bus?

Some GBA games, like Pokemon Ruby, contained an internal RTC with a small button battery to power it. When the cartridges were inserted and the GBA was powered on, did the RTC continue to run on the ...
forest's user avatar
  • 2,009
4 votes
1 answer
410 views

Amstrad CPC 6128 - Bench Power Supply Connection Setup

I am definitely at the very beginning of my refurb-journey and learning every step now on the way ... I struggle with the following: I saw a video by Noel's Retrolab where he troubleshooted a CPC. He ...
retronexus's user avatar
15 votes
7 answers
7k views

Why did the IBM PC have an internal power supply?

Microcomputers run off low voltage DC, but usually came with a power supply to produce a suitable DC current from the mains AC voltage. It was usual among early home computers to supply an external ...
Mark Williams's user avatar
0 votes
1 answer
237 views

How picky are CRTs about power cleanliness?

How picky are CRTs about the 'cleanliness' of the mains power? Cleanliness referring to electrical noise from thing like ac motors in fridges, powerline ethernet, etc. Cleanliness is also referring ...
Alexander M's user avatar
10 votes
1 answer
1k views

Why did the C64 use a separate "CAN" +5 V power supply for some chips?

The Commodore 64 had two separate +5 V power supplies: one supplied by the external PSU brick and a second one generated on-board from the 9 VAC via a 7805 regulator. This second +5 V power supply was ...
cjs's user avatar
  • 25k
5 votes
2 answers
1k views

Two graphics cards for retro gaming

I'm considering installing two graphics cards in my retro gaming setup (one AGP and one PCI) and was wondering if there are any drawbacks to doing so? The main things I'm thinking about are power ...
Sam's user avatar
  • 411
1 vote
0 answers
71 views

Thinkpad 380E keeps shutting down randomly [closed]

Recently, I got a 380E from ebay. Seller says that it has boot error and not working, but the error was typical 161/163. I've replaced nee BIOS battery, and error was gone. After that, I formatted ...
Kamome's user avatar
  • 163
3 votes
2 answers
363 views

Using generic SMPS adaptor on old IBM Thinkpad makes strange symptoms

I found abandoned IBM Thinkpad 560X inside of company's cabinet. So, I got curious and get generic AC-DC SMPS adapter for 10$. It was rated 16V 3.75A, diameter for plug is just right, and polarity was ...
Kamome's user avatar
  • 163
4 votes
1 answer
3k views

How can I make an external PSU for an Apple IIc?

I purchased an Apple IIc from an auction site, but it came without the external power supply unit. While this question and its answers describe how to open up the IIc and use alligator clips to power ...
cjs's user avatar
  • 25k
22 votes
1 answer
3k views

How does the C64 get an accurate TOD clock on both 60 Hz and 50 Hz power?

The C64 has two Time of Day (TOD) clocks, one in each of its 6526 CIA chips U1 and U2. These calculate time based on a 60 Hz or 50 Hz input to the TOD pin (pin 19); the clock input frequency assumed ...
cjs's user avatar
  • 25k
9 votes
1 answer
841 views

What's the best way to hook up an external power supply to the Apple IIc without a 7-pin female DIN plug?

As seems to be typical with Apple IIc purchases these days, mine came without the external power supply. I have ordered some 7-pin female DIN plugs and other adapters that will let me plug a modern ...
cjs's user avatar
  • 25k
2 votes
2 answers
1k views

How much PSU power do I need for an AMD 386DX-40 computer?

Just picked up my first retro PC the other day. Unfortunately, it's lacking a PSU so I need to find one. What kind of a PSU (in terms of wattage) do I need to comfortably run an AMD 386DX-40 system? ...
Violet Giraffe's user avatar
4 votes
1 answer
1k views

Discharging an AT power supply for maintenance

The power supply for one of my computers needs a new fan. How do I discharge the power-supply capacitors to make it safe to open up? With an ATX power supply, it's just a matter of unplugging it, ...
Mark's user avatar
  • 8,547
13 votes
4 answers
3k views

Do AT motherboards (286, 386, 486) really need -5V (besides redirecting it to ISA connectors)?

The power supply of my 386DX computer (an unknown brand M320 motherboard) is not trustworthy anymore, so I'm planning to use an ATX power supply, plus an ATX to AT adapter for P8-P9 connectors. The ...
mcleod_ideafix's user avatar
13 votes
5 answers
7k views

Does switching on an old games console without a cartridge damage it?

This is inspired by the question "What does a Nintendo Game Boy do when turned on without a game cartridge inserted?": Growing up in the 80s and 90s in the UK, it was "common knowledge" amongst my ...
Darren's user avatar
  • 241
8 votes
2 answers
1k views

Does the Commodore 64 power switch have a history of failing?

My original (1983?) Commodore 64 (brown breadbox with grey function keys) has trouble powering on. Specifically, when I flip the power switch the power LED will glow dimly and the machine fails to ...
Geo...'s user avatar
  • 10.2k
7 votes
1 answer
505 views

How do you open an Amiga A590 Power supply?

I have an Amiga 590 hard drive, but the power supply appears to be dead on it so I want to take a look inside. I have removed three screws from the underside but it still won't open, acting like there'...
Eifion's user avatar
  • 173
4 votes
2 answers
309 views

Sam Coupé power supply heat

I have a Sam Coupé and the last time I turn it on, i noticed a smell of components overheating. After opening the power supply I came to the conclusion that is the resistance R1 (50ºc with IR ...
Bruno Vilela's user avatar
5 votes
2 answers
714 views

Commodore PC-1 power supply measurements off

I have a Commodore PC-1 with a busted power supply. I have no desire to fix it as I don't have the know-how it is already 30 years old It is difficult to debug / find replacement components So I ...
ddewaele's user avatar
  • 151
8 votes
2 answers
1k views

How to troubleshoot Amiga 600 power issue?

I have an A600 Rev 2D (schematic), which is dead as a doorknob. It was that way when I acquired it some years ago, and it's mostly been in storage since. Between the 5V rail and GND I measure a low ...
Dampmaskin's user avatar
5 votes
3 answers
690 views

What to check before powering on TRS80 Model III in unknown condition [duplicate]

Having managed to source a TRS-80 Model III that I'm told hasn't been powered on for quite some time (and I suspect this is a massive understatement), I'm worried that the first thing that might ...
user avatar
37 votes
6 answers
9k views

Why does the Cray 2 use 400 Hz power, and why generate that from motors?

This Cray sales brochure details on page 4 that the Cray-2 uses 400 Hz power, and generates this from motors. 400 Hz power from motor generators I'm not sure that in 1986, the state of the art ...
Omar and Lorraine's user avatar
3 votes
1 answer
483 views

Transatlantic gray market Commodore PETs and 220V/50Hz vs. 115/60Hz

In the late seventies, Commodore sold the PET in Europe at a considerably higher price than in America; they could get away with this because there was less competition there. Some of the American ...
rwallace's user avatar
  • 60.2k
4 votes
4 answers
380 views

Running European retrocomputers on 60Hz power?

I have 3 European retro computers that I'm trying to run on North American power through a step-up transformer. So, I am using 220V/60Hz instead of the European standard of 220V/50Hz. BBC Master ...
Brian H's user avatar
  • 60.5k
10 votes
4 answers
2k views

Why the switch to "Mickey Mouse" (type C14) power cables?

Inspired by this question asking about "regular" power cables, I have been curious about (read: irritated by) the rise of "Mickey Mouse" power cables. Apparently they come from the same standards ...
KlaymenDK's user avatar
  • 905
29 votes
7 answers
13k views

Why did computers use a power supply with a socket?

Most home electrical appliances use a fixed power cord and have a on/off switch near the front. I was in many government electronics labs and that cord and socket was not used i.e HP test equipment. ...
jwzumwalt's user avatar
  • 4,499
4 votes
0 answers
323 views

Cost of Apple II switching power supply

Apple went to the trouble of designing a switching power supply at a time when they were still quite new and not widely used for consumer electronics, perhaps because Steve Jobs liked the aesthetics ...
rwallace's user avatar
  • 60.2k
147 votes
5 answers
52k views

It's now safe to turn off your computer

One thing I remember very well from my childhood is the screen you got at the end of a shutdown process on old computers: I don't know if this was a Windows 95/98/2000/ME only thing but I wonder why ...
arminb's user avatar
  • 1,341
112 votes
23 answers
39k views

Was there ever any reason to wait 30 seconds to restart a c.1995 PC?

I owned a PC in the mid-to-late 90s, and while everyone said when you turn it off and back on again, count to 30. But it also had an instant reset button down below. Was there ever really any risk ...
Mikey's user avatar
  • 1,161