Calling out for your help! To gather something that's currently missing in the 'MSX universe': a kind of database / overview of the power consumption of various MSX models. Especially: the ACTUAL power consumption in use, how that power is divided over various DC voltages, and peak vs. normal currents. NOT so much AC that's pulled from the wall, and even less what's written on the type label (although both figures can be useful). Afaik, such a 'database' does not exist.
Why? Mostly this: as you may have noticed, there's regular threads about electrolytic caps dying, internals of some MSX models getting rather hot, 100 <-> 120V issues, some external 'brick' missing, etc. And then usually follows some discussion about what could be used as replacement, how 'heavy' diodes are needed, what voltage(s) or current(s) a replacement brick should be able to supply, etc.
But the most important info is usually missing: what the machine in question actually consumes under normal use. Service manuals, type labels, component datasheets etc, or an educated guess is useful but a poor substitute for this info. Having a clearer picture on this would make it MUCH easier to recommend specific solutions, replacement psu models, or eg. what voltage regulator(s) would be up to the job.
What am I looking for? Primarily: actual MEASUREMENTS of the power consumption of MSX machines, under 'normal' use. Ideally of the DC currents consumed from the internal +5V, +12V and (rarely) -12V. With as few as possible cartridges inserted. If possible: peak, normal & lowest values seen.
Special points of interest:
- Info about how posted figures were obtained (measurement method).
- What hardware configuration was tested (for example: what cartridges were inserted if any. Internal ROMs replaced with EPROMs. NMOS vs CMOS Z80s. TMS9918 vs that Toshiba VDP, etc).
- UNregulated DC voltages found in specific power supplies (to calculate heat dissipation for their voltage regulators).
- The power consumption ADDED by various types of floppy drives (both in rest & during seek or read/write).
- The effect of what software is running (if any).
- The effect of speed upgrades like 6 or 7 MHz circuits.
If you own a Kill-A-Watt or similar device, and an MSX computer, then you can help! Actual power consumed (turned into heat inside your MSX) not "reactive power" is what's wanted. Although power factor, and efficiency of some MSX psu's might be interesting.
If you are a hardware person like myself, know how to measure voltage or DC current, and don't mind pulling the top of your MSX machine to take a few measurements, then you can help!
If you know such a person & can bring him/her and your MSX machine together to take some measurements, you can help!
If you have an MSX model for which no picture of the type label (with voltage / watts info) can be found on the internet, or an overview of what parts are on the mainboard, then you can help!
What am I NOT looking for?
- Info on a type label that's easily found on the internet.
- A power consumption figure that you found in some floppy drive's datasheet.
- Power consumption figures for individual IC's found in MSX machines.
- Less-accurate or less-complete figures for a model whose 'twin sister' has already been covered. But in the case of good measurements, multiple data points don't hurt.
- For the most part, power consumption of your run-of-the-mill MegaROM, memory mapper or SD card reader. Cartridges are external, extra, I can take measurements in that area myself, and regardless: there's a spec about what cartridges are allowed to consume. If a cartridge goes over that because designer didn't do his/her job, not my problem.
- Likewise for educated GUESSES concerning MSX model X, Y or Z.
- Lots of discussion about related subjects that 'pollutes' the informational contents of this thread.
Why am I asking YOU for help? I know how to pop the hood of an MSX machine, take some measurements & post results here. If you'd lock me into a room filled with MSX machines with the necessary tools, I could gather figures quickly. Buuuutttt... I only have a small collection of MSX machines myself. Owners of some unique MSX models are few & far between. And most of all: many hands make light work. If done correctly, a single measurement session is all that's needed for each MSX model, ever. Including machines that have identical hardware.
Consider it like writing some notes into a service manual. If you know the data for a Philips VG8020/20, then you know it for a VG8020/40, since those machines have near identical hardware inside (not the VG8020/00, though!). If you know it for a Sony HB-F700S, then it'll be the same for an F700P. Many examples like that.
I hope this can be a long-running thread, where from time to time someone (including myself) will post some figures measured for MSX model X, Y or Z that wasn't yet covered, or in more detail. Along the lines of that 'look under the hood' thread a while ago. Once enough figures are available, I intend to compile an easy-to-search list / spreadsheet or similar. For questions about how to measure things, or what readings mean: just ask.
Happy hunting!
I happen to own a SVI-728 myself, but without the AC adapter. Iirc it has some stupid power supply with video circuitry mixed on the same board. And using transistors rather than IC regulators. Very unusual, more trouble to feed in external DC power if desired. But mine has just that, so will 'dig up' that machine & post some more accurate numbers when I find the time.