Re: Replacing Tantalum caps with other types?

Posted on 2017-12-14, 15:49

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You can replace Tantalums with MLCC's, but take not of the voltage bias. They lose their capacitance as the voltage that is applied to them, gets closer to the rated value. A through-hole polymer capacitor is a better replacement in my opinion. However, you can offset the voltage bias by using …

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Re: Fried/Grilled sc-88 pro

Posted on 2017-12-14, 10:53

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

the converter says it can deliver/handle 1865 Watts and it was dead cold in the whole process. it also has a fuse which is fine. I think you misunderstood me. What I mean is that your converter is capable of powering high-power loads such as hairdryers and will give them the correct 110V voltage, …

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Re: Fried/Grilled sc-88 pro

Posted on 2017-12-14, 08:15

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

There are also voltage converters that are meant for a bit heavier loads so it is possible your converter has put out significantly larger voltage to this low power load and the cap vented because of overvoltage. It looks like there is no other damage. It could have been due to old age as well, but …

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Re: Autoexec.bat & Config.sys Help

Posted on 2017-12-13, 09:13

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

EMM386 does not have RAM parameter after it, so it won't create UMBs. It is a matter of taste if you want to have the I=B000-B7FF there, I would not put it, as it disables monochrome video modes that have the framebuffer at B000-B7FF.

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Re: Intelligent mode MPU-401 and how it's utilised.

Posted on 2017-12-12, 17:43

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

chrisNova777 wrote: cuttoon; is there any chance you can post some high quality images of the CMS 401 interface? theres a serious lack of info on that interface online The only pictures I've found make me think it uses licensed Roland chipset. Better images would reveal it.

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Re: PC Speaker don't beep

Posted on 2017-12-12, 17:28

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

If there is a header it usually meant to drive a real speaker, and usually piezos are integrated on motherboard. That's because piezos are not really similar loads like a speaker is, so driving a piezo (that looks like a capacitance really) with output that's meant to drive a real speaker (that …

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Re: OPL2LPT

Posted on 2017-12-12, 17:21

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

I wondered why they designed the chip like that anyway. Most chips have a bus interface that just keeps the bus busy until the chip is done. For example, I timed a write to the SN76489 chip, and that was 42 CPU cycles at 4.77 MHz. So about 11 IO cycles. But then I thought: Perhaps Yamaha realized …

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Re: OPL2LPT

Posted on 2017-12-12, 09:53

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

Writes to the OPL2 registers are extremely slow. After you write to the address port, you need to wait for 3.3 microseconds, and after you write to the data port, you need to wait for 23 microseconds. Writing to the printer port is much faster than that, so I think it should be possible to 'hide' …

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Re: A strange ISA Card?

Posted on 2017-12-10, 21:51

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Definitely not token ring but standard 10Mbit/s coaxial ethernet. I knew 10BASE2 ethernet was called cheapernet, but that's the first time I've seen it printed on a product, priceless 😀 It looks like the card can be jumpered to be compatible with NE1K, NE2K or WD cards, but I could be wrong though. …

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Re: x86 software vs hardware clocks

Posted on 2017-12-10, 20:20

by

by Jepael

in PC Emulation

in PC Emulation

Anyone figured out the exact 8/16 clocks of those? Are the Dosbox-X clocks already accurate? Or do they need adjusting to be using the clocks in the photo's? Clocks for 8MHz and 16MHz formats in ET3000 and ET4000? That depends wildly, but let's assume ideal case first. According to pictures and …

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Re: Reversing the Disney Sound Source

Posted on 2017-12-09, 21:36

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

2017-12-09 (1).png :/ from Amp Output, also happens without Amp (only when DSS is not active) Op-amps can be tricky sometimes. Can you post schematics, so I can take a look at what parts you have used and how you have connected them, and with which voltages? There might be an issue that's not …

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Re: trobuleshooting dead ps2 + serial ports

Posted on 2017-12-09, 21:33

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

chrisNova777: What are you trying to do with the serial ports that does not work? I mean, how have you tested if they are broken or not? Does a serial mouse work, or have you tried a loopback test with a terminal program? The thing is, the dongle might be too power hungry compared to a serial mouse …

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Re: x86 software vs hardware clocks

Posted on 2017-12-09, 21:23

by

by Jepael

in PC Emulation

in PC Emulation

UniPCemu's VGA standard clocks are now: #define VGA28MHZ 28321000.0 Why? Didn't we just went through a long discussion that the original and most widely used value is 28.322? IBM VGA array was originally integrated on the motherboard of PS/2 models, so they were the first implementations, not VGA …

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Re: Looking for someone to run a quick test on a real DOS machine

Posted on 2017-12-06, 15:45

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Jo22 wrote: That's an interesting thought. But then why did they spend some exra time for that level where they used the AdLib as a DAC ? Which level uses Adlib as a DAC? I am pretty familiar how Lemmings Adlib music/sfx driver works and have found no such evidence.

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Re: File transfer over serial Null Modem in DOS?

Posted on 2017-12-06, 15:36

by

by Jepael

in Marvin \ Software

in Marvin \ Software

Same programs you use to call to BBSes, such as Telix or Telemate. They understand most of the common protocols (archaic such as Kermit and newer such as zmodem). You will find same protocols being used in windows and linux terminal programs as well. Since hyperterm does not come with Windows any …

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Re: When Does VGA latch the start address register

Posted on 2017-12-06, 10:38

by

by Jepael

in Marvin \ Video

in Marvin \ Video

That is what I recall as well, but there's a lot of clones and who really knows at which point the start address register is latched. But safe to say, it is latched in the blanking area for sure. So at least if you change the address after vertical retrace, maybe even when screen is being drawn, you …

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Re: Something like jack audio switcher with autodetection of signal?

Posted on 2017-12-06, 10:29

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

Not that I know of. What usually people might do in this situation: 1) loop audio through all sound cards (line out to line in) so you get one out, but it has difficulties as software mutes audio inputs etc. 2) buy/build a passive switch box so you can select yourself which input is connected to …

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Re: How many years until Capacitors go bad?

Posted on 2017-12-06, 10:24

by

by Jepael

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

BLockOUT has some interesting questions, but answering them is not so simple. There are different kind of capacitors. By the nature of your questions, it appears you are specifically referring to electrolytic capacitors. On top of that, there are also many different kinds of electrolytic capacitors, …

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Re: CVX-2 : covox adapter

Posted on 2017-12-04, 22:19

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

But wasn't the Covox a complete system with amplified speaker, so shouldn't it be taken as a whole? I don't see why really. Many early sound cards were sold as complete kits with (cheap) speaker kits. I don't think anyone ever argued that the speakers need to be included for the overall quality of …

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Re: Reversing the Disney Sound Source

Posted on 2017-12-04, 21:21

by

by Jepael

in Marvin \ Sound

in Marvin \ Sound

so using a 25kOhm Resistor and a 100nf for a simple high pass would suffice ? :) This should cut off anything below 60hz right ? Audio in >---C----> Audio Out | R | GND It does not really cut off that much at 60Hz. With those component values, the cutoff frequency is about 64 Hz. And at cutoff …

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