Re: SCSI2SD - Comparison of SCSI SD, CF, and HDD performance

Posted on 2019-02-26, 10:18

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Indeed, the speed rating on SD cards (C10, U1, U3, V60, V90, etc..) only guarantees sequential large-block throughput with zero regard for random small-block IO performance. For the latter, you want the new 'Application Performance Class' rating, which appears as "A1" and "A2" on cards. The …

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Re: 486 cpu voltage regulator measurements

Posted on 2019-02-25, 21:24

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You can replace that TIP127A with a 125 or 126 as well, so long as it's not a *TU version. These are only ~2W rated and will blow pretty much instantly. I'd suggest adding a bent piece of aluminum or copper plate to form a simple radiator - this transistor didn't have it and as you can see didn't …

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Re: Old KEnitec 286 Plus (suntac) Rescue, will need help.

Posted on 2019-02-25, 20:18

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So you did not find connection from R13 right side to the 4069? Than it's a problem you have to solve now :) The circuit should look something like this, based on the tests so far: https://i.imgur.com/KxG62ev.png However I'm unsure about the first gate used, I guess it's 3-4 but could be a different …

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Re: Some problems I faced today

Posted on 2019-02-25, 17:45

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Without a multimeter you won't be able to do much. I mean a simple testing circuit made of battery+resistor+LED might do in a pinch but these days you can get a cheap multimeter for a few $ in most shops that carry electric goods like switches, sockets, fuses etc. Start with the keyboard socket and …

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Re: Is it safe to remove old CMOS batteries in this "different" way?

Posted on 2019-02-25, 15:16

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I concur, one sneeze with that rotating blade and that mobo is going to to require a lot of repair to work again, if ever. Also if you remove the battery along with the terminals you can put a socket in there (assuming there is enough space) - that would greatly simplify future replacements. Might …

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Re: SCSI2SD - Comparison of SCSI SD, CF, and HDD performance

Posted on 2019-02-25, 13:56

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

IPerforming the benchmark on a faster system might increase speed differences. Also, using different speed SD and CF cards may have some impact. According to Sandisk, the SanDisk Extreme SD card is rated for 90 MB/s, while the 200x CF card is rated for 30 MB/s. The SCSI host controller is limited …

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Re: Old KEnitec 286 Plus (suntac) Rescue, will need help.

Posted on 2019-02-25, 13:30

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I am somewhat on the fence with these cheap "osciloscopes". On one hand, it is a scope and works (mostly) within the advertised parameters - you will not get anything better for 30 Euro. And because it's cheap there won't be much of a loss if you break it by accident. On the other hand... it's very …

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Re: 486 cpu voltage regulator measurements

Posted on 2019-02-25, 10:12

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

TIP127A is a PNP power darlington, not your typical linear regulator like for example LM317. Anyway, looking at the photo, from left to right the pins of that transistor should be connected like this: Vreg, output (to 486 socket), +5V That 5V might be connected permanently or through a jumper so …

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Re: Old KEnitec 286 Plus (suntac) Rescue, will need help.

Posted on 2019-02-24, 23:30

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Well corrosion could still be the culprit but I think we should make sure the battery circuit is operating as it should. Personally I dislike desoldering parts from old PCBs like these, they can be very fragile. Trying to remove a chip can easily rip traces or pull vias, especially those already …

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Re: Old KEnitec 286 Plus (suntac) Rescue, will need help.

Posted on 2019-02-24, 19:37

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks for checking the POWER GOOD, we can now safely scratch that off the list. So you do get a reaction after bleeding C83? Well then there is no need to wait I think? Just short it by touching the pins with a resistor (anything from 100 ohm to 10k will do) for a second or two and it will be …

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Re: Need Help Identifying 486 MB and Upgrade Potential

Posted on 2019-02-24, 16:00

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It's hard to say without the manual but I don't see any way to disable that PQFP processor, so that signal is probably routed to the upgrade socket. Which means only 487 or ODP overdrive will work. So don't buy that DX4 just yet. EDIT: Or maybe I've misunderstood the JP6 description. It's problaby …

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Re: Old KEnitec 286 Plus (suntac) Rescue, will need help.

Posted on 2019-02-24, 15:15

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The PSU might be OK but it can still require some power draw on the 12V line. I've had some that would not even start or have crap 5V regulation when 12V is not in use. So that other PC will work because it simply draws more power. That's why I said to add an old HDD to the setup - just connect the …

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Re: Old KEnitec 286 Plus (suntac) Rescue, will need help.

Posted on 2019-02-24, 11:15

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Excellent work. So it would seem the 4-pin connector is indeed an external battery connector but it does not need to be jumpered for the RTC to work. You can connect external battery to pins 1 and 4 here with wires, but as you can see in that case you will get 2 diodes worth of voltage drop (D5 and …

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Re: Jumper manual needed for ISA IDE CD-ROM card - 74-1881A

Posted on 2019-02-24, 00:49

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes, the whole top row is tied to ground. So Mitsumi drives only? I have some Mitsumi drives, but the slowest is 8x. I also have 12x and 16x. Will the 8x work on this card? Or will it fry the card/drive? Given the age of the card, does NT4 and W95 have drivers built-in? Not just any Mitsumi, only …

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Re: How do you clean motherboards and cards ?

Posted on 2019-02-23, 20:27

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Water with a few drops of dishwashing liquid and brush (medium toothbrush for hard to reach places). Don't overdo with the detergent, you don't want bubbles obscuring the PCB. Soap is not so good (it excels at cleaning dirty plastic cases though). For rust - it depends what is rusted and how badly. …

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Re: Jumper manual needed for ISA IDE CD-ROM card - 74-1881A

Posted on 2019-02-23, 14:43

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Look at the backside of the Mitsumi card and see how many pins of that IDC40 connector are tied to ground. There were 3 custom CD-ROM protocols back in the day and (Mitsumi being one of them) all are only 8-bit. So if there's a lot of GND pins, it's a custom Mitsumi protocol card. Still usable but …

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Re: My CPU Collection

Posted on 2019-02-23, 00:13

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Wait, all AMD x2 CPUs are x3 capable? Or just the 3V3 write-back cache variants? I don't collect CPUs too look at them, I actually use them (if rarely) so I'm only interested in 386 and 5V 486. Nothing super fancy but that FM Towns 386 is uncommon as you can only get one by diassembling an early …

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Re: Old KEnitec 286 Plus (suntac) Rescue, will need help.

Posted on 2019-02-21, 20:58

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Please map that 4-pin header first. It might just save you a lot of work with testing the capacitors. I wasn't able to find the manual for your exact board so this me guessing but I think there should be a jumper on the 2 middle pins, and without it the CMOS and RTC are not getting power. This would …

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Re: Old KEnitec 286 Plus (suntac) Rescue, will need help.

Posted on 2019-02-20, 20:15

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by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks Deunan! Well the problem is not random at all. As Predator99 told me, the issue only appears when capacitors has energy. What i mean, i can reproduce the state of the beep codes everytime i want (i need 1-2 days to dry the caps). So, as Predator 99 stated i think i have to replace the caps …

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Re: Old KEnitec 286 Plus (suntac) Rescue, will need help.

Posted on 2019-02-20, 17:39

by

by Deunan

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've dealt with corroded PCBs in the past and yours might actually be worse than it looks. That it sometimes beeps and sometimes there isn't even a post code at all might suggest an electrical problem. Check again all the area around the leaked battery for any damaged traces, especially vias. See if …

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