Re: HP LaserJet 5MP

Posted on 2018-08-04, 01:06

by

by 133MHz

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I know someone who bought a Laserjet 6MP back in the 90s and still uses it to this very day. It was hooked up to an AppleTalk home network that ran on telephone wire using those PhoneNet adapters until they replaced the old Macs with modern PCs on an Ethernet network - I then stuck a D-Link parallel …

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Re: Components worth harvesting from dead PC parts?

Posted on 2018-07-31, 00:52

by

by 133MHz

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I salvage pretty much exactly what Tiido posted with the addition of jumper caps, brackets and screws. Here are some situations I can think of where having a bunch of salvaged parts would come in handy: Battery damage on motherboards usually corrodes nearby components like the AT power and keyboard …

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Re: Dead IBM 8513 repair, quiet ticking, no HV - I have no ideas left

Posted on 2018-07-30, 23:18

by

by 133MHz

in Marvin \ Video

in Marvin \ Video

I gave a more thorough read to that Sci.Electronics.Faq repair page and it mentions that the flybacks on these monitors are failure prone. 🙁 I'd still test the HOT and check the B+ under a dummy load though. If both the HOT and PSU test good by themselves then you can be sure it's the flyback.

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Re: Dead IBM 8513 repair, quiet ticking, no HV - I have no ideas left

Posted on 2018-07-30, 06:48

by

by 133MHz

in Marvin \ Video

in Marvin \ Video

Would that cause the entire HV circuit to come down? Most CRT displays derive the high voltage supply from the horizontal deflection stage. The horizontal waveform drives both the deflection coil and the flyback transformer, so most of the time when the horizontal deflection goes out you lose high …

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Re: Dead IBM 8513 repair, quiet ticking, no HV - I have no ideas left

Posted on 2018-07-29, 05:12

by

by 133MHz

in Marvin \ Video

in Marvin \ Video

Did you test the horizontal output transistor? A shorted HOT is the most common cause for the tick-tick-tick sound. And yes, it's normal for the degaussing PTC to get hot.

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Re: Needing original Gotek firmware

Posted on 2018-07-27, 02:45

by

by 133MHz

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

There's no public dump of the stock firmware that I know of, since the Chinese set the protection bits on the microcontroller so that you can't dump it from the device you bought, and they happen to sell various models with different features (and prices) which in essence are just software …

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Re: I recently found this hardware, AKA the Dumpster find thread.

Posted on 2018-07-27, 02:27

by

by 133MHz

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Focus drift can be caused by a bad CRT socket (corroded contacts - very likely particularly in humid climates or if stored in damp environments), flyback transformer (bad focus/screen divider - not very likely but some of these do fail every once in a while) or failure of the CRT itself (internal …

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Re: An accidental collection (Prince of Persia content)

Posted on 2018-07-11, 22:09

by

by 133MHz

in Marvin \ Software

in Marvin \ Software

xjas wrote: What else am I missing? The Super Famicom port of the first game by Arsys Software, which IMO is a thing of beauty. 😊

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Re: NEC JB-902ME-5 green monochrome monitor bad picture fix?

Posted on 2018-07-11, 21:50

by

by 133MHz

in Marvin \ Video

in Marvin \ Video

Nice! Glad you got it working, love these tiny green monitors :-) On many of these 'TV-type' monochrome displays the horizontal hold control is actually a variable inductor (instead of a potentiometer) where a ferrite core is being slid in and out of a coil, hence the knob can be turned many times …

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Re: NEC JB-902ME-5 green monochrome monitor bad picture fix?

Posted on 2018-07-10, 17:31

by

by 133MHz

in Marvin \ Video

in Marvin \ Video

Which knobs are on the back? It looks like the horizontal oscillator frequency is off, requiring adjustment of the H.HOLD or H.FREQ control.

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Re: OUT OF SCAN RANGE - On old videocard/monitor

Posted on 2018-07-08, 16:30

by

by 133MHz

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have gotten that with VLB cards when they're not making good contact with the slots on the motherboard - clean both the contacts on the card and the pins on the slots with alcohol and test several times. Also check the card PCB under a strong light and magnifying glass to see if there are any …

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Re: Can I Swap HDD With Dos To Different Motherboard

Posted on 2018-06-26, 22:25

by

by 133MHz

in Marvin \ Software

in Marvin \ Software

The only time I've seen an MS-DOS installation fail to boot when swapping motherboards (excl. HDD geometry) is when moving from a 286 or better system to an 8086/8088 one. I assume it has to do with DOS making use of 286+ CPU instructions when installed on such a system, since going the other way …

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Re: Did AC adapters / Power supply change a lot in the last 20 years?

Posted on 2018-06-26, 22:19

by

by 133MHz

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Jo22 wrote: Makes me wonder as to why FCC and similar organizations do just watch that issue growing these days. Same reason why the post office and customs are overwhelmed pretty much everywhere - they can't deal with the massive influx of cheap stuff from China.

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Re: Did AC adapters / Power supply change a lot in the last 20 years?

Posted on 2018-06-23, 23:42

by

by 133MHz

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

But it does bring up an interesting point. I've noticed over the years that RF seems to get gradually worse in my classic systems over time. I thought at first it might just be the components starting to wear out, or the tuners in modern HDTVs to blame. But now that I think about it, most of the …

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Re: Modifying a Character Set in VGA Bios

Posted on 2018-06-23, 17:29

by

by 133MHz

in Marvin \ Video

in Marvin \ Video

That’s a cool program but it seems to make the bios unbootable whenever I make any changes. Changing just one pixel then pressing s to save then reburning just causes a blank screen on the computer. You likely need to recalculate/fix the checksum on the modified image before burning. Some editors …

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Re: CRT “crack” sound + picture flicker

Posted on 2018-06-22, 19:27

by

by 133MHz

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hate to say it, but everytime I get that zap/crack sound and the display cuts out when you hear it, that is the flyback transformer. It's not always the flyback transformer itself. As Tiido correctly pointed out it can be caused by a humid/corroded CRT socket, and also by a dirty and/or incorrectly …

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Re: Need some Japanese help

Posted on 2018-06-09, 23:41

by

by 133MHz

in Milliways

in Milliways

First kanji is way too low res to be readable, the rest (roughly) says 'software for use with 3DO'. Typed out with '??' in place of the illegible character: 3DO ?? 用ソフト

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Re: CRT monitor Calibration - Anyone here ever did that?

Posted on 2018-06-02, 22:14

by

by 133MHz

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

If the convergence is so good overall except in that one spot don't touch the magnetic ring assembly - you'll likely make it worse if you do. Small errors in the corners like that are corrected with permalloy strips glued to the glass bell, these are added at the factory (or by a service technician) …

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Re: LCDs with non-square pixels

Posted on 2018-06-02, 05:46

by

by 133MHz

in Marvin \ Video

in Marvin \ Video

I've only known of early "HD" Plasma TV displays doing what you describe (1024x768 or 1024x1024 pixels in a 16:9 aspect ratio).

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Re: Gamma Controls for DOS using CRT monitor?

Posted on 2018-06-01, 00:35

by

by 133MHz

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Your monitor needs its white balance procedure redone (adjustment of the individual R/G/B bias/drive controls until a neutral grey is achieved along the entire luminance range). As Tiido said before me if the cahtodes are significantly worn out this could turn out to be impossible, but if the wear …

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