View Profile: modem7 - Vintage Computer Forum

Today, 07:35 PM

modem7 replied to a thread 5150 full height drives - 320k or 360k? in PCs and Clones

The one shown at here] ?

7 replies | 50 view(s)

Yesterday, 01:44 PM

modem7 replied to a thread Dummy Load in PCs and Clones

I have seen that '50W 5ohm resistor' specified at here], but not specified elsewhere. A 5Ω/50W resistor is going to be unsuitable for some power...

12 replies | 286 view(s)

Yesterday, 12:38 PM

tonata replied to a thread Repairing Oliveti M24 monitor in PCs and Clones

So it was not the pot indeed. I sprayed and I do not know how much time one needs to wait but it is the same as before. Thank you for all the...

20 replies | 702 view(s)

Yesterday, 07:19 AM

Exceter replied to a thread Will trade IBM 5162 XT/286 for IBM 5170 AT in Vintage Computer Items For Sale or Trade

It's too bad that you're in CA or I'd make that trade. I'm always down for a road trip but that's a little far even for me.

6 replies | 687 view(s)

January 24th, 2021, 01:43 PM

tonata replied to a thread Repairing Oliveti M24 monitor in PCs and Clones

Do you see where the multivibrator and/or the ramp capacitor are most likely located? When I disassemble it I will try to focus on this area.

20 replies | 702 view(s)

January 24th, 2021, 12:59 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

That is probably the keyboard doing a self test after receiving +5V.

45 replies | 802 view(s)

January 24th, 2021, 12:55 PM

modem7 replied to a thread oh look! I slipped and acquired a 5150! in PCs and Clones

Take a look through the XT compatible memory cards at here]. Having a very quick look there, I see that the AST Rampage! (as an example) offers both...

5 replies | 209 view(s)

January 23rd, 2021, 12:25 PM

tonata replied to a thread Repairing Oliveti M24 monitor in PCs and Clones

Thanks. I made a picture just to verify I was able to understand in English.

20 replies | 702 view(s)

January 23rd, 2021, 08:40 AM

tonata replied to a thread What's wrong with my 5151? in PCs and Clones

Hi, I think it could be the environment. Do you have something close to the monitor that could produce magnetic interference? Have you tested in...

7 replies | 145 view(s)

January 23rd, 2021, 08:36 AM

tonata replied to a thread Repairing Oliveti M24 monitor in PCs and Clones

No it says Toshiba CDU 1200. Thank for your hints! I will start with the pot because searching for a bad capacitor will be more complicated. I...

20 replies | 702 view(s)

January 23rd, 2021, 02:00 AM

modem7 replied to a thread oh look! I slipped and acquired a 5150! in PCs and Clones

A converter for an AT class keyboard, such as the one at here], is something that you may want to consider.

5 replies | 209 view(s)

January 20th, 2021, 01:00 PM

modem7 replied to a thread Miniscribe Model 3650 "error" in Vintage Computer Hardware

The drive's electronics are not sensing that the spindle is spinning. That could be because the spindle is not spinning, or the spindle is spinning...

4 replies | 83 view(s)

January 19th, 2021, 12:54 PM

tonata replied to a thread Repairing Oliveti M24 monitor in PCs and Clones

So I managed to adjust: - V.HOLD - H.HOLD and it got much better, but it still does not work. The H.SHIFT acts as an additional adjustment of...

20 replies | 702 view(s)

January 19th, 2021, 01:27 AM

tonata replied to a thread Monitor IBM 5153 - horizontal shift in PCs and Clones

Hi, I have a scrambled output on my Olivetti M24 monitor. It looks mostly like horizontal sync problem but not only. So I should focus on the...

8 replies | 438 view(s)

January 19th, 2021, 01:21 AM

tonata replied to a thread Repairing Oliveti M24 monitor in PCs and Clones

Hi, I am looking again at my Olivetti M24 monitor. The video card is OK, because I got a signal on a VGA monitor, but the VGA monitor gives a...

20 replies | 702 view(s)

January 18th, 2021, 01:51 PM

modem7 replied to a thread Z110 PSU +12V not working in Vintage Computer Hardware

See the photos of electrolytic capacitors at here]. By "triangles", I presume that you are referring to the triangular segments shown in the second...

9 replies | 108 view(s)

January 18th, 2021, 01:42 PM

modem7 replied to a thread High-capacity disk read errors on an AT in PCs and Clones

You are not seeing any issues at all using 360K floppies, so this does not sound like a 'dirty heads' issue. What is the background of the subject...

6 replies | 130 view(s)

January 17th, 2021, 01:53 PM

modem7 replied to a thread IBM 5170 restoration - PSU fixed, now RAM problems - SRAM replacement? in PCs and Clones

I am not following you. The parity calculating hardware (for motherboard RAM) is elsewhere on the motherboard with the piggyback DRAM's in the...

8 replies | 227 view(s)

January 15th, 2021, 01:48 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

In case you did not see it, mentioned at here] is the availability of prebuilt AT2XTKB (and some variants) on eBay.

45 replies | 802 view(s)

January 14th, 2021, 08:20 PM

modem7 replied to a thread Good program for polling all the IRQs, DMAs, I/O hex addresses? in Vintage Computer Software

Some other issues: * The RAM on some network cards does not appear in the motherboard's memory space until the driver for the card is loaded....

8 replies | 226 view(s)

January 14th, 2021, 08:03 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

C5 and R9 run from ground to +5V. When you have the keyboard plugged into the (unpowered) motherboard, measuring the resistance across C5 (or R9) is...

45 replies | 802 view(s)

January 14th, 2021, 07:07 PM

modem7 replied to a thread Getting an 8" FDD working with an IBM 5170? in PCs and Clones

In the past, I have tried to fit various half-height hard drives under the two floppy drives, but from memory, there are issues like the screw holes...

14 replies | 274 view(s)

January 14th, 2021, 07:01 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

Consider too the option of an AT class keyboard together with an adapter like the one at here]. BTW. I updated the circuit diagram even more.

45 replies | 802 view(s)

January 14th, 2021, 04:41 PM

modem7 replied to a thread Getting an 8" FDD working with an IBM 5170? in PCs and Clones

As far as I am aware, the subject card will simultaneously support up to two floppy drives and up to two hard drives. The limitation you write of...

14 replies | 274 view(s)

January 14th, 2021, 03:43 PM

modem7 replied to a thread IBM 1501492 - dead? in PCs and Clones

Further to last: I am "jumping the gun" here. If, via what I suggested, it is revealed that the controller is overloading the PSU, then there...

6 replies | 163 view(s)

January 14th, 2021, 02:09 PM

modem7 replied to a thread IBM 1501492 - dead? in PCs and Clones

Welcome to these forums. By your "The PSU starts", I am assuming that you are basing that on the fact that the PSU's fan is turning. If so,...

6 replies | 163 view(s)

January 14th, 2021, 01:47 PM

modem7 replied to a thread Help identify microcontroller in an XT keyboard in PCs and Clones

I am very experienced in 'recreating' circuit diagrams. But it is still easy to get confused. For example, this morning, I realised that I had...

45 replies | 802 view(s)

January 14th, 2021, 01:16 PM

modem7 replied to a thread Adding a CF card slot to a 5170 without wasting an expansion card bay? in PCs and Clones

On that subject, after a prompt weeks back from member Malc, I did some more experimentation, and I now have a VCF XT-IDE card that appears to 'play...

30 replies | 929 view(s)

January 14th, 2021, 09:27 AM

tonata replied to a thread Repairing IBM 5154 Color monitor in PCs and Clones

I found the specification: 275 VAC.

10 replies | 522 view(s)

January 14th, 2021, 07:43 AM

tonata replied to a thread Repairing IBM 5154 Color monitor in PCs and Clones

C5 and C6 are on the alternative or direct current in the power supply? I just realized that capacitors have different ratings for that. So mine...

10 replies | 522 view(s)

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