A friend of mine left me some ZX Spectrum clones produced in the 90′s in Czechoslovakia and Russia.

As you can see from the photos i have tried to find the right pinout of the RGB video and audio output.

Thanks again Andrea Pierdomenico.

Gallery:

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A friend of mine left me some ZX Spectrum clones produced in the 90′s in Czechoslovakia and Russia.

As you can see from the photos i have tried to find the right pinout of the RGB video and audio output.

Thanks again Andrea Pierdomenico.

Gallery:

source: https://k1.spdns.de/Vintage/Sinclair/82/Clones/Russia/LENINGRAD/

…from the author website:

Since the end of 2015, it became clear that the “good old” 1541 Ultimate-II was at the end of its life cycle. Xilinx, the manufacturer of the most important chip of the cartridge, had started to increase the prices of the chip. Also the memory chip started to be harder to get and at higher cost. When the news came that the company that made the black plastic cases for the 1541 Ultimate-II had lost the injection mold tool, it became evident that the 1541 Ultimate-II would be no more.

I have given it some thought. What would be the best way to continue with this project? When the feelings of being upset about the lost injection tool had subsided, I realized that this may be the perfect moment for an upgrade. This is when set backs change into opportunity.

Since then, a lot of work, and I really mean A LOT OF WORK has been done to create a successor: the “Ultimate-II+”.  Why not “III”, you may ask or think. Well, the foremost reason is the software. The install base of the “1541 Ultimate-II” is rather large (>3000 units), and I do not want to let my customers down that have just purchased a unit. This means that in case of new hardware, the same software should run on both the new board, as well as on the older board. So, the new board will offer similar functionality. You could see it just as an upgrade, not an entirely new product.

Although the “Ultimate-II+” is similar, there are also differences:

• No more MicroSD!  (… that needs to be pushed in with something sharp, could fall into the case, … etc)
• More USB ports (… one to compensate for the lost SD, and just one bonus: 3 in total)
• IEC connector moved (… further back to facilitate use on some C128 models)
• Integrated Ethernet (… no more need for an external USB2LAN adapter, and a smaller step to CS8900A compatibility)
• Dual Flash (… no more worry that a software bug or upgrade failure leads to a bricked device)
• Integrated Speaker (… who connects a speaker set to the audio jack for hearing drive sounds??)
• External power supply connector with auto-switch over circuit (… for stand alone mode, and to lower the demand on the power supply of the C64)
• Improved Audio (… audio codec, 24 bit/96 kHz*, for sampled sounds and SID emulation)
• Improved Tape connector (… no more custom board and able that snaps in on the bottom, but standard USB 3.0 cable)
• Improved power supply circuits (… for some reason they seemed to break down relatively often)
• Slightly bigger and faster FPGA, as to control the new features

source: 1541ultimate.net

A new version of the firmware for the interface 1541 Ultimate II is released. This version runs only on the 1541 Ultimate II cartridge (new fpga).

Release notes 3.0 beta 7:

r297 | gideonz | 2016-04-15 21:27:25 +0200 (Fri, 15 Apr 2016)

Download: 1541 Ultimate II Firmware v3.0 Beta 7 (1269)

source: 1541ultimate.net

Jean-François DEL NERO (who’s behind the HxC SD Floppy Emulator) recently has released a version of the HxC emulator firmware that is compatible with the STM32 chip used in the Gotek floppy emulators.

This means that the great functionality of the HxC SD emulator is now available on cheaper and more widely available hardware.

The bootloader to convert the Gotek floppy drive in HxC compatible must be purchased on the website HXC 2001 by sending an email to Jean-François DEL NERO. The price of the bootloader is one-off 10 Euro per Gotek that you want to update. Future updates of the software are free and can be made from a USB stick

The HXC Usb (Gotek) firmware supports:

Release notes Firmware USB HxCFloppyEmulator v3.0.8.2a

• HD floppy disk format issue corrected : write buffer size corrected.

Download: USB Stick STM32 (Gotek) HxC Firmware v3.0.8.2a (1181)

source: hxc2001.com

Jean-François DEL NERO (who’s behind the HxC SD Floppy Emulator) recently has released a version of the HxC emulator firmware that is compatible with the STM32 chip used in the Gotek floppy emulators.

This means that the great functionality of the HxC SD emulator is now available on cheaper and more widely available hardware.

The bootloader to convert the Gotek floppy drive in HxC compatible must be purchased on the website HXC 2001 by sending an email to Jean-François DEL NERO. The price of the bootloader is one-off 10 Euro per Gotek that you want to update. Future updates of the software are free and can be made from a USB stick

The HXC Usb (Gotek) firmware supports:

Release notes Firmware USB HxCFloppyEmulator v3.0.8.1a

• Last selected image save issue corrected.

Release notes Firmware USB HxCFloppyEmulator v3.0.8.0a

• “Autoboot”/ File selector mode :
  • Fast backward/forward mode : Keep the button pressed to speed up the image change.
  • Press both buttons in the same time to jump the autoboot/file selector image.
• Indexed mode :
  • Fast backward/forward mode : Keep the button pressed to speed up the image change.
  • Press both buttons in the same time to jump the DSKA0000 image.
• Up to 1000 indexed images (DSKA0000-DSKA0999).

Download: USB Stick STM32 (Gotek) HxC Firmware v3.0.8.1a (1037)

source: hxc2001.com

The Tulip system I was a 16-bit personal computer based on the Intel 8086 and made by Tulip Computers, formerly an import company for the Exidy Sorcerer, called CompuData Systems.

Its 6845-based video display controller could display 80×24 text in 8 different fonts for supporting different languages, including a (Videotex based) font for 2×3 pseudo graphic symbols for displaying 160×72 pixel graphics in text mode. The video display generator could also display graphics with a 384×288 or 768×288 (color) or 768×576 (monochrome) pixel resolution using its built-in NEC 7220 video display Coprocessor, which had hardware supported drawing functions, with a very advanced set of bit-block transfers, it could do line generating, arc, circle, ellipse, ellipse arc, filled arc, filled circle, filled ellipse, filled elliptical arc and many other varied commands.

Its memory could be upgraded in units of 128 KB up to 896 KB (much more than the 640 KB of the original PC).

It included a SASI hard disk interface (a predecessor of the SCSI-standard) and was optionally delivered with a 5 MB or 10 MB hard disk. The floppy disk size was 400 KB (10 sectors, instead of 8 or 9 with the IBM PC) or 800kb (80 tracks).

It ran at 8 MHz, almost twice the speed of the IBM PC XT which was launched only a few months earlier in July 1983. It had the possibility to use an 8087 coprocessor for math, which increased the speed to > 200 kflops, which was near mainframe data at that time.

After initially using CP/M-86 it quickly switched to using generic MS-DOS 2.00. There was a rudimentary IBM-BIOS-emulator, which allowed the user to use WordStar and a few other IBM-PC software, but Compudata B.V. shipped WordStar and some other software as adopted software for this computer. There was a programming support by Compudata B.V. with MS-Basic, MS-Pascal and MS-Fortran. On a private base, TeX and Turbo Pascal were ported to the Tulip System 1.

Gallery:

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Works that i have made before power on the computer:

• Removing the filter capacitor inside the power supply.
• Replaced the tantalum capacitors.
• Eprom (ROM) dump.
• Found the pinout for the Video composite signal.
• Cleaning.

Pinout for the Video composite:

Cleaning & Fix gallery:

Download:

• CompuData Tulip System 1 Eprom Dump (1176)
• TIM 2000 DOS/CPM 2.0 IMD/ImageDisk (755)

source: wikipedia

Commodore 64C (ASSY 250469) Repair (1 of 12)

Defect:

• Black Screen.

Replaced parts:

• 1 x MOS 6526 (U1)

Gallery of the repair:

Commodore 64C (ASSY 250469) Repair (2 of 12)

Defect:

• Black Screen.

Replaced parts:

• 2 x TMS 4464 (U10/U11)

Gallery of the repair:

Commodore 64C (ASSY 250469) Repair (3 of 12)

Defect:

• Black Screen.
• Keyboard Dead.

Replaced parts:

• 2 x TMS 4464 (U10/U11)
• 1 x MOS 6526 (U1)

Gallery of the repair:

Read more…

The motherboard conditions are not good, very badly. All capacitors have released acid, some are gone and the same for other components like the transistor Q233 2N3904 SMD amplifying for the video signal BLUE RGB. The Decoder U12 CXA1145 Sony has the pins eaten by the acid of the capacitors.

Poor Amiga …

Work to do:

• Solder resistance from E232R that is disconnected because the acid of the capacitors has leaked and corroded..
• Solder the transistor Q233 that is disconnected because the acid of the capacitors has leaked and corroded.
• Rebuilding a dozen pf pcb track between the IC U12 and the rest of the PCB and rebuilding also the through holes of the PCB.
• Replacing electrolytic capacitors, probably due to the state of the pitches i don’t use SMD capacitors.
• Replacing the male Harddisk connector some legs are broken at the base because the acid of the capacitors has leaked and corroded.

Gallery of the repair & cleaning:

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I start to saying that this type of repair should NOT be made, are not good although the repair can succeed, these damaged motherboards are good for spare parts.

It took me 10 hours to repair and if i ask 15,00 euro per hour like a housekeeper, would be 150,00 euro excluding components and cleaning case … but who pays 150,00+ euro ? no one in the world. :-D

This is one of the reasons because do not exist anymore electronic repairs or there are very few people can do it, nobody is willing to pay.

Works that have been made:

Foreword almost all pcb pads are leaked of the acid, although i have cleaned more times so as not to heat the electrolyte liquid that is worsening the situation, unfortunately the pcb pad could not resist to a new solder and they are broken.

• Soldered the E232R resistor, it’s no a good soldering because the pad are in a badly state but working.
• Soldered a transistors Q233 (2N3904) not SMD, the pitches are gone when i have tried to solder the SMD version.
• Rebuilt 10 x connections doing a horrible jumpers in bizarre places.
• Replaced the electrolytic capacitors.
• Replaced the male connector for the Harddisk.

It’s a shit … but it works!

Commodore Amiga 600 Gallery (Before & After):

Yet another Commodore 64 (USA-NTSC) repaired.

Defect:

• Garbage screen / Black screen.

Repair:

• Replaced 1 x PLA 906114
• Replaced 1 x MOS 7708 (74LS257)

Note:

• The first time the Garbage Screen was in Black & White and then after replacing the PLA 906114 a new Garbage Screen is back with some colors :-D (see photo)

Gallery of the repair:

Texas Instruments TI-99/4A Repair (#1)

Defect:

• Wave/Raster Lines.

Replaced parts:

• 1 x Variable Inductor 2 -> 4.5 μH (L100).

Gallery of repair:

Texas Instruments TI-99/4A Repair (#2)

I should point out that someone has already tried to repair, without success.

Defects:

• Black Screen (no raster, no sync) short circuit between 12v and 5v . . . and then . . .
• Wave/Raster Lines.
• Blue Screen with tiny Vertical lines and deafening sound.
• Garbage Screen.

Short Circuit Note:

• The short circuit was due to a malfunction of the IC: TIM9904ANL (U601)

Replaced parts:

• 1 x Variable Inductor 2 -> 4.5 μH (L100).
• 1 x TIM9904ANL (U601)
• 2 x MCM 6810P RAM 128×8 (U608 – U609)
• 1 x 74LS245 (U614)
• 1 x TMS9929 (U100)

Gallery of the repair:

Commodore PET 2001 Chiclet (1978) Fixed.

Defect:

• Garbage screen.

Repair:

The problem of this computer was caused by the oxide on all pins of the RAM and inside of the sockets as you can see from the photos.

To clean the pins of the IC i always use the same way, gently with a rasp nail on the ic pins and then spray a bit of air, see photo.

For cleaning the socket i scraping with a fine tip gently the contact inside the socket.

I have tested all with the ROM/RAM board and simulating the various BASIC and configurations of RAM and loaded some software, including my demo with the PET MicroSD by Dave Curran (Tynemouth Software)

Everything worked perfectly.

As you can see from the photos i have now a complete workstation for repair PET 2001 out of the box, avoiding to have on the table the computer that takes a lot of space.

Gallery of the repair:

Grundy Newbrain repaired

Defect:

• Dead.

Analysis:

• The acid of the capacitors has corroded some pcb tracks and pitches of the main pcb.
• One of the two flat cable (main pcb -> keyboard/vfd pcb) previously repaired cause short circuits and doesn’t work.
• Removing the Filter capacitor “RIFA” in the external PSU (removal made 7 months ago)

Repair # 1:

• Replaced all the electrolytic capacitors.
• Rebuild the PCB tracks corroded by the acid of the capacitors.
• Replaced the flat between the main PCB and the keyboard/vfd pcb.

The computer now turns on but the VFD (Vacuum Fluorescent Display) displays weird characters and the composite video signal is dead.

Repair # 2:

I have used a Z80 NOP generator that i have made some years ago for repairing ZX Spectrum/Sinclair and that causes the Z80 to process only “NOP” instructions
and consequently on the address lines we can see with a oscilloscope a perfect square wave.

With this simple “trick” i have immediately found the faulty component that break one of the address lines of the CPU (A1). The exact same fault was found by Thomas Gutmeier.

• Replaced 1 x 74LS257 (IC 412)

The computer now works perfectly.

Gallery of the repair:

12►

Download: Grundy NewBrain Schematics (1521)

Zenith Data Systems (ZDS) was a division of Zenith Electronics founded in 1979 after Zenith acquired Heathkit, which had, in 1977, entered the personal computer market.

Headquartered in Benton Harbor, Michigan, Zenith sold personal computers under both the Heath/Zenith and Zenith Data Systems names.

Gallery:

Laboratory Bench Transformer for repair Commodore CBM/PET series 2001/30xx/40xx(not fat – 8032 motherboard)

Transformer Output Pinout:

• PIN: 4 – 6 = ~16VAC
• PIN: 4 – 5 = ~8VAC
• PIN: 5 – 6 = ~8VAC
• PIN: 7 – 8 = ~16VAC
• PIN: 9 – 10 = ~16VAC

Input:

• 110v

Gallery:

Thanks to Andrea Pierdomenico for this great donation made some years ago.