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Archive for the ‘Projects / Repairs’ Category

ELEGOO UNO R3 – Hackvision

November 25th, 2020 3 comments
ELEGOO UNO R3 - Hackvision

I’m not posting anything new, it simply something that i wanted to do from ten years, assemble the “project” Hackvision using Arduino, now i’m using a clone: ELEGOO UNO R3.

There is nothing more to say and like you can see from the photos the games run well.

The games are compiled with ARDUINO IDE with the TV-OUT library.

Gallery:

Electronic diagram:

source: nootropicdesign.com/hackvision/games/

STM32F401CCU6 (Arm Cortex MCUs) SID Player by Bakisha

November 23rd, 2020 5 comments
STM32 (Arm Cortex MCUs) SID Player by Bakisha

STM32 (Arm Cortex MCUs) SID Player by Bakisha.

SID chip (6581 and 8580) and 6502 CPU emulator for STM32 (Arm Cortex MCUs). Compiled with Arduino IDE and uploaded with ST-LINK V2.

NOTE:

I have added to the original code of Bakisha the visualization of the 3 SID voices via 3 x Green LED.

Useless to write more about this, watch the video and the photos.

Special thanks goes to Bakisha for his work.

Components used for this project:

  • 1 x BreadBoard.
  • 1 x STM32F401CCU6 (STM32 Black Pill) or STM32F407VET6
  • 18 x BreadBoard jumper.
  • 1 x SD Card Module.
  • 3 x Green LED.
  • 1 x Resistor (100 Ohm)
  • 1 x Capacitor (100 nF)
  • 1 x Capacitor (10 uF – 16v)
  • 1 x Potentiometer (10KOhm)
  • 1 x Jack Audio 3.5 Female.

You can found the schematic here.

Gallery:

Video:

source: github.com/Bakisha/STM32-SID-PLAYER

Commodore PET CBM 3008 Motherboard and Monitor Repair

November 3rd, 2020 2 comments
Commodore PET Model CBM 3008 Motherboard and Monitor Repair

A person in need of my help of which i have already repaired several devices has contacted me and asked if i could make a repair of one of his Commodore PET with two different trouble.

  • The first fault was black screen on power up, meaning no image was displayed.
  • The second fault that occurred after a couple of days was a raster video distortion of the CRT monitor accompanied by a smell of burning (see photo)

The first fault was solved by replacing the UD7 ROM (901465-02) with an eprom (2532), the correct functioning test could be done by connecting the LCD monitor that i use for repairs via a video adapter.

The second fault was brilliantly resolved by replacing the voltage regulator installed on the pcb monitor, a 7812 which on the pin output did not always return 12v but rather a mix between 3v, 6v, 10v.

I also removed some pieces of foam rubber (see photo) which due to the glue used has damaged the back of the monitor PCB leaving obvious traces of corrosion and a black sticky stain that i have removed.

I also rebuilt a missing pin of the ROM UF14 (901447-10) that someone had thought to fix in a very rough way (see photo)

Gallery of the repair:

Download:

Philips NMS 8245: The usual melted belt of the Floppy Drive

August 26th, 2020 No comments
Philips MSX NMS 8245 usual melted belt

Philips NMS 8245: The usual melted belt of the Floppy Drive.

Gallery:

Philips Videopac G7000 a little bit Dirty but Working

August 10th, 2020 No comments
Philips Videopac G7000 a little bit Dirty but Working

Philips Videopac G7000 a little bit Dirty but Working. Nothing to write this time, just needed only a good clean up.

Gallery:

Dirty and Ruined Intellivision Black Screen repair

August 10th, 2020 No comments
Dirty and Ruined Intellivision Black Screen repair

Dirty and Ruined Intellivision *Black Screen* repair.

It would not have been nice to put the intellivision in a very worn state and without a controller inside the spare parts box without even trying it :-)

Obviously the intellivision was not working, black screen.

The repair was simple, i have replaced the AM9114 (U8-B) RAM with a NEC 2114 and everything started working better than before :-)

I have also removed both labels in a pitiful conditions, now it looks better than before.

Gallery of the repair:

Compudata (Exidy) Sorcerer II (DP1000-4)

June 28th, 2020 No comments
Compudata (Exidy) Sorcerer II (DP1000-4)

The restoration of the Sorcerer II of the Compudata (Exidy) was very simple, it was enough to replace all the tantalum capacitors with electrolytics one and make a good cleaning.

I tried the Sorcerer with the software downloadable at this link and to do a better understand the idea of the long loading (average 7 minutes) i have recorded the WAV file of the tape format on a Tape Cassette and used an old recorder to load the software, everything worked perfectly on the first try.

from Wikipedia;

The Sorcerer is a home computer system released in 1978 by the video game company Exidy.

It was comparatively advanced when released, especially when compared to the contemporary more commercially successful Commodore PET and TRS-80, but due to company focus on the coin operated video game marketplace resources were restricted for personal computer expansion and a separate division of the company was created.

Exidy Data Systems was headed by Paul Terrell to expand the product line to include small business computing with international distribution and technology license agreements to supplement corporate funding.

Distribution agreements with Dick Smith Electronics in Australia and Liveport in the UK as well as Compudata which included a manufacturing license to build, market and distribute the Tulip line of computers in Europe. Exidy sold the PC division to a Wall Street firm, Biotech, in 1983.

Gallery:

Usual boring repair of a Texas Instruments TI-99-4A

May 31st, 2020 No comments
Usual boring repair of a Texas Instruments TI-99-4A

Texas Instruments TI-99/4A Repair.

Defect:

  • Garbage boot screen.

Replaced parts:

  • 2 x TMS4116-15 RAM (U102 / U105)

Gallery of the repair:

Amiga 4000D – Nothing is thrown away from the pig

April 26th, 2020 No comments
A4000D - Nothing is thrown away from the pig

This Amiga 4000 is completely devastated on both sides of the PCB by the leaked acid of the battery and kept in a humid room for at least 20 years.

There are still a couple of things to keep, but i will do it later if necessary.

Amiga 4000D Black Screen (Paula / FastMEM / Full Recap) Repair

April 22nd, 2020 2 comments
Amiga 4000D Black Screen (Paula + FastMEM + Full Recap) Repair

First of all, a premise: All the repairs i do are for hobby purpose ONLY. It is NOT a job, and i fix stuff for a selected people group that i consider needs my help. All other people please ask somewhere else to get your items repaired back.

A guy contacted me asking help for a repair and after an exchange of messages i agreed to repair his Amiga 4000 which at boot only displayed a Black screen.

I immediately noticed a fairly important damage caused by battery and caps acid leakage.

After cleaned everything and replaced capacitors on motherboard / 3640 and PSU (the fault persisted, of course).

Next, i used the Chucky DIAGROM: the DIAGROM is useful to understand what might be that doesn’t work, and the output via RS232 is also very useful if nothing is displayed on the screen.

Unfortunately the DIAGROM worked partially because the mouse was completely dead and therefore i have used the output via Serial but this is also worked partially because evidently also the serial is dead but in some precarious moments i  have tried to run the Sound test and no sound was reproduced.

Moral: Partially working Serial port + Mouse not working + Audio not working = Paula.

Replaced the PAULA (U400) everything started to work correctly apart the FASTRAM with 4 x 4MB SIMM modules each the system sees only 2 in the U852/U853 positions for a total of 8MB.

The problem was a short circuit probably caused by the acid leaking from the battery, i had to clean the PCB for the tenth time and the problem was fixed.

No more other to say, except that i am happy i succeeded to repaired this Amiga 4000 for a person that needed my help.

Gallery of the repair:

Video:

6 x Texas Instruments TI-99/4A Repair

March 28th, 2020 1 comment
6 x Texas Instruments TI-99-4A Repair

Texas Instruments TI-99/4A Repair (1 of 6)

Defect:

  • Black Screen and deafening sound in background.

Replaced parts:

  • 1 x TMS 4732/2532 ROM (U610)
Texas Instruments TI-99-4A Repair (1 of 6)

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 Texas Instruments TI-99/4A Repair (2 of 6)

Defect:

  • Black Screen and deafening sound in background.

Replaced parts:

  • 1 x MCM 6810P (128 x 8-Bit Random-Access Memory TTL/DTL) (U608)
Texas Instruments TI-99-4A Repair (2 of 6)

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Texas Instruments TI-99/4A Repair (3 of 6)

Defect:

  • Black Screen and deafening sound in background.

Replaced parts:

  • 1 x 74LS138 (U504)
  • 1 x 74LS138 (U505)
Texas Instruments TI-99-4A Repair (3 of 6)

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Texas Instruments TI-99/4A Repair (4 of 6)

Defect:

  • Black Screen and deafening sound in background.

Replaced parts:

  • 1 x TMS 9900NL CPU (U600)
Texas Instruments TI-99-4A Repair (4 of 6)

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Texas Instruments TI-99/4A Repair (5 of 6)

Defect:

  • Garbage Boot Screen.

Replaced parts:

  • 1 x TMS4116-15 RAM (U106)
Texas Instruments TI-99-4A Repair (5 of 6)

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Texas Instruments TI-99/4A Repair (6 of 6)

Defect:

  • Various problems with audio playback.

Replaced parts:

  • 1 x SN76494N – Digital Complex Sound Generator (U511)
Texas Instruments TI-99-4A Repair (6 of 6)

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Recovery some components from a old ELTEC Slot Card

March 15th, 2020 No comments
Recovery some components from a old ELTEC Slot Card

There are not many interesting things to recover, for example the 256k x 4 ZIP Ram are absolutely useless.

So what i have recovered that could helpful (never) is the Motorola 68030RC20B CPU, the 68882RC25 math coprocessor and 3 x Clock Oscillator.

Gallery:

Commodore Monitor Model 1801

March 3rd, 2020 1 comment
Commodore Monitor Model 1801

This monitor is the PAL predecessor to the Commodore 1802. It appears to be a contemporary of the CM-141 and the brown-casing 1802. They both have dual inputs (Composite video/audio, and chroma/luma/audio) with a switch in front to select between them.

The Monitor although in excellent condition don’t work correctly, the image displayed was in black and white.

The problem was the oxidation of a little trimmer (see photo / orange trimmer) and it was enough to turn it a bit and put it back in its original position.

Other small defects fixed:

  • Bad geometry – Calibration of the Deflection yoke.
  • Out of Focus – Calibration Trimmer Focus on Flyback.
  • V-HOLD fine adjustment on the Monitor PCB.
  • Glued a piece of plastic broken at the base of the monitor.

Gallery:

Download: Commodore Monitor Model 1801 Instruction Manual (753)

source: gona.mactar.hu/Commodore/monitor/

ByteDelight ZX Diag Cart DIY KIT and Speccy Repair

March 3rd, 2020 No comments
ByteDelight ZX Spectrum Diag Cart

The ZX Diag Cart by ByteDelight will visually show all kinds of details of your ZX Spectrum, which is both looking cool and useful at the same time!

It will make diagnosing defects a lot easier:

  • Quickly check if voltages are present.
  • If there is a dataline ‘stuck’
  • If the M1 line is working…

The ZX Diag Cart automatically detects to which ZX Spectrum model it is connected, so it can control the ROM signals on ZX Spectrum 16/48K, 128K+, +2, +2A or +3, and many clones.

ZX Diag Cart Test and Sinclair ZX Spectrum 48k Issue 2 Repair:

I wanted to try this nice but also useful interface with my historical Sinclair ZX Spectrum 48k, not even doing it on purpose after several years of total inactivity the ZX Spectrum no longer worked.

The defect can i see is a total malfunction of the Basic interpreter with random errors and using the ZX Diag Cart i have see an error on all 16k RAM banks.

The voltage monitoring LEDs on the ZX Diag Cart show me that the -5v and the +12v are missing, consequently it was not a RAM problem but instead the transistor ZTX 650 (TR4)

Replaced the transistor it all work perfectly and passed all disgnostic test of the Diag Cart.

Gallery of the repair:

ByteDelight ZX Diag Cart Video:

Download:

source: bytedelight.com

Texas Instruments TI-99/4A Power Supply Repair

March 3rd, 2020 No comments
Texas Instruments TI-99 Power Supply Repair

Texas Instruments TI-99 Power Supply Repair.

Defect:

  • Missing 16v (AC)

Repair:

  • Replaced the Thermal Fuse with one of 125° 2A (see photo).

Gallery of the repair: