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Archive for the ‘Various’ Category

Amiga 2000 already repaired in April 2016 now Black Screen

March 17th, 2019 No comments
Amiga 2000 already repaired in April 2016 now  Black Screen

This Amiga 2000 is arrived in my lab in very poor condition in April 2016, the computer has been repaired and stored in an antistatic envelope.

Tested after almost 3 years, the computer does not show signs of life.

Having no video output, i have used the Chucky DIAGROM which through a serial connection i was able to identify 2 different problems with the RAM’s.

Defect:

  • Black Screen

Repair:

  • Rebuilt track on the 68000 DX side near resistor pack RP900 (previously good)
  • Rebuilt track RAM U529 signal CAS (previously good)
  • Replaced RAM LM 33256 U501 with TMS 4256 (previously working)

Below some random photo of the repair.

Gallery:

SNK Neo Geo MV1a Z80 Error Repair

February 27th, 2019 No comments
SNK Neo Geo MV1a Z80 Error Repair

SNK Neo Geo MV1a Z-80 Error Repair.

Defect:

  • No Sound (Z-80 Error)

Repair:

  • Replacement of the Z-80 CPU in PSOP40 format.

Note:

  • The error message “Z-80 Error” means everything and nothing, may be faulty the Z-80, SNK MASK-ROM SM1*, SNK NEO-D0 or also the YAMAHA YM2610.

With the Neo Diagnostics bios and with the M1 ROM burned and installed on the CHA Board of any NEO GEO cartridge, the problem can be better identified.

It is said that the error C3/00 that you see in the photos of NEO DIAGNOSTICS (write: C3 but reads: 00) is an almost assured a CPU problem, in fact, in this case it was.

The Z-80 CPU in PSOP40 format has been recovered from a failed SEGA GameGear.

Gallery:

source: neogeo diag

sidSwitcher Enhanced v2.02

February 11th, 2019 No comments
SidSwitcher Enhanced v2.02

Project born in 2017 for my SX-64++

I wanted to improve the schematics and make a PCB (thank to CodingKoala Labs), the previous version was made on prototyping board pcb.

I have also added some features that i need when i will install the FPGASID in the SX-64++ and like the previous version the sidSwitcher integrates perfectly with the Overlay-64 & Keyman-64.

This circuit is not for sale. Schematics, Gerber and Atmel hex will be available soon for Download.

P.S: This project can also be used as a simple SPDT of analog audio signals. 2 INPUTS and 1 OUTPUT.

Features:

  • Output for Overlay-64 (http://henning-liebenau.de/overlay64/)
  • Input Push Button or Keyman-64 (http://henning-liebenau.de/keyman64/)
  • Bicolor LED (SID1 GREEN / SID2 RED / SID1 + SID2 ORANGE)
  • Output Mono or Stereo SID1 (LEFT+RIGHT / LEFT) / SID2 (LEFT+RIGHT / RIGHT) / SID1 + SID2 (LEFT+RIGHT / LEFT-RIGHT)
  • Possibility to use the mute function.
  • Jumper for configuration.

Schematics: (Prototype and Final):

The following photos are of the first version, second enhanced version, prototype breadboard and pcb.

2 x Texas Instruments TI-99-4A Repair

December 25th, 2018 No comments
Texas Instruments TI-99-4A Repair

Texas Instruments TI-99/4A Repair (1 of 2)

Defect:

  • Black Screen and deafening sound in background.

Replaced parts:

  • 1 x TMS 4732/2532 ROM (U611)

Gallery of the repair:

Texas Instruments TI-99-4A Repair Texas Instruments TI-99-4A Repair

 

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Texas Instruments TI-99-4A Repair

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

Defect:

  • Garbage Screen.

Replaced parts:

  • 1 x TMS4116-20 RAM (U103).

Gallery of the repair:

Texas Instruments TI-99-4A Repair Texas Instruments TI-99-4A Repair Texas Instruments TI-99-4A Repair

 

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DownloadTI99 Technical Manual (79)

Commodore Amiga 600 which has seen better dayz

December 16th, 2018 No comments
Commodore Amiga 600 which has seen better dayz

This Commodore Amiga 600 is arrived in laboratory in immaculate state still with the warranty sticker.

Immediately after the disassembly i have immediately noticed that were are several problems of acid released from the capacitors and dirty that affected this poor Amiga 600 and its Floppy Drive.

A decoupling capacitor it’s exploded with a pit on the PCB side, solved this problem i started to replace all the electrolytic capacitors and to clean the pcb with specific products.

After the replacement of the electrolytic capacitors, i have tried to turn on the amiga that apparently worked, shame about the distorted sound and the floppy drive that read 1 time of 100.

I had to replace the electrolyte capacitor on the Floppy Drive and soon after i looked for the fault of the audio problem that 99% is always the usual LF374.

In this case it was not only LF374 but also a 10ohm resistor that did not let the +12v to the LF374 and a short-circuited ceramic decoupling capacitor.

Components that have been replaced:

  • IC LF374 substituted with a fully compatible TL084C (U15)
  • 10Ohm resistor (R301)
  • 330nF capacitor (C301)
  • 330nF capacitor (C41)

Unfortunately the welding of the LF374 did not come very well how i like to do it but the pad are destroyed and corroded by the acid and they were about to detach, indeed the pad of the pin 2 of the LF374 was really detached, that’s why the pin 1 and 2 of the IC LF374 are connected together, they were connected via the pad.

I leave you to the photos and the video.

Gallery:

Video:

Commodore SX-64 Keyboard Repair & Cleaning

December 16th, 2018 No comments
Commodore SX-64 Keyboard Repair & Cleaning

The Commodore-SX64 keyboard after some time isnt’t responding anymore (all or some keys). In this case, the keyboard needs some cleaning and repair.

First of all you have to disassembly the keyboard housing, pay particular attention to the screws, this plastic is very old and not of a good quality, it breaks only if you look it.

Gently remove the membrane and clean with alcohol all the metal contacts on the keyboard pcb and also clean all the contact pads on the membrane without alcohol.

Next i took some graphite in cream (Keypad Fix) to reconstruct the pads on the membrane by simply applying a very fine layer of graphite on the contacts.

Gallery:

Philips Monitor VS0080 without Audio Repair

December 16th, 2018 No comments
Philips Monitor VS0080 without Audio Repair

This monitor although fully functional in the video section, was missing audio. The integrated circuit of amplifying sound (TDA 2611A) was not powered.

The problem was a broken pcb track (see photo), solved this problem the sound is back.

Gallery:

Video Intercom vintage monitor recycled

December 16th, 2018 No comments
Video Intercom vintage monitor recycled

I received this small Black and White CRT monitor from a friend, Ciro Barile of TI-99 Italian User Club, this monitor was used as a video intercom and i didn’t know the power supply voltage, the pinout but especially if it worked.

Found the pinout and the power supply voltage i saw the image turned upside down, this because the monitor could be hooked both from top and from bottom, nothing could be easier it was enough to change the deflection yoke connector on the motherboard to flip the image.

I drilled two holes on the back of the case to facilitate access to the composite video input and power supply (12v 2A).

Pinout:

  • RED (Video)
  • GREEN (Ground)
  • BLACK (Positive)
  • BROWN (Ground)

Gallery:

Another 2 x Gotek (HXC) with some Enhancements

October 12th, 2018 No comments
Another 2 x Gotek (HXC) with some Enhancements

Another 2 x Gotek (HXC) with some Enhancements.

Enhancements:

  • OLED Display (light blue version)
  • Piezo Buzzer.
  • Rotary Encoder with knob.
  • Firmware HxC by J.F. Del Nero.

Gallery:

Credits for the best firmware Jean-françois Del Nero.

Alternative Cleaner for Floppy Disk 5¼

October 12th, 2018 No comments
Alternative Cleaner for Floppy Disk 5¼

Why throwing away a Commodore Floppy Disk Drive with a broken head it could become a great gadget to clean Floppy Disks.

How to do ? just disassemble the entire part that controls the movement of the head including the head itself.

The power supply used is 12v with at least 1A, you can see the connection in the photo.

Good Cleaning.

Gallery:

Video:

Myarc Geneve 9640 (Replacement filter caps and voltage regulators)

September 12th, 2018 No comments
Myarc Geneve 9640 (Replacement filter capacitors and voltage regulators)

Myarc Geneve 9640 (Replacement filter capacitors and voltage regulators).

I have replaced all the voltage regulators (7805 / 7812) of 1A with the 1.5A version and all the 22uF / 35v filter capacitors.

Will also be installed the missing heat sinks in the geneve with plastic case.

Mattel Intellivision with GSOD (Grey screen of death) Repair

September 12th, 2018 No comments
Mattel Intellivision MOD 5155 (PAL) with GSOD (Grey screen of death) Repair

Mattel Intellivision MOD 5155 (PAL) with GSOD (Grey screen of death) Repair.

Defect:

  • GSOD (Grey screen of death)

Components replaced:

  • 2 x wrong resistors (who has replaced ?!?) of 150 Ohm instead of 300 Ohm.
  • 1 x 74LS00 (burned because the value was wrong of the two resistors)
  • 1 x RAM GTE 3539 UCP (U19)

Gallery of the repair:

Download: Mattel Intellivision Service Manual & Datasheet (175)

Irradio XTC-506R Repaired again

August 21st, 2018 No comments
Irradio XTC-506R -  Repaired again

Irradio XTC-506R Repaired again.

It seems this small Irradio TV/Monitor always suffers from some problem, last time there were short circuits caused by the pressure of the cathode ray tube on the PCB.

This time some cold joints on the solder pads.it would have been very sad to throw it in the garbage trash.

Gallery of the work done:

Nintendo Virtual Boy Repair

August 21st, 2018 No comments
Nintendo Virtual Boy Repair

Nintendo Virtual Boy Repair.

First of all, i thank Andrea Pierdomenico for this fantastic gift.

Below i explain how i have repaired the Nintendo Virtual Boy which show the classic display malfunction problems (both).

I have used only a pencil eraser and a SMD Rework Station to fix the connections of the ribbon cable to the Display PCB of the Virtual Boy.

The process involves heating the connection of ribbon cable to the Display and using a pencil eraser to push segments of the ribbon cable to the PCB.

I configured the hot air station to 145 Degrees and 55 of Air Pressure and i made 3 fast transition without ever stopping at a specific point, pressing between one pass and another with the pencil eraser.

It Works!

Gallery of the work done:

UAV Video Upgrade for Atari Computers & Consoles

August 12th, 2018 No comments
UAV (Ultimate Atari Video) Video Upgrade for Atari Computers & Consoles

UAV (Ultimate Atari Video) Video Upgrade for Atari Computers & Consoles.

This circuit improves the signal video output and allow to use both output (SVIDEO and COMPOSITE). The circuit is compatible with all Atari 2600, 5200, 7800 consoles and all Atari Home Computers 400, 800, 1200 …

I thank my friend Charlie for giving me this circuit that i have immediately installed in my Atari 2600 Jr which i use with the Harmony SD Cartridge.

NOTE:

Don’t use the socket in place of the IC 4050 as seen in the photo. The external case of the Atari 2600Jr console is too thin and cannot be closed anymore.

Gallery of the work done:

source: atariage.com