I have removed the blown filter capacitor of both PSU and cleaned the dirty cables.

Gallery:

Yes, it’s a long story, because i have modded this Atari 2600 JR many times.

The first time have made a simple composite video mod without adding any external components, so i have made the composite mod with 1 transistor and a couple of resistors, the last composite mod is the UAV (Ultimate Atari Video) made from a dude of AtariAge that was given to me by my friend Charlie and today i have put 3 x RCA for video/audio output in place of a cable passed through the RF hole.

I used the same hole as the RF output for the VIDEO output and soldered a RCA connector in the same pcb pad of the RF RCA connector, i have used the same pcb track that was needed for the RF signal for the Composite signal, i have also removed a resistor (R19) to isolate the pcb track.

Gallery:

Ultimate64/U64 Speaker with a little improvement.

I didn’t really like to see the U64 Speaker which due to the small connector and weight he tended to tilt and was not aligned with the motherboard.

I solved the problem quite elegantly by inserting a small thickness of plastic glued with a drop of Loctite on the botton side of the U64 Speaker motherboard.

Gallery:

The problem of this radio of the late 60s was due to the lack of foam layer, certainly removed by someone.

The thin layer of foam inside the battery holder is needed to lock the batteries in their position, missing this thin layer of foam the radio turns off if it is bumped or moved.

Gallery:

source: museoscienza.org

Atari 2600 (4-switch units) PAL Composite Video Mod for my friend Charlie.

Gallery:

Atari 800XL Hardware Enhancements.

I have decided to upgrade my Atari 800XL with some hardware interfaces available on the Lotharek website.

Current situation of my Atari 800XL:

• Ultimate 1MB from Sebastian Bartkowicz (Candle) with the latest FJC Bios.
• VBXE + DIN Connector for RGB/Audio Output (RF Modulator Removed)
• Simple Stereo + U-Switch + Jack 3.5 Stereo for auxiliary Audio Output.
• SIDE 2 / AVG Cartridge

New interfaces installed:

• P-Covox + 3.5 Stereo Jack for Audio Output.
• SRAM 64Kb.

After installing the SRAM 64Kb module i have removed also this series of IC which are no longer used from the Atari 800XL.

• 8 X RAM NEC 4164C
• 2 x SN74LS158N
• 1 x DM74LS51N
• 1 x SN74LS375N
• 1 x Delay Line EP8212 (C060472-D)

Gallery:

Atari 800XL with a missing delay line EP8212 (CO60472) Repair.

Thanks to the SRAM 64Kb Module by Lotharek, i have been able to resurrect a Atari 800XL which lacked the EP8212 delay line (CO60472) which is no longer available as spare parts.

More information of the SRAM 64Kb Module visit the lotharek site.

Gallery:

Commodore A501 (REV 6C) Expansion Memory Unit Kissed by luck.

Why “lucky”? because the battery used in this Expansion Ram Unit (A501) was not VARTA but GP, these batteries resist slightly to aging and release less acid.

Gallery:

Atari 2600 (4-switch units) Repair.

Defect:

• Black Screen.

Replaced parts:

• 1 x CPU 6507 (A200)

Gallery of the repair:

My name is “jaundice” and my last name is “lucky”.  :-)

Why “lucky”? because the battery used in this Amiga was not VARTA but GP, these batteries resist slightly to aging and release less acid.

The only defect of this Amiga 500 Plus was the Floppy Drive which did not read any Floppy Disk, the motor running slower than normal, it was enough replace a 4.7uF electrolytic capacitor to make it work again.

I thank my friend Igor for the donation.

Gallery:

12►

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 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

Project born in 2017 for my SX-64++

I wanted to improve the schematics and make a PCB, 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.

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:

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

Defect:

• Garbage Screen.

Replaced parts:

• 1 x TMS4116-20 RAM (U103).

Gallery of the repair:

—————————————————————————————————————————————————-

Download: TI99 Technical Manual (828)

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:

12►

Video: