1 x MCM6810P (128 x 8-Bit Random-Access Memory TTL/DTL)
Texas Instruments TI-99/4A Repair (#2)
Blue Screen with tiny Vertical lines.
2 x IC MCM6810P (128 x 8-Bit Random-Access Memory TTL/DTL)
1 x IC CD3236A-NL (ROM)
1 x Capacitor 12 pF.
In one photo you can see the curious change made in this TI-99/4A by inserting a resistor in the pitch where in other motherboards is soldered a leg of a electrolytic capacitor and then one leg of the capacitor is welded and the not the other leg. Compliments.
Implemented functionality that allows to save a placeholder (unique for each .TAP file) pressing the red button on the back of the card. User can set back the read pointer at which TAP data is played back by pressing “Next” button on the card. Useful for multi load .TAP or games asking to reset the counter of the tape and then to rewind the tape that specific point.
I wanted to do a experiment to install a standard PC drive with a adapter (34 pins to 14 pins) on a Philips 8245. I would say that it work but i have tried about 20 Floppy Drives and only 1 it works ;-D
Ever since the birth of the Atari ST, different chip music formats have had different ways to use them. If you are coding a chip music player for the Atari ST you would have to use dozens and dozens of special ways to replay music.
But in the mid 90′s, BDC of Aura crew became tired of this inelegant system and decided to fix the issue once and for all. He then created the ‘SNDH’ file format. SNDH is actually the original songfile and replaycode with a header bolted on top of the music and replayer. The header has a unified calling interface no matter what type of chip music is hidden beneath it, and it has extended datas about the music.
I start to saying how much i hate repairing psu switching, one of the most boring things second only to the repair of CRT Monitor, at least for me.
However this repair was made. The failure is almost certainly caused by a copious spillage of electrolyte (conductive fluid usually formed from a salt solution or acid which is located inside of the electrolytic capacitors) and a dangerous test if the machine works again after the electrolyte was leaking over the pcb.
The moral of the story is easy to figure out, a short circuit has made several deaths, a good portion of the Primary (PWM) and Secondary.
The components that have been replaced are the following:
1 x Electrolytic Capacitor 3300µF 16v 105°
1 x Electrolytic Capacitor 1000µF 25v 105°
1 x Electrolytic Capacitor 2200µF 35v 105°
1 x Electrolytic Capacitor 1000µF 100v 105°
1 x Electrolytic Capacitor 330µF 160v 105°
1 x Electrolytic Capacitor 47µF 25v 85°
1 x Electrolytic Capacitor 10µF 100v 85°
1 x Electrolytic Capacitor 22µF 25v 85°
1 x Sanken Hybrid Voltage Reculator Module STR 53041
1 x Photocoupler TLP 541G
1 x Overcurrent Protection Elements ICP N10
1 x Transistor C1815GR
1 x Transistor DTC114 ESA (C114 ESA)
After 1 week i have decided to replace also all capacitors of the power supply section of the computer.