New Life Games LLC

NLG Users Repair Logs and Other Ramblings. Request your very own topic. Just ask any site staff. => Channelmaniac's Arcadecomponents' Old School Repair Logs => Topic started by: channelmaniac on May 04, 2014, 07:58:40 PM

Title: IBM PC/XT/AT Computers
Post by: channelmaniac on May 04, 2014, 07:58:40 PM

Model: IBM PC XT
Symptom: Dead

Power supply was in shutdown. Replaced shorted tantalum dual cap on the -12v line on the motherboard. Tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on July 29, 2020, 09:42:24 PM

Model: IBM PC XT
Symptom: Dead

Power supply was in shutdown. Replaced shorted tantalum dual cap on the +12v line on the motherboard. Tested

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on July 29, 2020, 09:43:26 PM

Model: IBM PC/XT
Symptom: Garbage on screen, Error message on boot.

Replaced 1 bad 4516 RAM chip (16K x 1, 5v only DRAM) on the CGA card and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on July 31, 2020, 09:52:16 PM

Model: Paradise PVGA 8-Bit
Symptom: Dead

Repaired broken leg on the Option ROM and tested

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on July 31, 2020, 09:53:51 PM

Model: Genoa Super VGA 5200
Symptom: Garbage on screen

Board had some corrosion damage. Patched one open trace at the end of the QFP pad on the main controller chip. Replaced a corroded 3 pin jumper. Tested successfully.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on October 11, 2020, 02:29:06 PM

Model: IBM CGA Card
Symptom: Power supply shut down with card in system.

Replaced a shorted tantalum capacitor and tested.

IBM used 3 leg Tantalum caps with the 2 outer being ground and the center being positive. They can be replaced with 2 legged caps - just watch the polarity when inserting them into the circuit.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on October 11, 2020, 09:40:46 PM

Model: IBM PC XT motherboard
Symptom: Dead. Missing part.

Board had corrosion damage.

Replaced corroded 8087 socket, missing 74LS158, and cleaned board. Replaced 2 corroded slot connectors and tested successfully.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 03, 2021, 02:55:55 PM

Model: IBM PCjr 128K Memory Sidecar
Symptom: Not seen by computer

Note: board was socketed but had no memory installed. It was jumpered for 512K of DRAM

Removed solder short between 2 address lines on the RAM chips, installed 16x 256Kb DRAM chips, and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 03, 2021, 02:58:23 PM

Model: IBM PCjr 128K Memory Sidecar
Symptom: Not seen by computer

Removed all 16 64Kb RAM chips, installed 16x sockets and 16x 256Kb DRAM chips, cut the trace between pins 1-2 of the .100 header and jumpered pins 2-3 to finish the upgrade. tested. Board still not seen. Replaced bad 74HC32 chip with a dead output. Computer can see the board but does not see the memory on it. Replaced bad 74HC244 buffer with dead outputs and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 03, 2021, 02:59:10 PM

Model: IBM PCjr 128K Memory Sidecar
Symptom: Not seen by computer

Removed all 16 64Kb RAM chips, installed 16x sockets and 16x 256Kb DRAM chips, cut the trace between pins 1-2 of the .100 header and jumpered pins 2-3 to finish the upgrade. tested. Board still not seen. Replaced bad 74HC32 chip with a racing output. Computer still cannot see the board and the address lines on the RAM are mostly dead. Replaced bad 74HC00 with a dead output. Tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 06, 2021, 04:43:14 PM

Model: IBM PCjr Speech Sidecar
Symptom: Error J on boot when attached

Replaced a bad 8255 PPI chip and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 06, 2021, 04:43:35 PM

Model: IBM PCjr Speech Sidecar
Symptom: Error J on boot when attached

Replaced a bad 8255 PPI chip and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 09, 2021, 08:17:15 PM

Model: IBM PCjr 128K Memory Sidecar
Symptom: ERROR A when attached to computer

Replaced bad 74HC151 in the address decoding circuit. Tested. Upgraded to 512K and retested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 09, 2021, 08:18:38 PM

Model: IBM PCjr 128K Memory Sidecar
Symptom: ERROR A when attached to computer

Replaced bad 74LS03 in the address decoding circuit. Tested, ERROR A. Replaced 74S409 controller IC and retested. Upgraded to 512K and tested. During burn-in testing, computer crashed with random garbage dotting the screen. Replaced bad 74HC151 in the address decoding circuit. Tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 16, 2021, 02:00:23 PM

Model: IBM PCjr Speech Sidecar
Symptom: Error J on boot when attached

Replaced a bad 8255 PPI chip and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 16, 2021, 02:00:48 PM

Model: IBM PCjr Speech Sidecar
Symptom: Error J on boot when attached

Replaced a bad 74HC32 and a bad 74HC139 chip and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 16, 2021, 02:01:07 PM

Model: IBM PCjr Speech Sidecar
Symptom: Not seen by the computer

Replaced a bad Option BIOS ROM chip and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 16, 2021, 02:01:53 PM

Model: IBM PCjr 128K Memory Sidecar
Symptom: Not seen by computer

Removed all 16 64Kb RAM chips, installed 16x sockets and 16x 256Kb DRAM chips, cut the trace between pins 1-2 of the .100 header and jumpered pins 2-3 to finish the upgrade. tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 16, 2021, 02:02:07 PM

Model: IBM PCjr 128K Memory Sidecar
Symptom: ERROR A

Removed all 16 64Kb RAM chips, installed 16x sockets and 16x 256Kb DRAM chips, cut the trace between pins 1-2 of the .100 header and jumpered pins 2-3 to finish the upgrade. tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 19, 2021, 04:38:25 PM

Model: IBM PCjr
Symptom: Dead, 2 beeps

PCB failed with an error pointing to "either the 8259 or the bus access to it." Found a short on pin 5 of the 74LS32 driving the /Chip Enable line for the 8259, causing the output to never go low to enable it. Replaced a 74LS04 with a shorted input and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on September 19, 2021, 06:41:10 PM

Model: IBM PCjr
Symptom: Dead, 2 beeps

PCB failed with an error of "VERTICAL STUCK ON SOLID" during initial BIOS testing. Replaced the 6845 CRTC chip and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on November 01, 2021, 10:40:51 PM

Model: IBM PCjr Speech Sidecar
Symptom: Unseen by computer

Replaced bad 74HC245 and tested

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on November 01, 2021, 10:41:17 PM

Model: IBM PCjr Speech Sidecar
Symptom: Error F CE

Replaced bad 74HC32 that had a dead output on pin 8. Tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on November 01, 2021, 10:41:49 PM

Model: IBM PCjr Speech Sidecar
Symptom: Unseen

Replaced bad 74HC32 (stuck outputs) and a bad 82C55 PPI chip that had sputtering outputs on pin 11. Tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on November 01, 2021, 10:42:32 PM

Model: IBM PCjr Speech Sidecar
Symptom: ERROR J

Replaced a bad 82C55 PPI chip and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on November 01, 2021, 10:42:51 PM

Model: IBM PCjr Speech Sidecar
Symptom: Unseen

Replaced bad 82C55 PPI chip and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on November 01, 2021, 10:43:08 PM

Model: IBM PCjr Speech Sidecar
Symptom: ERROR J

Replaced bad 82C55 and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on November 01, 2021, 10:43:31 PM

Model: IBM PCjr Speech Sidecar
Symptom: Speaker click, but no speech output

Replaced bad TMS5220NL speech synthesis chip and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on April 23, 2023, 02:39:21 PM

Model: Microsoft PCjr Booster memory sidecar
Symptom: Upgrade to 512K

Performed memory upgrade. Replaced corroded battery connector. Tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on April 23, 2023, 02:39:26 PM

Model: Microsoft PCjr Booster memory sidecar
Symptom: Upgrade to 512K

Performed memory upgrade. Replaced corroded battery connector. Tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on April 23, 2023, 02:39:30 PM

Model: Microsoft PCjr Booster memory sidecar
Symptom: Upgrade to 512K

Performed memory upgrade. Replaced corroded battery connector. Tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on April 23, 2023, 02:39:59 PM

Model: Microsoft PCjr Booster memory sidecar
Symptom: Upgrade to 512K

Performed memory upgrade. Replaced corroded battery connector. Tested. Clock was not incrementing. Replaced bad 18pf capacitor next to crystal and tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on June 14, 2023, 12:14:11 PM

Model: IBM PCjr 128K Sidecar
Symptom: ERROR A

Replaced 1 bad 64K DRAM chip and tested. Removed all DRAMs, installed 16 16-pin sockets, and installed 16 256K x 1 DRAM chips. Cut one trace and soldered one jumper to finish the upgrade to 512KB RAM. Tested.

Title: Re: IBM PC/XT/AT Computers
Post by: channelmaniac on June 20, 2023, 08:53:29 PM

Model: IBM PC/XT TEMPEST motherboard
Symptom: Dead

Reset DIP switches, replaced bad memory in Bank 0, and tested. Memory in unit was all desoldered pulls. Replaced all memory and retested as this board was being donated for a fundraising auction and needed to be in the best shape.