Uploaded August 2026 | Updated September 2026, 3 weeks ago
I take a look at a heavily battered Sinclair ZX Spectrum Issue 3B to see if the motherboard survived an impact to the case. After dismantling the machine, I run through initial resistance and diode checks before powering it on. Using both Retroleum and Phil Ruston diagnostic tools, I locate multiple faults in the lower and upper RAM.
The repair process involves carefully desoldering the faulty 4116 and 4532NL4 RAM chips, socketing the board, and installing replacements. Once the RAM issues are resolved and the computer boots properly, I install a reversible composite mod to improve the output signal. Finally, I test the original keyboard membrane to assess its condition before wrapping up the board repair.
─────────────────────────────
If you'd like to help keep the lights on (and the tools plugged in),
my Patreon is the best way to do it. Patrons get ad-free early access
to videos, behind-the-scenes updates, and entry to a super secret
Discord channel — plus my sincere gratitude, which is worth roughly
what you'd expect.
▸ Patreon: patreon.morefunretro.co.uk
─────────────────────────────
There's also the Retro Hardware Discord, where people who enjoy this
sort of thing gather to talk about it. It's better than it has any
right to be.
▸ Retro Hardware Discord: discord.gg/tsAbuAfqf9
─────────────────────────────
Second Channel: @morefunretro2
#ZXSpectrum
#RetroComputing
#techrepair
00:00:00 Intro and inspecting the case damage
00:03:05 Initial resistance and diode checks
00:04:48 Powering on and finding RAM failures
00:07:34 Checking voltages
00:09:31 Desoldering the faulty lower RAM chips
00:11:58 Testing the pulled RAM and installing replacements
00:15:02 Locating and removing the faulty upper RAM
00:17:25 Testing the new upper RAM chip
00:19:12 The spectrum is functional
00:23:33 Installing a reversible composite video mod
00:25:35 Testing the keyboard membrane
00:28:58 Wrap up and channel support
I take a look at a heavily battered Sinclair ZX Spectrum Issue 3B to see if the motherboard survived an impact to the case. After dismantling the machine, I run through initial resistance and diode checks before powering it on. Using both Retroleum and Phil Ruston diagnostic tools, I locate multiple faults in the lower and upper RAM.
The repair process involves carefully desoldering the faulty 4116 and 4532NL4 RAM chips, socketing the board, and installing replacements. Once the RAM issues are resolved and the computer boots properly, I install a reversible composite mod to improve the output signal. Finally, I test the original keyboard membrane to assess its condition before wrapping up the board repair.
─────────────────────────────
If you'd like to help keep the lights on (and the tools plugged in),
my Patreon is the best way to do it. Patrons get ad-free early access
to videos, behind-the-scenes updates, and entry to a super secret
Discord channel — plus my sincere gratitude, which is worth roughly
what you'd expect.
▸ Patreon: patreon.morefunretro.co.uk
─────────────────────────────
There's also the Retro Hardware Discord, where people who enjoy this
sort of thing gather to talk about it. It's better than it has any
right to be.
▸ Retro Hardware Discord: discord.gg/tsAbuAfqf9
─────────────────────────────
Second Channel: @morefunretro2
#ZXSpectrum
#RetroComputing
#techrepair
00:00:00 Intro and inspecting the case damage
00:03:05 Initial resistance and diode checks
00:04:48 Powering on and finding RAM failures
00:07:34 Checking voltages
00:09:31 Desoldering the faulty lower RAM chips
00:11:58 Testing the pulled RAM and installing replacements
00:15:02 Locating and removing the faulty upper RAM
00:17:25 Testing the new upper RAM chip
00:19:12 The spectrum is functional
00:23:33 Installing a reversible composite video mod
00:25:35 Testing the keyboard membrane
00:28:58 Wrap up and channel support
