pasterdb.blogg.se - Sinclair zx spectrum 48k for sale

SINCLAIR ZX SPECTRUM 48K FOR SALE MOD
SINCLAIR ZX SPECTRUM 48K FOR SALE MANUAL
SINCLAIR ZX SPECTRUM 48K FOR SALE FULL
SINCLAIR ZX SPECTRUM 48K FOR SALE SOFTWARE
SINCLAIR ZX SPECTRUM 48K FOR SALE PC

In the Spectrum, there is one IC per bit of memory. It then reads it back and finds that there is a 1 in some locations, indicating a stuck bit (white lines). In the above image, the SMART Card is writing 0’s to all upper RAM locations. SMART Card menu showing a stuck bit confirming issue with IC21 The SMART Card has another menu for showing a visual display of the contents on the upper RAM. This IC is part of the “upper RAM” – the upper 32KB.

SINCLAIR ZX SPECTRUM 48K FOR SALE SOFTWARE

Retroleum SMART Card has diagnostic software in ROM that has found a potential issue with upper RAM IC21 The SMART Card immediately showed up a possible error with one of the RAM chips – IC21. This device fits into the Spectrum’s expansion port and can boot into a ROM which checks out the RAM, the ROM, speaker, and allows you to check the keyboard.Īlways be sure to add or remove accessories from the expansion port with the power turned off, otherwise you may damage the Spectrum. I used my SMART Card from Retroleum to perform some checks on the hardware. A bench power supply was used to check the current drawn by the Spectrum was not too high, which may indicate a fault. It can also cut off the power if the current drawn is too high, which is a useful safety feature when repairing machines. I now have a bench power supply which shows how much current is being drawn by the machine. The lower RAM in the Spectrum has three voltage rails and is easily damaged if one rail is missing.Īll these checks passed OK on this machine. Issues with one can take out the other if power is applied. The above checks suggest that there are no issues with the power supply or RAM. In these checks we measure “apparent resistance” to give the machine a rough health check Pre-power checks using a digital multimeter.

Here is a link to a webpage where someone has listed the checks from the JoulesPerColomb video which may be of use if you are having a go at this yourself. These checks can highlight faults that if ignored, can cause further damage to the machine.

SINCLAIR ZX SPECTRUM 48K FOR SALE MANUAL

Pre-Power checksĪs per the Unofficial Sinclair Spectrum repair manual (I can’t find this on the internet at the moment), and JoulesPerCoulomb video on YouTube, there are some checks required before you power up a Spectrum.

Replace metal faceplate (surrounds the keyboard and has the alternative key legends printed on it)Īs usual, I wore an anti-static wrist band thought the repair, to avoid damaging or reducing the lifespan of any ICs.

Replace keyboard membrane (the electrical part of the keyboard).

Replace rubber key mat (the springy rubber part of the keyboard).

Repair any faults found (and there was a major fault discovered).

Video transistor replacement (increases image contrast when used with the above mod).

SINCLAIR ZX SPECTRUM 48K FOR SALE MOD

Composite video mod (replaces the noisy RF video output).

Replace 5 Volt regulator (gets hot!) with an efficient DC to DC convertor (doesn’t get hot).

Replace capacitors (these can go bad over time and cause faults or degrade picture quality).

SINCLAIR ZX SPECTRUM 48K FOR SALE FULL

Here is the full list of improvements made to this machine: However, I have since bought a desoldering station which allowed me to go further with this machine as we will see. Much of this restoration is a repeat of my previous video where I restored a pair of Spectrums. There are plenty of machines sold on eBay as “restored” when all they have done is replaced the capacitors and cleaned the front panel, but this Spectrum deserved a good deal more. The machine was in “fair” condition, showing signs of heavy use (a good thing!) Some of the legends on the keys had also rubbed off. There were some sticky labels (Your Sinclair, a popular Spectrum magazine from back in the day) and the metal plate was pitted as happens with good use.

SINCLAIR ZX SPECTRUM 48K FOR SALE PC

1985 (2) 1987 (1) 48K (2) 8 bit (2) adventure (1) Amiga (2) Amstrad CPC (2) Apple IIGS (1) Apple Macintosh (1) Atari ST (1) Back to The Future (2) BASIC (1) BNC (1) Bruce Lee (1) C64 (1) C64c (1) cartridge (1) CD-i (1) CGA (1) Commdoore 1541 (1) Commodore (1) Commodore 64 (5) Commodore Amiga (1) Commodore CDTV (1) computer (1) CP/M (1) datasette (1) disks (1) DOS (7) Ethernet (1) free (1) Game Boy Advance (1) Games (4) gaming (1) Happy New Year (1) Hardware (2) IBM PC (1) iOS (1) Iskra Delta (1) Mac (1) Marry Christmas (1) Master of Orion (1) MBasic (1) Micosoft Windows 3.11 (1) MicroProse (1) NES (2) Network (1) paper model (1) Partner (1) PC (3) PC 486 (1) Pharaon's Tomb (1) plans (1) Program (1) Programming (1) Programs (2) QBASIC (1) retrogaming (1) Sinclair (1) Single line (1) Sokoban (1) Star Wars: The Empire Strikes Back (1) strategy (2) Super Mario Bros.The machine was in a fair state on the outside.