components prone to fail

[rleao]

Hi,

I recently bought a zx spectrum 48k in ebay and i am very much in love with it. I will be going back to brazil next year (that makes importing stuff much harder), so I was planning to take some spare parts with me that are prone to fail. Are there any suggestions? I guess voltage regulators and passive components arent hard to find but maybe the ULA? Keyboard membrane? thanks a lot

richArdson

[Ast A. Moore]

The ULA is pretty much the only IC that you’ll need to worry about. If it’s a later board revision (Issue 5 and 6), then another custom IC is the ZX8401. The LM1889 and the lower RAM ICs are difficult—but not impossible—to come by nowadays, even though they used to be off-the-shelf parts.

I suggest getting a few more boards for spare parts.

Keyboard membranes are readily available from multiple sources, so I wouldn’t worry about those.

[1024MAK]

This is a list of recommended spares:

• 4116 (or equivalent) DRAM chips rated at 150ns,
• 4164 (or equivalent) DRAM chips rated at 200ns,
• ZTX651 or ZTX653 (to replace TR4)
• Z80A or CMOS version (rated 4MHz or greater)
• ULA if you can find one (and can afford one) or a ULA replacement,
• Various electrolytic capacitors (axial type) if the board still has the originals fitted,
• Maybe a spare keyboard membrane (depending on the condition of the one on your machine).

If the board is a lower issue than a 4B, then consider bringing the DC-DC up to Sinclair’s last modification version (see here). Or at least, take the parts with you...

Mark