First time Speccy owner

[pistolhamster]

Hi, from Copenhagen.

I have, for various reasons, gone retro, part nostalgia, part as a quiet and relaxing hobby that is far removed from the hectic online world. I already have a full C64 setup with a CRT monitor.

I went and bought a ZX Spectrum + on eBay the other night, because I never had this when I was younger, but always wanted one so I could play Fairlight II, which was never released on anything other than this machine and Amstrad CPC. Also, it fascinates me that this was already released in 1982, and endured for many many years.

Spectrum was a rare beast in Denmark in the 80s. I knew just one guy, who upgraded from a green Lambda to a ZX Spectrum with real keys. Not sure where he got it from, I never saw one in the shops. But since his father was English, I guess there was some nice stuff brought home from the UK.
It always struck me as really unorthodox (and clever) to use a bog standard cassette player as the storage device. I had a Vic 20 with a Datasette unit, expensive at the time, and he just hooked up this Blaupunkt recorder from an electronics store.

The unit arrived from the Blighted Isles smelling a bit of attic, with a manual, a tape recorder and packed in an old briefcase. It is a bit defunct. As a volunteer in our local Repair Café I have met an old electronics engineer that made me interested in learning this and fix old stuff. So this should be fun.

I started out doing a PSU Europlug modification, and it rattles quite a lot but outputs 11V. I hope that it is within the tolerance compared to the specification of 9V. It rattles quite a lot, probably from the copper coil vibrating at 50Hz.

It does work: shows video, and makes clicky sounds when I type something on the few keys that still work. The keyboard registers almost none of the keys except the rightmost row.

Most of the keys bounce fine, so the silicone mat underneath must work still.
When I have managed to sort that out, I want to do a composite mod of the output so I can connect it to my Commodore CRT.

And then perhaps one day assemble a Harlequin 128k version. But that is a project for the upcoming Winter.
Glad to be here.

[1024MAK]

Hello and welcome to our forum pistolhamster!



I hope you enjoy this forum

Yes, some of the power supply units (PSU) / mains adapters are a bit noisy (50Hz/100Hz). Most however are fine. Sinclair used at least four different manufacturers for these (Sinclair not actually making very much itself).

If it is really loud and is 100Hz, one of the bridge rectifier diodes may have failed.

They are unregulated, meaning that the output voltage depends on the amount of current drawn by the load. With nothing connected to the output (no load), the voltage on the UK1400 is typically between about 11V to 13V. It typically drops down to between 10V and 12V when powering a ZX Spectrum without any expansions/interfaces connected.

Note that the output voltage is also dependent on the mains voltage.

Inside the PSU, it’s just a conventional unregulated DC supply circuit. Comprised of a iron mains transformer, a thermal fuse (either mounted under the mains transformer on the PCB or as part of the primary windings), four rectifier diodes, and one or two electrolytic capacitors (depending on which manufacturer made it).

It’s a common fault for not all the keyboard keys to be ignored. Where the keyboard membrane tails loop around inside the machine, the membrane will have cracked and broken (it goes brittle as it ages) which breaks the metal tracks. I recommend replacement membranes from RWAP Software, as sold on www.sellmyretro.com or via other online websites.

Mark