ZX81 denigrated! (was Re: Approaches to projects)

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Wed Dec 1 00:17:14 2004

> > The ST454 needs some restoration - there's a brown stain in the inside of the
> > top plastic (polystyrene, according to the destructions) cover (from the
> > tape?) and the cabinet covering is peeling away. It is, however, fully
> > functional (electronically speaking). Valve complement is - EF86, ECC83,
> > ECL82, EM84, EZ80.
> >
> > If anyone's got a set of schematics for the ST454 (or knows which Philips
>
> It's not in Poole and Molloy, at least on that I can find. Can you give
> me more description, so I can see if I can identify the Philips equivalent.

OK, I think I've traced it. A 3rd party user guioe ('The Philips Tape
Recorder Book', 1st edition) states that the ST454 is equivalent to the
Philips EL3541 and the Cossor CR1602.

As luck would have it, the Philips model is one of the few not in Poole
and Molloy, but the Cossor one is. It seems to have undergone several
revisions over the years, the changes being :

1) The superimpose swtich (turns off the erase head) became a parallel
play button (plaus tracks 1 and 3 together).

2) The 2 pin pickup/radio input became a DIN socket (radio input and line
level ouptu) and, believe-it-or-not an IEC 5 pin pickup input.

3) THere ware circit changes, some quite significant.

I've checked the appropate volumes of Poole and Molloy, and the valves
match up with the ones you state.

To answer my questions :


>
> In particular :
>
> It's 4 track, does it have a Stereo socket [3]?

It should do. Left side of the machine. Early models didn't provide the
16V for the pre-amp here, though.


>
> What's the cabinet made of (most were rexine-covered plywood, a few later
> ones were plastic)

I think it's rexine-covered wood, at least for the Philips EL3541. But I
can't be sure, and this is something that may differ between
Philips/Cossor/Stella versions.


>
> How many speeds, what are they

Only one (the EL3542 is essentially the 3 speed model). Presumably 3+3/4 ips

>
> What controls and connectors do you have?

As you stanted foor connectors (2 pin radio input, 2 pin monittor
headphones, 2 pin estension speaker, DIN microphone, DIN stereo socket,
mechanical remote control). Controls look to be conventional Philips,
apart from the strainght-through amplifier switch near the connector
panel.

-tony
Received on Wed Dec 01 2004 - 00:17:14 GMT