tape-deaf Acorn Electron

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aqarius
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tape-deaf Acorn Electron

Postby aqarius » Sun Nov 05, 2017 5:19 pm

Hello,

I just joined the forum because I've been looking at expanding/improving my Acorn computer collection, starting with getting my Acorn Electron working again.

I was given it for free over 20 years and despite various problems, it's always booted up. The soldering on the DC input is bad and as a kid I used to deal with that by putting a heavy book or taping the cable to the bottom of the system to create downward pressure that kept the machine on (and no doubt damaged the soldering worse...)

When I first got it, I also had a problem with tapes rarely loading (despite the fact I'd seen it demonstrated working fine the day I got it), although one day it miraculously started working again. At the time I put that down to the tape dins previously not being pressed in firmly enough.

When I took it out of storage a few weeks ago, I found the RF output had stopped working (and looking inside, it's on wobbly solder as well), so the first thing I did was get an RGB scart, which is working fine.

I also got a (used) tape lead thats 7-pin din on the computer end, and breaks out into ear/mic/rem at the other. I haven't been able to load anything successfully (or even get a loading error) from this cable and my modern(ish) Sony cassette recorder, although it has recorded a BASIC program to it just fine. At least I assume it's fine in that I can hear it on the tape - obviously I can't get it to load back in. I don't currently have any means to test the 'ear' part of the cable other than trying to get the Electron to pick something up, so it could be at fault? It was sold to me as tested and working. I tried writing a quick BASIC program to print the value of the tape bit buffer, and I've never seen the value change for any input from the tape recorder. I have seen it get the odd bit through from accidental contact between the mic and rem connectors which I found very strange. The fact anything at all happens suggests to me the buffer is in listening mode (I didn't research the hardware very thoroughly yet but I gather the buffer is used for reading or writing depending on some other data direction register).

I've bought a different cassette recorder with a din connection, which I'll be picking up tomorrow. It's also got a rem input so I can try it with the old cable again. I've also tried the current set-up at a load of different tape volumes, and still never seen any recognition of a signal at all. Is there anything else I could try? If I had a multi-meter, is there anywhere I should check inside the electron to see if its internal components are working?

Thanks for reading. :)

EDIT: I just noticed there's a similar topic posted recently about tapes failing to load on a BBC, I'm looking at the general advice on that thread too.

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CMcDougall
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Re: tape-deaf Acorn Electron

Postby CMcDougall » Sun Nov 05, 2017 5:39 pm

Open the 7pin din end of your lead, take out (by pass) the stupid no need resistors that have failed after 30+years, sorted!

or your LS232 chip in the elk has failed, but you say it saved out, so can't be that...
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danielj
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Re: tape-deaf Acorn Electron

Postby danielj » Sun Nov 05, 2017 7:57 pm

It could be the LM326 - it's possible for one amp to go and the others be fine. That's IC13.

d.

aqarius
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Joined: Thu Nov 02, 2017 4:15 pm

Re: tape-deaf Acorn Electron

Postby aqarius » Tue Nov 07, 2017 3:33 pm

Thanks for the advice guys. I investigated the tape lead but I wasn't able to fully get the din plug open, I just don't know how #-o I can't actually see any sign of a resistor in there in any case. I got my cassette recorder with DIN output and a new 5 pin DIN cable, and the good news is the Electron's loading just fine with that setup! So it probably was the cable, or else the Sony cassette recorder just didn't output a usable signal. A lot of my old cheaper looking tapes won't load reliably anymore, but every acornsoft tape I've tried has worked. Now I need to buy some more, as I never did have much of a collection back in the day.

crj
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Re: tape-deaf Acorn Electron

Postby crj » Tue Nov 07, 2017 3:52 pm

aqarius wrote:Thanks for the advice guys. I investigated the tape lead but I wasn't able to fully get the din plug open, I just don't know how

There are broadly three kinds of DIN plug out there:
  • Moulded - you lose!
  • Cheap plastic - find the small rectangular hole in the plastic housing; use the blade of a screwdriver to poke in the little metal "tongue" and hold it there while sliding the housing back. Then hope the two halves of the metal shell haven't been soldered together.
  • Fancy metal - undo the screw and marvel as the thing comes apart in your hands. (-8

Kazzie
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Location: North Wales

Re: tape-deaf Acorn Electron

Postby Kazzie » Tue Nov 07, 2017 7:14 pm

aqarius wrote:Thanks for the advice guys. I investigated the tape lead but I wasn't able to fully get the din plug open, I just don't know how #-o I can't actually see any sign of a resistor in there in any case. I got my cassette recorder with DIN output and a new 5 pin DIN cable, and the good news is the Electron's loading just fine with that setup! So it probably was the cable, or else the Sony cassette recorder just didn't output a usable signal. A lot of my old cheaper looking tapes won't load reliably anymore, but every acornsoft tape I've tried has worked. Now I need to buy some more, as I never did have much of a collection back in the day.


Asa follow up, you can check an unopenable cable by using a multimeter on corresponding pins at each end of the cable. If you can get continuity (the *beeep*) then the pins are connected with no resistor. Otherwise, increase the resistance range. If you get a reading in the ohms or kilo-ohms (I don't know what resistor values were actually used ) then there's a resistor inline. On the other hand, if you turn your dial through to the megaohms before getting a reading (if at all) then you've either got a failed resistor or faulty wire.
Pudsey - BBC Model B 32k issue 7, Sidewise ROM board with 16K RAM

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paulv
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Re: tape-deaf Acorn Electron

Postby paulv » Tue Nov 07, 2017 7:30 pm

crj wrote:Then hope the two halves of the metal shell haven't been soldered together.


I've never come across this and it's never occurred to me to do it (although I can understand why someone might do it.... but.... doing that is a special kind of evil :twisted: :twisted:

Paul

aqarius
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Re: tape-deaf Acorn Electron

Postby aqarius » Wed Nov 08, 2017 2:26 am

paulv wrote:
crj wrote:Then hope the two halves of the metal shell haven't been soldered together.


I've never come across this and it's never occurred to me to do it (although I can understand why someone might do it.... but.... doing that is a special kind of evil :twisted: :twisted:

Paul


The one I have is of the cheap plastic variety, and I removed that part of it fine (its never going to be the same but that's ok) but once inside, the metal tube wasnt in two parts. It does have a 'seam' at the bottom but it's solid at the top where the indentation is. It has 3 holes on it, each with a plastic clip poking through, but I cant figure out how to release the innards from the tube. I *think* I know literally how to do it but I've only got two hands, the clips are pretty hard plastic and require two different types of pressure to release. I've already jabbed myself with a screwdriver trying to apply enough pressure to the top one (seems it just needs forced down hard) while unclipping the side ones (which are locking the black plastic inner cylinder in place), and as I have things working through the 5 pin DIN setup, my motivation to try any further is decreased somewhat :) Maybe if I want that motor control really badly in the future I'll try again!


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