BBC MICRO loading from cassette problem

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blackwitch
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BBC MICRO loading from cassette problem

Post by blackwitch » Sat Mar 16, 2019 12:01 pm

Hi all.

I'm trying to load from cassette but when I play a cassette I get the motor clicking on each block but nothing comes up on srcreen.

Can anyone tell me what I'm doing wrong please? or is it a fault?

Thanks

Kazzie
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Re: BBC MICRO loading from cassette problem

Post by Kazzie » Sat Mar 16, 2019 2:06 pm

Have you adjusted the volume on your cassette deck? Do you know you've plugged your leads in the right way around?

If the connection at the deck end is with headphone jacks, then try plugging in a pair of headphones (but not wearing them, in case it's too loud) and pressing "play". This can help you confirm that you've got sound coming out of your deck.
Last edited by Kazzie on Sat Mar 16, 2019 2:07 pm, edited 1 time in total.
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mr-macrisc
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Re: BBC MICRO loading from cassette problem

Post by mr-macrisc » Sat Mar 16, 2019 2:31 pm

Most period cassette players about 3/4 volume was a good start

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leenew
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Re: BBC MICRO loading from cassette problem

Post by leenew » Sat Mar 16, 2019 2:43 pm

If the relay is clicking but nothing is loading, (and you know your cassette recorder and cable are good), it could be that the LM324 OP Amp at IC35 has gone faulty. They are a bit flaky.
If you are lucky it will be socketted...

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AndyF
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Re: BBC MICRO loading from cassette problem

Post by AndyF » Sat Mar 16, 2019 3:00 pm

I was going to suggest that IC as well. I've changed a couple of the years. It seems that later models (but not all of them) are socketed, unless a previous owner changed it and fitted a socket. Random speculation being here Acorn perhaps had an unwell batch of them and decided to socket it to ensure warranty time costs were lower ?

At least its a small easy to replace IC and readily available cheaply.

I'd grab a multi meter first though and ensure your tape cable is wired properly if you can. You could if you wanted trace continuity from the phono/jack plug back to the 'backside' of the tape socket I suppose, that way you cover the DIN plug/socket connection too but no further. I'd not personally check it further than that, if that part was OK I'd simply replace the IC given its cheapness before doing any more diag but that's me. :oops:
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blackwitch
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Re: BBC MICRO loading from cassette problem

Post by blackwitch » Sat Mar 16, 2019 3:25 pm

Thanks guys.

I've just got the first program on the welcome cassette to load but it's taken ages and I've been hearing the relay click quickly a few times too..

I keeps getting, and Data?, Block? messages.

Can someone point out where to buy the IC from and where its located on the board?

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leenew
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Re: BBC MICRO loading from cassette problem

Post by leenew » Sat Mar 16, 2019 3:55 pm

5 for £2.19 including postage.... https://www.ebay.co.uk/itm/5-x-LM324-DI ... ctupt=true

It is the little chip to the left of the cassette socket. IC35. See here: http://8bs.com/inbbc.htm

Lee.

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AndyF
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Re: BBC MICRO loading from cassette problem

Post by AndyF » Sat Mar 16, 2019 6:10 pm

The relay on/off is likely normal.

The fact you're getting in effect tape errors like that to me suggest that the chip is alive or partially alive (it could still be the culprit) , although it could well be something like volume/tone settings or head azimuth too.

Do you have any other BBC tapes you can test it with ?

If you have a blank (blank!) tape and can save and load it back then it usually indicates its an alignment concern rather than anything else if other tapes don't work, ie: what you save on that tape player will load back but nothing else.
Last edited by AndyF on Sat Mar 16, 2019 6:11 pm, edited 1 time in total.
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Re: BBC MICRO loading from cassette problem

Post by blackwitch » Sun Mar 17, 2019 8:25 am

Hi guys.

That's great thanks for all your help so far.

Yesterday I managed to load Repton but it wouldn't get past block 20.

I tried Frak but that wouldn't even get past the header block.

I then tried Thrust which worked with only one hic-up.

So out of curiosity I cleaned the plug lead ends with some deoxit and tried again and.... Oh dear.

I'm no longer getting the relay clicking sound from the beeb. None whatsoever.

I checked the player to see if the signal is there which it was.

The only thing I've not checked is the lead so will do that today.

When I type CH. "" the motor relay clicks fine.

I have also done *MOTOR 1 and *MOTOR 0 and both click fine.

So I've ordered some of those chips today (with thanks) anyway as they are cheap enough.

The only other thing I can think of is the lead but it seems unlikely that it would be the case.

Any other ideas in what it could be? Could it be the chip has simply given up?

Kindest regards
Last edited by blackwitch on Sun Mar 17, 2019 8:27 am, edited 1 time in total.

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CMcDougall
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Re: BBC MICRO loading from cassette problem

Post by CMcDougall » Sun Mar 17, 2019 9:52 am

there is a resistor in the 7pin din end, take it out as probably failed like one of mine. Just by-pass it, sorted.

cleaning lead end should be better, but if moulded plastic with no access to bare wires, then probably broke on ear plug.
use a multimeter to check consistency of earth & ear
ImageImageImage

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AndyF
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Re: BBC MICRO loading from cassette problem

Post by AndyF » Sun Mar 17, 2019 12:59 pm

I concur with the above and its good to know you did at least get one file to load which is a positive sign.

You say you're not getting the relay click ?

Can you try a *M.1 command ? Then a *M.0 to operate said relay ?

You could try this I suppose:

Code: Select all

10 MODE 7
20 *TAPE
30 PROCD
40 *MOTOR1
50 PRINT ' "ON"
60 PROCD
70 *MOTOR 0
80 PRINT ' "OFF"
90 GOTO 30
100 DEFPROCD
110 FOR X=0 TO 5000 : NEXT X
120 ENDPROC
The delay is to avoid burning the contacts a bit with buzzing ( ! ) , I thought about keypresses but the few seconds on/off seems OK here. That should only take a moment to type in too. You could omit the print lines (50 and 80) if you wanted or rewrite it neater, I wrote it to make it 'easy to digest' for humans rather than give any regard to efficiency or indeed best practises, some of which I can clearly see I've failed on. :)
Last edited by AndyF on Sun Mar 17, 2019 1:00 pm, edited 1 time in total.
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CMcDougall
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Re: BBC MICRO loading from cassette problem

Post by CMcDougall » Sun Mar 17, 2019 2:37 pm

this will help if your leads are not melted together :
Attachments
plugEAR.jpg
ImageImageImage

blackwitch
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Re: BBC MICRO loading from cassette problem

Post by blackwitch » Mon Mar 18, 2019 8:03 am

Wow... Thanks guys.

Its been a good 30 years since I used a cassette loader so this has been a relearning exercise.

I've ordered a new cable anyway but would love to get an original type as shown in the pic above.

I've got a feeling it is the cable but it's all sealed up so I can't see what's going on.

However I have tested the continuity by I can't find a ground connection for 'ear' on the top center pin. Is this normal?

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MartinB
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Re: BBC MICRO loading from cassette problem

Post by MartinB » Mon Mar 18, 2019 1:02 pm

blackwitch wrote:However I have tested the continuity by I can't find a ground connection for 'ear' on the top center pin. Is this normal?
No, not 'normal'. There very definitely needs to be a connection from Pin 2 (top middle) of the DIN plug to at least one (ideally both) of the longer shaft portion (as opposed to the tip) of the Ear and Mic jack plugs.


.
Last edited by MartinB on Mon Mar 18, 2019 1:03 pm, edited 1 time in total.

blackwitch
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Re: BBC MICRO loading from cassette problem

Post by blackwitch » Mon Mar 18, 2019 1:18 pm

Ah... okay. Thanks.

I'm now thinking I've got the wrong type of cable. I'm sure I used to use it with my beeb... Grr!

That would be embarrassing.

lol

blackwitch
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Re: BBC MICRO loading from cassette problem

Post by blackwitch » Wed Mar 20, 2019 7:48 am

Hi guys.

Just to close this thread. It was the lead after all.

I got the new lead and it's loading perfectly fine. So no need for a new chip.

I'd just like to say many thanks for all your help and advice. It's great to know there are people out there who love the Beeb. :) =D> =D> =D> =D> =D> =D> :D

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AndyF
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Re: BBC MICRO loading from cassette problem

Post by AndyF » Thu Mar 21, 2019 8:12 am

it's good to know you've rectified the issue (thanks for posting back to say why too) and also excellent that the 'fix' was quick and easy. :mrgreen:
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