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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 12th Mar 2020, 9:07 pm   #21
SiriusHardware
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Default Re: ZX Spectrum Tuning Issue

On that black remote, the 'AV' button south-west of the main circular group of buttons would be the one which selects the video input, but only if the remote is an exact enough replacement for that to work.

Edit: Caught me again, I'm going to have to give you more time.

OK, so do you have anything else, a DVD player for example, which can output a composite video signal which you can feed into the AV input to test that?
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Old 12th Mar 2020, 9:46 pm   #22
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Default Re: ZX Spectrum Tuning Issue

It appears to be working! I wonder why
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Old 12th Mar 2020, 9:50 pm   #23
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Default Re: ZX Spectrum Tuning Issue

Yay!
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Old 12th Mar 2020, 9:51 pm   #24
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Default Re: ZX Spectrum Tuning Issue

Nice clean looking picture too. Maybe just tidying up that mod did the trick.
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Old 12th Mar 2020, 10:18 pm   #25
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Default Re: ZX Spectrum Tuning Issue

However!!!! Now it won’t load software! I’ve connected the ‘ear’ output from the tape recorder to the ‘mic’ socket on the spectrum - it doesn’t load and I don’t hear the bleeps which I remember I used to hear! I’ve tested the cassette player with headphones and there is output alright. I’ve tried two sets of leads so either both leads are damaged or it’s the Spectrum ! I could try a beep command?
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Old 12th Mar 2020, 10:19 pm   #26
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Default Re: ZX Spectrum Tuning Issue

Just when you thought you had it sussed!
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Old 12th Mar 2020, 10:21 pm   #27
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Default Re: ZX Spectrum Tuning Issue

Audio out / Earphone out on the recorder should go to EAR, not MIC, when trying to load programs.
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Old 12th Mar 2020, 11:27 pm   #28
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Default Re: ZX Spectrum Tuning Issue

Sorry-yes-that’s what I meant! Very late and I have a little brain!!
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Old 12th Mar 2020, 11:27 pm   #29
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Default Re: ZX Spectrum Tuning Issue

Ear out from cassette to Ear on Spectrum
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Old 12th Mar 2020, 11:29 pm   #30
John Earland
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Default Re: ZX Spectrum Tuning Issue

Haven’t tried saving any yet - will try tomorrow
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Old 12th Mar 2020, 11:39 pm   #31
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Default Re: ZX Spectrum Tuning Issue

Are you by any chance expecting to hear the sound of the loading program coming out through the TV? That didn't happen on the original Spectrum, sound only came out through the little onboard speaker as far as I know. Only in later Spectrums was the sound superimposed onto the video signal so that the sound came out through the TV.

If you actually want to hear game sound coming out of the TV, use an appropriate (3.5mm mono jack plug to phono plug) lead to connect the MIC or EAR socket (whichever works best - EAR will be loudest) on the Spectrum to the red or white socket on the AV-input on the TV.
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Old 12th Mar 2020, 11:46 pm   #32
John Earland
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Default Re: ZX Spectrum Tuning Issue

No. I’m expecting the sound to come out of the Spectrum. But it isn’t ☹️
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Old 12th Mar 2020, 11:51 pm   #33
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Default Re: ZX Spectrum Tuning Issue

In that case try one of the sound example programs from the manual or some other source as you yourself suggested to see if the onboard speaker is still working. Although, didn't you say you were hearing key clicks during your 'trying to get a picture' phase earlier?

I seem to remember that the speakers do fail, one or two of the retro spares sellers used to stock them.
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Old 13th Mar 2020, 7:49 am   #34
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Default Re: ZX Spectrum Tuning Issue

Normally, when you load a program, the screen around the central display area flickers rapidly with lines to indicate that the program is loading, you also get to hear the program bleeps as it does so. Neither is happening. Last time I used the Spectrum, which was about a year ago, it did those things, notes nothing. It just won’t load anything. When you press a keyboard let you can hear the little ‘click’ so I think the speaker is fine. Later today when I get home, I shall try to save a program. I’m not sure why this has stopped all of a sudden.
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Old 13th Mar 2020, 10:47 am   #35
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Default Re: ZX Spectrum Tuning Issue

Saving a program and then listening to see what has been saved will be a useful test as the tape-out and tape-in signals actually come out of / go into the same ULA pin.

Another check, plug your tape in/out lead of choice into the EAR socket, then measure from the tip of the plug at the unconnected end of the lead to the socket contact furthest away from the edge of the Spectrum PCB -should be zero resistance - and measure from the 'ring' on the plug on the unconnected end of the lead to the socket contact closest to the edge of the PCB - should also be zero resistance. Doing it this way is useful for two reasons - one, it checks the socket as well as the lead, and two, it holds one of the plugs on the lead still / steady so you only have to chase one of them around the bench with your meter.

(On the ZX machines the 3.5mm EAR and MIC sockets have conveniently open construction so you can easily get to the socket contacts as they are exposed on the top of the socket).
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Old 13th Mar 2020, 9:52 pm   #36
John Earland
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Default Re: ZX Spectrum Tuning Issue

Okay folks-I tried saving a short program. The Spectrum put out the usual flickering border to indicate that it is saving something but when I played it back all I got was a lot of loud background hiss and humming. Exactly like it was when trying to save programs from the ZX81. I suspect that it’s the tape recorder-though it plays back from the speaker fine. What do you think? I tried the beep command and that works fine. It could the the cables of course so I shall try the suggestions above.
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Old 13th Mar 2020, 10:18 pm   #37
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Default Re: ZX Spectrum Tuning Issue

Do that first, I think. "Always try the simple stuff first". Let us know what you get.

Is the cable the original two grey plugs / two black plugs cable which came with the Spectrum?
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Old 13th Mar 2020, 10:38 pm   #38
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Default Re: ZX Spectrum Tuning Issue

Quote:
Originally Posted by SiriusHardware View Post
Saving a program and then listening to see what has been saved will be a useful test as the tape-out and tape-in signals actually come out of / go into the same ULA pin.

Another check, plug your tape in/out lead of choice into the EAR socket, then measure from the tip of the plug at the unconnected end of the lead to the socket contact furthest away from the edge of the Spectrum PCB -should be zero resistance - and measure from the 'ring' on the plug on the unconnected end of the lead to the socket contact closest to the edge of the PCB - should also be zero resistance. Doing it this way is useful for two reasons - one, it checks the socket as well as the lead, and two, it holds one of the plugs on the lead still / steady so you only have to chase one of them around the bench with your meter.

(On the ZX machines the 3.5mm EAR and MIC sockets have conveniently open construction so you can easily get to the socket contacts as they are exposed on the top of the socket).
I tried your suggestions. I used two cables both have the same readings. On 20k ohms I tested the tip to the contact as you described and there was 0 resistance. When I did the same with the middle section of the unconnected plug and the socket contact furthest away from the edge of the pcb I got 1.00 - I’m presuming that’s okay?
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Old 13th Mar 2020, 10:39 pm   #39
John Earland
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Default Re: ZX Spectrum Tuning Issue

Quote:
Originally Posted by SiriusHardware View Post
Do that first, I think. "Always try the simple stuff first". Let us know what you get.

Is the cable the original two grey plugs / two black plugs cable which came with the Spectrum?
Unfortunately not-two cables I’ve had for a little while.
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Old 13th Mar 2020, 11:36 pm   #40
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Default Re: ZX Spectrum Tuning Issue

Quote:
Originally Posted by John Earland View Post
I tried your suggestions. I used two cables both have the same readings. On 20k ohms I tested the tip to the contact as you described and there was 0 resistance.

When I did the same with the middle section of the unconnected plug and the socket contact furthest away from the edge of the pcb I got 1.00 - I’m presuming that’s okay?
Not quite, the measurements asked for were:

-Tip of the plug which is not plugged in, to socket contact furthest away from the edge of the spectrum PCB. (Should be zero ohms)

-'Ring' of the plug which is not plugged in, to socket contact nearest the edge of the Spectrum PCB (should also be zero ohms).

As mentioned a while ago, if you are looking for an expected resistance value (zero ohms in this case) use the meter range which has the next highest resistance value. On your meter I think that would be the 200 Ohm range.

Can you confirm that the plugs on the ends of the leads you are using have two sections, not three (are mono, not stereo)? Also are these pre-formed leads with moulded plugs, or can the plug covers be unscrewed to expose the connections inside the plug?
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