Author Topic: CPC464 Works well BUT NO DEL Beep ? ( FIXED FINALLY )  (Read 1699 times)

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Offline Audronic

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Hi all

CPC464 Works well BUT NO DEL Beep ?

A strange one.
The CPC464 works normally .
Keyboard shows all the characters.
I can hear the Tape sounds as its loading.

BUT when on a new line I press the DEL key NO Beep ??
Also if I use the arrow keys and get to the end of a line NO BEEPS
Also No sound from Chuckie EGG

??     AY-3-8912 Sound generator  ??

Thanks.   Ray
« Last Edit: 02:00, 05 January 19 by Audronic »
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Offline Audronic

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Re: CPC464 Works well BUT NO DEL Beep ?
« Reply #1 on: 08:40, 31 December 18 »
Hi All


Ok it is not the AY-3-8912, I found a spare in the cupboard.


8255 ??? or what else ?


Thanks.   Ray
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Offline llopis

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Re: CPC464 Works well BUT NO DEL Beep ?
« Reply #2 on: 11:28, 31 December 18 »
I would guess the cable with the sound is broken somewhere. The signal goes in the cable that connects the cassette. Sometimes those cables rub against the edge of the cassette PCB and they wear out (or it could even be a bad solder joint--they seem to be really bad in the cassette area for some reason). I believe you still hear the cassette loading because that comes from a different path.

Offline Bryce

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Re: CPC464 Works well BUT NO DEL Beep ?
« Reply #3 on: 15:07, 31 December 18 »
The amplifier for the AY is on the tapedeck PCB but it's only a single trace (the three channels are already mixed into one). Check the trace from where they get mixed (R114, 115, 116) to the tapedeck connector (second last pin from the bottom) and then through the wire until it gets to the amplifiers input capacitor (C314). Continuity checks after that point aren't possible as the capacitor will block DC. With a scope you should be able to check how far the the sound signal is getting. Its destination is pin 12 of IC302 (LA5324).

Bryce.

Offline Audronic

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Re: CPC464 Works well BUT NO DEL Beep ?
« Reply #4 on: 09:14, 02 January 19 »
@Bryce


Thanks I will have a look.


Ray
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Offline Audronic

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Re: CPC464 Works well BUT NO DEL Beep ?
« Reply #5 on: 05:19, 04 January 19 »
@Bryce


Ok Thanks for the tips.
I plugged in a Dandanator which instantly plays Music.
An excellent tool to trace the audio signal.
I have audio at the pin G - (7) so the problem is in the Tape deck.
any way small progress

Thanks.   Ray

« Last Edit: 05:21, 04 January 19 by Audronic »
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Offline Bryce

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Re: CPC464 Works well BUT NO DEL Beep ?
« Reply #6 on: 11:28, 04 January 19 »
@Bryce


Ok Thanks for the tips.
I plugged in a Dandanator which instantly plays Music.
An excellent tool to trace the audio signal.
I have audio at the pin G - (7) so the problem is in the Tape deck.
any way small progress

Thanks.   Ray

Cool. Where did you get that picture from? It's wrong, the schematics aren't wrong. Pin F-6 is not connected on early 464's, but it's connected to the 5V rail on later 464's, so both versions are possible. The schematics only reflect the early versions.

Bryce.

Offline Audronic

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Re: CPC464 Works well BUT NO DEL Beep ?
« Reply #7 on: 11:39, 04 January 19 »
@Bryce


The info came from the Original Service manual, and then the Amended Service Manual which appears to be correct.
The Original indicates that F-6 is at GROUND potential On the board that I am working on its at +5 Volts ? (amended schematic)

Ray
« Last Edit: 12:00, 04 January 19 by Audronic »
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Offline Bryce

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Re: CPC464 Works well BUT NO DEL Beep ?
« Reply #8 on: 12:36, 04 January 19 »
Oh, then it's GND on the early versions, not N.C. Both versions definitely exist, I have encountered both over the years.

Bryce.

Offline Audronic

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Re: CPC464 Works well BUT NO DEL Beep ?
« Reply #9 on: 23:54, 04 January 19 »
@Bryce


Ok Thanks for that I will make sure I check on the Next 464 that I have to work on.


The board I am working on is :-  Z70200 (Old Board). MC0002b with + 5 Volts on Pin F-6


Thanks.   Ray
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

Offline Audronic

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Re: CPC464 Works well BUT NO DEL Beep ?
« Reply #10 on: 01:27, 05 January 19 »
@Bryce


I have a photo of the 5 Resistors that had HAIRLINE cracks before I moved them with a screwdriver. Arghhhhh
it look like something dropped on the board.
The Other 5 Are OK

Ray
Procrastinators Unite,
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As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

Offline Audronic

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Re: CPC464 Works well BUT NO DEL Beep ? (FIXED FINALLY)
« Reply #11 on: 02:00, 05 January 19 »
Hi All


Replaced the Resistors it now WORKS.


Thanks for your interest.


Ray
Procrastinators Unite,
If it Ain't Broke PLEASE Don't Fix it.
I keep telling you I am Not Pedantic.
As I Live " Down Under " I Take my Gravity Tablets and Wear my Magnetic Boots to Keep me from Falling off.

Offline Bryce

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Re: CPC464 Works well BUT NO DEL Beep ? ( FIXED FINALLY )
« Reply #12 on: 15:36, 05 January 19 »
Doh! What a pain. The board must have got seriously flexed at that point to crack them all.

Bryce.