CPC464 no sound out of speaker/loading

[Bryce]

Oh, those fatal words....attempted to align... That may be the reason it's so quite now...
What alignment method was used?

Bryce.

[Devilmarkus]

Cool tool to find good azimuth location for tape-head:

http://www.cpc-power.com/index.php?page=detail&num=6091

[Macc]

An actual azimuth cassette with the proper screwdriver, wouldnt pick up anything.  One point thats maybe worthy of note is that when saving he heard a very faint data noise

[Bryce]

It's difficult to analyse the problem much further without having the hardware, but it sounds like it needs someone with the right equipment and the CPC to take a look at it.

Bryce.

[Macc]

Is there no sound modification then?  Im sure I read somewhere about it (of course I could be wrong)

[Bryce]

Define sound modification? A hardware mod for the sound chip / cassette player?

Bryce.

[CanonMan]

If the CPC's sound is coming through okay then the sound amplifier chip, which according to the schematics I'm looking at is an LA4140, must be okay.

If you can't hear the sound from the tape deck and it won't load or save either, I'd replace the LA6324. A bog-standard LM324 should do the job just as well. Also check for dry joints or leaky capacitors on the tape deck PCB.

Not easy to do head azimuth adjustments on a mono deck, is it? Stereo decks are easier! I just hope the alignment isn't now shot to sh*t 

[Macc]

Im not sure about the mod, just heard about it somewhere because apparently (from what I have heard) the 464 is prone for it (allegedly)


Regarding Azimuth, correct me if im wrong but if it was fully tightened, isnt the old rule of one and half revolutions back usually in the right ball park?

[CanonMan]

Im not sure about the mod, just heard about it somewhere because apparently (from what I have heard) the 464 is prone for it (allegedly)


Regarding Azimuth, correct me if im wrong but if it was fully tightened, isnt the old rule of one and half revolutions back usually in the right ball park?

I've never heard of a sound mod for a 464 so can't comment.

As for the azimuth adjustment, I guess it depends on the mechanism, and no two tape mechanisms are the same! Bear in mind that the range where it would actually work is pretty small, to a test tape is the only real way to do it.

[Bryce]

The LA4140 only amplifies the signal going to the speaker. If it broke there would be no sound to the speaker, but the game would still load. The LA6324 amplifies the data stream going into the CPC. Either one of these could be damaged or both. It could also be a leaky capacitor (C315 or C318 are likely candidates) that's pulling the supply voltage to the Op-Amp down too low or transistor Q301 (Playhead pre-Amp). Another possible fault could be dirt on the Play/Record switch (SW301) which you should probably clean anyway just to check, because it's the easiest fix.

Bryce.

[Macc]

The LA4140 only amplifies the signal going to the speaker. If it broke there would be no sound to the speaker, but the game would still load. The LA6324 amplifies the data stream going into the CPC. Either one of these could be damaged or both. It could also be a leaky capacitor (C315 or C318 are likely candidates) that's pulling the supply voltage to the Op-Amp down too low or transistor Q301 (Playhead pre-Amp). Another possible fault could be dirt on the Play/Record switch (SW301) which you should probably clean anyway just to check, because it's the easiest fix.

Bryce.

Thanks Bryce, thats some food for thought, ill pass that information on.

[Gryzor]

Cool tool to find good azimuth location for tape-head:

http://www.cpc-power.com/index.php?page=detail&num=6091

Hey, cool tool!
Btw, did we all have the same cassette with the chopper game on the reverse side?