My Klyball 600D build

[ronin47]

So the cassette input doesn't work.

Using the Service Manual test procedure:

Jumper pin 9 (AUX) and pin 10 (MON) of J2 together.

Next the small testing routine:

10 PRINT "U";
20 GOTO 10
SAVE then enter
RUN then enter

Screenshot 2024-04-18 at 13.44.46.png (76.47 KiB) Viewed 226 times

Using this, I can see U66 getting the correct input to pin 2, pins 3&4 are grounded as per the schematic, pin 7 has 5v and C9 is the correct value.

I get no output at pin 6 of U66 though.

However it looks like I have the incorrect cap at C6 (150nF rather than 150pF), and IIRC it was another identical situation to this that caused me problems earlier on (I think with the clocks).

First I'll swap the cap out and if it still doesn't work then I'll pop a replacement CA3130 in.

[ronin47]

OK, so C6 replaced with the correct value but no difference.

I also pulled U62 in case that was bad, It wasn't, and also tried with one leg of C6 lifted, but still no output on Pin 6, so replacement CA3130's are ordered.

Provided I then get output from that I can then start to chase down where the output gets to and if R57 works to adjust the input as expected.

[jbtech]

Hi,

Correcting the value of C6 was a good step, too high a value there would most likely tend to make the inverter self oscillate.

Beware of fake CA3130 ICs from eBay, I received a few of those which I suspect were just some other op amp relabelled.

In many applications a 'substitute' part might still work but the CA3130 has an uncommon bi-fet input stage which is needed for this particular circuit to work.

Most op amps require a dual rail +/- Voltage supply or, if using a single positive supply the input signal needs to be biased to an intermediate Voltage for a transitiom on its input to be detected.

The CA3130 is fairly unique as it can cope with an input signal Voltage range which centres around 0V including a slightly negative Voltage even though its supply Voltage is 0 - +%V

Hopefully if you can source a genuine one that should solve the problem. The 'fake' ones I received had slightly different markings to the genuine one.

Below is a photo of the genuine one which I eventually sourced with the correct Intersil logo on it. If I can still find any of the fake ones I'll add a photo of those later.

Hope that helps, regards John.

ohiob.jpg (110.32 KiB) Viewed 215 times

[ronin47]

Yes, it could be a fake, but I have no way to really test it other than in the 600D.

I have some on order from a supplier who I can trust, even though they are eBay, I've had a lot from them but it's all been great.

To be fair, I did accidentally briefly connect the board to 8.5v, a genuine mistake, and it did kill a few IC's, so it's possible it's my own fault.

According to the datasheet, it can take a supply voltage of up to 16v, so that may not be the cause and it is a fake or never worked in the first place.

Trouble is it's too late to return the part, and for the cost I just can't be bothered with the hassle. Mine doesn't look like the one inyour photo that's for sure, and I only bought one at the time.

We'll see once the parts arrive I guess.

[Klyball]

digikey stocks them, i find i will go new for everything i can ,then china /ebay sellers i trust and only if they ship speedpak . been lucky so far with fake chips

[ronin47]

digikey stocks them, i find i will go new for everything i can ,then china /ebay sellers i trust and only if they ship speedpak . been lucky so far with fake chips

I've been lucky, I tend to use trusted sellers on eBay for my parts, though it has taken a few years to figure them out.

I think this may be the first fake I've had, and looking at it closely, the markings don't look right, the top is too smooth and looks re-done.

Because I buy in small quantities and over periods of time to spread the cost, I find places like Digi-Key, Mouser, Farnell etc to be too expensive for shipping, with parts for a few pounds costing upwards of £30 to ship, it's just maddening.

And with my trusted sellers shipping for free mostly, they get my money.

BTW is your D13 data separator available still? Or are the gerbers available? I'm about to start building my 610 and would really like a floppy disk, probably a Gotek TBH to use with my 600D.

Thanks

[ronin47]

So the replacement CA3130's arrived and just work. I get output at pin 6 and I also see a pulse at pin 5 of U69, and I have tweaked the pulse width using R57 to about 550uS as per the service manual.

IMG20240425094710.jpg (3.45 MiB) Viewed 65 times

Here are the new CA3130's (On the antistatic foam) compared to the original:

IMG20240425104130.jpg (2.84 MiB) Viewed 65 times

Looking at them side by side I now think that it's likely my original is a fake. It doesn't look right, too smooth and the laser etching is a bit too perfect.

My own fault as I didn't buy from one of my trusted eBay suppliers, so a lesson learned. I may have had to pay a little more in the end, but the replacements from a vendor I've used many times before worked first go.

Next I need to try saving and loading.

[ronin47]

Ok, so I have tried saving and loading. I hear output on the cassette deck monitor and it is saving to tape.

However, when I try to load I get garbage back in:

IMG20240425131726.jpg (4.97 MiB) Viewed 58 times

Of course it could be the cassette and/or the deck so I will try another. Of course it could be 'garbage out garbage in', so is there any way to verify that what I am saving is actually correct?

[bxdanny]

You could try loading a known-good audio file, like the ones available in the Games section of Mark's site, or the ones i posted for Sideburn in another thread. Connect the audio output from your PC to the audio input of the OSI and try to LOAD. If the input side of your cassette interface is working, you should get something intelligible.

[ronin47]

You could try loading a known-good audio file, like the ones available in the Games section of Mark's site, or the ones i posted for Sideburn in another thread. Connect the audio output from your PC to the audio input of the OSI and try to LOAD. If the input side of your cassette interface is working, you should get something intelligible.

Good point, I'll give it a go.