MSX Inbound!!

[rubber_jonnie]

@mrbombermillzy I'm going to start working through the MSX BASIC stuff, see what I can find.

Fingers crossed I'll have a way to save stuff off soon enough, then anything I write I can at least save.

[mrbombermillzy]

That's ok. We can have a better look once you sort the storage problem!

In the meantime, I will see if I can figure out what the deal is with the analog joystick<>paddles differences.

[rubber_jonnie]

That's ok. We can have a better look once you sort the storage problem!

In the meantime, I will see if I can figure out what the deal is with the analog joystick<>paddles differences.

Yeah, it's really kind of weird that the joystick is so obviously analog, but behaves as a digital stick. Once I have the storage sorted I will see about writing so decent test progs, mine so far have been basic.....

Bad BASIC joke I know!!

[rubber_jonnie]

@PhilC

I thought I'd move the chat re the Tosh and quiet cassette out over here.

Wow, there is shockingly little documentation on the Tosh, no service manual, no schematics, but tracing back the audio out, it goes directly to the TCX-1007, or MSX engine (AFAIK), so although there is an op dual amp onboard, it seems to be totally unrelated to the cassette out.

Seems like there are a couple of possibilities here.

1. The output from the TCX-1007 is low and this is normal. The original MSX cassette drives may have had some sort of amp present, so the low signal wasn't an issue.
2. The output from the TCX-1007 is low and this isn't normal. The IC might have a problem, or the handful of resistors and capacitor that seem to pull up the signal and smooth have bad components

I can easily check the signal at the TCX-1007 and also the resistors and capacitor, see what's what.

I'll report back later.

[rubber_jonnie]

Ok, so I have an answer it would seem.

At the TCX-1007, the signal is just fine:

IMG_20220219_160555.jpg (176.98 KiB) Viewed 2017 times

The signal is super clean and a decent voltage.


However, there is nothing between the TCX-1007 and the socket apart from:

IMG_20220219_150549.jpg (372.69 KiB) Viewed 2017 times

So R54, R55 and C16.

The TCX-1007 signal arrives at the left hand side of R54, where I have marked in blue, but then disappears. Wondering if the cap has died, but I only get mV at the socket.

Time for a closer look at those components I think.

I should add that I have checked the socket and there are no bad solder joints.

[Tomswork]

My mantra is tantalum caps short


Tom

[rubber_jonnie]

My mantra is tantalum caps short


Tom

I gotta say, I'm with you there. I will disconnect it tomorrow and see if it makes a difference to the signal.

[stephen_usher]

A quick resistance test should prove or disprove that.

[rubber_jonnie]

A quick resistance test should prove or disprove that.

Just not got round to further testing, going to be tomorrow now.

[rubber_jonnie]

Ok, so i pulled the cap, ESR is 3.1 ohms and it reads fine capacity wise, 333nF. I'll try running without it see if it makes a difference, but R54 is supposed to be 10K going by the markings, with 5% tolerance, which would be 500 ohms either side, but it's reading 8.75K, so well off. The othe resistor is 120R, but that reads just fine.

I have some 10Ks, so I'll find a good one and replace, see if it makes a difference.

I drew up the circuit last night and it looks like a voltage divider, so guessing if one resistor is out it'll throw it all out.