General Stuff(tm)

[rubber_jonnie]

Very well done sir!

Looks very cool and super useful.

[JezC]

Very well done sir!

Looks very cool and super useful.

@stephen_usher @rubber_jonnie Yes, definitely a great addition. I'm trying to save up for a decent scope but it's going to be a long time before I can get anything like that...very envious!

[BennehBoy]

want one

[stephen_usher]

Hehe... it was a random, "I rescued this dead oscilloscope from work. I've seen that you fix things, do you want it? I'll bring it around."

It's a nice 'scope but too big for every day stuff. If I were doing a fixing YouTube channel it would be very useful as it has VGA out, so it could be streamed via a capture device. But I don't make such videos, so...

[BennehBoy]

Swap you a Hantek DSO for it

[stephen_usher]

hehehe... got one of those already.

[stephen_usher]

Having got back from my Dad's place (our birthday weekend) and put the 486PC and oscilloscope into storage I looked around for a quick project.

Somewhere I have an Issue 7 ZX Spectrum motherboard with a dead ULA and wondered if I could diagnose it, so went into the loft. I couldn't find that one but there was another spectrum which I'd been donated a while back which didn't work. This was a 6A in a Spectrum+ case.

Looks like this one has the TR4/TR5 fault as it's not generating the +12V and -5V required by the 4116 RAM etc. Otherwise it looks to be trying to boot.

I'll have to see if I can get a supply of those transistors.

I wish I could find that Issue 7 though as that could be more interesting.

[rubber_jonnie]

Having got back from my Dad's place (our birthday weekend) and put the 486PC and oscilloscope into storage I looked around for a quick project.

Somewhere I have an Issue 7 ZX Spectrum motherboard with a dead ULA and wondered if I could diagnose it, so went into the loft. I couldn't find that one but there was another spectrum which I'd been donated a while back which didn't work. This was a 6A in a Spectrum+ case.

Looks like this one has the TR4/TR5 fault as it's not generating the +12V and -5V required by the 4116 RAM etc. Otherwise it looks to be trying to boot.

I'll have to see if I can get a supply of those transistors.

I wish I could find that Issue 7 though as that could be more interesting.

Nice, always good to see a Speccy up for some TLC

[stephen_usher]

Definitely TR4. With not quite the right NPN transistor, the +12V is close to 12V but the -5V is bouncing between -1.4V and -2V so it's not woring correctly, but it's close...

IMG_2563.jpg (69.99 KiB) Viewed 2673 times

One of the correct transistors is now on order.

[stephen_usher]

Found a broken (cut?!) 2K2 resistor, which feeds the -5V line.

Even with the wrong transistor and holding the said transistor in the holes I managed to get to a "© Sinclair Research 1982" screen. So, once the proper transistor arrives it'll be a working machine again. (I couldn't take a picture for obvious reasons.)