I’m not an electrical engineer, nor a speccy hobbiest, but this was fascinating. Your fault finding methodology was just perfect. It’s a shame this sort of logic is not taught in schools and colleges!
That was one of the most comprehensive repairs of a 48k spectrum I've seen yet. Delighted it worked out for you in the end. Hope you're getting use out of it still. Thanks for the vid.
Replacing the 7805 power regulator is a thing to do. With a switchmode regulator there is much less heat in the case, helping the life span of ULA, other chips, and caps.
Nice work, another Speccy saved. You’re like Quickdraw McGraw with that solder sucker! Funnily enough I had a similar fault, turned out to be a shorted address line somewhere under the lower RAM sockets. Did not show up on a continuity test, but was pulling the line high. A pain to track down (lots of desoldering and systematic testing…) but worth it in the end!
@@HappyLittleDiodes ah yeah, I missed so much myself, so I’ve been playing catch-up this past year. Lots of great folk in the community willing to share knowledge, seems to be a good time to jump in. Cheers for sharing your work, I’m away to watch the reverse engineering ones next. (Thinking of tackling an I/O project next with my newly fixed Speccy).
Hi Nick. It's definitely convenient, and being battery powered there's less risk of blowing it up with a ground loop. I don't think it can replace a decent bench scope, but it's cheap and cheerful and great for having a quick looksy. www.amazon.co.uk/YEAPOOK-Handheld-Oscilloscope-Professional-Bandwidth/dp/B07XBL4BTL/ref=sr_1_9?dchild=1&keywords=oscilloscope&qid=1620483616&sr=8-9
I’m not an electrical engineer, nor a speccy hobbiest, but this was fascinating. Your fault finding methodology was just perfect. It’s a shame this sort of logic is not taught in schools and colleges!
Thanks Paul that's really kind
That was one of the most comprehensive repairs of a 48k spectrum I've seen yet. Delighted it worked out for you in the end. Hope you're getting use out of it still. Thanks for the vid.
I, for one, welcome our new biomechanical woodlice overlords. x
Replacing the 7805 power regulator is a thing to do. With a switchmode regulator there is much less heat in the case, helping the life span of ULA, other chips, and caps.
Great video!
You're good with a soldering iron, too.
I had an early spectrum 48k and did quite a bit of CONTROL and DATA ACQUISITION with it.
Thank you!
Fantastic editing 👌
Nice work, another Speccy saved. You’re like Quickdraw McGraw with that solder sucker! Funnily enough I had a similar fault, turned out to be a shorted address line somewhere under the lower RAM sockets. Did not show up on a continuity test, but was pulling the line high. A pain to track down (lots of desoldering and systematic testing…) but worth it in the end!
Yeah it's a real "I AM INVINCIBLE!" Moment when it boots
@@HappyLittleDiodes I’m worried it’s addictive! That was my first real repair job, an eBay fixer-upper. How did you get started?
Play expo in Manchester made me realise I've been missing out on the retro scene. My boss gave me his speccy to repair when I kept going on about it
@@HappyLittleDiodes ah yeah, I missed so much myself, so I’ve been playing catch-up this past year. Lots of great folk in the community willing to share knowledge, seems to be a good time to jump in. Cheers for sharing your work, I’m away to watch the reverse engineering ones next. (Thinking of tackling an I/O project next with my newly fixed Speccy).
Keep me posted. The spectrum quartet was a good IO project to
Nice video Jim.
Thanks Peter! Long one this week
Very informative. Thanks
Zx Speccy + happy memories. My first computer!
In due course got a +3 what a nightmare. Design fault with the sound and unreliable floppy
I have a couple of plus 3s to get stuck into
amazing
will be ok to use TMS 4116- 20NL?
I should think you'll be fine. Retroleum sell 150 ns but honestly I don't know what the intended speed is
I bought Chinese caps for replacement, but they have a large spread of inaccuracy at a nominal value of 20% can I make a replacement like this?
Yes those will be fine. I recommend using axial caps
@@HappyLittleDiodes ok thanks. I found info in manual that it may be -10% to 80% so as I understand better if it will be hier than less.
Hi What Oscilliscope are you using please? Looks good, can you recommend it?
Hi Nick. It's definitely convenient, and being battery powered there's less risk of blowing it up with a ground loop. I don't think it can replace a decent bench scope, but it's cheap and cheerful and great for having a quick looksy. www.amazon.co.uk/YEAPOOK-Handheld-Oscilloscope-Professional-Bandwidth/dp/B07XBL4BTL/ref=sr_1_9?dchild=1&keywords=oscilloscope&qid=1620483616&sr=8-9