Repair and upgrade of a Sinclair ZX Spectrum 48k Part 3 of 3

In these videos I look at a problem with the Spectrum rubber keyboard and upgrade the following:
• Part 1 - Composite video modification - so you can use the Spectrum on a modem TV/Monitor
• Part 2 - 5v Regulator - runs at a smooth 5 volts’ and cooler so the large heatsink is no longer required
• Part 3 - Replace capacitors - this is done with all vintage electronics as the original capacitors can leak or as they age their values change.
Part 3 - Replacing the capacitors, final testing and playing games
00:00 Introduction and capacitor layout
02:30 removing the first capacitor
10:55 Soldering in the new capacitor
13:30 Replacing the other capacitors
14:45 Quick power on test
17:25 Finished replacing the capacitors, power on testing
22:10 Rebuilding the Spectrum
26:00 System Testing
29:00 Playing some games
30:45 Reasons why we have to change the capacitors
34:00 End and photos
All this talking is making my voice dry, if you want to buy me a coffee here is a link:
☕ www.buymeacoffee.com/MikesLED...
If you have enjoyed this please give it a thumbs up, join me for more videos by subscribing to my channel.
Links to information for the brilliant Manic Minor and the developer Matt Smith
en.wikipedia.org/wiki/Manic_M...
en.wikipedia.org/wiki/Matthew...)
Keyboard Membrane
www.ebay.co.uk/itm/324185843979
5v Switch mode replacement regulator
www.ebay.co.uk/itm/393902189624
ZX Spectrum Parts
www.retroleum.co.uk/zx-spectr...
www.retroleum.co.uk/spectrum-...
ZX Spectrum Issue 4 PCB Layout
spectrumforeveryone.com/wp-co...
Capacitor List
spectrumforeveryone.com/techn...
Music: Do Androids Dream of Electric Beats - By D-GR
(C) Used with permission. Link: / dave2000gray
Here are links to some of the tools
I use on my bench:-
Soldering and heatgun station
amzn.to/41Sn6g9
Manual desoldering pump
amzn.to/3IY0Zfx
Powered desoldering station
amzn.to/41Wesxi
Lead free solder
amzn.to/3F4oe6s
Soldering Iron Tip Cleaner
amzn.to/3l1mZhB

[@funwithcarsfeaturingdmlgam1847]

Love the retro video games at the end

[@andye2005]

Nice series, shows just how "stubborn" some components are when trying to remove them. (I prefer cutting the components out then desolder the remaining stub of the leads)
The large solder area that you had problems with is annoying - the desolder gun has such a small area of contact that it cannot push enough heat into the board,. Generally hot and fast does less damage, but it takes practice. Give your desoldering gun some help in such cases by applying your normal soldering iron to the area as well. That will do most of the work in melting the solder and the gun will do the rest. Think of it like using the manual desoldering pump and a standard iron.
You might want to review the video and see the effect of switching the lights off, your camera is good enough to be quite happy in the lower light, so you don't need to keep switching the light if you don't want to. 🙂
Those magnifying lamps, I have one as well, generally OK for inspection but I find not enough room when working under it.I keep bashing the lamp with the soldering iron handle. I have a few pairs of cheap reading glasses in the workshop, and they work a lot better. If you wear glasses already, then wear the reading glasses over the top, that will give you enough magnification, and you can then flip them up out of the way when not needed.
The capacitor testing - Check the ESR reading, the bigger caps had a 0.2 ohm for the new, and 0.7+ for the old. that's quite a difference, but not too bad. Still worth replacing. The 22uF caps were pretty much in spec, but they are so cheap that you might as well replace them while the computer was in bits as you did. A dedicated ESR meter might be worth looking into (They are easy to build) The readings on the component tester you have can be a bit off, but OK for comparisons. I also have one of the same testers, everyone should have one on the bench they are so useful and cheap...
The cap with the lead that fell off, rather than old, more like a cheap source at the time they were ordered! Not seen that issue for a long time. Usually it's the rubber seal popping out at the other end and the gunk leaking out that I have to deal with.
Andy

[@MikesLEDShed]

Thanks for your comments Andy 🙂

[@peddersoldchap]

Hi.
First, thank you for the series!
Second, what are the names of the diagnostic interfaces you used at the end of this video?
Cheers, P.
EDIT - One of them was the Retrolium DiagROM, I guess? From the photo at the end.

[@MikesLEDShed]

Hello - yes 1 is from retroleum the other is from byte delight

[@Phil-Sands]

SDo is it C47 or C74? 😆😆😆😆😆