Issue 3 ZX Spectrum 48K Refurb - DCDC Mod Walkthrough 

Love this and can smell that coffee from here, lovely. Wider tip on the iron would help get the heat into those joints especially on the big ground planes

Thanks for the heads up on the DCDC mod. I bought my first Speccy a few months back (Issue 2), but AFAIK it's not been DCDC modded. It's on my "to be recapped" list, so I should probably do the DCDC mod at the same time.

For a long time I've wanted to attempt one of those B-roll coffee making shoots; turns out it was much more difficult than I imagined.

The thin double sided tape is OEM. Sinclair made them cheap!

I used a 1/4 watt resistor on the 270 ohm R60 mod. I got 18 volts on the 12 volt rail. I hoping a 1/2 watt will get it back to 12 when it arrives.

The CPU has a date code from 1988 which means it can't be original.

I am glad the algorithm suggested you, subbed!!

Hello HLD. What acid did you use for the nut? And , did you use any product after the acid to prevent it from rusting again? Also , where did you get the replacement feet? And also, what's the point of the DC DC mod? When I read the title, I thought you were going to use a Traco Power.

Is there a parts list for the DCDC mod?

Did you insert the D19 backwards at R54 in the video? Shouldn't the cathode be on the LEFT side? You can see it at 13:40 in the video.

Hi. thank you for a great video. When I look at the schematic for issue 4a, resistor 60 has a value of 68 ohm. You change it to a 220 ohm resistor. Can you tell why?

Thanks for the DCDC mod walkthrough. Since I can not find a 1uf/63uf cap do you think I can get away with lower voltage (50v) or I should absolutely go higher (100)?

I also love the jokes :)

Can you post a link to these "checks" that you run as I have a fresh motherboard and would like to run through them?

Nice job. By the way what is the purpose of this dcdc mod? (i do also zx spectrum restorations)

Hell ! can you help ? i own a zx spectrum sinclair 48k that doesn´t load the games. They just get errors when first game screen opens or crash during the doalings and green little squares on some loading drawings. I inserted that to check the upper RAM chips : PRINT PEEK 23732 + 256 * PEEK 23733 the value result was wrong it was 32863 instead of 6553 »»»» I tested all the 8 upper RAM chips group on the board below (right side not the logical ones) using a fully working sinclair 48k and all 8 are good.

Issue 3, isn't that quite rare?

I shall use this to guide my refurb - thank you. This is the test video, right..? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-IzgCmldm2H4.html