Issue Two ZX Spectrum Repair - A Write Off?

[@kev7345]

If only this video was posted 3 years ago when i got hold of an issue 2 and spent weeks on end trying to convince myself that the garbled text on the screen was just the way that rom was supposed to work, I got lucky in getting hold of a replacement ULA fairly cheap but not before my sanity virtually expired...

[@TSteffi]

Another method of removing the pins from the board is: Hold the board upside down, just a few centimeters (maybe 2 inches for the imperialists) above your table. Then heat up the pin you want to remove, and while it is still melted, slap the board down on the table. This should cause the pin to fly out the other side, together with the solder. I learned that trick when working in manufacturing a long time ago. It works pretty well for small and/or strong PCBs. It is generally very gentle on the pads/through holes, but obviously puts some stress on the PCB itself. Use with caution.

[@chaoticsystem2211]

Nice idea with the vice. If the board isn't behaving, you tighten it a little more :D My rule of thumb is, when the heat from a chip hurts the thumb, i put on a heatsink...

[@RudysRetroIntel]

Excellent video and work as always!! Your videos have help me with my speccy repairs! Thanks for sharing

[@damianbutterworth2434]

I`ve drunkenly bought some clear circuit board varnish. I am going to vanish my Speccy circuit board. Perhaps it might of helped when I was changing the RAM when I found 2 round rings came off and I broke a link. I`ve got one of these off EBay for £50 coming Monday. I`m trying to collect computers that I had as a kid. :)

[@daveboulton3897]

Love watching these videos, some great tips and tricks to help us all. Thank you.

[@HappyLittleDiodes]

Thanks for watching!

[@DingsdaBumm]

Can ULAs with a minor fault be rescued with external logic ics? Good repair job. I prefer not to de-socket the ULA.

[@HappyLittleDiodes]

Yes I suppose they could be depending the exact nature of the fault

[@fredericfonteyne1945]

Neat job! I personally use dental floss to remove faceplates. No heating needed, no bending :-)

[@HappyLittleDiodes]

That is an interesting idea, I'll definitely try it next time

[@damianbutterworth2434]

WOW. I told you about the high voltage I was getting on the 12 volt rail. I took the chips out and it was 22 volts. I was doing the R60 resistor upgrade. I used a 1/4 watt resistor. Just put 2 x 200ohm(100ohm total) 1/4 resistors(1/2 watt total) in place and I`m getting 12.2 volts. I`ve got some 1/2 watt 270 ohm coming soon. I should of got the kit off Retroleum. Thanks for the help.

[@HappyLittleDiodes]

Was it a single 270ohm 1/4 watt resistor initially?

[@damianbutterworth2434]

@@HappyLittleDiodes It think it was 100 ohms. I never checked it. I just put 1/4 watt 270 ohm in from my Arduino stuff. Pity Retroleum never had any in stock. I`ve got some 1/2 watt 270 ohms on order. Thinking about it. I`ll check an old vid and see if I can see the bands.

[@HappyLittleDiodes]

Ah right yeah if the resistance was too low then your voltage would be too high. I blew up a ULA doing that

[@damianbutterworth2434]

@@HappyLittleDiodes I`ve still got a black square with some red dots flashing without the ram fitted. Hopefully the ULA survived. :)

[@MoreFunMakingIt]

Nice work! Digging the new editing style.

[@HappyLittleDiodes]

This is a direct result of upgrading from premiere elements to premiere pro

[@MoreFunMakingIt]

@@HappyLittleDiodes it's very easy to get carried away 😆 New toys and all that. I had to put all the effects in when I first started using Resolve

[@jaycee1980]

I really must get some of that 3M tape! One thing i would recommend with issue 2's is doing the DC-DC converter mod. Particularly if you do nothing else, change the -5V part of the circuit - the way the original is laid out is atrocious!!

[@Doombrain]

Another legend saved🎉

[@skeptic10]

Hey you got the same IIGGOO-pattern with the Retroleum test ROM. I had the same fault and it was also the ULA. I figured out it had pin (A0) shorted to GND which explains the pattern.

[@HappyLittleDiodes]

That's cool! How strange

[@JohnSmith-bh4zx]

Great work.

[@ratos74]

Hi! I have a simple question: On issue2 spectrums when change a dead 5C ula with a 6C or even with a vLA82, then is the spider mod (transistor on CPU) still necessary?

[@HappyLittleDiodes]

Hi. Yes it's still necessary, the shortcoming of the ULA would require more pins to resolve as I understand it, so the extra transistor had to stay

[@ratos74]

@@HappyLittleDiodes Thank you for the answer. Keep up the good work!

[@seankelly3997]

Great video 👍, I got similar garbage with a faulty ULA and one upper ram chip gone. Why are the modulator caps on issue 2 spectrums always nice and shiny and others are in bad condition?

[@HappyLittleDiodes]

I'm not sure about the modulator. I find it's just down to how well the machine has been kept. It also depends on any foam that has been stuck to it because that tends to go brown and crusty@@seankelly3997

[@NotMarkKnopfler]

Heatsink. Deffo. 😊

[@MikkyTee]

Im only getting 240p quality Jim..

[@HappyLittleDiodes]

Try refreshing Mikky, 4K is working here

[@MikkyTee]

@@HappyLittleDiodes yep sorted lad 👍🏼

[@lawrencemanning]

Ugh what’s the hold music playing in the background for?😮