Sparkly pixels

[Moggy]

Jesus H. Chrysler!!!
I have gained more knowledge in the last few posts than in the last thirty years.

Many thanks Mark,Karl and Retro-Techie for the input.

@Lardo.

Please persevere with this one Lardo I'm sure the old door wedge can be sorted let us know how you get on. Oh and in answer to your pet question, cat every time said the MOGGY!!!(which,should our European brothers not know, is a UK slang term for for a non pedigree cat)
Although for some strange reason ZX-Jens from the German forum insists on calling me MOOGY!

[1024MAK]

As well as the regulator circuitry, a large power consumer is the peripheral cells.

Don't confuse power consumption with dissipation! For example if current flows out of an I/O pin @4.5V (with 5V supply), that pin's driver only has to 'burn off' (dissipate) 5-4.5=0.5V @ that pin's current. The remaining 4.5V @ pin current is dissipated where that current goes (read: not inside the ULA). In short: an IC's supply current * voltage is not EXACTLY the same as its heat dissipation. But in most cases, the difference (determined by current "sourced" or "sinked" through I/O pins) is not big enough to matter much.

For pins that are configured as 5V digital outputs, yes. But the arrangement of the resistors and transistors of the peripheral cells can be (within limits) configured for other voltages. For example, the TV/Tape pin which has three voltage levels...
Also, we are talking relative differences here. The transistor and resistor power losses in the peripheral cells are relatively large compared to the losses in the CML matrix cells. That's all I meant.

Mark

[Lardo Boffin]

So, new regulator fitted (thanks Mark!).

No difference - I still get sparkly pixels!!!! The only notable difference is that I haven't yet had the whole screen go funny and it has been running long enough for that to happen while I am writing this.

So what does that leave? Capacitors? Admitting of defeat and sending it off to an expert to be fixed?

As an aside what is the best method for removing the old regulator? I tried de-solder braid and a solder removal gun but could not remove enough solder to remove the legs. In the end I snipped off the old reg and soldered the new one to the old legs... In the fine tradion of engineering botch jobs everywhere!

Lardo

[1024MAK]

Yes, cut them legs off

That's by far the easiest method, and one that I often use.

Mark

[Lardo Boffin]

Yes, cut them legs off

That's by far the easiest method, and one that I often use.

Mark

Glad it's not just me then! Does the same apply to capacitors? Or are they easier to remove?

As an aside what is the part number of the regulator and where can I get them from?

Thanks!

Lardo

[1024MAK]

I only have a few minutes to write this...
Any component that is going in the bin can be cut off...
Rapid, Farrell plus many others sell various "drop-in" regulators, plus many others.

More later...

Mark

[Lardo Boffin]

I only have a few minutes to write this...
Any component that is going in the bin can be cut off...
Rapid, Farrell plus many others sell various "drop-in" regulators, plus many others.

More later...

Mark

Thanks Mark. Just want to be sure I order the correct one!

[Lardo Boffin]

I saw this one based on a link from another thread on here:-

IMG_5472.JPG

(1.65 MiB) Downloaded 295 times

[balford]

That's the Australian version, you want to be ordering a UK-spec component

B

[Moggy]

I saw this one based on a link from another thread on here:-

IMG_5472.JPG

Yup that's my reg of choice.