shoestring

Yes, nice little touch. I always hated the yellow flesh colour. The new music is an improvement too.

Just to note in case you're looking at memory upgrades. With an Antonia 4MB board. There is no need to upgrade the internal memory to 64kb first. Everything is handled by the Antonia.

Another vote for the Ultimate-II.

I think the music is pretty cool. Its just that your ears arent yet adjusted to the harshness of the SID

Replaced the switch in mine very recently. There's a guy selling them on eBay. Not cheap, had to do some minor adjustments to get it to fit on the PCB. From now on I just keep the switch in the on position to avoid the same issue and power the monitor up via the mains.

I think a 1.5a fuse should do it then, I just don't have any on hand right now besides these 3a ones. I don't have a lot of upgrades. Just the Antonia board in the 600XL which is fantastic and a couple of other bits and pieces. The stock breadbin c64 draws a little more than the Atari with the same 5v circuit and even more with the Ultimate-II+ cartridge ( that thing sucks a lot of juice ) , so I'm definitely going to get myself a bunch of heat sinks for these.

I haven't put it on the scope yet but I suspect the DMM might be a bit off. So far I've only tested the circuit on the bench supply which can provide 5a and is happily blowing 3a fuses. I'm not sure about the transformer in the Atari supply pictured in the first post. It's rated at 1.5a but that might be based on 7805 itself. Will have to try a bunch of fuses in steps and activate the clamp to see which one is going to be suitable. The datasheet claims it can provide 3a with heatsink but I am sceptical. A fully decked out machine will draw over 1.5a so I might need something around there or slightly higher. I'm struggling to find heat sinks that will fit that small place. I don't fancy cutting any down to size..

I still think a crowbar / voltage clamp is in order and so I made some small changes. Kicks in once I wind the pot past 5.7v. Gonna have to play around with the resistor and see if I can get it to blow the fuse at a slightly lower voltage. But I'd say success at this point...

Ive done the same super video 2.1 upgrade in my 600xl and 800xl. I dont have my UAV yet but Ive also installed the SCCC in the 800 which uses the same circuit borrowed from Bryan. The 800 has a slightly better picture on my PVM but its hard to notice the difference on the 1084. Maybe Ill take some comparison shots. I was really impressed with the video quality in the 800 and I cant wait to get the UAV installed in my 65XE.

I literally laughed out loud at my desk at work. Hope you aren't too hung over in the morning.

Hey Phoenix.. this might explain it. http://www.ferret.com.au/c/tekmark-australia/tekmark-supply-the-australian-defence-force-with-tektronix-digital-phosphor-oscilloscopes-n1830793 I bought it second hand from an auction. Mine is not the C model though but still damn good for what I paid. Only powered up ~20 times when I got it so it was virtually unused. My guess is that their budget is large enough to updating this stuff to the latest tech.

https://electronics.stackexchange.com/questions/179233/making-lm78xx-fail-safe-against-short-open-reverese-bias-flyback-etc

You’ve only described one of its failure modes. They can fail quite spectacularly as well, when they short v_input to v_output. Bye bye Atari...

I have the same module in my c64 PSU. It runs a little hotter than the PSU powering the stock 65XE when I have Ultimate-II+ cartridge and a USB device connected to the back of the c64. The 600XL has an Antonia upgrade and the PS barely gets hot. I'm going to run some tests and see how much they draw. But according to the datasheet it should be able to deliver 3a without problems as long as there is a heatsink, without a heatsink it's guaranteed to provide 2a. I'm assuming the thermal protection will kick in if its delivering more than 2a without adequate dissipation of the heat.

I think you're referring to the SCCC made by Jurgen. I don't use the audio amp on the card because I use the existing jack ( not an external one ) and the built in amp in my 800 is loud enough. Some say it improves the audio or is louder, frankly I can't tell the difference. But I am going through a PVM which doesn't have the best speaker! http://atariage.com/forums/topic/260646-new-hardware-atari-400800-super-color-cpu-card/

I'll have to order a couple of those and give it a try. Thanks for the heads up.

In a stock machine that would be perfect, also a great alternative to the stock 7805 inside the C64 . Id still like to get a heatsink on there somehow if I could. I have nil experience with these so how does that perform when powering a fully loaded machine + upgrades ?

I was getting to it when I was in the process of rebuilding the board. But I was convinced that it deserves an Ultimate from Lotharek.

It has thermal protection and current limit protection. With that in mind it shuts itself down. These are national semiconductor branded. I believe TI bought them out and probably still have a huge stockpile of these. I’ll take some close ups of it when I get home but you can probably find some pretty good ones online

It uses the LM2596 rated at 3a with a heat sink, adjustable version. See data sheet below for details and specs. http://www.ti.com/lit/ds/symlink/lm2596.pdf Yes there are plenty of cheap Chinese fakes that cost a couple of bucks. This was around $7. Ive been using one in my C64 powersupply for awhile. Ive had no issues yet.

Just sharing some info that might help someone here. I'm a little particular when it comes to powering my precious 8 bit machines with old power supplies. The Atari power supply pictured below was one of the first types distributed with Atari machines in Australia during the early days. There is also an identical looking one that goes with the c64. The only good thing about these is that they're rebuildable. Besides there being no mains fuse anywhere they utilise a very simple circuit and a 7805 linear regulator which runs very hot ( even with a heatsink ) and is very inefficient. Here is the schematic which almost matches this circuit for the original power supply I have. I want to replace this with the more efficient switching regulator so I chose this DC-DC buck converter. I begin by doing some prep work and cut two wires to equal lengths. All soldered up to the input and outputs. I remove the cover of the power supply and the heatsink. Two things have to go. The voltage divider ( two resistors ) and the voltage regulator. I also remove the large cap temporarily to test it before putting it back in. At the time of writing I realise that I don't need the smaller cap on the output so I'll remove this later once I get my fuses. I power up the supply to locate 12v with my meter. This will be the left most pin ( input ) of where the 7805 used to be. Diagram of the device from the front. I solder the red wire to where the input used to be and the black wire ( ground ) to the ground pad of PCB then power it up. The module has a blue LED that lights up when it's powered on. I connect my DMM to the output of the module to check the voltage which I'll need to turn down. There is a little trimpot on the module. You'll need to turn it anti-clockwise quite a bit before the voltage starts to change. I adjust the voltage to just over 5v because I know it's going to drop under load slightly. I now connect the other ground wire to the ground pad and the red wire ( positive ) to output of where the 7805 used to be. With the Atari 65XE powered up the voltage only dropped by a hair. Final adjustment to 5v Optional step on the scope. Checking for a nice clean DC signal Just making sure she pasts the hardware test. I've been running this for a few hours now and the voltage and temperature is really stable. Even without a heatsink this barely gets warm. Not bad for a few bucks

Only ordered from him once and he was really pleasant, shipping was super fast to Australia. Got one of the last NOS 1050 power supplies from him for my NTSC 800, already had a 240v to 115v stepdown so that wasn't going to be a problem. Besides, those are impossible to find in Australia and it was cheaper to buy from the U.S than to build my own from scratch.

Get yourself an Ultimate-II+ cartridge. That's probably the best investment I made on my c64 recently.