STE: After installing Exxos PSU NetUSBee no-longer works.

[stephen_usher]

OK, here's a strange one.

Before I swapped the power supply on my STE my NetUSBee (Lite) worked perfectly on the machine, unlike on my TT.

Now that the STE has the Exxos PSU the NetUSBee is not working at all. In fact it's showing similar symptoms to when it's attached to the TT with unreliable reads and complete failure to write to the chips.

Also, without the NetUSBee attached the STE needs a reset after power-up maybe once every ten or more times but with the NetUSBee attached it's 100%.

Given how much more stable and clean the Exxos PSU is you'd have thought the issues would have been the other way around.

[exxos]

Steve had similar issues, the reset circuit caps need replacing. One of them needs upping in value as well. Can't check right now, but you can just replace both caps, and solder another 10uf across one and if doesn't help, swap the 10uf to the other cap.

Have a look here. https://www.exxosforum.co.uk/forum/viewt ... =10#p22727

Also loading on the cart port trips up because the bus pull ups are inadiquate normally. I had a issue while testing my diagnostic carts, that touching the top of the PCB caused the machine not to boot, that's how sensitive the things are.

[stephen_usher]

Would this also explain why the NetUSBee itself is non-functional? (One in about 20 power-ups it will reset its ethernet chip to the point where it gets a link light on the switch, but even then it doesn't respond programatically.)

Could your power supply be took good and not provide enough over-voltage?

As I said, these symptoms are very similar to the way the NetUSBee behaves on most TTs. Maybe their PSUs are too precise too?

[exxos]

Reset issue is just bad caps. I've not had any issues with my machines but others have. My PSU has a 1amp soft start, it doesn't just chuck 8 amps on the 5v rail. Though when the reset caps go bad, the reset circuit resets before the PSU has reached the full 5v. That results in having to press the reset switch after turn on. Also the reset circuit sux to start with.

Your other issues are likely because your old PSU was probably 4.8v. My PSU is the proper 5v. So you get more voltage across the board which can aggravate noise issues causing malfunctions. This is why I have been saying change the bus pull ups for years as they are not good enough.

Problem with any of these machines, is they are barely working out of the factory. Change 1 little thing and they screw up. Just changing the ROMs in a ste can cause dma issues. Some ROMs in a stfm can cause it not to boot. The list of issues is endless. This is also why I started to design a new motherboard, as the machines age, stuff is going out of tollerence and causing issues.