12v line running high

[geotrig]

Havent looked into this either , but have a taito ps that the 12v line seems to be running high, cant remember what i metered it at , ran a "test" board with it and nothing seemed out of whack ,sound section seemed to run just fine and no excessive heat on any chips any ideas.
Anyone ever successfully fix a power supply or have similar issue ?

its not related to my other issue !

[nem]

I don't think it will matter. Anything that's being run with the 12V rail isn't very picky about voltage. For instance in jamma boards the 12V rail powers the audio amps. Most amps have a supply voltage range of 10-30V. The 12V rail running low (< 10) is an issue, high not so much.

[geotrig]

Good to know and was somewhat along the lines of what i was thinking but havent seen it before either , the test board ran for ages with no issues I, but i wasnt going to hook up a cave pcb etc just in case.

[zak]

I had my Canary and Egret PSUs recapped, but I still don't trust them.

In the end I bought this for my Taito cabs (Canary and Egrets):

https://www.ebay.co.uk/itm/Power-Adapte ... Sw0m1c-RyG

And this PSU:

https://www.ebay.co.uk/itm/Prima-Black- ... 2749.l2649

Leaves the original wiring intact

[geotrig]

thanks zak that cable is very handy

[ChuChuFlamingo]

I strongly recommend anyone who has an Egret 2 PSU upgrade to a switch mode PSU such as a meanwell. They have better safety precautions than these old linear based ones. Here is the knowledge on why.

the M1300010B model used in the egret 2 (the frameless one, there is another modelwith a cage too) is a linear based power supply. What this means is the incoming AC voltage will affect the 5v rail. Say you put your 5v rail at 5.00 and the AC is 120 in a perfect world. If it goes up by any amount (1 volt AC up or down it is going to affect your 5v plus or minus). I had a pgm cartridge die because of this since the AC voltage went up to 133+ volts AC and the 5v line spiked to 5.3+ at jamma edge. Surge protectors are useless until 250V at best, 350-400V at worst. And no it wasn't just my psu, I had a NOS Egret 2 psu that displays identical behavior.

If you do a quick google you can see old threads on people saying things such as "5v rail pot is already at its lowest and the 5v is too high on low draw boards etc". The remedy to this is to use a 120volt to 100 volt stepdown converter.This alone proved by hypothesis since the voltage was super low with stepdown, high with it off. Note this won't save you on the 5v voltage flucuating even with this since stepdown transformers don't maintain a constant voltage. They just output a certain percentage of the input to the output within range.

It took me several years to notice this.No one would be the wiser. So yeah I wonder how many games have silently died because of this. By my calculations every 1 AC volt was equal to around .01-.02 more volts on the 5v line.

[markedkiller78]

Totally off topic here, but the egret 2 is meant to get 100v in.

By all means, replace it with a better, newer PSU. Tech has moved on a lot in 30 years. I would definitely “upgrade” if I had a problem with mine.

That being said, 133v is fine on a 120v appliance, but 120v on a 100v cab is +20% and already outside what’s regarded as a safe margin. 133v sustained is a problem waiting to happen.

Mains voltage does fluctuate and tolerances are built into it +/- 10% should be fine. It’s different in the uk, we’re 230-250v here, so need to step down but I’d always be stepping down to 100v as a starting point

[cools]

I strongly recommend anyone who has an Egret 2 PSU upgrade to a switch mode PSU such as a meanwell. They have better safety precautions than these old linear based ones. Here is the knowledge on why.

That's pretty interesting. Any way of telling (visually) whether a PSU is linear or switched?

[ChuChuFlamingo]

Linear use big ol transformers like AC adapters, take up more space, and weigh more. So if you see big coils/a transformer chances are it is one. Other than that you would have to look at the circuit.

Switch mode psus in comparison have a massively smaller footprint and weight.