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NEC TG-16/TE/TurboDuo => TG-16/TE/TurboDuo Discussion => Topic started by: JohnnyPhantom on December 06, 2012, 04:14:38 AM

Title: Using a AC adapter on a TurboExpress with lower voltage?
Post by: JohnnyPhantom on December 06, 2012, 04:14:38 AM

Hey everyone,

looking for the possible dangers here,
I have a power adapter that came from a old device thats been trashed long agi (possibly speakers or something, I always save the cords on stuff I toss) it has the right amps and polarity to be used on the Turbo Express, and the tip fits! but!

The voltage is only at 5v not the 7v the system wants. I know to use anything over 7v is bad since it could blow something.
but what are the dangers of using a power supply thats slightly less than what is asked?

I tested it and the device powers on and works what appears to be just fine, are there any long term effects?

Thanks everyone!

Title: Re: Using a AC adapter on a TurboExpress with lower voltage?
Post by: thesteve on December 06, 2012, 04:30:03 AM

at 5V it wouldnt work, so check it with a meter.
ran mine on 4 D batterys 6V for years no issue

Title: Re: Using a AC adapter on a TurboExpress with lower voltage?
Post by: JohnnyPhantom on December 06, 2012, 04:42:22 AM

Measured with a multimeter, the AC adapters pushing out 5.12V

I may be jumping to conclusions, I replaced all but 2 caps in the device, so I'm getting audio, and backlight, but not video just yet (waiting on the two caps to arrive in the mail, either tomorrow or Monday I'll have them) but it's acting exactly the same as with 6AA's I'll know for certain in a few days once the other caps arrive.

Title: Re: Using a AC adapter on a TurboExpress with lower voltage?
Post by: thesteve on December 06, 2012, 04:48:51 AM

5.12, will likely run a bit glitchy, as the regulator cant make 5V for the chips.
check the voltage at the card slot

Title: Re: Using a AC adapter on a TurboExpress with lower voltage?
Post by: JohnnyPhantom on December 06, 2012, 04:58:12 AM

where would I measure the voltage on the card slot?

Title: Re: Using a AC adapter on a TurboExpress with lower voltage?
Post by: JohnnyPhantom on December 06, 2012, 05:04:14 AM

If I measured the correct points, I get 4.38V, measuring ground with the far right top pin of the board, if looking at it from the inside, has the thickest printed circuit that runs all the way to the left that connects to the first pin on the ribbon cable.

Title: Re: Using a AC adapter on a TurboExpress with lower voltage?
Post by: thesteve on December 06, 2012, 05:59:35 AM

that is correct.
it should be 5V

Title: Re: Using a AC adapter on a TurboExpress with lower voltage?
Post by: JohnnyPhantom on December 06, 2012, 06:15:43 AM

do you get 5V there when running off the 4Ds at 6V?
I'll have to play with it more when I get the screen 100% up and running and look for glitching.

Title: Re: Using a AC adapter on a TurboExpress with lower voltage?
Post by: thesteve on December 06, 2012, 06:24:13 AM

i didnt check, at the time, but the regulator is solid at 0.7V drop
so anything above 5.7 should work

Title: Re: Using a AC adapter on a TurboExpress with lower voltage?
Post by: JohnnyPhantom on December 07, 2012, 04:03:01 AM

Ok System has been fully recapped, plays great, and tested with the 5V AC adapter, and the system runs fine, no glitches thus far, I'll post more findings once found