entropy continued?

This is where we talk about testing, measuring and repairing things. Sometimes we have to repair the equipment we use to test, measure and repair other things. It's an endless cycle of fixing the broken things we need to fix other broken things.
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JR.
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entropy continued?

Post by JR. » Thu Jan 17, 2019 9:30 pm

Testing one two... Since much of my entropy thread is about repairs, maybe it should be here.

A new observation about my solar driveway lamp modifications: the stock lamp clearly captures less light than Frank III... So turns on sooner at dusk and off sooner too. But for a bunch of time before winking off completely the stock lamp gets noticeably dimmer than Frank...

For example today that was cloudy and drizzled rain, the stock lamp has already gone dim and then out, while Frank is still full brightness (at least full for frank) With half the inductor it should be half the current as stock...but you can't tell from looking at it.

Yesterday was sunny and frank III was still rocking at 3AM while stock lamp was dead by midnight.

When Frank finally turns off it turns off decisively, as if that is how they should all work?

I have several new stock lamps just sitting but I like the improved Frank III so will see how long it works... I am almost tempted to source some smaller inductors to see how much difference that makes but seriously.... nah. :lol:

JR
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mediatechnology
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Re: entropy continued?

Post by mediatechnology » Fri Jan 18, 2019 1:11 pm

Well, the thread is about entropy.
It only becomes about repair if we actually do something about it. :lol:

But it does make sense to have it here.
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Re: entropy continued?

Post by Gold » Sun Jan 20, 2019 3:49 pm

I’m not sure this exactly entropy. I’m tweaking out a T filter type EQ for my console. I need eight channels for the console. Two four channel units. I have ten channels. I’m tweaking out a two channel version with pots. I will make the final units with rotary switches.

I basically gave up on my iPad setup for this. I wanted FFT so I could see bandwidth and center frequency easily. I’ve been fine with the Portable One. It’s not a visual representation but works fine with tone and gain.

I’m still working out construction details. The main filter PCB’s are about 16” x 4”. The controls are oriented horizontally. I will have to stack them four high. If I use standoffs then getting one in the middle out for service will be difficult.

I think I will mount each PCB on a 17” piece of 3/8”x3/8” aluminum stock. I’ll attach each horizontal piece of aluminum to the side panels of the chassis. That way the top and bottom covers can be removed cleanly. That provides pretty good access. If a middle PCB has to come out I just have to unscrew it from the side plates of the chassis. I have to try it first. The PCBs will be mounted very close to the rear of the four deck frequency selection switches. I’ll use Phoenix terminal blocks to attach the switches to the PCBs.

The EQ is sounding very good. I have to work out the gain steps and the frequency points.

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Re: entropy continued?

Post by Gold » Tue Feb 19, 2019 1:42 pm

I mentioned somewhere in a thread that I may have my first bench tech job at my studio rate. It came through. It's making an external power supply for a Sontec 250. It's mostly a metalworking job. Making the external box and putting a connector on the unit. I think there are a few more Sontec's around town that have been looking for this. As long as this goes well I may have a few more to do.

I will use Power One +/-28VDC supplies. The regulation down to +/-17VDC in the units happens on the filter boards so I'm leaving that alone. I was planning on not using remote sensing. Would you put a flameproof resistors in series with the rails? Would that help reduce any crosstalk through the power supply?

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Re: entropy continued?

Post by mediatechnology » Tue Feb 19, 2019 2:08 pm

Congrats on the bench gig.
I built a nice auto-changeover dual PSU with Condors for a remote truck's Soundcraft console years ago.
It was mostly a metal-working gig too.

How much current do they pull?
I wouldn't do remote sensing either.

I would add fuses to the outputs located in the PSU box.
Maybe add some LED lights after the fuses.
Flameproofs inside the Sontec probably aren't necessary.
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Re: entropy continued?

Post by Gold » Tue Feb 19, 2019 3:34 pm

mediatechnology wrote:
Tue Feb 19, 2019 2:08 pm
I would add fuses to the outputs located in the PSU box.
Maybe add some LED lights after the fuses.
Flameproofs inside the Sontec probably aren't necessary.
I was going to use thermal pushbutton circuit breakers. I've developed a dislike of fuses. You never have the right one and you have to open it to check if it has blown.

I haven't checked the current draw of the Sontec yet. I'm guessing around 250mA per channel. The PSU is 1A per leg. I was planning on hanging an LED from each DC rail.

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Re: entropy continued?

Post by mediatechnology » Tue Feb 19, 2019 4:09 pm

Breakers even better!
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Re: entropy continued?

Post by billshurv » Fri Feb 22, 2019 6:29 pm

Although I dislike doing it, every so often I have to bodge and hope. Tonight was one of those nights. Wife and Kids out so I could get around to something that is hard to do with them in the house. In this case prepping my subwoofer ready to fire it up for the first time in >20 years. I bought it missing bits so I have no idea when it was last powered up. So old electrolytic angst.

I don't have a variac and getting at the caps is a major PITA, so bodge time. Set the sub to 240V and plug it into my 110V transformer so they are at just under half normal voltage. Power on, no fzzt and the standby LED comes on as expected dimly. I feel dirty given I know full well the correct way to do this, but needs must.

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Re: entropy continued?

Post by mediatechnology » Sun Feb 24, 2019 7:39 pm

I recall something about an accelerometer being glued on?
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Re: entropy continued?

Post by billshurv » Mon Feb 25, 2019 5:53 am

Yes there is. That is my biggest worry as to what will happen if the glue has come loose and there is no feedback signal. Getting at it is non-trivial tho so have decided to risk it.

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