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[Doug Boyd]

Hi,

The manual refers to a mod that bypasses the on/off switch when using phantom power.

Does anyone have any info on this?  There are two sets of link pads on the PCB but thought I'd ask before firing up the soldering iron.

Cheers,

Doug

[g'bye, Dick Rees]

Hi,

The manual refers to a mod that bypasses the on/off switch when using phantom power.

Cheers,

Doug

Do you mean this?

"The On/Off switch is used for both phantom power and battery. To avoid battery drain when the unit is not in use, ensure that this switch is set to the upper OFF position when storing or packing the AR-133. Optionally, an internal link can allow phantom power to activate the AR-133 regardless of the On/Off switch setting. This link must be changed by an Authorised Technician only. Please refer to your Dealer/Distributor for details."

[Ed Walters]

Hi,

The manual refers to a mod that bypasses the on/off switch when using phantom power.

Does anyone have any info on this?  There are two sets of link pads on the PCB but thought I'd ask before firing up the soldering iron.

Cheers,

Doug

Try https://www.elektrotanya.com/bss_ar_133_sch.pdf/download.html

After looking at it for a while, you'll realize that shorting link 1 will bypass the power switch for phantom, while shorting link 2 and 1 is always on, all the time, battery or phantom.

This schematic is the first Google hit on a AR-133 shematic search.

And, regarding that "authorized dealer" crap above, that's the same rhetoric that says I can't fix my own car. Doesn't work for me. And, I'm an authorized Harman dealer.

Ed Walters

[Doug Boyd]

Thanks Ed, exactly what I was after.

Doug

[Jim McKeveny]

As in most "elegant" engineering:

1 - I do not want to need a DI.

2 - If I do need a DI, I want it to be as dumb a brick as possible.

3 - For a switch to be needed flipped for a DI to accept phantom is absurd. I have used AR-133s before and, because I must consider unwise switch-flipping by prior/current handlers, spec less "featured" products.

"Doing sound" is not about getting shit to work. When it comes to signal: Gimme a hardwire. Gimme a passive. Gimme a Countryman. Wireless?? Whole 'nother story.

[Hayden J. Nebus]

This link must be changed by an Authorised Technician only. Please refer to your Dealer/Distributor for details."

In the USA, Under 15 U.S.C. §2301-2312 1975 (magnuson-moss warranty act),  That clause cannot void your warranty. As a form of product tying, it may also be contrary to the Sherman antitrust act and/or the Clayton antitrust act.

You have a right to repair anything worth more than $15 that you own yourself, or via a 3rd party of your choosing, using appropriate 3rd party parts if you choose, without voiding your warranty. This includes your phone, computer, Etc. Warranty void stickers have no legal standing in America.

[Doug Boyd]

Exactly.  For me it seems illogical to have to activate 2 switches - desk phantom & DI power - to phantom power a DI.

Mod done - works as it should.

Doug

[Steve M Smith]

Does anyone ever use these with a battery?

For a switch to be needed flipped for a DI to accept phantom is absurd.

It is.  The switch could be on the battery only. A diode could protect the battery from seeing phantom power.


Steve.

[jason misterka]

Does anyone ever use these with a battery?



Steve.

We use them frequently with just a battery when using them as an isolation transformer when tying into house systems.  Processor inputs don't always have phantom.

Jason

[Geoff Doane]

Thanks for bringing this "feature" to the forum.  We've got a few of these at the day job, and although they're not my first choice, it's good to know about the potential shortcomings.

I went ahead and did the mod, breaking one jumper, and bridging the other.  The operation makes much more sense now.  If it's connected to phantom power, the DI is powered regardless of the switch position.  If you put a battery in it, you can run it without phantom, by turning the switch on.  There is already a diode in the circuit to prevent the battery from being back fed, even if the switch is on.

Incidentally, one of ours had a battery in it (good until 2008!) and the switch was on, but luckily it hadn't started to leak. 

Jason's application is an interesting one.  The AR-133 wouldn't be my first choice to use as an isolation transformer, but it does have a reasonably beefy transformer in there.  It might be worth noting that it does not have a balanced input, so it really should be used to drive a balanced line, not at the receiving end of a long line.

GTD

[ProSoundWeb Community]