How to check DC offset without any tools

What tools do I use? • Must-Have Tools For Wo...
This is a fun little DIY something I noticed playing around with vintage stereos over the years. Technically, you could fully adjust the DC offset without a multimeter, but I would not necessarily recommend that. This video is just for CHECKING, not setting. This applies to any receiver or amplifier with adjustable DC offset. Marantz, Pioneer, Sansui, Kenwood, and many other stereo brands made models that have adjustable DC offset, so this applies to any of those. Thanks for watching!

[@davidhigginbotham5451]

I learned more from your video that any of the DC offset content on KZbin that I've watched so far. Great tip!

[@texasamericanpatriot8535]

Thank you demonstrating simple old school electronic technique/diagnosis.

[@hpjunkie69]

Simple yet very effective.

[@ChillToMusic87]

Informative video, thank you.

[@michaelmalodrums9674]

Cool Tip my friend 👍🏼

[@andrewlittleboy8532]

Just checked mine and had 17mV on the right and 10mV on the left so made a quick adjustment. I have read that anything under 25 is supposed to be considered very good but may as well have as close to zero as possible.

[@pierrekitts7089]

Great tip, love your videos just about to embark on a full recap of a Marantz 2235B, I also have a 2250 and a Sansui 9090 to do as well. Suttle but important details you bring up in your videos are crucial for doing this hobby. Thank you and keep them coming.

[@CM-dw3gh]

How did the recap go Pierre?

[@pierrekitts7089]

@@CM-dw3gh have not found any time yet to complete the recap.

[@CM-dw3gh]

@@pierrekitts7089 I hear you. I've the same plans but time is never on my side either

[@paopaolin9400]

May I ask some question,what happen if we measure bias voltage and dc offset with the interconnect cable on and with speaker cable hooked?

[@ToHerbiarz]

Thanks!

[@radu5247]

Thank you!

[@mr.selfdestruct2917]

So cool.

[@Yiannis2112]

Very useful tip, but what is it that you change-regulate with the screwdriver? Also what will happen and why, if you touch the chassis with the white (+) speaker wire, as someone below suggested NOT to ever do?

[@mat.b.]

he turns the voltage regulator with the screwdriver

[@mat.b.]

so just to make sure, you have negative connected and you brush positive on the terminal, and if the speaker makes static then theres a DC issue?

[@AHFixIt]

Polarity doesn't matter but yeah, you got it. Always best to check with a multimeter though.

[@belabertalan]

That's a great trick, thanks. Where do you set the volume at when measuring dc offset?

[@AHFixIt]

0

[@belabertalan]

@@AHFixIt Thanks 👍

[@davewallace8219]

thank you

[@lucaspatterson]

Curious where you source your components from? Do you usually install new pots?

[@AHFixIt]

I get everything from Mouser and Digikey. Trimmer pots some are known to be troublesome and I'll replace those, but most of the time they're fine and can be cleaned with deoxit f5

[@Mr.-Wint]

The static noise on the right channel messured 0.60 but fluctuating, - the noise free left channel 0.08 and stable, - any suggestions ?

[@AHFixIt]

I'd consult the service manual for your unit and see if there is an adjustment for DC offset, and adjust it accordingly.

[@embermanalo7496]

Hi, just want to get your personal opinion inline with voltage biasing. Is it possible to properly adjust bias voltage using an ordinary digital multimeter. Thanks...

[@AHFixIt]

Yes! I do it here: kzbin.info/www/bejne/g5DSmYt7gK6qjZo

[@embermanalo7496]

@@AHFixIt Thank you for your prompt response inline with my query. Now I am confident to using it after I finish restoring my Sansui A-7 amplifier. Is it ok to ask more question in the future?...

[@AHFixIt]

Of course, I try to answer as many questions as I can. Be careful with sansui, they will give the bias in mA and you need to look at the schematic and convert it to volts with ohm's law. I can't provide much detail beyond that, unfortunately

[@embermanalo7496]

@@AHFixIt Thanks for the advice, I really appreciate it. No worries I had the schematic diagram and you're right, that the bias voltage is in mV...

[@johnroady9495]

I've been googeling for a while but couldn't find it: If we look at the back of a Marantz 2225, the following speaker output is connected to the white adjustment knob: Speakers main: R+ (left top) = R712 L+ (right top) = R711 Does anyone know to which speaker output R733 and R734 are connected to?

[@johnroady9495]

ps. I have pressed the 'Remote Speaker' function, but I don;'t hear any crackling when I turn the R733 and R734 knobs

[@kuronekosan2830]

Hi I have a 7.2ch av reciever and i just checked the dc offset I got the following results Pls tell me if any of the channel needs to be repaired Dc offset Front right -0.5 mv Front left -0.2 Center -5mv Surround Right -35.7 Surround left 5.1mv Height right -29mv Height left -12mv

[@carlrudd1858]

Well done. I guess my only Q would be - How did the DC offset become so out of adjustment in the first place.?

[@mat.b.]

he manually changed it for the example

[@carlrudd1858]

haha, well, there is that. Thanks@@mat.b.

[@timbabyfacesavage377]

Nice. I have a question for you do you sell any of you're stereo receivers ?

[@cpgixxer]

Touch the white wire to the output case and see what happens.....

[@AHFixIt]

🤣🤣

[@pauldow1648]

Could you answer your question.please.

[@JasonMontell2501]

@@pauldow1648 I think it releases the magic smoke

[@MiguelAngelVelazquez]

I'm not sure if a multimeter is the right tool to measure DC offset. You are measuring volts rms. Only with an oscilloscope you can see the full waveform and confirm it is fully symmetrical which means the positive peak matches the magnitude of the negative peak. In this case the wave center is on 0 volts which is not the same as 0 v rms measured by the multimeter. Knowing peak to peak or rms voltages tell us nothing about the symmetricality of the waveform. Nice video by the way.

[@v12alpine]

DC Multimeter is the correct tool. He's not talking about an AC waveform offset. It's the idle DC offset.