Using a Digital Multimeter + Amp Startup Procedure - AT THE BENCH!

Музыка

A Mojotone 45 kit build has been dropped off for me to do final checks and startup. In this clip I show you how I go about using the DMM to verify some basic voltage readings and adjust the bias.
Stay tuned for an Oscilloscope clip to follow with this amp.
0:00 Case study - Mojotone 45 kit
1:20 Bench setup
2:22 First Power up
3:54 Check Heaters
5:13 Check Bias Voltage
9:03 Out of Standby!
10:55 Measuring Plate Voltage
13:30 Screen Voltage
14:19 Phase Inverter Node
15:29 Preamp Node
16:35 Using a Bias probe
18:13 Adjusting the Bias
19:04 Rechecking the Voltages
20:23 Checking preamp socket pin voltages
21:49 Final thoughts
headfirstamplification.com

Пікірлер: 21

  • @Deus5691
    @Deus5691Ай бұрын

    Outstanding Video! You have wonderful way of explaining the technical aspects of why and what you are doing, that even a novice like myself can follow and easily understand, Bravo!!!!!

  • @HeadfirstAmps

    @HeadfirstAmps

    Ай бұрын

    Thanks!

  • @clintn6677
    @clintn66773 ай бұрын

    Haha I just built a Mojotone build using Alex's pcb and was wanting to find a vid on first power up and this is the first vid that popped up. I should know just go to your channel by now

  • @cheyneluke9330
    @cheyneluke93303 жыл бұрын

    Perfect timing! I’m nearly finished my amp and this is gold! Thanks Jason!

  • @chaos1291975
    @chaos12919759 ай бұрын

    thank you so much for making this video. i have just started on amps and could not find a good video explaining first start up and checks . i have just finished my jcm 800 build and i was not going to turn it on before finding a video on voltage checks and yours was perfect. you explained everything so someone new could understand. you also explained why you had to do these check. I would recommend this video to anyone new to amp building. i cant wait to see more of your videos. thank you again

  • @HeadfirstAmps

    @HeadfirstAmps

    9 ай бұрын

    Welcome aboard!

  • @hrsey71
    @hrsey712 жыл бұрын

    very helpful video! i had a bad (new) EL34 and it red plated. i wasnt paying attention and didnt notice until i saw smoke coming off the glowing resistor on the tube socket. thankfully the resistor did its job and didnt ruin anything

  • @brucetaylor1753
    @brucetaylor17533 жыл бұрын

    Great video. Looking forward to part 2.

  • @prook2001
    @prook20013 жыл бұрын

    Thanks Jason. This is very helpful (as always).

  • @petercornell2002
    @petercornell20023 жыл бұрын

    Great video, thanks Jason.

  • @VailAvenue
    @VailAvenue3 жыл бұрын

    Great video. Very helpful!

  • @rnrmfguitarworks
    @rnrmfguitarworks3 жыл бұрын

    Great vid! One other safety recommendation I would add: remove any watches/bracelets/rings on the hand you are using the probe with. 🤘🏻

  • @HeadfirstAmps

    @HeadfirstAmps

    3 жыл бұрын

    Agree with that tip!

  • @beachsidetech
    @beachsidetech3 жыл бұрын

    Great Video! You don't recommend using a variac to wind up mains on startup? I know some guys do that. Also, can you show how you connect the bias current meter? I don't think that was shown.

  • @HeadfirstAmps

    @HeadfirstAmps

    3 жыл бұрын

    I don't own one, never have. Just flick the switch mate! I show a still picture of the probe setup in the video at 16:58

  • @beachsidetech

    @beachsidetech

    3 жыл бұрын

    I can see how the meter itself is setup but you just say it’s connected to the power tubes but doesn’t show how. Thats what i was asking about.

  • @HeadfirstAmps

    @HeadfirstAmps

    3 жыл бұрын

    Ah ok, gotcha. Its one of these, www.amazon.com.au/dp/B07CR5DN1V/ref=cm_sw_r_cp_awdb_imm_E9CBNWAVFNKP1YFT7FP0 You plug the probe socket in between the tube and the chassis socket

  • @tallkien2250
    @tallkien22502 жыл бұрын

    Probably better to use a 10ohm load resistor instead of 8. Impedance and resistance are not 1:1

  • @HeadfirstAmps

    @HeadfirstAmps

    2 жыл бұрын

    They are not the same thing at all.

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