Yamaha M-60 Power Amp Adjustment and Demo
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- Опубліковано 19 сер 2024
- I have a Yamaha M-60 power amp in my second stereo system. It ran into the speaker protection mode recently. I used this opportunity to do a bias adjustment based on MFR's service manual. Also I compare it with my back up unit (Anthem MCA 30) by doing a demo test. The result tells me why I still love my M-60 power amp.
I picked up a MX600 from Ebay about a year ago, it didn't play so I picked it up for $52 plus $70 shipping, I installed a new cord and when I was inspecting it, I found a crack on the circuit board, repaired that and it's been working fine since, good video
Very nicely done. Can't thank you enough for taking the time to explain this process in a way that doesn't read like stereo instructions. (So to Speak). Subscribing now.
Thanks for the tip! However you should never put another component on top of an amp covering it fully like you did with your 5 disc cd player. An amp needs air around it. I’ve had my MX-830 for 29 years running fine the whole time. But I’ve let it breath nicely the whole time. Heat kills components- that’s a fact.
Thank you for the comments. You're absolutely correct. If the amplifier doesn't have good ventilation, the excessive heat affects how electronic components function and reduces their overall life span as well.
The M/60 runs warm enough without anything on top. I can imagine it went into protection due to the lack of ventilation.
Absolutely LOVE my Yamaha gear! I think my M-60 needs an adjustment like you has shown, thanks!
Yamaha sound is true music.
Klasse gemacht..
Sorry to bother you does your protection light come on when you first fire your yammy up then cut right off?
Vance
Yes. Because the protection circuit detect the higher voltage when starts turning on the power. It will stay on if the voltage of output does not go down to near 0 volt. Usually, the amp will take a couple seconds to kick in the speaker relay (which is out of protection mode) if the amp works properly.
never understood why they didnt put a wee fan in these furnaces ..... oh, ya the sooner they f up i guess you buy another one .....
Thanks for making the video.I too have a Yamaha m60 amp,,i bought in like New condition for $10.00,,couldn't pay for it fast enough.
Did you check the bias after pressing the auto class a button??
And did it reach 110mv??
My amp works fine and I just got done checking and adjusting the bias and removing the dried capacitor glue.
When I press the auto class a button it only goes to 82.4mv and 76.1mv not the 110mv like the manual suggests.
Is anything wrong?
Should I be concerned?
I apologize that I missed your 2 moths old comments. However, I didn't check the bias of AUTO A-CLASS button after checking A-B class bias. Also I think it is normal if it runs around 8omv under A-class operation - see threads from website :
www.diyaudio.com/forums/solid-state/291165-yamaha-m65-bias-adjustment-2.html
Would you say the same goes for a M65??
Yes. The adjustments for bias (idling current) are same. However, confirmation of Auto-A class function needs more than 20 mV (vs. idling) for M-65. And the service manual of M-60 shows exactly bias range which is 100-120 mV.
This is an excellent video, I’ve saved it away. I just picked up an M-65 amplifier and it has absolutely blown me away.
I have two questions:
1. What should I set the gain levers to? 0dB or closer to -2dB? They are being driven by a yamaha rx-a810 receiver. I do not know the output V RMS for the pre-outs.
2. Should I do this voltage adjustment? I have the service manual for the amplifier. I assume the amplifier was plugged in while doing these adjustments? What does changing the bias do?
Thanks!
The followings are answers to your question: (1) To adjust the VU meter you need a signal generator to provide a constant level of 1k hz frequency feeding to M-65 until the speaker output voltage to 28.3V, then adjust VR501(L) and VR502(R) until 0 db LED light up. confirm it by reducing the signal level until speaker output voltage to 25.2V, the 0 db LED should be off. So it won't work if you plan using a receiver's signal to adjust VU meter. (2) To achieve the best performance for the amplifier it requires the transistors are working under proper voltage and bias. The characteristics of transistor may change due to the age. such as the emitter resistance, transfer resistance, and internal feedback resistance, may also occur. The result of these changes is a loss of power gain, changes in bias conditions, and possible permanent damage to the transistor. That is why the amplifier needs these adjustments to make sure they are working properly. Yes, you need the power to be on when doing the adjustments. Hope above info. helps.
@@VintageAudioFan Thank you for your reply.
1. I'm not concerned about the VU meter, I'm concerned with setting the gain for the amplifier (the two dials on the front) to match my receiver pre-out voltages. The input sensitivity for the amplifier is 1.28V. My guess is this should ideally match what the receiver is providing? I do not know. This is not my hobby or profession.
2. This was immensely helpful, and this video inspired me to do what looks like a relatively simple repair (simply adjust two potentiometers) so that I read 10mV across the resistors. I looked at some videos on how an amplifier works and what distinguishes a class A and class AB and class C amplifier, so now I can sort of understand what I'm trying to achieve here. I checked the service manual for the M-65 and the steps are identical to the M-60.
@@FryChicken Sorry, here is the purpose of the setting gain control on your question 1: In general, the amplifiers need to accept an input signal with as much voltage as possible for it to produce full power. The source of inputs today may include phono, tuner, CD player and tape recorder. They all have different amplitudes of output. Less amplifier sensitivity (lower gain setting) helps to reduce noise. When the amplifier gains are set properly, you get full power from your amp without unnecessary hiss or background noise. There are few methods for adjusting gain controls: by ear, with a small amplified speaker, with an oscilloscope or with a distortion detection device. Because we often don't own the measure equipment, so setting by ear with music (i.e. from your rx-a810) is very difficult and can lead to inconsistent settings. Using an oscilloscope to set an amplifier’s gain control is one of the best ways to get an accurate reading. Oscilloscopes work for any frequency, so they are very flexible.
@@VintageAudioFan Ah ok, gotcha. So how do I set the gain?
@@FryChicken I owned quite a few power amplifiers (i.e. Mark Levinson ML-9, Anthem MCA-30, GAS Son of Ampzilla.......) which none of them were built with the gain controls like Yamaha M-60/65. So it is acceptable to leave the gain control to maximum setting (wide open) in most of power amplifiers, and use the control of preamp to adjust signal input feeding to power amp. However, you just don't want turn up the volume (of preamp) to a point causing the distortion. Above is just my personal opinion. Here I attached is a thread on website which include the discussions regarding how to set gain on power amp: audiokarma.org/forums/index.php?threads/setting-gain-on-a-power-amp.728423/
Yamaha M-60 sounds much better (my opinion)
It also depends on the match up of the preamp. I have tried an Accuphase C-240 preamp on Anthem MCA30. The sound is very good. I think it is something to do with the bass, the C-240 makes up the weakness of the MCA30.
Did you have the unit plugged in while testing or using the multimeter to test the circuit?
It needs the power on to do the adjustments.
@@VintageAudioFan Awesome, thanks. Currently testing on my M-70
I have a chance to get a Anthem mca-2 or a Yamaha MX-600u both for the same price, so which one of those amplifiers would you recommend and why?
I don't own exact same amplifiers for Anthem MCA-2 and Yamaha MX-600U as you mentioned. Based on my experiences, I always love the sound of Yamaha's products which were made in between 1976-1980. For example, CR-2020 receiver, C-2a preamplifier and M-2 power amplifier which I highly recommended. I think MX-600u should be placed as same class as M-60 which I gave it a high praise also. Here are two things that you my want to pay attention are (1) the match up between amplifiers and speakers and (2) what type of amp functions you are going to use. Answer (1): Some of the inefficient speakers may need more powerful amplifier to drive them, in that case you may want to consider MCA-2. (2) If you use amp for A/V system, you also may want to use MCA-2 to bring it to higher dynamic range of sound. Other than that I still think the Yamaha MX-600U shall do very well in listening music. I hope this information helps.
My main integraded amp is the Yamaha AX-592 2x100 watts into 8 Ohms i bought it brand new in 1998 and i like it very much but i also want your opinion if it happened for you to test it of course :-)
@@Badassvidsz Sorry, I am not familiar with AX-592 since most of my vintage audio collections were made before 90's. However, The Yamaha's amps are famous for their accuracy and musical performance. So I think you made the right choice when you picked up the AX-592 as your main amp in 20 years ago. Regarding the test, you can download the service manual from "hifi engine". Since the newer amps are built with a lots of IC circuits which are more difficult for doing DIY services. So I suggest that if if it doesn't break, then let it along. Thanks for your comments.
Sounds like the Yamaha has a lower input sensitivity.
Input sensitivity: 1.5 V for 180 W into 8 ohms (Anthem MCA 30) and 1.24V for 160 watts per channel into 8Ω (Yamaha M-60).
Yamaha M-60 sounds much better (my opinion).