Technics SU-V9 adjusment procedure questions

right channel i am monitoring its -ve

21.9 / 22mv at 10mins another 5 later, had to turn off clicking sound again, around 23mv i think didnt look more concerned to turn it off

nice warmth on heatsink this time at 10mins ( not overly warm) again Q6111 and its heatsink has all the heat

let it cool and check

right channel at 1 min

then will monitor left

what the hell is the clicking:dunno:, wasnt present earlier, maybe leaving DMM on all the time from start up


fired up again right channel ( didnt have to adjust left, but maybe gave right too much)

around 30 secs and a bit - 0.8mv then the clicking sound again, i turn it off


mmm, so maybe service manual is correct 1mv at 1min then it warms up to 21 -23mv range, dont want to cook the poor V9


previous post:
left channel, was good went to 1.1mv in a about a minute

right channel, not sure started low, may have turn it up a bit more, but i had it at 1.2mv at about 1 min currently 5mins - later 18mv, see what is at 10min

** attempt again ***
clicking sounding - my brother had a look also, around or under diodes maybe a transistor - strange reaction with DMM

update:
fired up sound was happening, my brother filmed while i monitor meter 1.5 mv around 45 secs so higher than left, which also made the same sound

video soon
 
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after removing ear plugs and looking at the video is the relay - sure i got the speaker selector turned off not sure why its going a bit crazy with the meter First click is the relay

hope the relay is not damaged can hear a clck springy sound

maybe set speaker selector as per manual for adjusting and re adjust after bias?

 
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Are you measuring across one 0.22 ohm resistor, or across 0.44ohm (external pins of double resistor)?

Just check the values I mentioned (mV vs mA) Having around 20 to 50 mA flowing won't damage the amp, if bias stabilizes around that. Don't mix mA with mV. If you are measuring across ONE 0.22 ohm resistor, 10mV means 45mA. I'd stay under that value. If bias keep rising , turn off the amp, turn the trimpots a bit back, and try again.

Adjust everything in the same order the manual specifies.

If in doubt, keep the bias on the low side. Some amps are idling with just 12 to 20mA.
 
Not sure if one of the relays load impedance or soft tap relay act as a protection relay also.

0.22 ohm for one channel and 0.44 for both? not sure how to read mA. Right channel got to around 22 23mv, its a bit high maybe, left was 1.2mv at 1min

half of one to middle point 00.5ohm and a and end pin of left 00.7 and same values for right

trimpots left 2.3 ohm and right 1.3 ohm, then back to resistors 1.6ohm. I turned right trimpot back a little as was 1.8mv at 1min vs left at 1.1mv

might need to desolder and turn trimpots back to zero ohm and start over, adjusting to 1mv at around 1minute
 
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Don't worry about trimpots resistance, just adjust the bias current to a safe value. 23mV across 0.22 ohm is 104mA, a high value for bias current.

If you are measuring across one single 0.22 ohm resistor (between middle pin and one end), keep the voltage under 10mV. That's 45mA, quite safe value for any amplifier. 5mV means 20mA, even safer. If with 5mV the amp sounds OK, I'd set it there.
 
It was sitting arond 21- 23, i heard the relay sound almost 24. I never monitored left over the clicking relay sound. Seemed to sound okay with zero ohms, try to get to 5mv or 10mv a channel
 
Adjust like service manual says, at 1st minute, and monitor voltage, and if it goes too high, try to adjust a bit lower. As I mentioned, bias is a very small current compared to the amp playing loud, so even 100mA (0.1A) won't damage the output transistors (which can dissipate several Watts, and for sure several Ampere).
 
Baily,
Thanks for checking, I had the V9 a bit on the high side23/24mv , desolder and turn trimmers to 0 ohm and around 20mins and near will start to turn up or follow manual and monitor
17mv 20mins for both channels, dial in left and right at 17mv

Baily , Fernando, new problem also with relay clicking randomly - not sure what caused it, goes funny so is not a good idea to do adjusments

I am thinking it was fine till i started with the bias? maybe turn down and max out trimpot as per manual and do impednace once bias is done
 
checked J20 from main to speaker pcb pin 3 + 16.73 and pin 2 -16.76 V
DC offset 00.4 left but seems to spike quickly -70 then back to 00.4
right channel 01.4 spikes quickly and returns also

dim bulb amp clicked once with speaker selector off and stayed dim
fire off amp power up speaker selector in, one click THEN clicking issue again

touched a bit of solder that might be suspect dry joint

anyway the same

2 clicks, then alittle later one the random clicking with speaker selector in


this might help , it was working prior to doing adjustments - meter upset it? something else or bias high or something else

ran it on low bias ( trimmers at zero ohm) for 2hr or so
 
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Remember, you need to do all the adjustments without the DBT.

I don't think the bias is related to your relay clicking. You was fixing and adjusting the impedance detector circuit, the problem could be there too.

If bias is steady, let it alone by now, (or if you want, turn it down a little), and focus on the relay. Identify the function of that relay.

If it starts to act up when engaging the speaker selector, narrow the search there, perhaps a solder bridge. Without speakers connected, it shouldn't be any difference with speaker selector engaged or not. If speakers connected, perhaps the impedance detector is just at some threshold engaging and disengaging.

Check DC offset just in case, speaker selector engaged, no speaker connected.
 
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i set up impedance circuit perfectly 0V and -0.1v.

i intially heard faint click when i turned on the meter to do the bias, sometimes i turned meter on before turning on the amp?

speaker selectors not engaged, still the faint click , but now it clicks and then clicks randomly

i'll check DC offset again/ See if transistor to relay is okay
 
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Make sure you have the DMM set to measure VOLTAGE, not AMPERES. An ammeter is a short circuit for any circuit you connect.
 
i have it on mv, and i assume that A---- is the mA secton with 20m 200m and 10. The V9 seems to run to problems, now relay clicking, maybe its a protection or another issue

possible cause - solder blob on speaker pcb that must have dropped from my box i had on amp

powered up amp - no clicking after 2 mins so maybe is good, checked Q707/6 C/E 1 and C=E 1/1614

I feel stupid with that mistake but hope that is all it is or not something else
 

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* update *

started amp, speaker selectors not engaged, just one click then not anything else

turned on amp
checked at 10mins around 8mv
checked a little after 20mins 22.9mv and only 8.8mv left

adjusted both to 17.0v

made a few adjustments after 20mins maybe another 10 min or so to get them roughtly the same bias

heatsink nice and warm to touch, it would never get warm only if played for a long time

14.6 and 15.2 around before turning off?

should i fire up and concentrate on one channel at a time do that then re fire and do the other?
 
If bias is sable at those values I'd let it alone by now. You could do a new test, just power on the amp and see if it stabilizes again without any intervention at those values.

And forget about it, and focus on the relay problem, if still there.

15mA across 0.22 ohm is 68mA, that's fine.
 
last time no relay problem just one click but speaker selector was off

i will try to see if it settles and stays stable without much fluctuations

since right channel was the higher starting with that

1min (littler over 1.1mv)

report and update at 20min

once i sort right move to left

UPDATE:
17.8 highest around 20mins , so did a few adjustments 30mins plus

i got both sides around 17.0mv (slight fluctuatons 16.9 17.0 and holding -17.3 during monitoring)

amp has never been so nice and warm - heatsink never been warm even after long play i could touch it! The repair place in Germany didnt do bias or something? - i can see the connectors have been out before ( input phono)
 
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Small fluctuations are normal, it's the thermal tracking circuit doing it's job.

I'd try sound with headphones, or speakers to see if the relay is working OK.
 
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