yamaha a-960 no sound or lights?help...

sleepyweasel

sleepyweasel

Well-Known Member
I just got a a-960, but its not working. I read on another site(thevintageknob) that if the LED for the power button isn't lighting up then nothing will work? It will light up the mm or mc red led, but nothing else.

I only found one fuse (250v 12amp IIRC...pretty sure its good, because i get no red mm/mc light with it pulled) are there others, or is this led most likely the problem.....if so what do i do to fix(or bypass to check?) the led(sorry noob).

thanks for any help, -K
 
:worthless

I'm not familiar with that unit, but does it have a protection relay? If all the fuses are good, maybe the other lamps are all burned out. Check to see if it has pre-out/main-in jacks in the back. If it does, are the jumpers missing?

EDIT: Don't be afraid to take the cover off and have a look around for anything that may look amiss. Broken wires, blown fuses etc.

Are you tech minded enough to go inside with a volt/ohm meter and do some basic checking? Even without a schematic, its possible to do some basic power checks with a volt meter.
 
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cademan said:
:worthless

I'm not familiar with that unit, but does it have a protection relay? If all the fuses are good, maybe the other lamps are all burned out. Check to see if it has pre-out/main-in jacks in the back. If it does, are the jumpers missing?

EDIT: Don't be afraid to take the cover off and have a look around for anything that may look amiss. Broken wires, blown fuses etc.

Are you tech minded enough to go inside with a volt/ohm meter and do some basic checking? Even without a schematic, its possible to do some basic power checks with a volt meter.
Click to expand...

I'm not sure if it has a protection relay.....There is another thread on the a-960 with attached files that may help me, but i dont have the correct software to open them.
I have taken the cover off, and nothing looks too obviouse, will look a little more though. read this, as it describes exactly what mine is doing....says if power led doesnt work then no sound.
http://www.thevintageknob.org/YAMAHA/A960/A960-numbers.html

Looks like at least a place to start, any idea what type LED I need to use? I can go to radio shack in the morning:dunno:

can I test the wires to the led with the meter?or are leds too low voltage to test?kinda strange that the led not working makes the whole unit go down?????

I definately can check with my multimeter, I just don't know what to check...LOL....also I don't know the terminology, so be descriptive...haha
 
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I read the link, and it basically says that if there is no LED illumination, then there is no sound. What this means is that if there were a power supply problem and no power is coming off of the power supply board, then the LED will not lite. Not sure where you got that link or if the guy even knows what he's talking about.

The LED itself is just a visual indicator and really has nothing to do with the unit not functioning. LED's vary rarily burn out, but if you think its bad, then disconnect the LED from the receiver and try it with a battery. If the LED lights up with a battery, then the problem is else where and I would assume it to be a power supply problem.
 
I had to re-read it a few times, I think what hes saying is if there is a problem with the power button led, then nothing will work EXCEPT the red led "MM"........I thought the same thing..." how the..:nono:..would an led not working power the whole amp down?"

What size batery to use:banana:
 
sleepyweasel said:
I'm not sure if it has a protection relay.....There is another thread on the a-960 with attached files that may help me, but i dont have the correct software to open them.
I have taken the cover off, and nothing looks too obviouse, will look a little more though. read this, as it describes exactly what mine is doing....says if power led doesnt work then no sound.
http://www.thevintageknob.org/YAMAHA/A960/A960-numbers.html

Looks like at least a place to start, any idea what type LED I need to use? I can go to radio shack in the morning:dunno:

can I test the wires to the led with the meter?or are leds too low voltage to test?kinda strange that the led not working makes the whole unit go down?????

I definately can check with my multimeter, I just don't know what to check...LOL....also I don't know the terminology, so be descriptive...haha
Click to expand...

No LED -- No power-- First thing to check is fuses cause you have a inop power supply.No power supply-no work..LED's very very seldom fail.Need to troubleshoot the power supply.
 
To start, the A-960 does not have LEDs for those illuminated push buttons, but uses 14V lamps. Second, it's Achillies heel is the balance control.
 
It works!!!

It wasn't an led, it looks like a small lamp, and it was blown, bypassed the lamp and it works great. ......tried to replace the bulb, but it blew emediately(replacement bulb was 6v - 25mA) any ideas on a replacement lamp voltage?

original lamp is marked "TOSIN" on the shrink wrap, and underneith "2 0"
( zero is smaller yet than the 2 and has a / through it)
 
merrylander said:
To start, the A-960 does not have LEDs for those illuminated push buttons, but uses 14V lamps. Second, it's Achillies heel is the balance control.
Click to expand...

sorry, merrylander, i didn't refresh before my last post. I also did some digging and it seems those 14.5 80mA bulbs are hard to come by, is there anything at my local radio shack that will work?any way to use a resistor and a 12v mini lamp? any reason i cant just bypass the lamp and twist those wires together?

It must have 2 achillies heels, because a bulb burning out and shutting the whole unit down is kinda wacked.

EDIT: what program do i need (besides PSP) to open those attachments in the other thread?
 
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Jon_Logan said:
DONT do that! get a 15 volt 1W att zener in there or something else. There's a service bulletin explaining Yamaha's solution. ...probably in that other thread



hence the A-960 II
Click to expand...

where do i get a zener? you will have to excuse me, i dont know anything about these beasts.

the bulb acts as a fuse then? can i get a .08amp fuse?if there is such a thing
 
You can get a zener diode from Digi-Key among others. Maybe Radio Shack will have it, but I've left them more disappointed then happy these days.

Your right, the lamp acts like a fuse ....sort of. If the current path is broken, some portion of the circuit gets no current. A fuse does behave this way, but the lamp has a larger voltage across it than a fuse would have. You need a component in there that has a voltage drop across it, while suppling current. ...like a lamp (of the correct type) or a zener diode (of the correct type). .....but not a fuse, or twisted together wires. A 170 ohm, 2 Watt resistor would work too, if you don't care about replacing the lamp. You could always install the resistor or the zener doide and put an LED with a series 1k ohm resistor for the Power "lamp".
 
Contact Dave (dgwojo) for the correct bulb. Looking at the schematic the power lamp seems to be in series with the protection relay, so it could be as simple as putting in a new lamp.

BTW the A-960-II was because of some litigation by Carver over the power supply in the A-960. Personally I hate those damned power supplies, real Rube Goldberg.
 
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The A-960 II has the balance control problem too - it's not limited to the original A-960.
 
...whatever the reasons Yamaha went from the A-960 to the A-960 II, the series II does not have the "lamp out, no power up" problem.
 
ecluser, thanks for the pdf's you sent me.

it looks like no matter what i need those 14.5v bulbs. can i just put that in or is the zener mod a must. i have a hard time reading the wiring diagrams, just never needed to before now:tears:.

jon sugested a 15v 1w zener diode, would this work ok? or a 170 ohm 2 w resister.

If I can I would like to get away from the 14.5volt bulbs....hard to find now, how hard will it be in 5-10 years from now. i dont have to have an LED, but it would be nice. anyome care to whip up a layman's wireing diagram for that? thanks for all you guys' help
 
I preffer the zener option. The purpose of the zeners is to protect the lamps from burning at power-on, particularly when less than three lamps are supposed to light up.

It's been a long time since I worked on my A-960. Before I bought the service manual for the A-960, I worked with a manual for the A-760 that was on line to figure how this circuit works. Someone reported that he used 14.5V lamps shunted by 14V zeners in his A-760. Since 14.5V, 80mA lamps were available locally, this is the mod I implemented in my unit, and it works.

It is possible to swapp the bulbs for LEDs, you may need a 180 Ohm (2W) resistor in parallel with each LED circuit, in order to have approximately the same current in TR351.
 
I would like to explain why the amp will not work if one of the lamp is burnt.

In normal condition, there is 6V at the base of TR351. This voltage is set by the zener diode D334. At this moment transistor TR346 conducts and activates the photocoupler TR501, which is part of the preregulator board.

If the collector of TR351 is open (burnt lamp), TR351 doesn't conduct from collector to emitter but his Base-Emitter junction is still present in the circuit. There will be a very small current (~ 1.15mA) in the network R448//R449//R450, from resistor R436 connected to the 55V supply. The base of TR351 will be at ~1.3V. This will be also the base voltage for TR346. Since the emitter of TR346 is at 5.5V, TR346 will not conduct. This will prevent the optocoupler from turning-on the amp.

I've made a sketch but I can't joint the file, my cota is almost over!

If you want it, PM me and send me your address. I will send you the file.

Have a nice day!
 
thanks

Here is a simplified diagram that was sent to me by ecluser.
 

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