Yamaha A-500 and A-520 Thread

Hello Everyone!

I found it the little bastard, of course the MATSUSHITA JD2aD Relay, currently i clean it with Kontakt 60 (washed out isoprophyle and finished it with Kontakt 61) now its perfect but i look after the replacement. Also i ordered the new capacitors, when arrives it i replace them.
Best wishes!
Megott
 
Hello Everyone!

I found it the little bastard, of course the MATSUSHITA JD2aD Relay, currently i clean it with Kontakt 60 (washed out isoprophyle and finished it with Kontakt 61) now its perfect but i look after the replacement. Also i ordered the new capacitors, when arrives it i replace them.
Best wishes!
Megott

Good work! And welcome to Audiokarma.

For the relay, this will work just fine.
https://www.conrad.de/de/printrelais-24-vdc-8-a-2-wechsler-finder-405290240000-1-st-502882.html
You will have to cut off 2 legs and then it will be a drop in fit.

Cheers,
James
 
Good work! And welcome to Audiokarma.

For the relay, this will work just fine.
https://www.conrad.de/de/printrelais-24-vdc-8-a-2-wechsler-finder-405290240000-1-st-502882.html
You will have to cut off 2 legs and then it will be a drop in fit.

Cheers,
James

Hello James!

Thank you for your answer!

I replaced all electrolytic caps to Panasonic (FC series) and WIMA foils, and the two big 12.000uF came from an original replacement(! :banana:) (i measured 11.980 and 11.950 values of them) just like the speaker terminals and Matsusuhia relays also. The old capacitors was perfect condition (ELNA-s, Rubicon-s and (maybe?) United Chemi-Con-s) just like the new ones, saddly the two big 12.000uF just(!) 10.400 and 9800uF what i measured. But who cares, i already ordered the new ones, so i replace them.

I thinkin' about to replace the vol pot to an Alps Blue Beauty Pot. What are you think?

The replaced parts:
IMG_0116.JPG
 
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Hello James!

Thank you for your answer!

I replaced all electrolytic caps to Panasonic (FC series) and WIMA foils, and the two big 12.000uF came from an original replacement(! :banana:) (i measured 11.980 and 11.950 values of them) just like the speaker terminals and Matsusuhia relays also. The old capacitors was perfect condition (ELNA-s, Rubicon-s and (maybe?) United Chemi-Con-s) just like the new ones, saddly the two big 12.000uF just(!) 10.400 and 9800uF what i measured. But who cares, i already ordered the new ones, so i replace them.

I thinkin' about to replace the vol pot to an Alps Blue Beauty Pot. What are you think?

The replaced parts:
View attachment 1176016

Hi Megott,
This is the first that I've heard of this pot. I just now looked for them at HiFi Collective and see that they aren't all that expensive. Might be an interesting experiment. If you go for it please let us know how it turns out.

What did you replace the speaker terminals with? Photos! :) I've been thinking of having my friend bring his A-500 back to me for some upgrades, including replacing the speaker terminals. So I'm interested to see what you did.

Cheers,
James
 
Hi James!

I used the original replacement parts to speaker terminals. As you can see in the photo the old one's upper right is broked, so i found a little shop in my country, who sell this old yamaha replacement parts.
As like you, i also thinking about the terminal mod, i ordered some gold banana connector, to make a better connection to speaker wires, but i dont want to cut out the rear panel, because the 8 banana teminal much bigger (need more space vertically) then the original connector.

"my friend bring his A-500 back to me for some upgrades"
What is it the other upgrades? :D

Cheers!

Norbert (aka Megott)
 
"What did you choose for trim-pots?"

It's coming from Bourns, i must to open widely the legs to fit the old one's holes.

The bigger caps meaning better/bigger sound? :D
The KMH series is fit perfectly in?

Norbert
 
"What did you choose for trim-pots?"

It's coming from Bourns, i must to open widely the legs to fit the old one's holes.

The bigger caps meaning better/bigger sound? :D
The KMH series is fit perfectly in?

Norbert

See posts #75 to 78.

Cheers,
James
 
Hello everyone,
I have a Yamaha A520 with two sets of Accessory send/receive sockets on the back. Do you use jumpers? I found that removing the jumpers is still working. Can someone explain why?
Thanks a lot!
 
Can someone explain why?
Because your not interrupting the signal path.If it still passes audio. Look on the rear side of those RCA jacks and see if they have been hard wire by-passed.
 
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Thank you for your answer.
1) Although my A520 can work with or without these two jumpers, the sound is very different.

2) The strange thing is, I unplug the jumper, measure the center of the Send/Receive socket with a meter, and find that they are not turned on, but the amplifier is still working normally.

3) Unfortunately, the chassis cannot be opened because the threads of the two screws are damaged.

Best regards,
 
You'll need to find a way to open the amplifier if you want a certain answer.
Those jacks may either be joined poorly internally, or by adding something other than straight wire (eg resistors or an RC network). In any case the if the jumpers are in place you are bypassing any modified or poor connection - so I'd keep the jumpers installed as avionic said.

Usually with a little creativity you can get most damaged screws out, are the threads stripped or is it the head that is damaged?
If only the head you can dremel (or with more care, hacksaw) a slot in the head, and if it's the threads you can perhaps drill most of the head off and then pop it off (with the rest off the good screws removed from the unit). Sometimes you can grab the screw head with vise grips. There is always a way.
 
LH twist drill bit.Drill with the switch in reverse. Usually backs the screws right out.
 
Ok, I will give it a try.

I think you are right, these accessory jacks on A520 should be part of the RC network because they are not grounded.
The AST-a90M that I have used, the sockets are grounded, and there is no sound when the jumper is unplugged.

Best regards,
 
The service manual schematic shows the signal path going directly through the Acc jumpers with no other route or bypass, and shows the outside rings on the Acc RCA sockets being connected to ground. The A-520 that I have here makes no sound with the jumpers pulled.

The damaged screws show that someone has been in the amp, and if you have any kind of sound with the Acc jumpers pulled then someone has done something evil inside the amp, either at the acc jacks where they are soldered to their small pcb or on the front input board. I'd be wanting to remove the damaged screws and find out what, as well as getting the Sony Bond glue out of there and checking for damage, at a minimum.

Once you get it open post some photos of where the Acc jacks are soldered to the small board.

Yamaha A-520-01.jpeg

Cheers,
James
 
Thank you! This is exactly what I suspect, although its sound is not bad.
I paid $150 from the local auction site, no jumpers attached, they said that the A520 does not need them.
I hope to open it this weekend.

Best regards,
 
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