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TheBatsEar

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Anyone interested in looking inside Yamaha amps? I have a bunch in my collection, most of them need repair, all of them have to be opened eventually for dusting.

I'll start with some pictures i made inside a A-S1000 that i bought for 500€ in mint condition. This one weighs 25kg, it's a serious amp. For example, if you move the bass knob from 0, a relay clicks and adds it into the signal path. A bit of dust inside and a black sharpie marking on the volume knob was all that was wrong with it. The amp was about 11 years old when i got it, i eventually ugraded to a A-S1200 and sold this one for 600€. To me it sounded just as good as the A-S1200, but lacks standby and VU meters.

Not a scratch. Very large, heavy and deep:
1.jpg


Wood panels in piano finish:
2.jpg


Brass terminals:
3.jpg


There is a thick metal bridge that makes sure the amp reaches peak robustness:
4.jpg


The amp is made almost fully symmetric. The yellow stuff on the transformer bugged me a bit, it was hardened lacquer. Every cable is tied down with cable ties. Nothing can move.
5.jpg


Yamaha labelled caps, made by Nippon Chemi-Con Corporation, the largest manufacturer of electrolytic capacitors (not to be confused with Nichicon):
6.jpg


From left to right, bass, treble, balance and volume. The ICs don't get energy as long as the treble is set to 0 for example. If you change the treble to +1 or -1, a relay clicks and powers those chips. The volume knob doesn't change the volume, but gives a resistor value to this board, which then changes the volume. Should be easy to repair once the variable resistor goes bad in 20 or so years:
7.jpg


And here the left channel power amp:
8.jpg


Since i don't have the device anymore, i can't make new detailed pics, but i can of course give details on what you can see here. I had to heavily shrink the pictures down.

If there is interest, tell me, next would be a comparison of Yamaha A-S501 and A-S701.

I also have the R-S202D, A-S300, RX-300, A-550, RX-10, AX-10 and of course the A-S1200.
 
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TheBatsEar

TheBatsEar

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TheBatsEar

TheBatsEar

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bloodshoteyed

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sold it for 600? if i knew that i'd have bought it in an instant...EU prices are crazy lately, with only one even on ebay (for 995)...
 
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TheBatsEar

TheBatsEar

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Made 100€ profit, so that's ok. When i bought it, the seller had a CD-S1000 for 200€ more. The door wouldn't open. of course i took it. There was just a string that transports the door, which slipped from a roll. Fixed it in 5 minutes. Kept the player so far for my SACDs.

IMG_20201019_112824.jpg


The rack cost me 24€ (three Ikea Lack for 8€ each). What a bargain ;-)
 
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trl

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You really seem to like the Yamaha luxury devices. :) They're really pretty indeed...and good sounding.
 

MakeMineVinyl

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A lot of wires! :)
I find typical Japanese gear to be a rat's nest of wires - too many wires not very well dressed or thought out. And their circuit boards tend to be a bit messy too. Of course not that many end users look inside, and don't care.
 
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TheBatsEar

TheBatsEar

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You really seem to like the Yamaha luxury devices. :) They're really pretty indeed...and good sounding.

Well, i sure do like them. Have never heard them referred to as luxury devices however. But i guess it's not wrong. I'm sure there are other worthy japanese brands, but somehow i always liked Yamahas stuff the most.

Also, as you can see partly, i have a bunch of tapedecks, cd players, turntables, and tuners from the 70ies and 80ies with matching design. Even their cheap network streamer NP-S303 fits in.
 

pma

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I find typical Japanese gear to be a rat's nest of wires - too many wires not very well dressed or thought out. And their circuit boards tend to be a bit messy too. Of course not that many end users look inside, and don't care.
It may worsen S/N and distortion. And when I googled some reviews, the reviewers complain of lack of details and impact, so it may be the case.
 

MakeMineVinyl

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It may worsen S/N and distortion. And when I googled some reviews, the reviewers complain of lack of details and impact, so it may be the case.
At the least, the variability of how the wires are routed from unit to unit can give rise to different units measuring differently with things like crosstalk, distortion and such. If most signal carrying routes are cast in stone by being part of a PCB, then there is less likelihood of unit-to-unit variation.
 

mhardy6647

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I find typical Japanese gear to be a rat's nest of wires - too many wires not very well dressed or thought out. And their circuit boards tend to be a bit messy too. Of course not that many end users look inside, and don't care.
They're better than they used to be.
This is a mid-1960s Pioneer SX-34B (push-pull 6BM8 stereo receiver), in its Allied Radio Electronics "Knight 333" morph. I replaced coupling caps in this one -- it was a bit of a challenge to find coupling caps that fit.
I like to say say of the typical 1960s (point to point) Japanese hifi hardware - it looks like the result of a dog ingesting a closetful of wire and then barfing it up. :rolleyes:

Knight333underneath by Mark Hardy, on Flickr
 

MakeMineVinyl

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They're better than they used to be.
This is a mid-1960s Pioneer SX-34B (push-pull 6BM8 stereo receiver), in its Allied Radio Electronics "Knight 333" morph. I replaced coupling caps in this one -- it was a bit of a challenge to find coupling caps that fit.
I like to say say of the typical 1960s (point to point) Japanese hifi hardware - it looks like the result of a dog ingesting a closetful of wire and then barfing it up. :rolleyes:

Knight333underneath by Mark Hardy, on Flickr
Almost all of the older tube gear tended to be a rat's nest, including some professional stuff - Exhibit A: my Ampex 354 professional tape machine's electronics. It at least used a PCB, but the wiring was still a mess, and a pain to work on.

Ampex 354 Electronics.jpg
 

mhardy6647

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Not all of it.

Fisher 400 receiver (before refreshing)

Richards400belowbefore by Mark Hardy, on Flickr

Marantz 8B power amplifier (before refreshing)

Marantz8Bbefore by Mark Hardy, on Flickr

McIntosh used, what do they call them, turretboards(?) for their p to p wiring.
1617039626577.png

(also a before refreshing image, of an MC-225, but not my photo -- borrowed from AK)
 
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TheBatsEar

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it looks like the result of a dog ingesting a closetful of wire and then barfing it up. :rolleyes:


What's beauty to the spider, is chaos to the fly.
 
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TheBatsEar

TheBatsEar

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Well, i reserved empty posts at the top, but i can't edit them anymore, so they are lost now.

Anyway, here is a comparison between Yamaha A-S501 and Yamaha A-S701. They are in the midst of Yamahas consumer line. There is a smaller model A-S301 (less power than the A-S501) and a larger model (A-S801 has USB input).

This is what they look like, 501 on top of the 701:
11.jpg


Really nice for the money, the enclosures are almost the same:
10.jpg


Only one difference on the front:
0_501.jpg

0_701.jpg

The 701 has a CD direct amp path, which means there are a few more parts inside, as you can see later.

The backside, A-S501 on top:
12.jpg

As you can see, the removeable power cable is purely cosmetic, it lacks ground connection. The HIGH/LOW impedance switch should be at high at all times. At low the amp uses a winding on the transformer that outputs a few volts less. Not sure what the point is.

Digital input board, top is A-S501, bottom is A-S701. they are the same. Sadly, the quality of the image is bad. Prominent is the large heat sink for the 5 volt USB power supply:
7_501.jpg

7_701.jpg



Time to show the goods, A-S501 on top:
2_501.jpg

2_701.jpg


Input section, A-S501 on top. Red plastic insulation, the A-S701 has white insulation:
3_501.jpg

3_701.jpg

On the lower right, the A-S701 has more parts. I think that is the "CD direct amp" path.

Power amp board, A-S501 on top:
4_501.jpg

4_701.jpg



Different power transistors, A-S501 on top:
6_501.jpg

6_701.jpg


That's it, hope you enjoyed the pics.

Should i do the A-S1200 or A-1020 next?
 
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Kachda

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Great pictures. Please keep them coming
 
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TheBatsEar

TheBatsEar

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Thanks mate, i'll try. :)
 

MakeMineVinyl

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Well, i reserved empty posts at the top, but i can't edit them anymore, so they are lost now.

Anyway, here is a comparison between Yamaha A-S501 and Yamaha A-S701. They are in the midst of Yamahas consumer line. There is a smaller model A-S301 (less power than the A-S501) and a larger model (A-S801 has USB input).

This is what they look like, 501 on top of the 701:
View attachment 121934

Really nice for the money, the enclosures are almost the same:
View attachment 121940

Only one difference on the front:
View attachment 121935
View attachment 121936
The 701 has a CD direct amp path, which means there are a few more parts inside, as you can see later.

The backside, A-S501 on top:
View attachment 121937
As you can see, the removeable power cable is purely cosmetic, it lacks ground connection. The HIGH/LOW impedance switch should be at high at all times. At low the amp uses a winding on the transformer that outputs a few volts less. Not sure what the point is.

Digital input board, top is A-S501, bottom is A-S701. they are the same. Sadly, the quality of the image is bad. Prominent is the large heat sink for the 5 volt USB power supply:
View attachment 121938
View attachment 121939


Time to show the goods, A-S501 on top:
View attachment 121941
View attachment 121942

Input section, A-S501 on top. Red plastic insulation, the A-S701 has white insulation:
View attachment 121943
View attachment 121944
On the lower right, the A-S701 has more parts. I think that is the "CD direct amp" path.

Power amp board, A-S501 on top:
View attachment 121945
View attachment 121947


Different power transistors, A-S501 on top:
View attachment 121949
View attachment 121950

That's it, hope you enjoyed the pics.

Should i do the A-S1200 or A-1020 next?
They sure go to a lot of trouble to avoid the use of double sided circuit boards with all those jumpers. I can't imagine the extensive use of jumpers is any cheaper, or perhaps they have another rationale? Some of the jumpers appear to be bypassing unused features in un-populated areas of the PCB.
 
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