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Yamaha newbie A-700 resto thread

Figured that it would be useful information:

I haven't cleaned anything yet, but out of curiosity I connected only the the left speaker and left input. I can just barely hear sound from the speaker, with the volume turned all the way to maximum. In this one-speaker, one-input configuration, pressing mono makes it slightly louder but still barely audible. I assume this is from channel crosstalk.

I've also tested continuity between every connector that connects different boards I could find and they all test fine. I will keep hunting.
 
See if there's crap in the headphone jack. Recommend cleaning it. Insert a jack in & out a few times. :music: (while powered off lol)
Might be a little Wima crammed in there too :biggrin:
 
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Soundscape said:
See if there's crap in the headphone jack. Recommend cleaning it. Insert a jack in & out a few times. :music: (while powered off lol)
Might be a little Wima crammed in there too :biggrin:
Click to expand...
Lol. I sure hope that it's not all the caps I replaced. I'm stumped though, I've been pondering this all day.

Not sure why I didn't think of headphones. I have cleaned the jack. It acts weirder with headphones. Without the mono switch on, turning the balance switch to the right does nothing, turning it to the left makes the volume disappear from both. So, it's like the headphones are just getting right channel output on both sides, even in stereo mode.

With the balance in the center, mono on, sound only comes from the right headphone. Turning the balance switch slightly to the right makes sound come from both, all the way to the right, sound is equal. Turning it to the left in mono mode produces expected left channel only.

Completely different behavior from the speakers. I'm confused lol. I'm giving up for the day. I reckon I'll be able to diagnose better once I can actually remove things from boards.
 
Ok, I lied, I can't quit trying to figure this out. I noticed most of the 3-prong connectors have xxR and xxL, but there is also a middle "E". L and R are obvious, but what is "E"?
 
Well, I don't know exactly how, but I screwed up big time. I was checking continuity between all the cables today, and I unplugged two of the ribbon cables that run from the main board to the input selector board, leaving the one for tuner/etc. plugged in. I didn't change anything else other than that and deoxiting the mute/mono/direct switches again last night.

I plugged everything in again to see if anything changed. I should've had it on the DBT, but I didn't because it's been fine off of it. I turned it on and as I was plugging in the RCA cord to the tuner input, I heard sparks and smelled smoke.

1000008703.jpg

1000008704.jpg

1000008705.jpg

The volume was at zero and Class A was not engaged. It was turned on for probably 30 seconds before it happened. All of the heatsink transistors (2SC3370, 2SA1333, 2SA1306, 2SC3298) on the right channel are testing bad now as well.

My newbieness is definitely showing in a big way now, I can't believe I made a mistake like this. With these hard to obtain output devices blown, and no way of telling what else on the board might be blown without a bunch of testing, I think I'm definitely in way over my head than I was before. It might be time to cut my losses and walk away from this for now. Sorry y'all, I'm just really disappointed in myself. I have a lot more to learn before I go trying to do something like this again.
 
Nashou66 said:
That sucks, but don't get mad. This is now a learning experience, been there done that. Did you reconnect the ribbon cables correctly or were you one or two pins off?

Its unclear if you re connected them before you powered it up.
Click to expand...
Thanks for the words of encouragement. I'm not so much mad as I am extremely disappointed.

I already removed the ribbon cables so I can't remember if I connected it correctly, but I did leave C7 and C8 disconnected when I had powered it up.

I noticed when I was removing 2SC3370 to check it with my tester, that I hadn't screwed it all the way flush so it wasn't pressing up against the thermal pad/heatsink. Could it have overheated and failed? It's completely shorted between all three legs, my TC1 tester just goes into "self-test mode" when I try to test the transistor, which is what it does when you short 1,2,3 with the piece of metal the tester comes with.
 
1000008706.jpg
1000008707.jpg

2SA1306A is testing as a "resistor", lol. But 2SC3298A seems fine.

2SA1333 isn't even registering, "unknown or damaged part".
 
analogwisdom said:
Well, I don't know exactly how, but I screwed up big time. I was checking continuity between all the cables today, and I unplugged two of the ribbon cables that run from the main board to the input selector board, leaving the one for tuner/etc. plugged in. I didn't change anything else other than that and deoxiting the mute/mono/direct switches again last night.

I plugged everything in again to see if anything changed. I should've had it on the DBT, but I didn't because it's been fine off of it. I turned it on and as I was plugging in the RCA cord to the tuner input, I heard sparks and smelled smoke.

View attachment 3139481

View attachment 3139482

View attachment 3139483

The volume was at zero and Class A was not engaged. It was turned on for probably 30 seconds before it happened. All of the heatsink transistors (2SC3370, 2SA1333, 2SA1306, 2SC3298) on the right channel are testing bad now as well.

My newbieness is definitely showing in a big way now, I can't believe I made a mistake like this. With these hard to obtain output devices blown, and no way of telling what else on the board might be blown without a bunch of testing, I think I'm definitely in way over my head than I was before. It might be time to cut my losses and walk away from this for now. Sorry y'all, I'm just really disappointed in myself. I have a lot more to learn before I go trying to do something like this again.
Click to expand...

Well, everyone of us that is in this as a hobby has had one of those events, especially (but not limited to) at the beginning.

At this point unless it becomes a financial disaster you are at the point where you will learn a lot of things that will be useful for the long haul.

My absolute best advice that I can give you at this point if you decide to continue is to now engage in a talk with Avionic. And my next best advice is to do exactly what he says step by step and ignore what everyone else says if it is in conflict with what he says or gets in the way.

Cheers,
James
 
Bratwurst7s said:
Well, everyone of us that is in this as a hobby has had one of those events, especially (but not limited to) at the beginning.

At this point unless it becomes a financial disaster you are at the point where you will learn a lot of things that will be useful for the long haul.

My absolute best advice that I can give you at this point if you decide to continue is to now engage in a talk with Avionic. And my next best advice is to do exactly what he says step by step and ignore what everyone else says if it is in conflict with what he says or gets in the way.

Cheers,
James
Click to expand...
Thanks. I want to continue, I feel like I need to with the time I've already put into it.


I found these parts on eBay, I made sure to avoid China sellers. Should I buy these as replacements, or try to look for modern substitutes?

2SA1333
2SC3370 (R)

2SA1306A
2SC3298A

2SA1145

Here's what I found for the two burnt resistors. I believe these are the flame proof ones, please correct me if these won't be good substitutions:

R302 - CPF1220R00FKE36 (220Ω, 1W)
R394 - CPF21K8000FKE14 (1.8KΩ, 2W)
 
analogwisdom said:
Thanks. I want to continue, I feel like I need to with the time I've already put into it.


I found these parts on eBay, I made sure to avoid China sellers. Should I buy these as replacements, or try to look for modern substitutes?

2SA1333
2SC3370 (R)

2SA1306A
2SC3298A

2SA1145

Here's what I found for the two burnt resistors. I believe these are the flame proof ones, please correct me if these won't be good substitutions:

R302 - CPF1220R00FKE36 (220Ω, 1W)
R394 - CPF21K8000FKE14 (1.8KΩ, 2W)
Click to expand...
I'm about to go to bed, but I will look at this in the morning (GMT+1).

But, from this point forward, anything that I may say or advise, if Avionic has other advise, ignore me. He is a profi, I am an amateur.

Cheers,
James
 

pdf1.alldatasheet.net

2SA1333_15 PDF

Part #: 2SA1333_15. Description: Silicon PNP Power Transistors. File Size: 165.18 Kbytes. Manufacturer: Quanzhou Jinmei Electronic Co.,Ltd..
pdf1.alldatasheet.net


transistor 2SC3370 - complementary type

complementary type: 2SC3370, 2SA1333
www.web-bcs.com

Some pertinent info .

Also if you can find a T03P package equivalent electrical outputs you can use these mounting clips to hold them in the original holes

s-l960.jpg

s-l960.jpg


s-l960.jpg


Makes a nice clean job .



www.ebay.com

MT200 To TO3P Power Output Transistor Adapter Panel | eBay

For your consideration is an adapter plate that allows you to adapt a TO3P transistor in place of an MT200 transistor. These boards are made out of an aluminum PCB substrate, making them both incredibly rigid and strong, and impervious to any issues caused by the heat emitted from the power...
www.ebay.com
 
For the other two I came up with this, the NPN and PNP, these should work if the 100mhz isn't a factor as these are only 30mhz .

2SA1305 and 2SC3298



Anyone else have something better from he these?

I just rather get equivalents than take a gamble with fakes from Ebay. Although I have had good luck but I only buy from people Have dealt with before who I know have the right **** ;)

Nashou
 
Nashou66 said:
For the other two I came up with this, the NPN and PNP, these should work if the 100mhz isn't a factor as these are only 30mhz .

2SA1305 and 2SC3298



Anyone else have something better from he these?

I just rather get equivalents than take a gamble with fakes from Ebay. Although I have had good luck but I only buy from people Have dealt with before who I know have the right **** ;)

Nashou
Click to expand...

Thanks for linking these. Just before you posted I was doing to ask if the MJE 15032/15033 will work...
 
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