Yamaha CA 600 Repair 2026

[mbz]

How do I 1000% verify the correct way it should be pointing.

Do you have the round face or flat face on the heat sink, expect flat face.

 

[Nashou66]

Do you have the round face or flat face on the heat sink, expect flat face.

Shouldn't it be the round face facing if the 1845 is ECB?

 

[PioneerPro]

Your diagram in pix 4 appears correct with possible exception being TR607, your pix is not real clear. Pin 1(emitter) is to be closest leg to TR611, confirm this.

It is not, it is the opposite. The flat part of the KSC1845 is facing down so it is ECB with the E closest to the corner of the board and the B pin closest to the TR611.

 

[PioneerPro]

I think you mean 2SC458, correct?

Was it this type? the outhouse style?

No they were the rounded style with the flat face. Both the 2sc458 and the ksc1845 I replaced it with the flat face pointing down.

That is why I made the drawing. I do not understand the symbols on the schematics but if I knew for sure the correct orientation I could check all these transistors.

I really need someone to draw on my drawing the correct way the transistors need to face. Once again the arrows on my drawing show how they are facing now.

 

[PioneerPro]

Do you have the round face or flat face on the heat sink, expect flat face.

I feel stupid but I do not know what you are asking me here.

 

[PioneerPro]

Shouldn't it be the round face facing if the 1845 is ECB?

Here is the KSC1845. It is the same orientation as the 2SC458 that came out.

 

[PioneerPro]

OK, so I gave myself a crash course in reading transistor schematics and the way I understand it is that the symbol for it always has a small arrow and that small arrow is always points at or away from the EMITTER leg.

TR607 shows the Emitter at the exact opposite of how I have it. Now someone please tell me how the factory 2SC458's were in backwords?

 

[Nashou66]

I f you look at the board layout diagram the Emiter is towards the interior of the board not the outer edge. Also the emitter is connected to the
Capacitor C621's leg that a is also towards the interior of the board. You need to flip it around.

Here is what I mean

 

[PioneerPro]

If you look at the board layout diagram the Emiter is towards the interior of the board not the outer edge. Also the emitter is connected to the
Capacitor C621's leg that a is also towards the interior of the board. You need to flip it around.


I flipped them around so to me that means it faces up, it's flat side faces up, the part with the writing on it faces up.

I am still confused on the other 5 transistors. Can you do for me what you did on this transistor with the red writing on the other 5 please.

 

[Nashou66]

If you look at how the E B C are on the layout you should figure out how the symbols match the Lettering I added. Now it up to you to learn the symboling
for the E C B .

 

[mbz]

Shouldn't it be the round face facing if the 1845 is ECB?

Glad someone is reading these posts.

Yeah, there was some doubt, Yamaha print the transistor icon on the component side of the board.
Also the transistor is used for bias temp compensation, parts list has 2SC458 C,D not the LG, so, if I was yamaha I would have the flat face, for better thermal transfer, facing the heat sink. The fallback position was always,
Pin 1 (emitter) closest to TR611 (post #58)

edit Yeah, orientation looks incorrect, should be round face to heatsink.
Pin 1 (emitter) closest to TR611.
Tracing tracks from TR607e should have connections to TR605c and TR611b

 

[Sparkplug]

If you look at how the E B C are on the layout you should figure out how the symbols match the Lettering I added. Now it up to you to learn the symboling
for the E C B .

Can’t see any of your pix in any browser …

 

[Nashou66]

Can’t see any of your pix in any browser …

Weird, I use flickr and lately it seems some work and some don't . I wonder if Ak wont allow certain sizes possibly?

Let me add it again here .

Using an 800 size instead of the 1200 i used earlier

And now the 1200 size

And now the larger 1600

Do any show up?

 

[PioneerPro]

I see all three thank you.

 

[satpaul]

I see the first two.

 

[PioneerPro]

Weird, I use flickr and lately it seems some work and some don't . I wonder if Ak wont allow certain sizes possibly?

Let me add it again here

Thank You So very Much. This is exactly what I needed to verify every transistor except TR607 was correct so that is the good news.

The bad news is the DBT still goes on just as soon as I plug the metal can output transistors in. It starts out kind of bright but as soon as I install the 2 screws holding down the transistors the bulb gets a little brighter.

I now have replaced over 50% of each board and there is nothing on either board that looks burned or in bad condition. I know that means nothing but I guess what I need to do now is test any other resister or coil or capacitors that I did not change and go from there.

Unless anyone has another suggestion?

 

[avionic]

Personally. I never change the 2SC458's bias thermal tracking pieces unless they are indeed bad.

OEM pieces were 2SC458LG " out houses" My 2¢.

PS. I haven't seen a bad one yet.

 

[Sparkplug]

Weird, I use flickr and lately it seems some work and some don't . I wonder if Ak wont allow certain sizes possibly?

Let me add it again here .

Using an 800 size instead of the 1200 i used earlier

And now the 1200 size

And now the larger 1600

Do any show up?

Sorry for late reply, was out all day buying parts!

The 1600 size doesn’t show up. Must be the size, are the file names similar?

 

[Sparkplug]

PS. I haven't seen a bad one yet.

Same here, the only time I change them by default is when upgrading B-2s. I fear if they fail they’ll take the SKs and SJs with.

 

[mbz]

OEM pieces were 2SC458LG " out houses"

So someone replaced the LG's but got the pinout wrong with the replacement

The bad news is the DBT still goes on just as soon as I plug the metal can output transistors in. It starts out kind of bright but as soon as I install the 2 screws holding down the transistors the bulb gets a little brighter.

Screws form connection to collector. Possibly a output b-e short or maybe a driver issue.
What voltage are you seeing at R651 (red), +1.2V
R637 (blue) +0.6V
R639 (green) -0.6V
C621 (purple) -1.2V