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Yamaha C-4 very urgent

Dr. Ear

Dr. Ear

Super Member
I removed D127 (a failure prone VD1212) from the "Function C. Board" and when I wanted to mount the replacement, two in series connected diodes N4148, I discovered that there was no marking on the pcb regarding the orientation, which is exceptional because it is clearly marked everywhere else. In the SM I cannot find this diode at all, only in the schematics. Could somebody please give me a hint.
 
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On the copy of the service manual I have, I see D127 at the bottom left of the big "SW 123" square in the middle of the "Function C. Board"

The diodes are oriented in a way that they "point" towards the center of the board, meaning the cathode is more towards the center of the board.

I do not own a C-4 and only found this manual online, but the scan is not that great. If anyone of our resident Yamaha-pros can double-check, that'd be great!

az
 
Your correct..This particular C-4 has the silkscreened VD1212 symbol on the PCB.
 

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Thank you very much you helped me a lot! I have mounted it in this way, just wanted to make shure it is OK. My SM is partly almost unreadable.
 
Thank you, I have finished the project. The C-4 sounds good now and looks like new. But you cannot always trust the schematics. I have found two additional VD1212 diodes in the phono stage which are not mentioned in the schematics. On the pcb there is only a symbol for a simple wire bridge.
BTW, does somebody have an idea for a nice substitute for the yellow and green rubber condoms for the bulbs, they are almost vanished. In an A-1 I once tried LED's but I did not like the look.
 
BTW, does somebody have an idea for a nice substitute for the yellow and green rubber condoms for the bulbs
Click to expand...
Yep.LED's.Those little rubber booties seem to always tear when removing old burnt out lamps or dry rot..
 
The LED's I have tried in my A-1 had a somewhat focused beam so that the button was not illuminated evenly with a bright spot in the center. Are there LED's available with a less focused beam?
 
No not really..Heres a C-4 I just finished.I've tried quite a few different shades of green,pure green and the closest I can come up with is cyan.
If I could find a cyan with a luminous intensty of around 4200 ucd and a viewing angle of 60 degree it would be much better.These are 30 degree Avago pieces.Size T-1 3/4 amber and cyan.
 

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This looks quite good. The clue is the amber diode, I only had a yellow one which was rather pale.
See my nice setup with the B-6 and the C-4.
 

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Very nice collection .. Here is a LED color chart that I found very useful.
 

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I'm keeping the classic bulbs. In front of them, under the button, I put a piece of filter for theater lights, have found exact green and amber. It works perfectly.

LIX
 
lixaudio said:
I'm keeping the classic bulbs. In front of them, under the button, I put a piece of filter for theater lights, have found exact green and amber. It works perfectly.

LIX
Click to expand...

Could you please post a pic or a link because I don't know what "filters for theater lights" look like.
 
I have found out that Kingbright has LED's (Part Nr. 247-1448) which have a radiation angle of 140 degrees. I will try those.
 
dgwojo has colored condoms for the lamps on these guys.

Now Dr. Ear, you must send to me your A-Sxxxx pieces!

How do they sound compared to our beloved vintage Yamaha gear?
 
brutal said:
dgwojo has colored condoms for the lamps on these guys.

Now Dr. Ear, you must send to me your A-Sxxxx pieces!

How do they sound compared to our beloved vintage Yamaha gear?
Click to expand...

With CD, the new 2000 series combo is almost unbeatable, especially when using the symmetric out/inputs. The sound is detailed and warm and musical. You don't miss anything.
With my all time favorite MM system, the AT-20 Sla, the C-4 and the C-80 win. The phono stage of the A-S2000 sounds with MM much too bright and lean. With my MC, the AT-33 PTG, things are different, I can't tell which pre is better. The A-S2000 or maybe the CX-1? When playing *very loud* I love the effortless power of the B-6. This amp is incredible fast (must be fast, no mass and an extremely short signal path). I play most time with the vintage gear but I would not give away the newbies. I appreciate their build quality and honor Yamaha's serious attempt to do things right again. Iit is always nice to have a choice.
 
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