Cracked ground solder connection on the RCA jack. Or a separated outer ground shell ( broken RCA jack ).. This happens when using very tight gripping interconnect cables.
Yamaha A1 integrated amp (phono issue)
- Thread starter MadcapLaughs
- Start date
best-groove
Active Member
Hallo, for example which brand and model of cables could be used?
I noticed on my A-1 that the cables of the MC input run on the side of the side panel, they are orange and blue for the two channels while for the MM input they are red and white and run over the final transistor radiators but no black cables as you indicated for both connections to the phono stages
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I found the original cable are more than adequate . I have had no issues with them. But you could try some Mogaami Microphone wires. Maybe use the Quad on to reduce cable size as its high in the A-1 chassis. Look for the thinest cable you can find.
Athanasios
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best-groove
Active Member
@Nashou66 Hi and thanks for the reply; I have no problems using the Straigh Wire Interconnect that I used it in the past between turntables and phono preamps or the very thin Van Damme microphone or the Van Den Hul D502 Hybrid as they are all loose cables that I have, I also have some pieces of the old Monster Cable Interlink 300.
I am concerned that Van Damme and VDH can shield more, but they should be connected correctly to get the best shielding by having two cables plus an external shield.
I am concerned that Van Damme and VDH can shield more, but they should be connected correctly to get the best shielding by having two cables plus an external shield.
dksp
Active Member
Hi all, resurrecting this thread.
I had my Yamaha A-1 in storage for 3-4 years. I switched it with another amp back then because I had a similar issue: noise in the phono circuit with random pops in the speakers. A few weeks ago I installed it again, and to my surprise the problem was gone, and I used a couple of hours daily since then. But today, after 1-2 hours of listening it happened again.
See video clip of the issue:
I had my Yamaha A-1 in storage for 3-4 years. I switched it with another amp back then because I had a similar issue: noise in the phono circuit with random pops in the speakers. A few weeks ago I installed it again, and to my surprise the problem was gone, and I used a couple of hours daily since then. But today, after 1-2 hours of listening it happened again.
- I unplugged the turntable at the back of the amp, same.
- Only the right channel is affected.
- The speaker pops more, the more you turn the volume up.
- It only happens on the phono circuit, in both standard phono and direct (DISC) modes.
- The amp is completely silent when in aux or tuner mode.
- It only happens when in MC mode.
- The amp is completely silent when switched to MM.
See video clip of the issue:
You need to clean the Phono switches and the Disc button.
Also clean the tape monitor button while you're at it.
If you have not changed the relay yet it also my need to be changed out soon.
Athanasios
dksp
Active Member
Thanks both. I will check and clean all contacts, switches and pots while th amp is apart.
I already cleaned the relay a few years ago and it still works fine, no problem there. It's still the original one.
But I don't think cleaning and resoldering will be enough.
For me the audio acts rather like a failing transistor in the right channel on the MC preamp board…
I already cleaned the relay a few years ago and it still works fine, no problem there. It's still the original one.
But I don't think cleaning and resoldering will be enough.
For me the audio acts rather like a failing transistor in the right channel on the MC preamp board…
It might be the 2sk100. It's a pain to get to. I think i may have mentioned that in one of my threads on the A-1, not sure if it was the phono eq board( pain in ass) or the main driver board 2sk100. I think its in both.Thanks both. I will check and clean all contacts, switches and pots while th amp is apart.
I already cleaned the relay a few years ago and it still works fine, no problem there. It's still the original one.
But I don't think cleaning and resoldering will be enough.
For me the audio acts rather like a failing transistor in the right channel on the MC preamp board…
Athanasios
dksp
Active Member
Thanks 
I haven't looked inside the amp yet. From what I see in the service manual, the MC board would be the VR & SW Circuit Board NA07044 (european model). Right?
There are two types of transistors on this board: 2SC2300 and 2SA998
I cannot find those online. Are there any suitable replacements?
I would like to order replacement parts before opening the amp.
I haven't looked inside the amp yet. From what I see in the service manual, the MC board would be the VR & SW Circuit Board NA07044 (european model). Right?
There are two types of transistors on this board: 2SC2300 and 2SA998
I cannot find those online. Are there any suitable replacements?
I would like to order replacement parts before opening the amp.
Sparkplug
Super Member
These are complimentary transistors and were discontinued long ago. For replacements, I’d use KSC2383Y:
And KSA1013Y:
Although the data sheet doesn’t say so, looking at the specs, they are practically complimentary, you should be fine using them.
It is.
best-groove
Active Member
First thing I would do is replace the relay and check the transistors that power it for cold solder joints.
Athanasios
dksp
Active Member
Success, it's up and running again. 
After 3 hours of continuous listening to records, no parasite noises at all in the speakers. When no record is running, still total silence, even at 50% of the volume. This was not the case before.
I ordered the KSC2383Y and KSA1013Y as suggested by member Sparkplug (THANK YOU ) and replaced all four pairs of transistors. As the 9V battery of my component tester was completely flat, I didn't test the transistors I removed.
The biggest problem was the disassembly of the amp, as I managed to strip the head of a screw (it was glued in place) and had to drill it out. Replaced it with one found in my parts bin. I only removed the top and bottom covers, and the front plate. This was enough to get access to the board and I managed to replace the transistors with the board still in circuit.
Note that the transistors on the board were not the same as those mentioned in the service manual (2SC2300 and 2SA998), but D786 and B737.
After 3 hours of continuous listening to records, no parasite noises at all in the speakers. When no record is running, still total silence, even at 50% of the volume. This was not the case before.I ordered the KSC2383Y and KSA1013Y as suggested by member Sparkplug (THANK YOU
) and replaced all four pairs of transistors. As the 9V battery of my component tester was completely flat, I didn't test the transistors I removed.The biggest problem was the disassembly of the amp, as I managed to strip the head of a screw (it was glued in place) and had to drill it out. Replaced it with one found in my parts bin. I only removed the top and bottom covers, and the front plate. This was enough to get access to the board and I managed to replace the transistors with the board still in circuit.
Note that the transistors on the board were not the same as those mentioned in the service manual (2SC2300 and 2SA998), but D786 and B737.