I have purchased a 100v ac Yamaha Ca-1000 from Japan and I intend to use it in Australia which supplies 230v ac
Rather than purchase a step down transformer I was wondering if it were possible to reconfigure and modify the transformer to run on 230v.
The repair manual states that this is the same transformer for all countries.
Liam
Rather than purchase a step down transformer I was wondering if it were possible to reconfigure and modify the transformer to run on 230v.
The repair manual states that this is the same transformer for all countries.
Liam
Page 25 of the service manual explains how to do that.
Yamaha CA-1000 - Manual - Stereo Pre-Main Amplifier - HiFi Engine
Yamaha CA-1000 - Manual - Stereo Pre-Main Amplifier - HiFi Engine
If it was a Japanese home market product, it will be 100V only, there will be no tappings inside to change the primary to other voltages.
Just buy a stepdown, but get a Japanese model, sold in Japan for Japanese people to take with them to 220v/240v countries. Decent ones have an internal twin primary (220/240) and sometimes a switchable secondary (100/110/120) so the transformer can be trimmed to the mains voltage more accurately.
Bear in mind, we are officially 'nominally' 230v now in Australia (with a greater tolerance), but no infrastructure has changed from the nominal 240v we have had for decades. I sit at 241v here right now and at peak times, it may be 230v. At low load periods, it may be 254v.
What does that matter? Well, when you are stepping down to 100v, the difference is 10v, so be careful the stepdown is actually sitting on 100v when at a typical line voltage.
Don't buy a chinese stepdown, they are usually US set for 220/120 and you'll cook your amp.
Just buy a stepdown, but get a Japanese model, sold in Japan for Japanese people to take with them to 220v/240v countries. Decent ones have an internal twin primary (220/240) and sometimes a switchable secondary (100/110/120) so the transformer can be trimmed to the mains voltage more accurately.
Bear in mind, we are officially 'nominally' 230v now in Australia (with a greater tolerance), but no infrastructure has changed from the nominal 240v we have had for decades. I sit at 241v here right now and at peak times, it may be 230v. At low load periods, it may be 254v.
What does that matter? Well, when you are stepping down to 100v, the difference is 10v, so be careful the stepdown is actually sitting on 100v when at a typical line voltage.
Don't buy a chinese stepdown, they are usually US set for 220/120 and you'll cook your amp.
Not all Yamaha are able to run on 50hz.
Unless it has a 50hz transformer, it cannot be run on 50hz, even if you step the voltage down.
The micro-switches that switch the lower voltages in for class A mode frequently fail, causing the amplifier to be ruined. I suggest these be removed and the class A function disabled.
Unless it has a 50hz transformer, it cannot be run on 50hz, even if you step the voltage down.
The micro-switches that switch the lower voltages in for class A mode frequently fail, causing the amplifier to be ruined. I suggest these be removed and the class A function disabled.
Be fair. The microswitches are 40+ years old and the silvered contacts and springs in the mode switch are well past their use-by dates, but his may be perfectly fine.
Have them cleaned and the microswitches replaced, but not bypassed. They are cheap, but the technician needs to ensure the cleaning contact job is done carefully- that may cost a bit. IMO, disabling the switchable Class A simply because we've all had to replace quite a number of old omron microswitches is not a good solution nor recommended. Its a lazy cop out.
There are plenty of commutating rail switchable Class A amps out there and many use relays, microswitches and optically driven bias stepping. They are all prone to failure eventually, just as Class G and speaker relays cause trouble. In fact, all moving parts will fail eventually.
The CA-800 and 1000 are perfectly reliable unless you are someone who slowly moves the class A switch under power/high volume. The bias switch section needs frequent movement to wipe the internal contacts. Best done with the power off.
Anyway, his Japanese amplifier will have 100V XXHz on the back. If it's 50Hz, he's good to go with a stepdown.
Less scaremongering and more solutions.
Have them cleaned and the microswitches replaced, but not bypassed. They are cheap, but the technician needs to ensure the cleaning contact job is done carefully- that may cost a bit. IMO, disabling the switchable Class A simply because we've all had to replace quite a number of old omron microswitches is not a good solution nor recommended. Its a lazy cop out.
There are plenty of commutating rail switchable Class A amps out there and many use relays, microswitches and optically driven bias stepping. They are all prone to failure eventually, just as Class G and speaker relays cause trouble. In fact, all moving parts will fail eventually.
The CA-800 and 1000 are perfectly reliable unless you are someone who slowly moves the class A switch under power/high volume. The bias switch section needs frequent movement to wipe the internal contacts. Best done with the power off.
Anyway, his Japanese amplifier will have 100V XXHz on the back. If it's 50Hz, he's good to go with a stepdown.
Less scaremongering and more solutions.
From what I've seen, transformers can usually handle going from 50 Hz to 60 Hz without any problem.
In the Americas, power transformers are single voltage only. Why? I don't know, but it is a pain in the rear for consumers and distributors alike. As for bias changes into "class A", all it really does is crank the bias higher. The amp runs hotter but not in class A, best to avoid that setting all together. The amplifier will last longer in it's normal "AB" mode. The hot setting doesn't make it sound any better either.
-Chris
In the Americas, power transformers are single voltage only. Why? I don't know, but it is a pain in the rear for consumers and distributors alike. As for bias changes into "class A", all it really does is crank the bias higher. The amp runs hotter but not in class A, best to avoid that setting all together. The amplifier will last longer in it's normal "AB" mode. The hot setting doesn't make it sound any better either.
-Chris
"From what I've seen, transformers can usually handle going from 50 Hz to 60 Hz without any problem."
Correct, but the reverse is a problem (running a 60hz transformer on 50hz).
"Its a lazy cop out."
Leave the transformer switches alone, but limit the bias to class AB only. It protects the amplifier, without harming the sound.
(When switching from class AB to class A at low volume levels on good speakers, no change in sound can be discerned. This assumes the bias is set properly for class AB mode).
I've had to scrap these amps when the bias sticks in class A mode while the transformer taps are in class AB mode (former authorized Yamaha service center).
Do what you feel comfortable with.
Correct, but the reverse is a problem (running a 60hz transformer on 50hz).
"Its a lazy cop out."
Leave the transformer switches alone, but limit the bias to class AB only. It protects the amplifier, without harming the sound.
(When switching from class AB to class A at low volume levels on good speakers, no change in sound can be discerned. This assumes the bias is set properly for class AB mode).
I've had to scrap these amps when the bias sticks in class A mode while the transformer taps are in class AB mode (former authorized Yamaha service center).
Do what you feel comfortable with.
Hi djk,
I haven't seen that problem with the taps stuck on high while the bias is also high. That must burn the heck out of everything. Canada's decreed our thermal fuse would be 10 °C lower than the UL fuse. We saw "dead" transformers by the boat load. The transformers were perfectly fine, no odor at all. But the thermals were all open. That cost Yamaha Canada dearly. I actually saw skids of new transformers coming in. We also did M.I., but those transformers were more robust and didn't fail. Rarely anyway.
-Chris
Me too.
I haven't seen that problem with the taps stuck on high while the bias is also high. That must burn the heck out of everything. Canada's decreed our thermal fuse would be 10 °C lower than the UL fuse. We saw "dead" transformers by the boat load. The transformers were perfectly fine, no odor at all. But the thermals were all open. That cost Yamaha Canada dearly. I actually saw skids of new transformers coming in. We also did M.I., but those transformers were more robust and didn't fail. Rarely anyway.
-Chris
The Service manual linked in post2 states:
GENERAL
Power Source AC110, 117, 130, 220, 240V
50~60Hz
Power Consumption
Rated
European model 560W
That tells me that the European model used a universal transformer that worked everywhere except the 100Vac Japanese regions.
Just check which transformer is actually inside the unit.
A technician will recognise a universal transformer in an instant, if you have taken the cover off for them.
GENERAL
Power Source AC110, 117, 130, 220, 240V
50~60Hz
Power Consumption
Rated
European model 560W
That tells me that the European model used a universal transformer that worked everywhere except the 100Vac Japanese regions.
Just check which transformer is actually inside the unit.
A technician will recognise a universal transformer in an instant, if you have taken the cover off for them.
Thanks Everybody I appreciate the replys.
$200-$300 cost of transformer will buy me a lot of capacitors and transistors etc to recondition this classic amp. Any 240/230 volt work will be checked and tested by an electrician before power up. With my current setup on my refurbished and perfectly tuned ca-800 all my friends and family confirm (when blind tested) that Class A mode is much better sound quality. Please find attached photos.
Liam
$200-$300 cost of transformer will buy me a lot of capacitors and transistors etc to recondition this classic amp. Any 240/230 volt work will be checked and tested by an electrician before power up. With my current setup on my refurbished and perfectly tuned ca-800 all my friends and family confirm (when blind tested) that Class A mode is much better sound quality. Please find attached photos.
Liam
Attachments
![DSCN1211[1].JPG](/community/data/attachments/519/519913-a8ddffb608dcdec3461bd195232fff1e.jpg)
![DSCN1210[1].JPG](/community/data/attachments/519/519919-f6ecb7c214e98760ad139245805911bd.jpg)
Walk the full Mile and have the job done by the electrician you have available instead of just checked.
FWIW, I and 99% of Techs charge DOUBLE if a job not only has to be done but messy attempts must be removed first.
Not forgetting that by approving your job they are becoming responsible for it.
Any real Tech will then far prefer to do the job himself.
" We saw "dead" transformers by the boat load."
Mainly with Sony transformers at our shop, no so many Yamaha transformers.
I sometimes replaced the thermal switches in the primary (if I could get the proper ones).
"all my friends and family confirm (when blind tested) that Class A mode is much better sound quality."
It was a selling feature for sure, but honestly, I never met anyone that could hear the difference on the CA1000 or CA800 if the class AB bias was properly set.
YMMV (as they say).
Mainly with Sony transformers at our shop, no so many Yamaha transformers.
I sometimes replaced the thermal switches in the primary (if I could get the proper ones).
"all my friends and family confirm (when blind tested) that Class A mode is much better sound quality."
It was a selling feature for sure, but honestly, I never met anyone that could hear the difference on the CA1000 or CA800 if the class AB bias was properly set.
YMMV (as they say).
I have to agree, the Class A vs Class AB is inaudible to me and there's no appreciable change to anything but power output and heat dissipation.
I run the few switchables I have in class AB (I like the high rails for high transients).
The switchable ones come in handy in winter however, a nice hot amp just seems to sound subjectively better than a cold one.
I do however have a Marantz PM95 (Mosfet switchable A/AB) that I prefer in Class A for most listening.
As for thermal fuses. I hate them. Stupid idea, shocking reliability. Many otherwise perfect transformers were scrapped due to premature failure of those little bastard devices. Mandated by authorities with no idea.
I run the few switchables I have in class AB (I like the high rails for high transients).
The switchable ones come in handy in winter however, a nice hot amp just seems to sound subjectively better than a cold one.
I do however have a Marantz PM95 (Mosfet switchable A/AB) that I prefer in Class A for most listening.
As for thermal fuses. I hate them. Stupid idea, shocking reliability. Many otherwise perfect transformers were scrapped due to premature failure of those little bastard devices. Mandated by authorities with no idea.
Hi John,
With Mosfets it is a completely different story. For a properly biased A/B stage using BJTs, minimum distortion is found a little after the bias starts, like about 5 mA in many sets. But it drifts and so you want to be a little higher than that to avoid cross-over distortion.
Any of these "class A" amplifiers are not really. They are "cranked up bias" only, and that serves little to no purpose. The one amp that was a common brand was the Luxman M-05 amplifier. I think it's class A was real.
Why do people hear a difference when there isn't one? Expectation bias. So if you are going to test something like this, have the demonstration amplifier set up before running your experiment. Also, because of the high heat sink temperature, you can't switch from high bias to low bias again and listen. The normal A/B mode can easily have crossover distortion under those conditions. So for a test, you can only switch from class A/B to high bias, but not back. I'm going to bet that you will not really hear any difference in the high bias mode.
-Chris
With Mosfets it is a completely different story. For a properly biased A/B stage using BJTs, minimum distortion is found a little after the bias starts, like about 5 mA in many sets. But it drifts and so you want to be a little higher than that to avoid cross-over distortion.
Any of these "class A" amplifiers are not really. They are "cranked up bias" only, and that serves little to no purpose. The one amp that was a common brand was the Luxman M-05 amplifier. I think it's class A was real.
Why do people hear a difference when there isn't one? Expectation bias. So if you are going to test something like this, have the demonstration amplifier set up before running your experiment. Also, because of the high heat sink temperature, you can't switch from high bias to low bias again and listen. The normal A/B mode can easily have crossover distortion under those conditions. So for a test, you can only switch from class A/B to high bias, but not back. I'm going to bet that you will not really hear any difference in the high bias mode.
-Chris
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.