Hi All,
I have been reading a lot on this forum - Trully amazing!
1 year ago I bough second hand a Yamaha HTR-5840 followed by a pair of Wharfedale Pacific PI-10. 2 month ago the Yamaha died and it is the best think that happened to me. I replaced it with a Yaqin MC-10L that I brought back from China (2300HKD incl shipping
)
While the sound is fantastic, I have a few issues with the quality of the parts.
1. Numerous websites mention that the MC-10L is 23kg, but mine is more like 17kg. I don't understand how this is possible...
2. The RCA plugs are of poor quality. One came off when I disconnected my cable. The gold color is not clear, looking kind of dirty.
3. After staying on for 10 hours (I am burning it in), there was electricity in the volume knob. When I touch it, it is not like an electrical shock, but I can clearly feel the electricity going into my hand.
I am planning to replace all the RCA plugs with good ones. Anything in particular I should be carefull with? Any advise on brand / model?
Would anyone have an idea why there os electricity in the volume knob? Also when I turn it, the resistance is not uniform troughout (it requires more strenght to go from 0 to 33% than from 33% to 66%). Would changing the potentionmeter solve all my problems? If so, does anyone have the parameter of the potentiometer (to make sure I buy the right one)? Cound someone recomment brand / model (is TOCO from Japan good?)
Thanks a lot,
Serge
I have been reading a lot on this forum - Trully amazing!
1 year ago I bough second hand a Yamaha HTR-5840 followed by a pair of Wharfedale Pacific PI-10. 2 month ago the Yamaha died and it is the best think that happened to me. I replaced it with a Yaqin MC-10L that I brought back from China (2300HKD incl shipping
)While the sound is fantastic, I have a few issues with the quality of the parts.
1. Numerous websites mention that the MC-10L is 23kg, but mine is more like 17kg. I don't understand how this is possible...
2. The RCA plugs are of poor quality. One came off when I disconnected my cable. The gold color is not clear, looking kind of dirty.
3. After staying on for 10 hours (I am burning it in), there was electricity in the volume knob. When I touch it, it is not like an electrical shock, but I can clearly feel the electricity going into my hand.
I am planning to replace all the RCA plugs with good ones. Anything in particular I should be carefull with? Any advise on brand / model?
Would anyone have an idea why there os electricity in the volume knob? Also when I turn it, the resistance is not uniform troughout (it requires more strenght to go from 0 to 33% than from 33% to 66%). Would changing the potentionmeter solve all my problems? If so, does anyone have the parameter of the potentiometer (to make sure I buy the right one)? Cound someone recomment brand / model (is TOCO from Japan good?)
Thanks a lot,
Serge
If the volume pot has a metal knob, you are feeling a tingle because you have a mildly 'hot' chassis! This is probably caused by something on the primary side of the power transformer (or the tranny itself) leaking AC line current to chassis. This is a potentially fatal situation! Especially if your power cord does not have a safety ground (green wire).
Take this unit to a competent TV/audio tech immediately!
Take this unit to a competent TV/audio tech immediately!
The feeling you get in the volume knob might be caused by the hot and return of your main power being reversed. The old 120VAC plugs that weren't polarized, one spade wider than the other, would often cause this type of "tingling" on metal parts of whatever they powered. Flipping the plug over so the spades went in the other slot usually fixed the tingling problem.
As mentioned, if you're not knowledgeable about the mains power, take it to a knowledgeable technician.
Mike
As mentioned, if you're not knowledgeable about the mains power, take it to a knowledgeable technician.
Mike
Thanks guys!
Audiocarp:
Are you saying that a cable that is located between the power plug and the transformator is touching the case? and that this would be the cause? Why can't I fix myself? If I bring it to someone it will cost the same as a new one.
By "hot" chasis, do you mean warm?
How do I find out if my power has a green wire? Do I need to open the cable?
Mikje:
What is the hot? and what is the return?
My amp is 220V.
By "spades", do you mean the metalic pins that are at the end of the power cable and that goes into the amp? If so, this connection is not symetrical, so it can only be plugged in one direction.
Audiocarp:
Are you saying that a cable that is located between the power plug and the transformator is touching the case? and that this would be the cause? Why can't I fix myself? If I bring it to someone it will cost the same as a new one.
By "hot" chasis, do you mean warm?
How do I find out if my power has a green wire? Do I need to open the cable?
Mikje:
What is the hot? and what is the return?
My amp is 220V.
By "spades", do you mean the metalic pins that are at the end of the power cable and that goes into the amp? If so, this connection is not symetrical, so it can only be plugged in one direction.
By your questions it is clear that you can't fix this yourself.
By your questions it is clear that you can't fix this yourself. Take the unit to a qualified technician to have the power cable replaced.
Electrical wiring in Hong Kong - Wikipedia, the free encyclopedia
BS 1363 is the mainstream wiring system in Hong Kong. In old buildings, the BS 546 system is also common.
Due to its proximity to mainland China, electrical products from there are quite common in Hong Kong. Many Hong Kongers and mainland Chinese immigrants purchase electrical products in mainland China and use them in Hong Kong. Even if an item of equipment meets the safety requirements inside mainland China, there are plug and socket compatibility problems when using them in Hong Kong.
Before the enforcement of the Electrical Products (Safety) Regulation, many types of plugs could be found in Hong Kong. Using this old equipment sometimes leads to plug and socket mating problems. Nowadays, virtually all plugs fitted in equipment sold in Hong Kong are BS 1363 compatible.
Many overseas citizens who bring equipment in from their home countries do not use the British wiring system. Citizens from the United Kingdom and countries that use British wiring systems normally do not encounter plug-and-socket issues in Hong Kong.
By your questions it is clear that you can't fix this yourself. Take the unit to a qualified technician to have the power cable replaced.
Electrical wiring in Hong Kong - Wikipedia, the free encyclopedia
BS 1363 is the mainstream wiring system in Hong Kong. In old buildings, the BS 546 system is also common.
Due to its proximity to mainland China, electrical products from there are quite common in Hong Kong. Many Hong Kongers and mainland Chinese immigrants purchase electrical products in mainland China and use them in Hong Kong. Even if an item of equipment meets the safety requirements inside mainland China, there are plug and socket compatibility problems when using them in Hong Kong.
Before the enforcement of the Electrical Products (Safety) Regulation, many types of plugs could be found in Hong Kong. Using this old equipment sometimes leads to plug and socket mating problems. Nowadays, virtually all plugs fitted in equipment sold in Hong Kong are BS 1363 compatible.
Many overseas citizens who bring equipment in from their home countries do not use the British wiring system. Citizens from the United Kingdom and countries that use British wiring systems normally do not encounter plug-and-socket issues in Hong Kong.
Sergedc, it's probably not a bare contact or wire touching the case, but, something more subtle, like electrical leakage from the power transformer or the power switch. If Hong Kong's wiring is like Japan's, you have no third wire in the power cable grounding the case to an actual earth ground, so, this could get really nasty if you touch the volume control and happen to also touch something else which is grounded, like plumbing.
The third wire would come out at the end of your power plug as a third contact.
Well, if the cost of the amp is as much as getting it fixed, then, your the obvious choice is to open the window, and toss it out! (;o))
The third wire would come out at the end of your power plug as a third contact.
Well, if the cost of the amp is as much as getting it fixed, then, your the obvious choice is to open the window, and toss it out! (;o))
I had this exact issue with my MC-10L which was delivered to me without an Earth connection being made on the mains input connector. In the early days this was normal for these amps as the manufacturers felt that connecting an Earth might cause hum loop problems. My Yaqin became tingly not through a leak from the mains input or even the transformer. It was caused by external equipment being non earthed as it was supposed to be Class 2 double insulated equipment and which I often scorn about due to the fact that metal output connectors are provided. The offending piece of kit was a cable TV box with audio output, this being fed with 2-core cable but had a hot chassis due to its inbuilt switched mode power supply input filters. The hot chassis eventually led to a failure of the audio inputs to a PC sound card. I decided to fit an earth connection to the MC-10L, just a short link of wire required from the vacant Earth pin of the mains input connector to the amps chassis. I had no hum loop problem except a very small in obtrusive one when the PC is connected, probably due to the PC being powered on a distant power outlet. I made a request to Yaqin that they should earth all of their amplifiers as these were indeed Class 1 equipment and was the proper thing to do. You may have an early un-earthed model. Regarding the action of the volume control, it may be your source impedance that is upsetting its action. There is no coupling capacitor and everything you connect will be in parallel with a 20k ohm pot and yes, I sometimes think that is perhaps a little low for a valve amplifier, though I have not had any problems with it. Disconnect all inputs to the amplifier and check if the tingling is still there? Hopefully it will have gone and by connecting each input in turn you will find the real culprit. With regard to the quality of the RCA jacks, I have not had any issue but with the wiring I have, unacceptable crosstalk. So I use a remote switch box though re-wiring of the amp might help.
All, thanks a lot for the input.
I live in Singapore. I am away until wednesday. I will then open the chassis and check what is happening.
The only RCA input connected to the amp is a Creative X-fi USB.
1. I will try to remove the X-fi USB and see if the problem persist.
2. I will check on the earth connection of the power plug. I understand it should be touching the chassis. If it is not, do I just solder it on the chassis?
Hi-Q, I am currently reading you DOC on the MC-10L, great work.
I have an electricity measuring tool, how do I check how much electricity is in the chassis? I will put one leg of the tool on the chassis, but where do I put the second one (any metalic piece not connected to electricity?)?
Yes I don't know much about eletricity, although I had one class on it in uni, but I am very decided about learning and I will not give up (or through the amp by the windows).
Any good link with safety recommendation before I open the chassis? I obviously would prefer not to die
Serge
I live in Singapore. I am away until wednesday. I will then open the chassis and check what is happening.
The only RCA input connected to the amp is a Creative X-fi USB.
1. I will try to remove the X-fi USB and see if the problem persist.
2. I will check on the earth connection of the power plug. I understand it should be touching the chassis. If it is not, do I just solder it on the chassis?
Hi-Q, I am currently reading you DOC on the MC-10L, great work.
I have an electricity measuring tool, how do I check how much electricity is in the chassis? I will put one leg of the tool on the chassis, but where do I put the second one (any metalic piece not connected to electricity?)?
Yes I don't know much about eletricity, although I had one class on it in uni, but I am very decided about learning and I will not give up (or through the amp by the windows).
Any good link with safety recommendation before I open the chassis? I obviously would prefer not to die
Serge
Also, what I am feeling is not a tingling. I define "a tingling" as a brief feeling in my finger that would make me release the knob imediatelly. Instead, when I am touching the knob, at first nothing happens, but after few seconds, I feel something is getting into my finger. The longer I leave my finger on the knob, the stronger it become. (maybe this is what you meant by tingling, but though it was worth clarifying).
Serge
Serge
Hi!
You get what you pay for... if you are lucky. In many cases you get even less...
China gear, especially grey imported comonents are often of lesser quality than those meant for the official importers. They are also notoriously known for omitting the safety ground on the metal chassis.
Get this to an experienced technician who makes the unit save! Obviously the chassis is not grounded. A fault could cause even more serious voltages on the chassis without a fuse tripping..
Best regards
Thomas
You get what you pay for... if you are lucky. In many cases you get even less...
China gear, especially grey imported comonents are often of lesser quality than those meant for the official importers. They are also notoriously known for omitting the safety ground on the metal chassis.
Get this to an experienced technician who makes the unit save! Obviously the chassis is not grounded. A fault could cause even more serious voltages on the chassis without a fuse tripping..
Best regards
Thomas
Thomas is correct, I made quite a forceful request to Yaqin via one of their agents to get a safety earth fitted and was assured that all new production would have this fitted. All you need to do Serge is find someone with appropriate skills to connect a short earthing wire from the large Earth pin (probably vacant in your case) to a suitable solder tag mounted on the chassis work close by. You can check for a 'hot' chassis by setting your Multimeter to AC Volts and connecting it between the metal chassis of the amplifier and a good local Earth e.g. Supply point Earth pin.
It is unfortunate that the amplifier layout does not make it easy to add an anti-hum loop circuit. With regard to the 'hot' cable box at my location, it was indeed the box causing the problem as the symptoms disappeared once power was removed from this item. In fact I had received some nasty little bites before the Yaqin was installed as my previous SS amplifier did not have an earth connection and one had to be very careful when manipulating the RCA jacks!
Les
It is unfortunate that the amplifier layout does not make it easy to add an anti-hum loop circuit. With regard to the 'hot' cable box at my location, it was indeed the box causing the problem as the symptoms disappeared once power was removed from this item. In fact I had received some nasty little bites before the Yaqin was installed as my previous SS amplifier did not have an earth connection and one had to be very careful when manipulating the RCA jacks!
Les
All, Lets be clear, there is noone I can bring it to. I have to fix it myself. This is DYI forum, not BITS (bring it to someone...).So I need to connect 1. "a short earthing wire" : is that a particular vire? What caracteristic am I looking for?2. "from the large Earth pin" - I am clear on this one3. "to a suitable solder tag mounted on the chasis" : What is a tag? How to mount it to the chasis?Do I just solder the cable on the chasis? This should not be too complicated to do? Why insisting on bringing to a specialist? Serge
Like Fran said, safety. There's lots of stuff that beginners can play with where the worst thing that can happen is smoking some components. Then there's situations like this where, if you don't know what you're doing (and you don't, please take everyone's word for that), death can easily result. Yours or, worse yet, some innocent person.
Don't screw around. Have a competent professional fix this (in a city the size of Singapore, there will be dozens) and take it as a lesson about buying cheesy equipment. This is life and death stuff, not fine points of sound.
All,
Thanks a lot for all your explanation. I bought a multimeter and with the info you provided manage to confirm that my chasis was hot. When I put the black side of the multimeter on the ground in my wall and the other (red) side of the multimeter on the chasis, I had between 10 and 20 V.
The problem was that the Yaquin was provided with the wrong power plug (the seller is sending me another one) and I had to use a power adaptor. The power adapter was not transfering the earth from the wall up to the Amp.
It is now all sorted.
FYI : Singapore plug is suppose to be 230V but I have 242-245 coming out. No surprise that I already blew of the 2 250V fuse....
Next will be repairing my RCA connector. Anything I should look at when buying the RCA plugs? I am considering the 4 below:
ÕýÆ·ÃÀ¹úCMC 816-U ¶Æ½ð´¿Í Á¬»¨²å×ù RCA×ù-ÌÔ±¦Íø
ºÉÀ¼VAN DEN HUI£¨·¶µÇºÀ£©¸ßÆ·ÖÊ´¿Í¶Æ½ðRCA×ù-ÌÔ±¦Íø
¡¾·¢ÉÕÊ×Ñ¡¡¿ ̨ÍåÔ²ú ¶Æ½ð ´¿Í RCA ĸ×ù-ÌÔ±¦Íø
CMC OEM¸ß¼¶´¿Í¶Æ½ð ²»µôÉ« RCAÁ«»¨²å×ù ÐźÅÏß²å×ù Á«»¨×ù-ÌÔ±¦Íø
Do you beleave that the quality of the RCA connector make a big difference? I would expect so....
Finnally, how tough would it be to add an headphone output to the MC10L? Any has tried doing this?
Serge
Thanks a lot for all your explanation. I bought a multimeter and with the info you provided manage to confirm that my chasis was hot. When I put the black side of the multimeter on the ground in my wall and the other (red) side of the multimeter on the chasis, I had between 10 and 20 V.
The problem was that the Yaquin was provided with the wrong power plug (the seller is sending me another one) and I had to use a power adaptor. The power adapter was not transfering the earth from the wall up to the Amp.
It is now all sorted.
FYI : Singapore plug is suppose to be 230V but I have 242-245 coming out. No surprise that I already blew of the 2 250V fuse....
Next will be repairing my RCA connector. Anything I should look at when buying the RCA plugs? I am considering the 4 below:
ÕýÆ·ÃÀ¹úCMC 816-U ¶Æ½ð´¿Í Á¬»¨²å×ù RCA×ù-ÌÔ±¦Íø
ºÉÀ¼VAN DEN HUI£¨·¶µÇºÀ£©¸ßÆ·ÖÊ´¿Í¶Æ½ðRCA×ù-ÌÔ±¦Íø
¡¾·¢ÉÕÊ×Ñ¡¡¿ ̨ÍåÔ²ú ¶Æ½ð ´¿Í RCA ĸ×ù-ÌÔ±¦Íø
CMC OEM¸ß¼¶´¿Í¶Æ½ð ²»µôÉ« RCAÁ«»¨²å×ù ÐźÅÏß²å×ù Á«»¨×ù-ÌÔ±¦Íø
Do you beleave that the quality of the RCA connector make a big difference? I would expect so....
Finnally, how tough would it be to add an headphone output to the MC10L? Any has tried doing this?
Serge
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