Hello all the experts out here,
I bought this amp a few months ago on eBay. 2 weeks ago while listening to it for over 2 hours, I noticed heavy smoke coming from the left side of the amp. One of the hv capacitors blew up. It is 220uF/250v. For the last 2 weeks, I have been reading intensely about mods and other people problems yet I could not find a suitable schematic for my amp. First of all, my amp has 7 tubes: 4x kt88, 2x 6n8p and 1x 6n3. All the schematics I found has 8 tubes.
Also if you notice the power PCB, there is a modification done (by the factory, not me) with the yellow wire. Maybe I got a lemon. Anyway, I need your advice: should i replace the capacitor(s) with 220uF/400v? Would this solve my problem? I also want to eliminate the Triode/UL switch but I need a good schematic for that. Any other suggestions please help me so I can enjoy again “the sound of the music”.
Thanks,
alecu7
I bought this amp a few months ago on eBay. 2 weeks ago while listening to it for over 2 hours, I noticed heavy smoke coming from the left side of the amp. One of the hv capacitors blew up. It is 220uF/250v. For the last 2 weeks, I have been reading intensely about mods and other people problems yet I could not find a suitable schematic for my amp. First of all, my amp has 7 tubes: 4x kt88, 2x 6n8p and 1x 6n3. All the schematics I found has 8 tubes.
Also if you notice the power PCB, there is a modification done (by the factory, not me) with the yellow wire. Maybe I got a lemon. Anyway, I need your advice: should i replace the capacitor(s) with 220uF/400v? Would this solve my problem? I also want to eliminate the Triode/UL switch but I need a good schematic for that. Any other suggestions please help me so I can enjoy again “the sound of the music”.
Thanks,
alecu7
Attachments
Replacing the bad capacitor will of course be necessary. Replacing both of them with good brand name units is also a good idea. Going up to 400V parts is probably a smart move provided you can find capacitors that will physically fit. A 400 volt part will probably be a little bigger, so take careful measurments to assure they will fit.
Another thing I would do is to reduce the value of the two voltage divider resistors across the capacitors from 220K to 100K 2 watts. This will help assure that you are below the internal leakage of the capacitors themselves which is necessary for them to do their job of equalizing the voltage. There's some talk, with diagrams, of the Music Angel KT88 here.
http://www.diyaudio.com/forums/tubes-valves/163950-music-angel-kt88-correct-circuit.html
Another thing I would do is to reduce the value of the two voltage divider resistors across the capacitors from 220K to 100K 2 watts. This will help assure that you are below the internal leakage of the capacitors themselves which is necessary for them to do their job of equalizing the voltage. There's some talk, with diagrams, of the Music Angel KT88 here.
http://www.diyaudio.com/forums/tubes-valves/163950-music-angel-kt88-correct-circuit.html
Last edited:
Panasonic, Nippon, Nichicon, Mallory, Sprague to name a few. I'm unfamiliar with Digikey's product line so you'll have to look.
The amp you have is the Music Angel YC-808MK KT88.
The XDSE 800 is the more common version, with lots of info available on this and other forums.
You are not the first one with blown caps in the YC-808 after a week or two. The PS caps seem to be a bit close to, or under, the required voltage ratings.
Attached is a picture where the suspect caps are identified.
(Sorry, I have no schematic for this one)
SveinB
The XDSE 800 is the more common version, with lots of info available on this and other forums.
You are not the first one with blown caps in the YC-808 after a week or two. The PS caps seem to be a bit close to, or under, the required voltage ratings.
Attached is a picture where the suspect caps are identified.
(Sorry, I have no schematic for this one)
SveinB
Attachments
That's great. This is the amp I have. I already bought 2pcs. 220uF/350V for the caps on the left side. I never thought to change the ones on the right side. But that's great. Thank you.
Digikey link: Digi-Key - 493-1225-ND (Manufacturer - UVR2V221MRD6)
There are 220uF/350V and are Nichicon. Hope there are ok. Thanks,
Electronically they are fine. Hope they are not too tall so you can mount them on that board as the originals were and have it fit in the amp.
chinese tube amplifiers
here is what the manufacturer states on his page: ( as usual overestimates himself):
We engage in power amplifier research and production more than 10 years.
Produce high-fidelity the electron tubes amalgamate work putting (gallbladder) , electron tube earphone , grade electron tube ago, before put stone work behind gallbladder, grade before Hi-Fi is pure, grade after being pure, AV home theater work is put, the progression yard mixes the Chinese percussion instrument in front of the Karaoka disc, the advanced work of sound appliances in the car is put, the stereo work of the computer is put, high-grade power amplifiers , such as Dolby AC-3 series ,etc.. The products are sold to the American-European developed country and all parts of the world mainly. And get the favorable comment.
Our factory especially pays attention to talents, the designer comes from the electronic university of every famous brand , engaged in the specialized electronic engineer of stereo . Our factory has already passed national 3C and CE authentication . The staff pass vocational training on duty. It is self-contained to measure, the raw materials select for use and import Japan , U.S.A. , Germany, Taiwan and domestic famous factory raw materials, through screening strictly, wearing out, quality is first-class. The after-sale service is perfect, for many years, gain the favor of the counterparts people from all walks of life!
Warmly welcome all old and new customers messenger write to us the connection , negotiate. Our factory can produce other electronic products according to customer's request development in addition!
first class capacitors: no they are fake as many other components or pre used and cleaned
... one gets what one pays for
here is what the manufacturer states on his page: ( as usual overestimates himself):
We engage in power amplifier research and production more than 10 years.
Produce high-fidelity the electron tubes amalgamate work putting (gallbladder) , electron tube earphone , grade electron tube ago, before put stone work behind gallbladder, grade before Hi-Fi is pure, grade after being pure, AV home theater work is put, the progression yard mixes the Chinese percussion instrument in front of the Karaoka disc, the advanced work of sound appliances in the car is put, the stereo work of the computer is put, high-grade power amplifiers , such as Dolby AC-3 series ,etc.. The products are sold to the American-European developed country and all parts of the world mainly. And get the favorable comment.
Our factory especially pays attention to talents, the designer comes from the electronic university of every famous brand , engaged in the specialized electronic engineer of stereo . Our factory has already passed national 3C and CE authentication . The staff pass vocational training on duty. It is self-contained to measure, the raw materials select for use and import Japan , U.S.A. , Germany, Taiwan and domestic famous factory raw materials, through screening strictly, wearing out, quality is first-class. The after-sale service is perfect, for many years, gain the favor of the counterparts people from all walks of life!
Warmly welcome all old and new customers messenger write to us the connection , negotiate. Our factory can produce other electronic products according to customer's request development in addition!
first class capacitors: no they are fake as many other components or pre used and cleaned
... one gets what one pays for
I believe the quoted text is from the www.yaqin.cn website, who are not the manufacturer of any Music Angel amplifiers.
Most of the MA amplifiers, including the Meng series, seem to be manufactured by www.yogoo,com
The MA yc-808mk, in spite of sharing the MA name, seem to be manufactured by someone else, not yet identified.
I agree that the build quality of many of these products leaves a little to be desired, but some of the MA amps from yogoo can be made to sound astonishingly well with some good small signal tubes.
SveinB.
music hells angel
yes, you are correct. but by his statement, he is the manufacturer. also for possible claims. the text was copied / pasted from his site. thats the way, chinese are working. they say, they are in foshan, near to guangzhou, and its close to me ( shenzhen) maybe i drop in there, to see, what they really are, if i am in the area. we know, they are selling a lot of tube amp stuff, rather cheap under this brand. maybe , most are also done in home-work ( really, some do that). most of them dont have suitable equipment or even needed nowledge. as someone said here in the forum: for transformers any magnet wire available or insulation tape, or capacitor will do the job. as i study some pictures, the PCB and built quality is doubtful from music angel.
wether if its is ÉýÒÕÒôÏì ¾«Æ·ÜöÝÍ or not, or it is the same company, operating under different names, as they always like to do, the amplifier is not the hit.
below the average, just to make fast money. they dont are anything...
yes, you are correct. but by his statement, he is the manufacturer. also for possible claims. the text was copied / pasted from his site. thats the way, chinese are working. they say, they are in foshan, near to guangzhou, and its close to me ( shenzhen) maybe i drop in there, to see, what they really are, if i am in the area. we know, they are selling a lot of tube amp stuff, rather cheap under this brand. maybe , most are also done in home-work ( really, some do that). most of them dont have suitable equipment or even needed nowledge. as someone said here in the forum: for transformers any magnet wire available or insulation tape, or capacitor will do the job. as i study some pictures, the PCB and built quality is doubtful from music angel.
wether if its is ÉýÒÕÒôÏì ¾«Æ·ÜöÝÍ or not, or it is the same company, operating under different names, as they always like to do, the amplifier is not the hit.
below the average, just to make fast money. they dont are anything...
I bought the other 2 capacitors as well.
They are from Digikey as well, part number P13315-ND
820UF 500V made by Panasonic. They are the biggest I can fit inside the amp.
As for the other comments made here, I think we the people from "American-European developed country" trust chinese workmanship too much. On the other hand there must be smart chinese people out there since they launch satellites, but for sure none of them worked on my amp.
Anyway, is there anything else I should change? I really want to eliminate the triode/ul switch. I'm going to try and trace the schematic.
Thank you all for your responses.
They are from Digikey as well, part number P13315-ND
820UF 500V made by Panasonic. They are the biggest I can fit inside the amp.
As for the other comments made here, I think we the people from "American-European developed country" trust chinese workmanship too much. On the other hand there must be smart chinese people out there since they launch satellites, but for sure none of them worked on my amp.
Anyway, is there anything else I should change? I really want to eliminate the triode/ul switch. I'm going to try and trace the schematic.
Thank you all for your responses.
In people we just take the gallbladder out and it solves all sorts of problems. Maybe there is the answer...
I'm assuming that perhaps tube is mis-translated as 'gall bladder' in machine translators. I've experienced this with Mandarin translator plug ins in Firefox, ultimately the translations were so bad as to be useless. I no longer bother...
Removing gall bladders solves a lot of problems, and sometimes creates others..
I'm assuming that perhaps tube is mis-translated as 'gall bladder' in machine translators. I've experienced this with Mandarin translator plug ins in Firefox, ultimately the translations were so bad as to be useless. I no longer bother...
Removing gall bladders solves a lot of problems, and sometimes creates others..
At least the translators provide entertainment.
But I for one am going to disect my next Chinese amp and remove whatever I think is the gallbladder. I guess if it the tubes, it will solve the noise issue.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.