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Feb 7, 2019 17:56:00 GMT -5
Post by DavidR on Feb 7, 2019 17:56:00 GMT -5
Mundorf is a name. A good name, but this is an electrolytic capactitor we're talkin' about here, right? Lot's of available stuff for WAY less than such a premium. Any hint as to WHY what is essentially a commodity item is on offer for such a wacky price? ReRead DYohns's post. Big PS caps last a long time. What else could be going on with that amp to cause what you are seeing? Manufacturing DEFECT Hey, Sum Chow: screw up on capacitor line 4.
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Feb 8, 2019 2:24:13 GMT -5
Post by dragonV on Feb 8, 2019 2:24:13 GMT -5
Panasonic caps are really good, by the way. I used them in all my DIY amps back in the day. Now, before you spend money, what makes you certain the amp needs caps, and that if the caps are blown it's not something else in the power supply that is blowing them? Thanks for reply. Two of the caps are blown out the top. Emotiva's suggests replacing as a set (8). May well be other issues, but will find out once tech has a look. The caps in particular were very hard to source last time, so wanted to try and get some ready when drop it off. From searching they are VERY hard to find in stock and from a safe supplier. This is even though plenty of big name companies make ones to spec. This might explain why Emotiva has advised they cannot supply. All I have found in stock, and from a trusted supplier (and that meet spec) are the expensive Mundorfs....) Cheers
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Feb 8, 2019 2:32:11 GMT -5
Post by dragonV on Feb 8, 2019 2:32:11 GMT -5
Mundorf is a name. A good name, but this is an electrolytic capactitor we're talkin' about here, right? Lot's of available stuff for WAY less than such a premium. Any hint as to WHY what is essentially a commodity item is on offer for such a wacky price? ReRead DYohns's post. Big PS caps last a long time. What else could be going on with that amp to cause what you are seeing? Thanks for reply. Yes they should last a lot longer than this, and spares should be available but unfortunately they are not. There may well be another issue with the amp. Once the tech has it will find out for sure. So far the Mundorf are all that that has been found in stock, meet spec and from a reputable supplier. Open to suggestions!!! Cheers
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Post by chicagorspec on Feb 8, 2019 7:52:22 GMT -5
Mundorf is a name. A good name, but this is an electrolytic capactitor we're talkin' about here, right? Lot's of available stuff for WAY less than such a premium. Any hint as to WHY what is essentially a commodity item is on offer for such a wacky price? ReRead DYohns's post. Big PS caps last a long time. What else could be going on with that amp to cause what you are seeing? Thanks for reply. Yes they should last a lot longer than this, and spares should be available but unfortunately they are not. There may well be another issue with the amp. Once the tech has it will find out for sure. So far the Mundorf are all that that has been found in stock, meet spec and from a reputable supplier. Open to suggestions!!! Cheers I’m the four repair SA-250 guy. Cut your losses and buy an amp from a decent manufacturer, since you asked...
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DYohn
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Feb 8, 2019 7:58:02 GMT -5
Post by DYohn on Feb 8, 2019 7:58:02 GMT -5
The caps in particular were very hard to source last time, When you say "last time" are you saying this has happened before?
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Feb 8, 2019 8:50:48 GMT -5
Post by dragonV on Feb 8, 2019 8:50:48 GMT -5
The caps in particular were very hard to source last time, When you say "last time" are you saying this has happened before? Yes second time round with this amp, see earlier posts in thread. Emotiva has always been great for me with past gear, but this amp is probably on its last chance now.
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DYohn
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Feb 8, 2019 8:53:59 GMT -5
Post by DYohn on Feb 8, 2019 8:53:59 GMT -5
When you say "last time" are you saying this has happened before? Yes second time round with this amp, see earlier posts in thread. Emotiva has always been great for me with past gear, but this amp is probably on its last chance now. If the caps have failed before, STOP. Replacing them again will not solve the problem. How much did you pay for this amp? How much are these repairs costing you? Have you looked at alternatives?
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Feb 8, 2019 9:10:25 GMT -5
Post by DavidR on Feb 8, 2019 9:10:25 GMT -5
Are you running at 220V ?
Your caps have vented because of being over stressed or they could have been defective.
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Feb 8, 2019 12:59:12 GMT -5
Post by leonski on Feb 8, 2019 12:59:12 GMT -5
Are you running at 220V ? Your caps have vented because of being over stressed or they could have been defective. No matter what the voltage of the amp, you are just swapping transformers or switching from primary winding to primary winding by back panel switch. Once output from the transformer ALL amps in that series should be identical....The 80volt capacitor rating imples a LOWER output voltage from the PS. Possible problem? Bought a 60hz amp to run on 50hz. OR the incoming power which should be maybe 220 nominal is running closer to 240 or some such. As it turns out, a 50hz transformer WILL run on 60hz, but not the other way around. A 60hz transformer run on 50hz, for some reason, won't be right. The 'Losses' will be much higher and it'll run HOT. Could this effect PS caps? Somebody with a schematic needs to go thru this amp.....
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Feb 8, 2019 13:05:12 GMT -5
Post by DavidR on Feb 8, 2019 13:05:12 GMT -5
Are you running at 220V ? Your caps have vented because of being over stressed or they could have been defective. No matter what the voltage of the amp, you are just swapping transformers or switching from primary winding to primary winding by back panel switch. Once output from the transformer ALL amps in that series should be identical....The 80volt capacitor rating imples a LOWER output voltage from the PS. Possible problem? Bought a 60hz amp to run on 50hz. OR the incoming power which should be maybe 220 nominal is running closer to 240 or some such. As it turns out, a 50hz transformer WILL run on 60hz, but not the other way around. A 60hz transformer run on 50hz, for some reason, won't be right. The 'Losses' will be much higher and it'll run HOT. Could this effect PS caps? Somebody with a schematic needs to go thru this amp..... Exactly and is why I brought up 220V that is used in Australia. Caps vent when they are pushed too hard.
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Feb 8, 2019 13:14:55 GMT -5
Post by leonski on Feb 8, 2019 13:14:55 GMT -5
IF a 110/120 amp were plugged into 220 the PS caps popping would be the LEAST of your worries.
Properly configured, the 'back end' of the PS: that part from the transformer 2ndary ON will not know the difference.
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DYohn
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Post by DYohn on Feb 8, 2019 13:50:28 GMT -5
... or perhaps whatever regulates the voltage in the P/S is kaput. Whatever is going on, it is entirely unlikely that modern electrolytic power caps will fail on their own, and approaching zero probability that it would happen twice absent some other cause.
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Feb 8, 2019 14:22:54 GMT -5
Post by Ex_Vintage on Feb 8, 2019 14:22:54 GMT -5
The difference between an 85c and a 105c rated cap in system design is less about the expected ambient or operating temperature and more about having better control over ESR and taking advantage of the materials (teflon) used in a 105c cap to get a more linear performance through the expected usage band. Any standard electrolytic with sufficient voltage range will likely work, but the designer chose the more expensive 105c cap to get a particular performance advantage. Dielectric absorption for an electrolytic is an issue when used in the audio path, not so much as a 10,000 uf power support capacitor. The primary use of teflon is in high temperature film cap applications, not in high microfarad power supply caps.
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Feb 8, 2019 14:29:31 GMT -5
via mobile
DYohn likes this
Post by pedrocols on Feb 8, 2019 14:29:31 GMT -5
Just get a new amp. Get a tube amp☺️
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Feb 8, 2019 15:09:19 GMT -5
Post by leonski on Feb 8, 2019 15:09:19 GMT -5
The difference between an 85c and a 105c rated cap in system design is less about the expected ambient or operating temperature and more about having better control over ESR and taking advantage of the materials (teflon) used in a 105c cap to get a more linear performance through the expected usage band. Any standard electrolytic with sufficient voltage range will likely work, but the designer chose the more expensive 105c cap to get a particular performance advantage. Dielectric absorption for an electrolytic is an issue when used in the audio path, not so much as a 10,000 uf power support capacitor. The primary use of teflon is in high temperature film cap applications, not in high microfarad power supply caps. Aren't the big PS caps.....10,000mfd and up, for example ALL made pretty much the same, with an Aluma paste? A large capacitor manufacturer, KEMET, has a cool video online which shows some of the processes involved in such manufacture. The WIKI: en.wikipedia.org/wiki/Aluminum_electrolytic_capacitorOne very fast way to destroy such capacitors is to expose them to excess AC or even the 'wrong' polarity DC. One thing to look at, based on this information, would be the Bridge rectifiers of the broken amp. Excess leakage current at maybe 2 volts or above, will wreck such capacitors in short order. Such rectifiers are Dirt Cheap and should be easily replaced.
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Feb 8, 2019 20:26:02 GMT -5
Post by dragonV on Feb 8, 2019 20:26:02 GMT -5
Thanks for all the replies. Will definitely pass on to the tech, if it is to be repaired. Won't be sinking many more dollars into it, will take this good advice. So wait and see but may just be time to give up on the SA-250, and move on to another amp as others have recommended. Bit of a shame. Emotiva products have been great with me over the years, and their support just as good. This amp does sound great when working!!!
Will have a look around at options. Bit worried that earlier on in thread, another Australian owner said he has been waiting since November last year for parts on his gen 3 amp repair!! Anyway many thanks to all those who have given great feedback/replies. All much appreciated. Cheers
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Feb 9, 2019 2:05:50 GMT -5
Post by leonski on Feb 9, 2019 2:05:50 GMT -5
'Parts' covers a lot of ground. 2 major categories. 'Proprietary' where a company, usuually a 'biggie' makes or HAS made a part which nobody else has access to. Specialiezed Chips for HT receivers. Maybe even a run of semiconductors, like Nelson Pass did for his VFET amplifier project. SONY made VFET transistors a LONG time ago than stopped. Pass had foundry make him some.
Non-Propriettary stuff like resistors and capacitors and MOST integrated circuits, including but not limited to OpAmps, Power Devices, and 'obsolete'. I dont know that anyone specifies a resistor or capacitor NOT readily available, though they may spec it (like 105c capacitors) for longevity or other technical reasons. You can usually 'do' with the closest stock part. Crossovers in speakers can be an exception with inductors, which as they vary, take the crossover frequency with them. Magnepan is well known among the DIY guys for using not-quite-standard inductors. Those 10k mfd caps the OP needs? Can be replaced by 12k mfd without blinking, IF they fit...... The big PS caps are like 20% tolerance, so it is less than 'critical'.
For transistor, for example, several sources of 'cross reference' books exist. NTE is a source of information and ON Semiconductor is a foundry which makes a huge selection for aftermarket use.
Don't forget that virtually ALL transistors can be 'second sourced'. If a company only makes certain devices in ONE place that's bad. If they have an accident which severly interrupts production? Customers are screwed. The idea is to make the same part in more than one wafer fab. All parts of a given part # are qualified and considered 'interchangeable.
Your Tech should have access to ALL non-proprietary parts. I don't know that EMO uses much in the proprietary line, in amps or maybe preamps. The HT stuff? Up for grabs, from my limited view.
The LAST category is chassis / 'hardware'. Unless you've really messed up and dropped your gear down a flight of stairs, I don't see this being an issue.
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Feb 12, 2019 19:27:23 GMT -5
Post by Ex_Vintage on Feb 12, 2019 19:27:23 GMT -5
Dielectric absorption for an electrolytic is an issue when used in the audio path, not so much as a 10,000 uf power support capacitor. The primary use of teflon is in high temperature film cap applications, not in high microfarad power supply caps. Aren't the big PS caps.....10,000mfd and up, for example ALL made pretty much the same, with an Aluma paste? A large capacitor manufacturer, KEMET, has a cool video online which shows some of the processes involved in such manufacture. The WIKI: en.wikipedia.org/wiki/Aluminum_electrolytic_capacitorOne very fast way to destroy such capacitors is to expose them to excess AC or even the 'wrong' polarity DC. One thing to look at, based on this information, would be the Bridge rectifiers of the broken amp. Excess leakage current at maybe 2 volts or above, will wreck such capacitors in short order. Such rectifiers are Dirt Cheap and should be easily replaced. Large micro farad electrolytic caps are made from aluminum foil, a paper or film insulator and an electrolyte such as ethylene glycol. The aluminum foil is etched to maximize surface area and provide a large CV product. The primary stress on an electrolytic capacitor is heat. Heat created either by current flow, or ambient operating temperature will determine the lifetime of the cap. Electrolytic caps "wear out" due to vaporization of the electrolyte and a subsequent reduction in capacitance. This is why I question the need for 105C caps in an amplifier that has adequate free air convection and is used in a home environment. The 85C caps would do fine, and they can be had in a "audio grade" from Digi-Key for less than 10 bucks each.
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Feb 12, 2019 19:47:41 GMT -5
Post by leonski on Feb 12, 2019 19:47:41 GMT -5
105c caps SHOULD have a longer lifetime and higher reliability. If the amp came with 105c, THAT'S what goes back in. period. If the amp came with 85c, No Harm in going to 105c.
The advantage of the Liquid-type 'lytics is they are self healing. The anode foil will REOXIDE.
And when a piece of equipemnt has been out of service for an extended time period, it can be saved sometimes by brining up the voltage SLOWLY with a Variac and allowing the caps to heal.
Nelson Pass is on record as saying that such 'wet' caps SHOULD last 20 years or more. No that it means anything, but I have an old Kenwood Ingtegrated with original caps. This amp is around 30 years old and my nephew uses it for his guitar, of all things.
'Audio Grade'? I don't know. Many DIY guys I know use the Panasonic 'computer grade', whatever the heck THAT means.
And YES, by all means. Cooler gear lasts longer with fewer wacky failures. People that stack stuff up and shake their heads when stuff breaks makes me shake MY head.
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Post by audiosyndrome on Feb 12, 2019 19:57:37 GMT -5
And if you cannot find 105, than 85 is fine. Period.
Who knows why Emo used 105 to begin with; they got a good deal on a lot, used them in other earlier equipment and had many leftover, etc..
Russ
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