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Repair to faulty amp
Greetings,
I know there are a few here who are very well qualified with hifi (and particularly amplifier) electronic design. Can you help? I have an Alchemist Nexus amplifier which, when turned above a certain volume, screeches loudly through the speaker output. I believe that the amp is outputting DC - does that sound right? I have removed two burnt out resistors - identical on each channel on the PCB - and I had already replaced two 4 amp output fuses before testing produced the results described and before I removed the burnt resistors. Can anyone confirm my translation of the resistor colour codes (gathered from an identical amp as those in the faulty amp were badly burnt): 1st digit: Brown: 1 2nd digit Black: 0 Multiplier: Black: 0 Quality: Brown: 1 I make this 10 ohms of a high-tolerance 1%/1000 hour anticipated failure? I want to be certain as, while I am confident that my soldering skills are up to the task (the components are not surface mount), I have not carried out such a repair before without the aid of a manufacturer's service manual before. I have created a small rollover image at http://www.alchemisthifi.info/fault/resistor.htm which allows you to compare the damage on the bad amp with the good amp. The manufacturer (Alchemist) is no longer in business and there are no circuit diagrams about. Beyond the resistor confirmation, any constructive advice you can offer about my approach would be appreciated. TIA. |
Repair to faulty amp
JustMe wrote:
Greetings, I know there are a few here who are very well qualified with hifi (and particularly amplifier) electronic design. Can you help? I have an Alchemist Nexus amplifier which, when turned above a certain volume, screeches loudly through the speaker output. I believe that the amp is outputting DC - does that sound right? I have removed two burnt out resistors - identical on each channel on the PCB - and I had already replaced two 4 amp output fuses before testing produced the results described and before I removed the burnt resistors. Can anyone confirm my translation of the resistor colour codes (gathered from an identical amp as those in the faulty amp were badly burnt): 1st digit: Brown: 1 2nd digit Black: 0 Multiplier: Black: 0 Quality: Brown: 1 I make this 10 ohms of a high-tolerance 1%/1000 hour anticipated failure? I want to be certain as, while I am confident that my soldering skills are up to the task (the components are not surface mount), I have not carried out such a repair before without the aid of a manufacturer's service manual before. I have created a small rollover image at http://www.alchemisthifi.info/fault/resistor.htm which allows you to compare the damage on the bad amp with the good amp. The manufacturer (Alchemist) is no longer in business and there are no circuit diagrams about. Beyond the resistor confirmation, any constructive advice you can offer about my approach would be appreciated. TIA. In all probability the burnt out resistor(s) are not the cause of the problem but an effect of it. Resistors very rarely fail short circuit so it is likely that whatever this resistor is connected to has actually failed and taken out the resistor with it. Ian -- Ian Bell |
Repair to faulty amp
Contact Chris Found at He designed a few alchemist
products and would certainly help if he can. He's a friendly chap (lives in Fulham) Andy === Andy Evans === Visit our Website:- http://www.artsandmedia.com Audio, music and health pages and interesting links. |
Repair to faulty amp
"Ian Bell" wrote in message
... JustMe wrote: Greetings, I know there are a few here who are very well qualified with hifi (and particularly amplifier) electronic design. Can you help? I have an Alchemist Nexus amplifier which, when turned above a certain volume, screeches loudly through the speaker output. I believe that the amp is outputting DC - does that sound right? I have removed two burnt out resistors - identical on each channel on the PCB - and I had already replaced two 4 amp output fuses before testing produced the results described and before I removed the burnt resistors. Can anyone confirm my translation of the resistor colour codes (gathered from an identical amp as those in the faulty amp were badly burnt): 1st digit: Brown: 1 2nd digit Black: 0 Multiplier: Black: 0 Quality: Brown: 1 I make this 10 ohms of a high-tolerance 1%/1000 hour anticipated failure? I want to be certain as, while I am confident that my soldering skills are up to the task (the components are not surface mount), I have not carried out such a repair before without the aid of a manufacturer's service manual before. I have created a small rollover image at http://www.alchemisthifi.info/fault/resistor.htm which allows you to compare the damage on the bad amp with the good amp. The manufacturer (Alchemist) is no longer in business and there are no circuit diagrams about. Beyond the resistor confirmation, any constructive advice you can offer about my approach would be appreciated. TIA. In all probability the burnt out resistor(s) are not the cause of the problem but an effect of it. Resistors very rarely fail short circuit so it is likely that whatever this resistor is connected to has actually failed and taken out the resistor with it. Ian Yes, I wondered about that too but, with my limited knowledge, I've not been able to identify any other faulty components - what else would cause an amp to go DC in the manner described at the top? The o.p transistors all compare well with those in the good amp, for instance. Either way, they need replacing and so I thought I'd start there, even if I have to replace them again, after. Have I read the resistor's rating correctly? |
Repair to faulty amp
"Andy Evans" wrote in message
... Contact Chris Found at He designed a few alchemist products and would certainly help if he can. He's a friendly chap (lives in Fulham) Andy I believe the Nexus amp was designed by Glen Gayle - Chris designed their digital products and the Product8 pre amp too. I could send it to Glen, but I'd really like to try and sort it at home, if I can. |
Repair to faulty amp
I believe the Nexus amp was designed by Glen Gayle - Chris designed their
digital products and the Product8 pre amp too. I could send it to Glen, but I'd really like to try and sort it at home, if I can. you can email Chris and he'll give you his phone number - he may be able to tell you what to do over the phone. Andy === Andy Evans === Visit our Website:- http://www.artsandmedia.com Audio, music and health pages and interesting links. |
Repair to faulty amp
JustMe wrote:
"Ian Bell" wrote in message ... JustMe wrote: Greetings, I know there are a few here who are very well qualified with hifi (and particularly amplifier) electronic design. Can you help? I have an Alchemist Nexus amplifier which, when turned above a certain volume, screeches loudly through the speaker output. I believe that the amp is outputting DC - does that sound right? I have removed two burnt out resistors - identical on each channel on the PCB - and I had already replaced two 4 amp output fuses before testing produced the results described and before I removed the burnt resistors. Can anyone confirm my translation of the resistor colour codes (gathered from an identical amp as those in the faulty amp were badly burnt): 1st digit: Brown: 1 2nd digit Black: 0 Multiplier: Black: 0 Quality: Brown: 1 I make this 10 ohms of a high-tolerance 1%/1000 hour anticipated failure? I want to be certain as, while I am confident that my soldering skills are up to the task (the components are not surface mount), I have not carried out such a repair before without the aid of a manufacturer's service manual before. I have created a small rollover image at http://www.alchemisthifi.info/fault/resistor.htm which allows you to compare the damage on the bad amp with the good amp. The manufacturer (Alchemist) is no longer in business and there are no circuit diagrams about. Beyond the resistor confirmation, any constructive advice you can offer about my approach would be appreciated. TIA. In all probability the burnt out resistor(s) are not the cause of the problem but an effect of it. Resistors very rarely fail short circuit so it is likely that whatever this resistor is connected to has actually failed and taken out the resistor with it. Ian Yes, I wondered about that too but, with my limited knowledge, I've not been able to identify any other faulty components - what else would cause an amp to go DC in the manner described at the top? The o.p transistors all compare well with those in the good amp, for instance. When you say compare well what do you mean? And when you say the amp outputs dc, between what points do you measure this, what value do you read and how does it compare with a good amp? If the output trannys are OK then it may well be their drive circuit that is giving the problem but you really need a circuit to get into this levele of detail. Either way, they need replacing and so I thought I'd start there, even if I have to replace them again, after. Have I read the resistor's rating correctly? Looks like 10ohms 1% to me. IAn -- Ian Bell |
Repair to faulty amp
JustMe wrote: Greetings, I know there are a few here who are very well qualified with hifi (and particularly amplifier) electronic design. Can you help? I have an Alchemist Nexus amplifier which, when turned above a certain volume, screeches loudly through the speaker output. I believe that the amp is outputting DC - does that sound right? No. I have removed two burnt out resistors - identical on each channel on the PCB - and I had already replaced two 4 amp output fuses before testing produced the results described and before I removed the burnt resistors. Can anyone confirm my translation of the resistor colour codes (gathered from an identical amp as those in the faulty amp were badly burnt): 1st digit: Brown: 1 2nd digit Black: 0 Multiplier: Black: 0 Quality: Brown: 1 I make this 10 ohms of a high-tolerance 1%/1000 hour anticipated failure? Resistors don't have " 1000 hour anticipated failure " bands ! I want to be certain as, while I am confident that my soldering skills are up to the task (the components are not surface mount), I have not carried out such a repair before without the aid of a manufacturer's service manual before. I have created a small rollover image at http://www.alchemisthifi.info/fault/resistor.htm which allows you to compare the damage on the bad amp with the good amp. The manufacturer (Alchemist) is no longer in business and there are no circuit diagrams about. Beyond the resistor confirmation, any constructive advice you can offer about my approach would be appreciated. If you don't know how to troubleshoot - give up or give it to someone who does. Graham |
Repair to faulty amp
In article , JustMe
wrote: Greetings, I know there are a few here who are very well qualified with hifi (and particularly amplifier) electronic design. Can you help? I have an Alchemist Nexus amplifier which, when turned above a certain volume, screeches loudly through the speaker output. I believe that the amp is outputting DC - does that sound right? No. Sounds more like instability causing oscillations for some strange reason. May be that the PSU is unhappy so the amp is 'motor boating'. (Pure guess on my part.) A meter should tell you if the output d.c. is correct, etc. Similarly, you could use one to check the resistor values. I have removed two burnt out resistors - identical on each channel on the PCB - and I had already replaced two 4 amp output fuses before testing produced the results described and before I removed the burnt resistors. Can anyone confirm my translation of the resistor colour codes (gathered from an identical amp as those in the faulty amp were badly burnt): 1st digit: Brown: 1 2nd digit Black: 0 Multiplier: Black: 0 Quality: Brown: 1 I make this 10 ohms of a high-tolerance 1%/1000 hour anticipated failure? I want to be certain as, while I am confident that my soldering skills are up to the task (the components are not surface mount), I have not carried out such a repair before without the aid of a manufacturer's service manual before. I would tend to recommend testing the amp using a current-limited bench PSU. Otherwise you may just waste more resistors and/or fuses if the unit repeats the problem whenever you turn it on. Faulty power amps can tend to be distructive unless controlled. :-) You also ideally need a diagram for diagnosing any fault that may not be obvious. 10 Ohms sounds too high for o/p resistors to me. Sounds more like drivers, or similar, but I have no idea as I don't know the design. The dead resistors may mean some transistors have failed. resistors may good slow-blow fuses. Alas the 'slow' bit means the transistors go short in microseconds, and then the resistors fry in milliseconds... I have created a small rollover image at http://www.alchemisthifi.info/fault/resistor.htm which allows you to compare the damage on the bad amp with the good amp. The manufacturer (Alchemist) is no longer in business and there are no circuit diagrams about. Take up Andy's advice re contacting the designer. :-) FWIW I don't have any diagrams for the amp. If I did I'd be happy to try and advise. (If anyone has a diagram I'd love a copy to add to my collection. :-) ) Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
Repair to faulty amp
On Tue, 09 Nov 2004 22:05:19 +0000, JustMe wrote:
Can anyone confirm my translation of the resistor colour codes (gathered from an identical amp as those in the faulty amp were badly burnt): 1st digit: Brown: 1 2nd digit Black: 0 Multiplier: Black: 0 Quality: Brown: 1 I make this 10 ohms of a high-tolerance 1%/1000 hour anticipated failure? If the amp is pretty old then you are right, apart from the 4th band which usually means 1% tolerance (silver=10%, gold=5%, red=2%). Some old resistors had a salmon pink band at the end to signify "high stability" - but that is a while ago! There are now resistors with 4 bands, where the 4th band is the multiplier. In this case your value would be 1k. These are produced so that you can revel in delightful values like 91k! How about measuring a known good resistor out of the other amp and comparing them? A resistor will almost always fail open circuit or high in value. If the other amp has been working fine, and its resistors are not burned, then you should be looking for whatever caused the burning (e.g. a shorted transistor or something like that allowing excessive current flow for too long). -- Mick (no M$ software on here... :-) ) Web: http://www.nascom.info |
Repair to faulty amp
In article , mick
wrote: On Tue, 09 Nov 2004 22:05:19 +0000, JustMe wrote: There are now resistors with 4 bands, where the 4th band is the multiplier. In this case your value would be 1k. These are produced so that you can revel in delightful values like 91k! Good point. I had forgotten that! How about measuring a known good resistor out of the other amp and comparing them? A resistor will almost always fail open circuit or high in value. If the other amp has been working fine, and its resistors are not burned, then you should be looking for whatever caused the burning (e.g. a shorted transistor or something like that allowing excessive current flow for too long). I find it frustrating not to have a diagram of the amp! I am now curious as to what has gone wrong. :-) Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
Repair to faulty amp
"Pooh Bear" wrote in message ... JustMe wrote: Greetings, I know there are a few here who are very well qualified with hifi (and particularly amplifier) electronic design. Can you help? I have an Alchemist Nexus amplifier which, when turned above a certain volume, screeches loudly through the speaker output. I believe that the amp is outputting DC - does that sound right? No. I have removed two burnt out resistors - identical on each channel on the PCB - and I had already replaced two 4 amp output fuses before testing produced the results described and before I removed the burnt resistors. Can anyone confirm my translation of the resistor colour codes (gathered from an identical amp as those in the faulty amp were badly burnt): 1st digit: Brown: 1 2nd digit Black: 0 Multiplier: Black: 0 Quality: Brown: 1 I make this 10 ohms of a high-tolerance 1%/1000 hour anticipated failure? Resistors don't have " 1000 hour anticipated failure " bands ! I believe that they have a failure rating which is a percentage after 1000 hours, hence 1% per 1000 hours - 1% anticipated failure after 1000 hours. Is this wrong? I want to be certain as, while I am confident that my soldering skills are up to the task (the components are not surface mount), I have not carried out such a repair before without the aid of a manufacturer's service manual before. I have created a small rollover image at http://www.alchemisthifi.info/fault/resistor.htm which allows you to compare the damage on the bad amp with the good amp. The manufacturer (Alchemist) is no longer in business and there are no circuit diagrams about. Beyond the resistor confirmation, any constructive advice you can offer about my approach would be appreciated. If you don't know how to troubleshoot - give up or give it to someone who does. That's very helpful - I'll learn a lot like that - thanks. Graham |
Repair to faulty amp
Greetings,
I know there are a few here who are very well qualified with hifi (and particularly amplifier) electronic design. Can you help? I have an Alchemist Nexus amplifier which, when turned above a certain volume, screeches loudly through the speaker output. I believe that the amp is outputting DC - does that sound right? No. Sounds more like instability causing oscillations for some strange reason. May be that the PSU is unhappy so the amp is 'motor boating'. (Pure guess on my part.) Yup, you're right. A meter should tell you if the output d.c. is correct, etc. Similarly, you could use one to check the resistor values. I have removed two burnt out resistors - identical on each channel on the PCB - and I had already replaced two 4 amp output fuses before testing produced the results described and before I removed the burnt resistors. Can anyone confirm my translation of the resistor colour codes (gathered from an identical amp as those in the faulty amp were badly burnt): 1st digit: Brown: 1 2nd digit Black: 0 Multiplier: Black: 0 Quality: Brown: 1 I make this 10 ohms of a high-tolerance 1%/1000 hour anticipated failure? I want to be certain as, while I am confident that my soldering skills are up to the task (the components are not surface mount), I have not carried out such a repair before without the aid of a manufacturer's service manual before. I would tend to recommend testing the amp using a current-limited bench PSU. Otherwise you may just waste more resistors and/or fuses if the unit repeats the problem whenever you turn it on. Faulty power amps can tend to be distructive unless controlled. :-) Yes, I bought plenty of resistors and fuses, in case the faulty simply recurred straight away - as someone else said, an effect of a different fault rather than the fault itself. You also ideally need a diagram for diagnosing any fault that may not be obvious. Sadly not available :o( 10 Ohms sounds too high for o/p resistors to me. Sounds more like drivers, or similar, but I have no idea as I don't know the design. The dead resistors may mean some transistors have failed. resistors may good slow-blow fuses. Alas the 'slow' bit means the transistors go short in microseconds, and then the resistors fry in milliseconds... I have created a small rollover image at http://www.alchemisthifi.info/fault/resistor.htm which allows you to compare the damage on the bad amp with the good amp. The manufacturer (Alchemist) is no longer in business and there are no circuit diagrams about. Take up Andy's advice re contacting the designer. :-) Done and he confirmed what you said at the top as a likely fault, given my description. A quick change of the resistors has, so far, proved successful - the amp has now been running for 1/2 hour without fault and I am able to turn the volume high without the noise I got before. So far so good... FWIW I don't have any diagrams for the amp. If I did I'd be happy to try and advise. (If anyone has a diagram I'd love a copy to add to my collection. :-) ) I've been trying to track down circuit diagrams for Alchemist amps for a few years, without any joy. Slainte, Jim THANKS! |
Repair to faulty amp
In article , JustMe
wrote: Greetings, I know there are a few here who are very well qualified with hifi (and particularly amplifier) electronic design. Can you help? I have an Alchemist Nexus amplifier which, when turned above a certain volume, screeches loudly through the speaker output. I believe that the amp is outputting DC - does that sound right? No. Sounds more like instability causing oscillations for some strange reason. May be that the PSU is unhappy so the amp is 'motor boating'. (Pure guess on my part.) Yup, you're right. Must admit that is a pleasing surprise, as it was just an 'educated guess'! [snip] I would tend to recommend testing the amp using a current-limited bench PSU. Otherwise you may just waste more resistors and/or fuses if the unit repeats the problem whenever you turn it on. Faulty power amps can tend to be distructive unless controlled. :-) Yes, I bought plenty of resistors and fuses, in case the faulty simply recurred straight away - as someone else said, an effect of a different fault rather than the fault itself. The potential risk if you don't have a limited PSU is that each time you turn a faulty amp on, it may destroy different components, so do increasing levels of harm. However all being 'semi-OK', this won't occur. 8-] You also ideally need a diagram for diagnosing any fault that may not be obvious. Sadly not available :o( [snip] Take up Andy's advice re contacting the designer. :-) Done and he confirmed what you said at the top as a likely fault, given my description. A quick change of the resistors has, so far, proved successful - the amp has now been running for 1/2 hour without fault and I am able to turn the volume high without the noise I got before. So far so good... What would concern me is: what prompted the failure in the first place? The implication being that it might re-occur at some point. However some failures are due to 'random' component defects, so don't recur. Hence life isn't always tidy enough to resolve this. If the amp continues to work OK, then that is good enough news... :-) FWIW I don't have any diagrams for the amp. If I did I'd be happy to try and advise. (If anyone has a diagram I'd love a copy to add to my collection. :-) ) I've been trying to track down circuit diagrams for Alchemist amps for a few years, without any joy. Can Andy/you ask the designer for them? If he is better organised than myself he probably has his own copies. They may be copyright, but they should not be commericial in confidence. Indeed, having them available is in the interest of those who wish to service and use the units. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
Repair to faulty amp
On Thu, 11 Nov 2004 09:45:17 +0000, Jim Lesurf wrote:
snip I find it frustrating not to have a diagram of the amp! I am now curious as to what has gone wrong. :-) Me three... :-) -- Mick (no M$ software on here... :-) ) Web: http://www.nascom.info |
Repair to faulty amp
JustMe wrote: "Pooh Bear" wrote in message ... Resistors don't have " 1000 hour anticipated failure " bands ! I believe that they have a failure rating which is a percentage after 1000 hours, hence 1% per 1000 hours - 1% anticipated failure after 1000 hours. Is this wrong? Yes If you don't know how to troubleshoot - give up or give it to someone who does. That's very helpful - I'll learn a lot like that - thanks. Just being practical - it's not something that's easy unless you already know a lot about repairs in general. There's more scope for combustion with power amps ! Graham. |
Repair to faulty amp
JustMe wrote:
"Pooh Bear" wrote in message ... Resistors don't have " 1000 hour anticipated failure " bands ! I believe that they have a failure rating which is a percentage after 1000 hours, hence 1% per 1000 hours - 1% anticipated failure after 1000 hours. Is this wrong? Yes Well let me bow down before you, oh wonderous one. Would you be so kind as to make the effort to exapnd on your monosyllabic response and provide an adequate explanation, rather than the patronising, ego-massage-seeking, know-all responses you have given me so far in this thread? Or are you *that* special that any knowledge you have over and above those around you is sacred and not for plebs like me? If you don't know how to troubleshoot - give up or give it to someone who does. That's very helpful - I'll learn a lot like that - thanks. Just being practical - it's not something that's easy unless you already know a lot about repairs in general. Your replies have been most impractical - you state I am incorrect, yet do not explain how or why. Your best advice has been not to bother - if that's the best you can offer, then maybe you should take the same advice? The repair is now complete and, during the last 24 hours, the amp has performed flawlessly, thanks to the advise of Ian, Jim, Mick and Glen and a few hours searching Google. Hopefully I will experience no further trouble. There's more scope for combustion with power amps ! Than what? Graham. |
Repair to faulty amp
Greetings,
I know there are a few here who are very well qualified with hifi (and particularly amplifier) electronic design. Can you help? I have an Alchemist Nexus amplifier which, when turned above a certain volume, screeches loudly through the speaker output. I believe that the amp is outputting DC - does that sound right? No. Sounds more like instability causing oscillations for some strange reason. May be that the PSU is unhappy so the amp is 'motor boating'. (Pure guess on my part.) Yup, you're right. Must admit that is a pleasing surprise, as it was just an 'educated guess'! [snip] I would tend to recommend testing the amp using a current-limited bench PSU. Otherwise you may just waste more resistors and/or fuses if the unit repeats the problem whenever you turn it on. Faulty power amps can tend to be distructive unless controlled. :-) Yes, I bought plenty of resistors and fuses, in case the faulty simply recurred straight away - as someone else said, an effect of a different fault rather than the fault itself. The potential risk if you don't have a limited PSU is that each time you turn a faulty amp on, it may destroy different components, so do increasing levels of harm. However all being 'semi-OK', this won't occur. 8-] I appreciate your concern and knew that I was taking a chance, however I fancied having a go and hoped to (A) learn something and (B) save myself some cash and bother. You also ideally need a diagram for diagnosing any fault that may not be obvious. Sadly not available :o( [snip] Take up Andy's advice re contacting the designer. :-) Done and he confirmed what you said at the top as a likely fault, given my description. A quick change of the resistors has, so far, proved successful - the amp has now been running for 1/2 hour without fault and I am able to turn the volume high without the noise I got before. So far so good... What would concern me is: what prompted the failure in the first place? The implication being that it might re-occur at some point. However some failures are due to 'random' component defects, so don't recur. Hence life isn't always tidy enough to resolve this. If the amp continues to work OK, then that is good enough news... :-) Understood. The amp was used in an inappropiate environment before I owned it (as faulty). It was used in a commercial environment, likely by people who had consumed an excess of alcohol, in what would have been a hot and damp - possibly wet - atmosphere. The reason I asked about the values of the resistors was that I believe that they have a tolerance to temperature whcih can vary, dependent on the quality of the part. Hopefully it is good news :o) FWIW I don't have any diagrams for the amp. If I did I'd be happy to try and advise. (If anyone has a diagram I'd love a copy to add to my collection. :-) ) I've been trying to track down circuit diagrams for Alchemist amps for a few years, without any joy. Can Andy/you ask the designer for them? If he is better organised than myself he probably has his own copies. They may be copyright, but they should not be commericial in confidence. Indeed, having them available is in the interest of those who wish to service and use the units. I have asked the designer before, but he doesn't have them :o( I agree, making them available would be great. I have asked a few service departments and foriegn distributors too, but to no avail. He has always been very helpful, advised me on other products and repaired other faulty items that I have owned. This time I wanted to try for myself and save us both the hassle. Slainte, Jim Thanks again for your help! |
Repair to faulty amp
In message , Pooh Bear
writes JustMe wrote: "Pooh Bear" wrote in message ... Resistors don't have " 1000 hour anticipated failure " bands ! I believe that they have a failure rating which is a percentage after 1000 hours, hence 1% per 1000 hours - 1% anticipated failure after 1000 hours. Is this wrong? Yes If you don't know how to troubleshoot - give up or give it to someone who does. That's very helpful - I'll learn a lot like that - thanks. Just being practical - it's not something that's easy unless you already know a lot about repairs in general. There's more scope for combustion with power amps ! Graham. The last band is simply a tolerance, brown being 1%. In other words a 100k 1% would have a value somewhere between 99k and 101k. A red band is 2%, and gold is 5%. -- Chris Morriss |
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