Hi all,
I've recently bought a second-hand Roksan Kandy KA-1 MkIII amp. The amp looks like new, both from the outside and inside. It also worked absolutely fine for a few days.
However, it started suffering from two issues when I turn it on (standby) from cold:
The main issue is that sometimes (more often than not), when I turn on the amplifier, there is static in the left channel. Static gets a lot quieter after a minute or so, but the left channel remains quieter for ~5 minutes. After the amp warms up, it sounds fine - there is no static and sound balance is correct.
Turning the volume knob has no effect on the static level, turning it almost all the way up does "interrupt" the static momentarily, but it doesn't help.
If the amp is turned off (standby) and back on within a few minutes, there are no issues with static.
The second issue also relates to cold/warm amp start - if the amp is turned on from cold, there is a slight pop from the speakers when speaker relays engage. The pop is barely audible if the amp is turned on while it's still warm. I've seen DC offset begin too high mentioned in Roksan's FAQ.
The final issue is not related to cold start, and I'm not even sure it's an issue: even when the volume knob is turned all the way down, you can still hear the music (very faintly)
I've contacted both the seller and Roksan and I'm waiting for their replies, but I'd like to know if this is an easy fix, since I'd love to keep the amp. I know how to use a soldering iron and a multimeter, but I could use some guidance 🙂
Thank you!
I've recently bought a second-hand Roksan Kandy KA-1 MkIII amp. The amp looks like new, both from the outside and inside. It also worked absolutely fine for a few days.
However, it started suffering from two issues when I turn it on (standby) from cold:
The main issue is that sometimes (more often than not), when I turn on the amplifier, there is static in the left channel. Static gets a lot quieter after a minute or so, but the left channel remains quieter for ~5 minutes. After the amp warms up, it sounds fine - there is no static and sound balance is correct.
Turning the volume knob has no effect on the static level, turning it almost all the way up does "interrupt" the static momentarily, but it doesn't help.
If the amp is turned off (standby) and back on within a few minutes, there are no issues with static.
The second issue also relates to cold/warm amp start - if the amp is turned on from cold, there is a slight pop from the speakers when speaker relays engage. The pop is barely audible if the amp is turned on while it's still warm. I've seen DC offset begin too high mentioned in Roksan's FAQ.
The final issue is not related to cold start, and I'm not even sure it's an issue: even when the volume knob is turned all the way down, you can still hear the music (very faintly)
I've contacted both the seller and Roksan and I'm waiting for their replies, but I'd like to know if this is an easy fix, since I'd love to keep the amp. I know how to use a soldering iron and a multimeter, but I could use some guidance 🙂
Thank you!
Hi Bozho,
It looks like one of the electrolytic capacitors starts failing in one of the channels, however this kind of issues require some knowledge and experience do diagnose even for a service engineer or circuit designer. It's not the reason to change the amp - normal thing after some time. However, I would just let some pro to fix the issue, the question is where to find a good one then 😉
Cheers,
Valery
It looks like one of the electrolytic capacitors starts failing in one of the channels, however this kind of issues require some knowledge and experience do diagnose even for a service engineer or circuit designer. It's not the reason to change the amp - normal thing after some time. However, I would just let some pro to fix the issue, the question is where to find a good one then 😉
Cheers,
Valery
Hi guys,
Caps were my suspicion as well. I got a quote from Roksan technical support, they'd charge a minimum of £160 labour plus parts. Considering I paid £250 for the amp, servicing it there would probably double the price 🙂
If I do decide to attempt repairs on my own, would it make sense to simply replace all the electrolytic capacitors (or at least the most probable suspects)?
I was not able to find a service manual online yet 🙁
Caps were my suspicion as well. I got a quote from Roksan technical support, they'd charge a minimum of £160 labour plus parts. Considering I paid £250 for the amp, servicing it there would probably double the price 🙂
If I do decide to attempt repairs on my own, would it make sense to simply replace all the electrolytic capacitors (or at least the most probable suspects)?
I was not able to find a service manual online yet 🙁
send some pictures on the inside I have the same amp but working. Hopefully someone will send the service manual!!
Hi guys,
Apologies for not replying over the weekend, was quite busy.
I think I've found the culprit - the headphone socket.
The amp has a small separate volume control PBC with a motorised volume pot and a headphone socket.
The pcb is mounted using a tall spacer and a screw on the far left corner, which connects the PCB ground to chassis, and a volume pot nut on the faceplate.
I've noticed that the problem appears and disappears when I press the headphone socket in different directions - both with headphones and speakers. I've checked for cold solder joints, but it's not that. It looks like there's something wrong with internals. Is that plausible?
I noticed that the socket is quite snug against the bottom of its faceplate hole. Could something like vibrations during transport have damaged the socket internally?
Thank you!
Apologies for not replying over the weekend, was quite busy.
I think I've found the culprit - the headphone socket.
The amp has a small separate volume control PBC with a motorised volume pot and a headphone socket.
The pcb is mounted using a tall spacer and a screw on the far left corner, which connects the PCB ground to chassis, and a volume pot nut on the faceplate.
I've noticed that the problem appears and disappears when I press the headphone socket in different directions - both with headphones and speakers. I've checked for cold solder joints, but it's not that. It looks like there's something wrong with internals. Is that plausible?
I noticed that the socket is quite snug against the bottom of its faceplate hole. Could something like vibrations during transport have damaged the socket internally?
Thank you!
I have no idea what Roksan use for their hardware, but headphone sockets have plated contact surfaces and these can oxidise or corrode and become coated in household grime. In other words, the electrical contacts become intermittent with high, fluctuating resistance. The solution is to use them - frequently but not many owners do now - just buy expensive headphone amplifiers instead.
It could even just be an assembly problem if the socket bush is hard against any side of the fascia hole - could even be washers used on the tall spacer (or not, if it has been tinkered with).
Rather than mess with things you may not be sure of, you could take this to any audio repairer. If it's working as you say, it's not likely to have anything serious wrong with it and may be worth the money for peace of mind.
It could even just be an assembly problem if the socket bush is hard against any side of the fascia hole - could even be washers used on the tall spacer (or not, if it has been tinkered with).
Rather than mess with things you may not be sure of, you could take this to any audio repairer. If it's working as you say, it's not likely to have anything serious wrong with it and may be worth the money for peace of mind.
Hi Ian,
Thank you for the reply.
So, it's possible that damage/problems with the headphone socket could cause problems on the speakers signal path? There must be some feedback from it, since the speaker relays cut out when I plug in headphones...
I'm waiting to hear from a Roksan engineer, the problem is that their initial service rate is close to what I paid for the amp 🙂
If this is a simple replacement job, I can handle it. If it's something more complicated, I'll have to look for an independent repair shop...
Regards,
Marko
Thank you for the reply.
So, it's possible that damage/problems with the headphone socket could cause problems on the speakers signal path? There must be some feedback from it, since the speaker relays cut out when I plug in headphones...
I'm waiting to hear from a Roksan engineer, the problem is that their initial service rate is close to what I paid for the amp 🙂
If this is a simple replacement job, I can handle it. If it's something more complicated, I'll have to look for an independent repair shop...
Regards,
Marko
In more detail, the headphone socket usually incorporates an independent switch that cuts power to the speaker relay coil when the headphone jack is inserted. The relay contacts then open, disconnecting the speakers in the same way as when you turn off the power. So the socket contacts won't be directly making the speaker output connection. Only the headphones are connected via the socket's ring and tip contacts but these can go bad too.
I mention the problem because I have had a couple of amplifiers on the bench that were wired that way but the relay action was weak with little contact pressure so the sound was erratic - varying from loud to soft, distorted, crackling, chattering - you name it! I had to replace both the switch and relay to get reliable performance.
Don't assume though, that because a fault description you read here seems to be like your problem, that it is indeed the case. A service tech would know how to interpret symptoms and ask the right questions to get to the real base of the problem but that takes some time, tools and investigation on your part. It's better to let someone experienced look at your amp to identify the real problem, as suggested.
When you are looking at repair costs, realistically you have to use the new price of the gear for relative value. If you paid only $50 for the amp, you couldn't expect to have it repaired for $25. If the new price is/was $1000, a $150 repair bill could be considered reasonable though.
I mention the problem because I have had a couple of amplifiers on the bench that were wired that way but the relay action was weak with little contact pressure so the sound was erratic - varying from loud to soft, distorted, crackling, chattering - you name it! I had to replace both the switch and relay to get reliable performance.
Don't assume though, that because a fault description you read here seems to be like your problem, that it is indeed the case. A service tech would know how to interpret symptoms and ask the right questions to get to the real base of the problem but that takes some time, tools and investigation on your part. It's better to let someone experienced look at your amp to identify the real problem, as suggested.
When you are looking at repair costs, realistically you have to use the new price of the gear for relative value. If you paid only $50 for the amp, you couldn't expect to have it repaired for $25. If the new price is/was $1000, a $150 repair bill could be considered reasonable though.
hey thats where all the audio connects go. the pre /headphones and left and right all meet at that pcb make sure they are all pushed in properly
Did a service manual, or sketch on a cigarette packet ever materialise?
Are you wondering? Pre-amp issue. Lots of dished caps. One channel deeper sounding, quieter, physically warm. The other cold, louder seeming, not nice. As outlined above, the pre-amp goes to the volume, then the main amp. It does so using separate cables for left and right, so you can swap them to narrow things down.
Are you wondering? Pre-amp issue. Lots of dished caps. One channel deeper sounding, quieter, physically warm. The other cold, louder seeming, not nice. As outlined above, the pre-amp goes to the volume, then the main amp. It does so using separate cables for left and right, so you can swap them to narrow things down.
Hi, this was nearly 10 years ago. I don't even remember what happened to it 😂
