Hi all!
I have recently purchased a rotel RB-1010 power amplifier and have been trying to source some new varistors (Sanken SV-04S) {old ones not working}. unfortunately I have not had much luck and it seems that they are unobtainable. I just wondered if anybody had any ideas as to where I might source these or a similar varistor that would do the job!
Any help would be greatly appreciated!
Many thanks!
Ross!
I have recently purchased a rotel RB-1010 power amplifier and have been trying to source some new varistors (Sanken SV-04S) {old ones not working}. unfortunately I have not had much luck and it seems that they are unobtainable. I just wondered if anybody had any ideas as to where I might source these or a similar varistor that would do the job!
Any help would be greatly appreciated!
Many thanks!
Ross!
You should be able to find a service dealer in the uk, they usually keep or can order replacement parts otherwise go here B&W Group North America Service & Support Homepage and choose the parts centre.
Hi folks!
It is not connected across the mains or anywhere near to the mains transformer! unfortunately I have no idea what it is supposed to do or why it is connected to the main heatsinks of the amplifier! On the circuit diagrams it is just shown as 4 diodes in a row! I have visited the B&W website and also rang there service centre! they were very helpful but could not supply me with the parts that I needed. I have been trying to source this part for a long time and cannot find much if any information as to what it is and where I can find a replacement. Its proving to be a massive headache!
A service manual for the amplifier can be found at the above mentioned site and the information on the part I am looking for can be found at the website stated below:-
SV04S datasheet and application note, data sheet, circuit, pdf, cross reference, pinout | Datasheet Archive
If anybody more experienced than myself wants to take a look at the circuit diagram and shed a light on what this varistor does and how and what I can do to replace it! it would be much appreciated!
Thanks again to those that have replyed to the post and hope that the information above will be of some assistance!
cheers! Ross
It is not connected across the mains or anywhere near to the mains transformer! unfortunately I have no idea what it is supposed to do or why it is connected to the main heatsinks of the amplifier! On the circuit diagrams it is just shown as 4 diodes in a row! I have visited the B&W website and also rang there service centre! they were very helpful but could not supply me with the parts that I needed. I have been trying to source this part for a long time and cannot find much if any information as to what it is and where I can find a replacement. Its proving to be a massive headache!
A service manual for the amplifier can be found at the above mentioned site and the information on the part I am looking for can be found at the website stated below:-
SV04S datasheet and application note, data sheet, circuit, pdf, cross reference, pinout | Datasheet Archive
If anybody more experienced than myself wants to take a look at the circuit diagram and shed a light on what this varistor does and how and what I can do to replace it! it would be much appreciated!
Thanks again to those that have replyed to the post and hope that the information above will be of some assistance!
cheers! Ross
hi Ross
the SV04S is not a varistor (although Rotel call them that in the service manual)
these devices are 3 series connected silicone diodes in one package specially made for bias control in amplifiers they are temperature sensitive and are very often mounted on the out put transistors or heatsink. the allows the bias of the output stage to track with temperature.
are you sure that they have blown, test them as 3 series connected silicone diodes, volt drop will be about 2 volts @10ma test current. if they are blown it is very likely that there will be more damage in the output and driver stages.
as a substitute use 3 ordinary silicone diodes connected in series, thes have to be thermaly in contact with the heat sink, but electrically isolated from it.
i always subtitute the diodes first without putting in contact with the heat sink. just to get the amp up and running, it will work this way as a test.
a tip after the amp is running i use thermal bonding glue to fix them.
diodes i use are 1n4002 or similar.
regards
bob
the SV04S is not a varistor (although Rotel call them that in the service manual)
these devices are 3 series connected silicone diodes in one package specially made for bias control in amplifiers they are temperature sensitive and are very often mounted on the out put transistors or heatsink. the allows the bias of the output stage to track with temperature.
are you sure that they have blown, test them as 3 series connected silicone diodes, volt drop will be about 2 volts @10ma test current. if they are blown it is very likely that there will be more damage in the output and driver stages.
as a substitute use 3 ordinary silicone diodes connected in series, thes have to be thermaly in contact with the heat sink, but electrically isolated from it.
i always subtitute the diodes first without putting in contact with the heat sink. just to get the amp up and running, it will work this way as a test.
a tip after the amp is running i use thermal bonding glue to fix them.
diodes i use are 1n4002 or similar.
regards
bob
Hi Bob!
Thanks for the reply and suggestion It looks like making my own may be the only option! The amplifier itself has been tampered with quite a bit by the previous owner and was described on ebay as being inoperative on one channel. When I opened the unit I found alot of damage had been caused; PCB track lifted, broken and missing and one cicuit board had even been snapped in half and glued back togeather. The previous owner had replaced output and driver transistors on one side of the amplifier as well. The diodes that I have described which are linked to the heatsinks of the main amplifier and the smaller driver transistor on the same channel are not the originals and have been made by the previous owner to replace the old units! These are the ones that I would like to replace as I have tested them and they are both totally dead. I have replaced quite a few components myself including output and driver transistors and all components which were linked to them but all the components that I have taken out have tested fine and don't appear to be faulty in any way. Being that they all tested correctly and the home made diodes did not! Do you think that these are what is stopping the one channel from working? Also with regard to making diodes myself how would I connect them to the heatsink properly and where could I get the glue needed to insulate them?
Cheers and Thanks again Bob!
Ross
Thanks for the reply and suggestion It looks like making my own may be the only option! The amplifier itself has been tampered with quite a bit by the previous owner and was described on ebay as being inoperative on one channel. When I opened the unit I found alot of damage had been caused; PCB track lifted, broken and missing and one cicuit board had even been snapped in half and glued back togeather. The previous owner had replaced output and driver transistors on one side of the amplifier as well. The diodes that I have described which are linked to the heatsinks of the main amplifier and the smaller driver transistor on the same channel are not the originals and have been made by the previous owner to replace the old units! These are the ones that I would like to replace as I have tested them and they are both totally dead. I have replaced quite a few components myself including output and driver transistors and all components which were linked to them but all the components that I have taken out have tested fine and don't appear to be faulty in any way. Being that they all tested correctly and the home made diodes did not! Do you think that these are what is stopping the one channel from working? Also with regard to making diodes myself how would I connect them to the heatsink properly and where could I get the glue needed to insulate them?
Cheers and Thanks again Bob!
Ross
hi Ross
this is quite a complex amp to cut your teeth on, the diodes are esential for the amp to work as they provide the bias voltage for the output stage.
how did you test them? i would use a 9 volt battery in series with a 680 ohm resistor across them, this is roughly 10mA, measure the voltage across the diode string should be around 2v. out of circuit of course.
with so many parts blown in the output stage i would test all the semi conductors, transistors and diodes before applying power. work methodicaly through the whole board, one by one. if in dout compare with good channel part etc.
not knowing your level of competence or the equipment availible to you it is hard to give more advise, if you dont understand what i have said above maby stop there. safety first.
however when you think the amp is ready to test use a mains light bulb in series with the mains to limit the current in case of another fault, be very carfull with this conection safety first. on switch on the bulb will light brightly for a second or two then dim down.
the adesive is here Buy PCB Compounds and Adhesives Thermal bonding epoxy adhesive,20ml Electrolube ERTBS20S online from RS for next day delivery.
this is quite a complex amp to cut your teeth on, the diodes are esential for the amp to work as they provide the bias voltage for the output stage.
how did you test them? i would use a 9 volt battery in series with a 680 ohm resistor across them, this is roughly 10mA, measure the voltage across the diode string should be around 2v. out of circuit of course.
with so many parts blown in the output stage i would test all the semi conductors, transistors and diodes before applying power. work methodicaly through the whole board, one by one. if in dout compare with good channel part etc.
not knowing your level of competence or the equipment availible to you it is hard to give more advise, if you dont understand what i have said above maby stop there. safety first.
however when you think the amp is ready to test use a mains light bulb in series with the mains to limit the current in case of another fault, be very carfull with this conection safety first. on switch on the bulb will light brightly for a second or two then dim down.
the adesive is here Buy PCB Compounds and Adhesives Thermal bonding epoxy adhesive,20ml Electrolube ERTBS20S online from RS for next day delivery.
Hi bob!
Thanks again for your reply!
I do have some experience with electronics and know how to perform basic tests with a multimeter on components! but as for performing tests in the way you desribed or any circuit testing it is all pretty new stuff to me.
If you could provide diagrams of the tests you are describing it would be a great help as I work more effectively when I have a picture reference to apply the written knowledge to!
As far as test equipment goes I have an amprobe multimeter which tests all the basic things such as resistance and capacitance and also AC and DC voltages.
The diode strings in the amplifier number 4 diodes in series! I wondered if the 3 diode strings that you had described in the last post would be suitable or would I have to use four as per the originals!
Hope this answers some of your questions and again thanks for you help! it is very much appreciated! If it werent for people like yourself I would be very stuck indeed!
Cheers! Ross!
Thanks again for your reply!
I do have some experience with electronics and know how to perform basic tests with a multimeter on components! but as for performing tests in the way you desribed or any circuit testing it is all pretty new stuff to me.
If you could provide diagrams of the tests you are describing it would be a great help as I work more effectively when I have a picture reference to apply the written knowledge to!
As far as test equipment goes I have an amprobe multimeter which tests all the basic things such as resistance and capacitance and also AC and DC voltages.
The diode strings in the amplifier number 4 diodes in series! I wondered if the 3 diode strings that you had described in the last post would be suitable or would I have to use four as per the originals!
Hope this answers some of your questions and again thanks for you help! it is very much appreciated! If it werent for people like yourself I would be very stuck indeed!
Cheers! Ross!
Hi bob!
Forgot to post this on the last message!
I tested the diodes with a multimeter on the diode setting with the correct polarity and they didnt even register! this is why I believe them to be defunkt!
Are they suppose to behave in a different way to a singular diode with regards to testing or is my prognosis correct??
Cheers! and thanks again! Ross!
Forgot to post this on the last message!
I tested the diodes with a multimeter on the diode setting with the correct polarity and they didnt even register! this is why I believe them to be defunkt!
Are they suppose to behave in a different way to a singular diode with regards to testing or is my prognosis correct??
Cheers! and thanks again! Ross!
hi again
sorry i meant 4 diodes not 3.
yes they are four diodes in series and might not measure anything on the diode test function on the meter you have, i would expect the voltage drop to be around 2.8 volts. i would test these as described.
connect the diode in series with a 9v battery and a 680 ohm resistor, then measure the volt drop across the diode. for this test the diode must be the correct way round, ie anode to the + terminal of the battery.
the resistor ensures that about 10ma flows in the diode string
sorry i meant 4 diodes not 3.
yes they are four diodes in series and might not measure anything on the diode test function on the meter you have, i would expect the voltage drop to be around 2.8 volts. i would test these as described.
connect the diode in series with a 9v battery and a 680 ohm resistor, then measure the volt drop across the diode. for this test the diode must be the correct way round, ie anode to the + terminal of the battery.
the resistor ensures that about 10ma flows in the diode string
Fuses blowing!!!!
Hi all!
Tested the varistors and perfect with the suggested message from bob!
Now I have a very different problem! Decided to put the amp back togeather and test it!
So made all the neccessary connections speakers etc and powered it up! The lights came on but there was no click from the two protection relays and no sound!
I switched it off and on furhter inspection found two fuses to be blown inside the amp which were mounted on a board with 4 other fuses! these are directly connected to a rectifier and six big capacitors! changed the two fuses and selected all the correct ratings for the others as they were all wrong and then switched on again! This time one of the other fuses blew ( connected to the mains transformer, power switch, and mains lead supply) and no power at all dead!
I then changed top fuse and left the other two fuses out and the lights came on again!
Does anyone have any idea what the problem could be? I have read that blown rectifiers or shorted caps can cause this to happen but I guess the relevant question is why did it go in the first place!
Any help would be greatly appreciated!
Cheers! Ross!
Hi all!
Tested the varistors and perfect with the suggested message from bob!
Now I have a very different problem! Decided to put the amp back togeather and test it!
So made all the neccessary connections speakers etc and powered it up! The lights came on but there was no click from the two protection relays and no sound!
I switched it off and on furhter inspection found two fuses to be blown inside the amp which were mounted on a board with 4 other fuses! these are directly connected to a rectifier and six big capacitors! changed the two fuses and selected all the correct ratings for the others as they were all wrong and then switched on again! This time one of the other fuses blew ( connected to the mains transformer, power switch, and mains lead supply) and no power at all dead!
I then changed top fuse and left the other two fuses out and the lights came on again!
Does anyone have any idea what the problem could be? I have read that blown rectifiers or shorted caps can cause this to happen but I guess the relevant question is why did it go in the first place!
Any help would be greatly appreciated!
Cheers! Ross!
hi Ross
never apply power to a 'repaired' amp with speakers connected or straight to the mains. this is a definate recipe for disaster.
as stated earlier this is a sofisticated amp and is not the sort of thing to cut your teeth on. the fault cannot be guessed at or by pulling parts and testing them. the job needs to be worked through methodacally, requiring a good level of understanding, skill and competence.
this is not a slur but an observation, i am very worried about your safety. for example fuse F801 is the mains fuse and is live at all times
which fuses are blowing F801 to F806 ? the answer to this is will narrow the problem down a bit
still think it is time for a technician
never apply power to a 'repaired' amp with speakers connected or straight to the mains. this is a definate recipe for disaster.
as stated earlier this is a sofisticated amp and is not the sort of thing to cut your teeth on. the fault cannot be guessed at or by pulling parts and testing them. the job needs to be worked through methodacally, requiring a good level of understanding, skill and competence.
this is not a slur but an observation, i am very worried about your safety. for example fuse F801 is the mains fuse and is live at all times
which fuses are blowing F801 to F806 ? the answer to this is will narrow the problem down a bit
still think it is time for a technician
Amp blowing fuses!
Hi folks!
Have recently rebuilt the amplifier after testing the diodes strings which tested correctly!
I now have a different problem! The amp blows 2 fuses immediately when I press the power switch! I have replaced many components and if you look through this thread you should get some idea as to waht exactly has been replaced.
Recently I have tested a rectifier and the components linked to it and they were all fine! I also replaced the six smoothing capacitors with brand new ones and still the same problem!
Does anybody have any ideas as to what could be causing the problem?
Cheers! Ross
Hi folks!
Have recently rebuilt the amplifier after testing the diodes strings which tested correctly!
I now have a different problem! The amp blows 2 fuses immediately when I press the power switch! I have replaced many components and if you look through this thread you should get some idea as to waht exactly has been replaced.
Recently I have tested a rectifier and the components linked to it and they were all fine! I also replaced the six smoothing capacitors with brand new ones and still the same problem!
Does anybody have any ideas as to what could be causing the problem?
Cheers! Ross
reply to bobs post!
Sorry bob didnt spot your reply!
Blowing fuses are as follows:
F802, F803
I appreciate what your saying about my safety and the complexty of the problem! right now I am pretty much at a dead end anyway! I had thought that there might possibly be a simpler answer as to why it is not working but that is not proving to be the case!
Any glimmer of light on the issue would be aprecciated!
Cheers bob and thanks for your help on this problem!
Sorry bob didnt spot your reply!
Blowing fuses are as follows:
F802, F803
I appreciate what your saying about my safety and the complexty of the problem! right now I am pretty much at a dead end anyway! I had thought that there might possibly be a simpler answer as to why it is not working but that is not proving to be the case!
Any glimmer of light on the issue would be aprecciated!
Cheers bob and thanks for your help on this problem!
Hi,
I checked the spec for the SVD4S and it is a zener diode 2.4V 1 ma. You said that you can not buy it. I found one that it is possible that you can use it. The BZX552v4 and is available in Mouser. In the spec it is show that the package is a 84. It looks like the diode is in a terminal lug so you can mount it in a chassis with an screw. My suggestion is buy it and glue it using RTV through the lug you crimp the wire. They are using it to compensate accordingly to temperature changes.
I checked the spec for the SVD4S and it is a zener diode 2.4V 1 ma. You said that you can not buy it. I found one that it is possible that you can use it. The BZX552v4 and is available in Mouser. In the spec it is show that the package is a 84. It looks like the diode is in a terminal lug so you can mount it in a chassis with an screw. My suggestion is buy it and glue it using RTV through the lug you crimp the wire. They are using it to compensate accordingly to temperature changes.
hi Ross
the fuses f802 and f803 are the HT fuses for the power output stage, for both channels.
i think that they are rated at 6.3A, these blowing has almost certainly damaged more components, possibly the same ones you have replaced.
this highlights what i said about the test setup using a mains lamp, this would have saved the fuses and any other parts from blowing again.
as to a glimmer of light on the problem, here is the very basics.
are you sure that only one channel is faulty?
i would first of all be sure of this, split the problem in half, that way already we are narrowing it down.
when i was sure of the channel that was good the next step is to remove and test all the semiconductors diodes and transistors and check they are the correct types and test them, working your way through methodacally,
when satisfied test the amp with 1 Amp fuses on the HT and the light bulb.
if the protect relay does not engage (click) then fault find.
as stated before this is the very basics. i cannot emphasis enough that this is a complex amp and cannot be repaired by willy nilly guess work.
time for a technician, please be safe
the fuses f802 and f803 are the HT fuses for the power output stage, for both channels.
i think that they are rated at 6.3A, these blowing has almost certainly damaged more components, possibly the same ones you have replaced.
this highlights what i said about the test setup using a mains lamp, this would have saved the fuses and any other parts from blowing again.
as to a glimmer of light on the problem, here is the very basics.
are you sure that only one channel is faulty?
i would first of all be sure of this, split the problem in half, that way already we are narrowing it down.
when i was sure of the channel that was good the next step is to remove and test all the semiconductors diodes and transistors and check they are the correct types and test them, working your way through methodacally,
when satisfied test the amp with 1 Amp fuses on the HT and the light bulb.
if the protect relay does not engage (click) then fault find.
as stated before this is the very basics. i cannot emphasis enough that this is a complex amp and cannot be repaired by willy nilly guess work.
time for a technician, please be safe
Excess circuit board heat etc!
Hi everbody!
I managed to get the rotel working back at the start of september and have used it a couple of times and seems to work fine but I have two things that are concerning me and these are as follows:-
1.)The unit has one main circuit board which contains most of the amps running gear and a small circuit board which is attached directly to the end of it. When the amp is switched on the small circuit board starts to produce what I would call an unusual amount of heat. There is a power supply for this board which also produces a lot of heat. It will start to do this within the first five minutes of use whether the amp is producing sound or not. The rest of the amplifier remains cool and even after use at moderate volume levels remains this way.
2.)I have used the amplifier with both 4 and 8 ohm speakers but when the volume is increased using the 4 ohm units it can only power them to a moderate volume before the protection circuit cuts in. My old amplifier is a less powerful unit but is considerably louder and seems more able to drive the 4 ohm units (why?). Both amps are rated to be able to drive 4 ohm speakers.
I have made all the relevant voltage tests with a multimeter as described on the schematic and they all test fine and seem to be within the given tolerance ratings! I just wondered if anybody might have experienced a similar sort of problem or even whether somebody had actually owned one of these themselves and new how it should operate when it is functioning properly.
Any help or suggestions greatly appreciated!
Many thanks!
Ross!
Hi everbody!
I managed to get the rotel working back at the start of september and have used it a couple of times and seems to work fine but I have two things that are concerning me and these are as follows:-
1.)The unit has one main circuit board which contains most of the amps running gear and a small circuit board which is attached directly to the end of it. When the amp is switched on the small circuit board starts to produce what I would call an unusual amount of heat. There is a power supply for this board which also produces a lot of heat. It will start to do this within the first five minutes of use whether the amp is producing sound or not. The rest of the amplifier remains cool and even after use at moderate volume levels remains this way.
2.)I have used the amplifier with both 4 and 8 ohm speakers but when the volume is increased using the 4 ohm units it can only power them to a moderate volume before the protection circuit cuts in. My old amplifier is a less powerful unit but is considerably louder and seems more able to drive the 4 ohm units (why?). Both amps are rated to be able to drive 4 ohm speakers.
I have made all the relevant voltage tests with a multimeter as described on the schematic and they all test fine and seem to be within the given tolerance ratings! I just wondered if anybody might have experienced a similar sort of problem or even whether somebody had actually owned one of these themselves and new how it should operate when it is functioning properly.
Any help or suggestions greatly appreciated!
Many thanks!
Ross!
SV 02,03,04,05,06 Diode failures
In many years of servicing units using these diodes for bias regulation in output stages from Akai to Yamaha, these diodes fail after time whereas the momentarily open leaving the output stage in full conduction and subsequently destroying much of the related power amp. Testing them is almost futile BUT, if you attach a diode checker and subject the diode to extreme temps, like freon or the tip of a soldering iron, your test WILL indicate an open condition. The only problem now is finding replacements. I can almost 100% guarantee you that replacement of these devices will be your resolution along with the extensive collateral damage caused by the defective diodes.
I too have several amplifiers waiting for these diodes of which I had acquired 10, but got misplaced when cleaning up after a devastating store fire (ugh).
PEACE (and cheers)
Brian
In many years of servicing units using these diodes for bias regulation in output stages from Akai to Yamaha, these diodes fail after time whereas the momentarily open leaving the output stage in full conduction and subsequently destroying much of the related power amp. Testing them is almost futile BUT, if you attach a diode checker and subject the diode to extreme temps, like freon or the tip of a soldering iron, your test WILL indicate an open condition. The only problem now is finding replacements. I can almost 100% guarantee you that replacement of these devices will be your resolution along with the extensive collateral damage caused by the defective diodes.
I too have several amplifiers waiting for these diodes of which I had acquired 10, but got misplaced when cleaning up after a devastating store fire (ugh).
PEACE (and cheers)
Brian
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.