Don't bother with ebay, as you will likely end up with poor quality junk from most sellers, especially the Chinese ones (no racism here - simply fact).
Try Farnell. They seem to have relaxed their minimum order policy. They even have 2N3055 made by ST if you don't want to mess about.
Try Farnell. They seem to have relaxed their minimum order policy. They even have 2N3055 made by ST if you don't want to mess about.
I recently got some BD317, they were cheap, and from Motorola. Perhaps not that easy to find, though. They should be good equivalents.
The amp whose guts you show is *modern* and uses modern ST 2N3055, which are easily available (I buy them by the 100's , by the way, straight from ARROW or AVNET), so your best bet is to use the same.
Discussions about old 2N3055 are fine, technically correct, but do not apply to what you have in *that* amp.
So go get a pair now 😛
Discussions about old 2N3055 are fine, technically correct, but do not apply to what you have in *that* amp.
So go get a pair now 😛
Thank you all very much for your input, I really didn't expect so many replies.
-I also appreciate very much all your advice Indianajo, but I don't think I have the necessary electronics knowledge or the equipment (I only have a DVM and a soldering iron) to mess about with scopes, caps and test for oscillations etc so I think i need to keep it simple.
The sound on the left channel has been working fine for a few months OK with the CDIL 2n3055's but as I said it just doesn't sound as clear, sharp/extended or has the resolution of the left channel which were the original ST 2N3055s.
This has been bugging me for months and thought I just had a hearing problem in my right ear. I even dismantled my speakers to check the uprated crossovers I installed last year to see if something was amiss. I just assumed all 2N3055 transistors were all equal but now I understand they are not and this is obviously where my problem lies🙁
Maybe Jaycee is right and I should just try and get some more ST's from Farnell or CPC to match the good channel as I know they will definitely work and sound pretty good. Maybe I was being a little too adventurous to think I could try different trannys but it's obviously not that simple. I just wanna hear my music like it used to sound 🙂
Thanks to all of you, I really learned stuff from all this.
-I also appreciate very much all your advice Indianajo, but I don't think I have the necessary electronics knowledge or the equipment (I only have a DVM and a soldering iron) to mess about with scopes, caps and test for oscillations etc so I think i need to keep it simple.
The sound on the left channel has been working fine for a few months OK with the CDIL 2n3055's but as I said it just doesn't sound as clear, sharp/extended or has the resolution of the left channel which were the original ST 2N3055s.
This has been bugging me for months and thought I just had a hearing problem in my right ear. I even dismantled my speakers to check the uprated crossovers I installed last year to see if something was amiss. I just assumed all 2N3055 transistors were all equal but now I understand they are not and this is obviously where my problem lies🙁
Maybe Jaycee is right and I should just try and get some more ST's from Farnell or CPC to match the good channel as I know they will definitely work and sound pretty good. Maybe I was being a little too adventurous to think I could try different trannys but it's obviously not that simple. I just wanna hear my music like it used to sound 🙂
Thanks to all of you, I really learned stuff from all this.
Hi mart.s
OT: I was just looking at the picture you posted....
Is that earth wire original? It seems unusual to run a safety earth wire from the IEC connector to the top of the torroid, not the chassis. Is the chassis metal?
Regard
OT: I was just looking at the picture you posted....
Is that earth wire original? It seems unusual to run a safety earth wire from the IEC connector to the top of the torroid, not the chassis. Is the chassis metal?
Regard
"It seems unusual to run a safety earth wire from the IEC connector to the top of the torroid,"
If it touches the mounting bolt it will act as a shorted turn.
If it touches the mounting bolt it will act as a shorted turn.
Re: Earth wire
..Hmm you have me a little worried now, I did have to remove the Torroid from the bottom chassis to get to the main circuit board to change the trannys. I was sure I put it back the way I found it.
The earth wire is connected to a metal bolt which goes through two metal disks on either side of the Torroid which is then bolted directly to the bottom metal chassis. I think the two metal disks act as an earth shield at the same time as a fixing to the chassis. It's a strange setup and actually horrible to work on.
I just Googled my amp (pictures) to see the inside of other Alto's and it appears to be correct.
..Hmm you have me a little worried now, I did have to remove the Torroid from the bottom chassis to get to the main circuit board to change the trannys. I was sure I put it back the way I found it.
The earth wire is connected to a metal bolt which goes through two metal disks on either side of the Torroid which is then bolted directly to the bottom metal chassis. I think the two metal disks act as an earth shield at the same time as a fixing to the chassis. It's a strange setup and actually horrible to work on.
I just Googled my amp (pictures) to see the inside of other Alto's and it appears to be correct.
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It may be correct from the manufacturer's standpoint, but it's technically scary. If that bolt functions as the manufacturer hopes (ground to chassis) then it also functions in a way the manufacturer has ignored. The top of that bolt will have one turn's worth AC voltage on it and if any of the wires leading away from it come in contact with the chassis again, very high current will flow through them. Also, all signal and power terminated to that bolt will be humming along at one turn's worth of AC voltage above chassis ground (potential at the bottom of the bolt. Since nothing is smoking, those currents aren't flowing, and what would happen instead is the Chassis is "buzzing" at one turns worth potential about ground. Where did this thing come from? Are you sure the bolt is not isolated on the bottom or something, and they're just using the top as a "free terminal"? (Measure resistance from the top of the bolt to anywhere on the chassis you can get a connection.)
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I suppose it won't be problem if the top of the bolt is the only connection to power ground (ie chassis is not connected to power ground elsewhere). Problem would come when you connect to other equipment which has grounded chassis. Am I right?
Pretty much. If the chassis, signal, and power grounds are all left floating from external ground connections you'll be alright. The trouble comes from not generally being able to guarantee any of that in normal use. I would disconnect everything from that bolt and put a new stud or bolt somewhere else on a cleaned area of the chassis (electrical connection). Then it will be safe and sound.
The nut on top of the transformer washers should only be used to mount the transformer.
The nut on top of the transformer washers should only be used to mount the transformer.
Agree. I've been trying to think of any good reason to connect to top of the bolt - and I can't think of one - unless it's something so obscure and esoteric that nobody else knows about it. Difficult to believe that that was how it was designed...
On the other hand, we are all assuming that the chassis is a general ground. Perhaps it is not and is electrically isolated from all ground points except through that connection to the top of the bolt. That would explain the two leads going to the bolt - maybe one from each channel's ground on the pcb - which between them could include the grounds for all external connections? Weird, but possible... Waddya think?
Andrew and Mike, I'm not sure I really understand what you mean with the earth problem. It looks like from all the other pictures of this amp on the net, it is the way it supposed to be.
You will notice there is another earth wire from the the top connection point that I'm sure also goes to the chassis underneath the transformer but not sure where the black wire goes as I cant remember.
Rephil has kindly donated some ST 2N3055's so when I open the amp up again I will have a closer look and maybe make some mods to the earthing arrangement.
Do you guys think it would it make any difference if the earth connections were made at the bottom underneath the torroid where it bolts to the chassis instead of the top?
One last question while I'm here. Would changing the rectifier diodes for faster/better ones and increasing the value of the power supply cap and DC coupling caps be of any benefit?
You will notice there is another earth wire from the the top connection point that I'm sure also goes to the chassis underneath the transformer but not sure where the black wire goes as I cant remember.
Rephil has kindly donated some ST 2N3055's so when I open the amp up again I will have a closer look and maybe make some mods to the earthing arrangement.
Do you guys think it would it make any difference if the earth connections were made at the bottom underneath the torroid where it bolts to the chassis instead of the top?
One last question while I'm here. Would changing the rectifier diodes for faster/better ones and increasing the value of the power supply cap and DC coupling caps be of any benefit?
I agree that you must have reassembled it correctly - I can't see any way those ground leads could reach the other end of the bolt underneath the chassis. So somehow, it must work as you've got it now. Are you sure that one of those wires goes to the other end of the bolt? There would be no point in that unless you were a pyromaniac (and who would want to short-circuit the ends of a steel bolt?).
Is the amp double-insulated? Does it actually have a connection to mains earth at all? 🙂
Is the amp double-insulated? Does it actually have a connection to mains earth at all? 🙂
Where did this thing come from?
Not sure I understand what you meant Andrew by "where did this thing come from" If you mean who designed and built it then it was Audio Innovations who made some well reviewed tube amps a while back, This amp was designed to sound similar to their tube amps while using transistors for more power at low cost. And I can tell you it does sound very good once fully warmed up. There have been a few negative comments by some people who tried this amp and did not like the sound or did not find it particularly special.
But those people have missed out big time by being impatient and not allowing her to get nice and hot or using mismatched speakers and source. It sounds truly awful when first powered up.
But. when this thing has warmed properly after about 45 minutes of use the sound is truly hypnotizing and beguiling. I also find the bass and output power more than enough to shake the floorboards with plenty of punch and precision -another thing some critics mentioned while testing it.
Not sure I understand what you meant Andrew by "where did this thing come from" If you mean who designed and built it then it was Audio Innovations who made some well reviewed tube amps a while back, This amp was designed to sound similar to their tube amps while using transistors for more power at low cost. And I can tell you it does sound very good once fully warmed up. There have been a few negative comments by some people who tried this amp and did not like the sound or did not find it particularly special.
But those people have missed out big time by being impatient and not allowing her to get nice and hot or using mismatched speakers and source. It sounds truly awful when first powered up.
But. when this thing has warmed properly after about 45 minutes of use the sound is truly hypnotizing and beguiling. I also find the bass and output power more than enough to shake the floorboards with plenty of punch and precision -another thing some critics mentioned while testing it.
Doesn't it show from the picture that the mains earth (that comes from the power socket at the back) actually goes to the earth strap on top of the transformer?
I cant actually be sure where the other earth wire goes as it was quite some time ago I repaired it, I assumed it would go to the chassis on the bottom somewhere.
If it wasn't such a pig to open up and disassemble I would do it now to have a look.
I am going to open it up next week again so I will post more pics then.
I don't get any mains hum even with the volume turned right up with no input so I would assume the earths must be good.
I do remember using my DMM connected between chassis and top of the power transistor case and I did get a voltage reading if that helps.
I cant actually be sure where the other earth wire goes as it was quite some time ago I repaired it, I assumed it would go to the chassis on the bottom somewhere.
If it wasn't such a pig to open up and disassemble I would do it now to have a look.
I am going to open it up next week again so I will post more pics then.
I don't get any mains hum even with the volume turned right up with no input so I would assume the earths must be good.
I do remember using my DMM connected between chassis and top of the power transistor case and I did get a voltage reading if that helps.
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It seems safety earth regulations are different from country to country. Rod's article on earthing may be a good starting point if you decide to redo the earthing scheme.
http://sound.westhost.com/earthing.htm
If you simply add a wire from the earth on the IEC connector to the chassis you will end up with a shorted turn and you will get transformer overheating until the fuse blows, assuming the fuse is the correct size!
http://sound.westhost.com/earthing.htm
If you simply add a wire from the earth on the IEC connector to the chassis you will end up with a shorted turn and you will get transformer overheating until the fuse blows, assuming the fuse is the correct size!
So what you are saying is that you dont think the earth wire on the top of the torroid from the IEC connector is actually electrically connected to the chassis and if it was it would cause issues.
I still dont understand why it would cause a problem if the IEC connector was connected straight to the chassis and the other earth points, I thought that was the whole point of earth grounding so if a live wire touches the case it would blow the mains fuse. I dont see how current can get induced into those earth wires or overheat the transformer.
It has worked fine like this since I bought it (about 7 years) and nobody else with these amps have mentioned any problems like that.😕
-And here is me thinking I had a reasonable understanding of electricity, obviously not, Surely the designers would not overlook something like this.
I still dont understand why it would cause a problem if the IEC connector was connected straight to the chassis and the other earth points, I thought that was the whole point of earth grounding so if a live wire touches the case it would blow the mains fuse. I dont see how current can get induced into those earth wires or overheat the transformer.
It has worked fine like this since I bought it (about 7 years) and nobody else with these amps have mentioned any problems like that.😕
-And here is me thinking I had a reasonable understanding of electricity, obviously not, Surely the designers would not overlook something like this.
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