Hi Carlos, please check this thread...
http://www.diyaudio.com/forums/showthread.php?postid=1444201#post1444201
He can only adjust bias by 10mV... seems like a problem with the vbe multiplier... also as he said he is using a 40V supply, would the resitor in the bias board not need some small adjustment...?
http://www.diyaudio.com/forums/showthread.php?postid=1444201#post1444201
He can only adjust bias by 10mV... seems like a problem with the vbe multiplier... also as he said he is using a 40V supply, would the resitor in the bias board not need some small adjustment...?
No modifications needed..he must track for errors.
If something do not works, if bias do not adjust or do not go to the correct point, or off set do not adjust or do not make the off set voltage very low....this means errors...human mistakes...he has to check all he made, all resistances values, all polarities, all solders for bugs.
You see that hundreds were built... and all them worked..this unit not working fine because it is not standard..say..there are errors.
This is very normal..happens daily, even with experienced people..and only the one has the board in front of his face can check all details.... he is telling me the board is sick...so... some organ is not working fine.... we have to find what is wrong...what organ is not operating properly.... i can deduce, by the informs that unit is sick..just that...i can imagine thousand possibilities but i cannot fly to his place to watch the board...unfortunattelly, our friend will have to check this by himself.
regards,
Carlos
If something do not works, if bias do not adjust or do not go to the correct point, or off set do not adjust or do not make the off set voltage very low....this means errors...human mistakes...he has to check all he made, all resistances values, all polarities, all solders for bugs.
You see that hundreds were built... and all them worked..this unit not working fine because it is not standard..say..there are errors.
This is very normal..happens daily, even with experienced people..and only the one has the board in front of his face can check all details.... he is telling me the board is sick...so... some organ is not working fine.... we have to find what is wrong...what organ is not operating properly.... i can deduce, by the informs that unit is sick..just that...i can imagine thousand possibilities but i cannot fly to his place to watch the board...unfortunattelly, our friend will have to check this by himself.
regards,
Carlos
Thanks Carlos, i was thinking the same :/
I've narrowed it down to either; bad soldering: a new iron and a general thickening of soldering should do the trick there; or bad transistors? Nordic, you said you got fake 2sc5200 from mantech; were they marked "Toshiba" by any chance.. anyway of checking whether I got fakes? And would fakes even cause the trouble I'm having?
I've narrowed it down to either; bad soldering: a new iron and a general thickening of soldering should do the trick there; or bad transistors? Nordic, you said you got fake 2sc5200 from mantech; were they marked "Toshiba" by any chance.. anyway of checking whether I got fakes? And would fakes even cause the trouble I'm having?
Yep they were marked Toshiba...
If it is printed on a shiny recess it almost certainly is fake... take pliers and break one open... many pictures of what the real thing should look like here on the interwebs... if it is fake it will have a tiny die like the one I posted on your thread....
Ask if they don't have ISC or Fairchild ones for you... haveing much better luck with those...
They are totaly unstable, in some cases plain unbiasable... bias would either go from switched off transistors to almost flameing transistors...
Double check also the wattage of the resistors, some are marked for slightly higher dissipation...
If it is printed on a shiny recess it almost certainly is fake... take pliers and break one open... many pictures of what the real thing should look like here on the interwebs... if it is fake it will have a tiny die like the one I posted on your thread....
Ask if they don't have ISC or Fairchild ones for you... haveing much better luck with those...
They are totaly unstable, in some cases plain unbiasable... bias would either go from switched off transistors to almost flameing transistors...
Double check also the wattage of the resistors, some are marked for slightly higher dissipation...
Hello
Here is photos of the face of the case for the mini Dx I've made for a friend.
Since my camera are caput, I've bring the amp wood face plate to a friend so he can take the photos and later he send it to me by email. The case itself are plain black color.
Bye
Gaetan
Here is photos of the face of the case for the mini Dx I've made for a friend.
Since my camera are caput, I've bring the amp wood face plate to a friend so he can take the photos and later he send it to me by email. The case itself are plain black color.
Bye
Gaetan
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Like the wood 
If I may offer a tip for your next project...
At the hardware shops they have these small foam paintrollers, like 1" to 2" wide.... They give a much smoother/more even finish than brushes... the foam bits are replaceable and cheap, so not worth battleing to clean afterwards.
If I may offer a tip for your next project...
At the hardware shops they have these small foam paintrollers, like 1" to 2" wide.... They give a much smoother/more even finish than brushes... the foam bits are replaceable and cheap, so not worth battleing to clean afterwards.
Hello Carlos and Nordic
I can have news about you guy's by reading the two Dx thread, it's going good for you.
I use flat foam, I sould try foam roller, this mini Dx wood front plate are made of maple wood, lot of work, cuting, planing with a wood plane, sanding, hard woods are nicer but need lot of works.
For next time I may use metal face plate but I still love wood.
Now I'm working on a tube output for a tda1541 Dac, because I've found a nice bargain of 10 new old stock Russian 6n2p-er tubes (same than 12ax7 ), those russian military tube last between 5,000 and 10,000 hours, I have enough tube to maby also try to do an hybrid amp using Self II BJT output with those tube as a input, just to eard how it sound, I'm reading now a lot about tube amp making but I would not go up to a all tube amp because of the output tubes and transformer cost, but it is interesting to learn about that kind of amps.
Here in Quebec province we ad so much snow everywhere, in the north it's worse, in Quebec city, they ad 4 meter of snow since the start of the winter, and tomorow we will have a second big snow storm in that same week. For myself I have enough of that snoweeee winter
Bye
Gaetan
I can have news about you guy's by reading the two Dx thread, it's going good for you.
I use flat foam, I sould try foam roller, this mini Dx wood front plate are made of maple wood, lot of work, cuting, planing with a wood plane, sanding, hard woods are nicer but need lot of works.
For next time I may use metal face plate but I still love wood.
Now I'm working on a tube output for a tda1541 Dac, because I've found a nice bargain of 10 new old stock Russian 6n2p-er tubes (same than 12ax7 ), those russian military tube last between 5,000 and 10,000 hours, I have enough tube to maby also try to do an hybrid amp using Self II BJT output with those tube as a input, just to eard how it sound, I'm reading now a lot about tube amp making but I would not go up to a all tube amp because of the output tubes and transformer cost, but it is interesting to learn about that kind of amps.
Here in Quebec province we ad so much snow everywhere, in the north it's worse, in Quebec city, they ad 4 meter of snow since the start of the winter, and tomorow we will have a second big snow storm in that same week. For myself I have enough of that snoweeee winter
Bye
Gaetan
Klaas Venstra last year gift to me arrived...surprise!
He sent me a board and 2 transistores and brazilian customs have blocked and asked me 50 dollares.... i left the thing there with them.... this year they decide to send it to my adress..... maybe they have analised better...this is not "importation" subjected to taxation into the "aduana"...because value is under 50 dollares.
Well..i am glad i have received.
Here is the weather is very hot those days Gaetan, temperature around 32 daily... this day we had 15 minutes strong rain, the first rain in 45 days.
But temperature continue high..... i think i will have mosquitos this nigth because of the rain..ahahahaha
regards,
Carlos
He sent me a board and 2 transistores and brazilian customs have blocked and asked me 50 dollares.... i left the thing there with them.... this year they decide to send it to my adress..... maybe they have analised better...this is not "importation" subjected to taxation into the "aduana"...because value is under 50 dollares.
Well..i am glad i have received.
Here is the weather is very hot those days Gaetan, temperature around 32 daily... this day we had 15 minutes strong rain, the first rain in 45 days.
But temperature continue high..... i think i will have mosquitos this nigth because of the rain..ahahahaha
regards,
Carlos
Attachments
Carlos is not the only one haveing fun...
Haveing tonnes of long slender PCB offcuts after makeing the PI prototypes, I decided to make something that can use em...
I call it the DX classic II.
Based on the original DX amplifier, but with integrated PSU and extra output pair.
Image may be a bit dark for you guys not useing LCD displays yet...
Another angle and colour for more contrast..
Haveing tonnes of long slender PCB offcuts after makeing the PI prototypes, I decided to make something that can use em...
I call it the DX classic II.
Based on the original DX amplifier, but with integrated PSU and extra output pair.
Image may be a bit dark for you guys not useing LCD displays yet...
Another angle and colour for more contrast..
Nico, awesome !
Hello all,
Nordic, your layout are great !
Carlos will be still so proud of you, his nephew.
Filtering stage ( CRC ) and two outputs pair amp on the same board ! You are close to get one of the most affordable, ready-to-soldering and good sounding device.
Great ! Amazing !
PS : Is it possible to get hi-resolution picture of your rendering ?
Hello all,
Nordic, your layout are great !
Carlos will be still so proud of you, his nephew.
Filtering stage ( CRC ) and two outputs pair amp on the same board ! You are close to get one of the most affordable, ready-to-soldering and good sounding device.
Great ! Amazing !
PS : Is it possible to get hi-resolution picture of your rendering ?
Thanks...
Carlos and me have slightly diffirent tastes, so I would not go out on a limb to say he would like it...
I attached a slightly larger pic... about at the upload limit...
Thanks for the remider, the PSU is a C-L-C design, the resistors had to g oto the bottoom of the boards and be wound with inductors...
Carlos and me have slightly diffirent tastes, so I would not go out on a limb to say he would like it...
I attached a slightly larger pic... about at the upload limit...
Thanks for the remider, the PSU is a C-L-C design, the resistors had to g oto the bottoom of the boards and be wound with inductors...
Attachments
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