[w357]

 
So, welcome to modify the (FAQ) Teclast t51 to more or less acceptable quality of sound.
Thanks for this modification to  an ideologist of the player Griess Vsevolod V. aka "Storb"
  Seva, his enthusiasm pushed us all to you at this difficult work! Thank you for this invaluable experience!
At first I was going to publish photos of each stage of modification, but after unsuccessful attempts of followers, decided not to paint everything in as much detail is enough for two or three main images ... the reason is simple - if you do not understand this question and wish to give the finger to what  solder, you still too early to start, will be less dead player ... teaching materiel, to gain experience ...
  let's ... begin ...
First you need a tool. Qualitative and not cheap ... but without it you should not even try, for a non-working player will get ... and no "go and my soldering iron to 40W ... I sharpened it sharp" ...
You will need:
1. good soldering station with antistatic soldering iron, a set of interchangeable stings. Calibrate the thermostat before the experiments. All subsequent steps to produce at or above 250 ° C and the duration of soldering no more than 5 seconds
2. Tweezers with fine needle ends, preferably curved, for soldering SMD and thin wires in the process of mod.
3. Thin Phillips screwdriver.
4. Multimeter with high accuracy (I use VC9805A)
5. Flux for soldering SMD and BGA, brand, or RMA-223 YX-223 in a syringe with a fine needle
6. Antistatic mat
7. Preferred headlamp flashlight or good lighting of the workplace
8. A tool for repair of cellular
9. Sharp clerical knife wire stripper
10. Tool to wash flux CRAMOLIN FLUX-OFF (Yeah. .. even this flux is better to wash)
11. Well may be something else pops up in the course of the story ...
 
Secondly I want to warn in advance: the player is very low quality components. they literally die from careless breath. So in the supply not to touch! The only exception - stabilizers and inverters power amplifiers. But here we should act with extreme caution.
And third - all modification should be made possible for one approach with a single Desoldering the battery! when you connect the battery back, breaks a spark between it and board. this can cause the death of charging circuit on the board. Than less time you unsolder / solder accumulator, than less likely to receive a one-time player (I already tried it on myself).
 
DISASSEMBLE PLAYER
can use this kit to repair cellular tools. around the perimeter of the body has 10 catches. on 3 sides and 2 above and below. arrangement of something like the Apple products.
Unsolder BATTERY
and remove it aside for a long time. watching so that no wires are connected. Otherwise, will work protection and battery will be blocked. For  unlock the battery Y should give on its findings the charging voltage.
Cables of touchscreen NOT unsolder, DO NOT REMOVE ...
Y  generally do not touch it at any stage of modification. Especially cable sensor.
Unsolder following components:

Its just part of this mod
  anyone else interesting? 

 

[david1978jp]

Wow, wonderful write up. Thank you.
Is the difficulty of this mod  8 out 10? Can I say, not for a newbie?

 

[w357]

Its very hard for Newbies  but sound will be like Hifiman 801 or Colourfly 4.

 

[w357]

 
All that is circled with colored frames:
1. red - shunts power DACs and operational amplifiers.
2. blue - the amplifier low-pass filter and amplifier for headphones.
3. Green - capacitors of low-pass filter
4. Orange - kit of headphone amplifier (two resistors and two capacitors in pairs for each channel)
5. Purple - 5V voltage regulators for DAC and LPF (of 3 stub - one in the same place, but on the back of side of the board)
6. Pink - 3V voltage regulators of headphone amplifier
7. Yellow - power inverters of operational amplifiers
Nothing else to touch it, unless Y want to become a non-working player!
stabilizers, inverters, and operational amplifiers unsolder it's best flat-tip type "cutter" or "paddle". It allows you to warm up once all the legs on one side of the chip and lift it.
low-pass filter replacement stabilizer placed on the reverse side of the board will have to unscrew the two screws and remove the motherboard from the case. in this case you should try to not bend it to cracked lead-free soldering processor! better once bend the edge of the case.
after removal of the components should be removed excess solder .
REPLACEMENT PARTS
Look above and change in strict compliance:
1. change it for quality ceramic NP0 0,1 uF. I set the capacitors of the firm Murata. here it should be noted that shunts are a pair of DACs capacities of 10uF and 0,1 uF. Unsolder  it all and put in place Murat 10uF (space for smaller capacity are empty).This replacement will clear some power DACs and the opers of noise.
2. still skip this point ...
3. Change at the highest quality film capacitors, which will be found. I put WIMA FKS2. Ideally would put sulfide Panasonic, but only if it is available soldering hair-dryer, infrared  station, or a stove. Soldering iron sulfide capacity would be killed instantly. This is replacement capacitors once and for all fix the problem Player’s bright sound.
  4. just unsolder and forget. No replacement necessary ...
  5. change in LP2985AIM5-5.0
  6. change in LP2985AIM5-3.0
  7. change to TPS60403.
Now we choose the op-amp for low pass
  that is, return to step 2, missed earlier ...
 
  here we have some leeway to set the desired character of the future sound mod.
  from what I've tried it myself, I offer the following options:
LM6172 - dynamic sound, quite smooth, melodious. slightly rounded attack (because of the smoothed small parts), good depth, punch in midbase.
LM4562 - on analyticity and the level of distortion is comparable to the previous version, but has a slightly more melodic sound. cleanest RF, isolated middle and dry, but tight bass. the overall sound is extremely detailed, accurate midrange-oriented, fast. I myself stopped on this amplifier.
[review of amps translated partly]
WARNING! installing low-pass filter amplifier to its outputs (1 and 2 in the photo) to the level above the board! they should not be soldered to the board (in air)! In this case, the line out audio player goes straight to the DAC on the negative feedback loops of op-amp low-pass filter. Of course don’t uselow impedance load to LO  if you do not want to kill inadvertently DACs.
After all these steps, wash board using CRAMOLIN FLUX-OFF (can be in two or three times with a toothbrush, for better removal of flux), giving dry.
 
Headphone amplifier
    currently there are several options Amplifier:
 
  1. well-known "Storb modes" based on the AD8397. it will not consider

 
  2. Storb analogue-mode PCB authorship Symmcat

 

[w357]

 
This option also is based on the operational amplifier as the AD8397, but other than shown in the diagram, you must add two buffer tanks (capacitors) 220uF on the power of the amplifier. use better quality Panasonic AM. Wiring diagram is clear from the following scheme. Bypasses (shunts) C1, C2, C3 should be applied film quality (eg WIMA)

3. My previous version of the amplifier, but this time based on opa LT1886-compensated

 

[w357]

 
Description of sound  AD8397 and  LT1886 I skipped …
NOTE: the paths on the amplifier board especially the outputs goes with high power current. Therefore it is better to make a track as possible fat and use the PCB with a maximum thick layer of copper. Otherwise we get a drawdown of the dynamics and bass ...
  wash board using CRAMOLIN FLUX-OFF and brush, dry the well.
INSTALLATION headphone amplifier
  and here the fun begins ...
Take the wire MGTF 0.07 sq. mm or some other very good wire of the same section.
  Solder two lengths of wire to the previously raised by low-pass filter outputs of the operational amplifier (between  legs of AMP  and board is better lay isolation)

(In this photo amp version still without compensation)

 

[w357]

 
The other ends of these wires solder to 1 and 2 outputs of volume control on the reverse side of the board. With 4 and 5 legs of outputs of the controller solder  else two wires and lead them back to the front of the board. Wire around the volume control must be laid very carefully so that you could close the case. They are and strive to get either between the screen and motherboard, or between the power button and the card. Need to lay them between the screen and click.

 

[lee730]

Quote:

Its very hard for Newbies  but sound will be like Hifiman 801 or Colourfly 4.

Nice work w357. Looks promising.

 

[w357]

 
From the same picture we see, what are dangerously close to the wire  the volume control  and from the control unit sensor screen. This is a 100% probability guarantees us a lot of noise into the channel  from touch screen and an overall decline of purity and transparency of sound even when turned off. To avoid this, stick with the lower back of the screen, cables and sensor module aluminum duct tape (do not forget to cut a hole under the power button. Isolate the aluminum tape with original tape.
Now finally put the motherboard in place. We no longer need to remove it from the body.
Wires soldered to the 4 and 5, the volume control outputs to the inputs we solder headphone amplifier.
Also connect by the wires contacts of outputs of AMP & jack for headphones (L and R on the first photo).
Power amplifier for headphones takes from the motherboard with 4 and 8 contacts at his native TDA1308 (V-V and the first picture).
Ground for the amplifier to take from one of your contacts of bypass (shunt) power, indicated by the arrow on the first photo.
Neatly laid an amplifier on board, pre-insulate bottom shielding layer tape or duct tape. Wires must be routed around the amplifier, but in any case not below it, the height of the amplifier and so critical.
Solder the battery (tried to solder the wires quickly, without a spark, dipping the end of the wire is melted into a drop of solder on the motherboard).
Try to turn on. Listen to the result.
If everything works and everything is done carefully, the cover must close almost back to back. If not locked, you can try to replace film capacitors in bypass power on the board of headphone amplifier with a lower (critical limit - 3 mm).
 Good luck =)
Do you have any questions, ask in the original theme.

  Moded by Hardcorist 

 

 

[Hardcorist]

w357, thanks Yuri =)
I hope that this modification will provide for someone good example. Sound quality is more affordable than many think

 

[turokrocks]

Quote:

 
From the same picture we see, what are dangerously close to the wire  the volume control  and from the control unit sensor screen. This is a 100% probability guarantees us a lot of noise into the channel  from touch screen and an overall decline of purity and transparency of sound even when turned off. To avoid this, stick with the lower back of the screen, cables and sensor module aluminum duct tape (do not forget to cut a hole under the power button. Isolate the aluminum tape with original tape.
Now finally put the motherboard in place. We no longer need to remove it from the body.
Wires soldered to the 4 and 5, the volume control outputs to the inputs we solder headphone amplifier.
Also connect by the wires contacts of outputs of AMP & jack for headphones (L and R on the first photo).
Power amplifier for headphones takes from the motherboard with 4 and 8 contacts at his native TDA1308 (V-V and the first picture).
Ground for the amplifier to take from one of your contacts of bypass (shunt) power, indicated by the arrow on the first photo.
Neatly laid an amplifier on board, pre-insulate bottom shielding layer tape or duct tape. Wires must be routed around the amplifier, but in any case not below it, the height of the amplifier and so critical.
Solder the battery (tried to solder the wires quickly, without a spark, dipping the end of the wire is melted into a drop of solder on the motherboard).
Try to turn on. Listen to the result.
If everything works and everything is done carefully, the cover must close almost back to back. If not locked, you can try to replace film capacitors in bypass power on the board of headphone amplifier with a lower (critical limit - 3 mm).
 Good luck =)
Do you have any questions, ask in the original theme.

  Moded by Hardcorist 

 

I wish someone can do it fro me, for a price......
 

 

[Migou67]

and for me also
 
Quote:

I wish someone can do it fro me, for a price......
 

 

 

[Hardcorist]

This is not a commercial project and I had no purpose to earn money, so all the information is laid out in easy access. Anyone can repeat it, if provided my authorship and references to the source.
 
Yesterday I made ​​some improvements, which have raised a little sound quality, but to describe them in detail I do not want. Technically competent people themselves can find ways to improve the design and people are not competent technically, should refrain from interfering in the design of the player.
 
I want once again to warn: the quality of components in the player is so low that any careless or thoughtless action can lead to his death.
 
 
A little correction: the sound of my player's superior sound Colorfly C4, but inferior sounding HM-801, due to the weak implementation of the DAC.
All the modification affects only the analog path.

 

[w357]

    Just install righthands.dll & brain.dll + datasheets + instruction above + experimental Tec = enjoyment or dead player 

 
 
Quote:

Yesterday I made ​​some improvements, which have raised a little sound quality, but to describe them in detail I do not want. Technically competent people themselves can find ways to improve the design and people are not competent technically, should refrain from interfering in the design of the player.

 

 

[glassmoon]

and for me also

 

heh +1 here... need to find some willing diy-er with skills and equipment
I am also curious how the AlexRoma's "light mod" will turn out