Iwannebuy TA2024 mod potential?

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Was impressed by the sound of Sure board TA2024, on this thread.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=112395

After minimal mod, the sound is excellent. So I wanted another board to "fully mod" and ended up buying almost identical Iwannebuy TA2024 here for $17: http://cgi.ebay.com/ClassT-T-AMP-TA...a249965&_trksid=p4634.c0.m14.l1262&_trkparms=|293:2|294:30#ht_2611wt_958

There is slight difference and can't figure out how to mod. What surprised me is in stock form (just opened the package and hooked up to my speaker, the sound is surprisingly good. Although I can tell the modded Sure is better.

Has someone looked and modded this board? Looks of this board is better with good soldering and higher quality than the Sure board. Even cheaper...

Anyone have idea on how to improve this board?


thanks,

gychang
 

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audio1st said:
Hi gychang,

You will have to be our eyes and ears for this one. This board does look almost identical to the Sure board.
Could you take a photo of the front and back of the board and perhaps measure the DC (mV) at the speaker terminals?
Cheers..



DC offset is nearly deadon. -16mV, and 2mV, no need to destroy resistors...

Hope the picture gives u some idea. Noticed C25 seems to have been desoldered already, C3, C24 are intact as D1, not sure which resistor R2 is pointing to.

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.

An externally hosted image should be here but it was not working when we last tested it.


the pictures are pure stock, no cleaning of the PCB, will plan on cleaning. Only minor costemetic with banana legs are different lengths...
gychang
 
Hi gychang

Thanks for taking the photos...
The DC is low because they have left off the six resistors that made up the Sure DC offset cct, (no resistors to remove).:)
The input caps seem to be in the same place, you will know by the bass if they are a similar value as the Sure, 800nF (C13 & C21).
C3 & C24 may be OK, (100pF?) if the treble does not roll off as the volume increases?

The board is not the same as the one in the advert, the original photo you posted.
 
audio1st said:
Hi gychang

Thanks for taking the photos...
The DC is low because they have left off the six resistors that made up the Sure DC offset cct, (no resistors to remove).:)
The input caps seem to be in the same place, you will know by the bass if they are a similar value as the Sure, 800nF (C13 & C21).
C3 & C24 may be OK, (100pF?) if the treble does not roll off as the volume increases?

The board is not the same as the one in the advert, the original photo you posted.


Is there a way to find the value of C13 & C21?, multimeter?, read the fine print with magnifing glass?

Guess for now no active mod til more folks chime in... Will continue to burn in and listen and compare.

gychang
 
audio1st said:
Hi gychang

C3 & C24 may be OK, (100pF?) if the treble does not roll off as the volume increases?


I have listened to about 2hrs of music and this board is impressive in stock form. The sound is indeed surprisingly good. Sure board in stock form was markedly inadequate, this is different.

Being a tinkerer Shall I desolder both C3 & C24?, I don't notice obvious lack of high freq at all.

I would encourage others to take a plunge for $17 from ebay (including shipping).

gychang
 
gychang said:


Being a tinkerer Shall I desolder both C3 & C24?, I don't notice obvious lack of high freq at all.

gychang


You go for it;) and you know you are going to want to improve the input caps (C13&C21 beige, no small print) as well next:devilr:

C25 is there, all the SMD caps are beige with no markings. The missing item is probably so you can link the fault pin to the mute pin? The other missing item is marked LED so they may have considered a power on indicator?
 
audio1st said:



You go for it;) and you know you are going to want to improve the input caps (C13&C21 beige, no small print) as well next:devilr:

C25 is there, all the SMD caps are beige with no markings. The missing item is probably so you can link the fault pin to the mute pin? The other missing item is marked LED so they may have considered a power on indicator?

thanks for the suggestions, now the markings all make sense.

time to mod...

gychang
 
audio1st said:



You go for it;)



I desoldered the C3, C24, the sounds good, sparkly, at least did not sound worse then before. Now the input caps.

1. I plan to solder input caps (2-Dayton DMPC-3.3 3.3uF 250V Polypropylene Capacitor) to C3-C13, and C24-C21 as shown on audio1st graph, what I am not sure is my caps does not seem to clearly mark the polarity (attached the small picture below from the web site-can't locate mine but somewhere, hopefully I can look at this and can figure out which is +, does the + leg go on C13 or C3 side? Is the + toward the center of the PCB?

2. Large picture is the caps I have laying around, can the 2 smaller ones be used as tank caps? (in which case I will need 2).

3. Does the large one have any role in this mod?


An externally hosted image should be here but it was not working when we last tested it.


gychang
 

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gychang said:



1. I plan to solder input caps (2-Dayton DMPC-3.3 3.3uF 250V Polypropylene Capacitor) to C3-C13, and C24-C21 as shown on audio1st graph.

gychang


my mistake the size of input caps will be too big to solder on the small pads, will plan on connecting them to input terminals after C13, C21 are soldered across the pads.

gychang
 
problems on mod!

I wanted to put new input caps, and volume pot with on-off. Mainly following audio1st excellent photo from Sure TA2024 upgrade.

1. Desoldered and bridged D1, C13, but C21, the pad came off and following the below photo based on Sure TA2024, as u can see I think I have it right but now when I turn on just static on both channels, with the C21 pad exposed before C24-R14 bridge only Ch1 as expected played music.
2. Input caps are in, and so is the tank cap (by the way when I disconnected this cap, music did not change on Ch1, is this expected?).

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.

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.


on this board, there is unmarked resistor below C21, should I solder to this resistor?

I hope some can help me out.

gychang
 
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