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AudioTime
Member
Joined 2011
2021-07-09 4:32 am
#6
- 2021-07-09 4:32 am
- #6
Thanks, NareshBrd.
These are my concerns:
1) How to I feed the sound into the amplifier? I am using the motherboard sound card, and it only has 5 channels analog out, and it do not have any optical out.
2) When replacing the amplifier board in the subwoofer, how do I secure it?
3) There bound to have heat generated, how is the heat to be dissipated?
4) Where can I get a case if I wish to make it a standalone amplifier?
I believed that the board should be powerful enough to push the subwoofer speaker (I am not sure what is the specs at the moment.
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NareshBrd
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Joined 2017
2021-07-09 4:51 am
#7
- 2021-07-09 4:51 am
- #7
What is your location?
First see what happened to the circuit, and all speakers are okay.
1. It has specific analog inputs, cords we get here.
2. The existing one is secured how? Use those mountings if possible. Or long screws with insulating stand offs.
3. Heat sink comes with the kit, may have to make holes in cabinet, but since the old one lasted so long, not going to be an issue.
4. Cases you can make from plywood, or sheet metal. Easiest to repurpose an old cabinet from VCR, dish receiver etc.
5. The woofer takes only about 10 WRMS, not a big load, certainly loud enough. Well within the kit capacity.
See your intended kit can drive 4/5 speakers and 1 woofer, different sellers have different models as per number of speakers.
And put a larger than recommended transformer, safer.
Not a SMPS/adapter fan...the power adapter looks tiny, that will give you the real story about output from the existing circuit.
Volts x Amps = Watts.
I do not expect more than 25 from that , the one in photos on the net.
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AudioTime
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Joined 2011
2021-07-09 9:20 am
#8
A
AudioTime
Member
Joined 2011
2021-07-13 12:25 pm
#9
- 2021-07-13 12:25 pm
- #9
Finally managed to pull out the amplifier board. The capacity and the joints look ok.
IMG_20210713_190329[1] on Flickr
IMG_20210713_190310[1] on Flickr
IMG_20210713_190259[1] on Flickr
IMG_20210713_190232[1] on Flickr
Anyway, I have replaced it with a Logitech speaker set.
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NareshBrd
Member
Joined 2017
2021-07-13 12:56 pm
#10
- 2021-07-13 12:56 pm
- #10
Looks like it needs minor maintenance, the capacitors are cheap 85 degrees, but the ICs are Philips and ST, so worth the trouble.
Change the power supply capacitors ,check speaker connectors and for burn marks, and generally any loose contacts.
Remove the glue from the track side, sometimes it becomes conductive.
It looks well made ..
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AudioTime
Member
Joined 2011
2021-07-14 3:59 am
#11
- 2021-07-14 3:59 am
- #11
There are quite a number of GR85 degrees capacitors, do you mean to replace all of them? Or just the big capacitor? What are the better capacitors?
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NareshBrd
Member
Joined 2017
2021-07-14 4:34 am
#12
- 2021-07-14 4:34 am
- #12
The location for most is next to the heat sink...so need to change.
First the smoothing capacitors in the power supply, and the coupling capacitors in the input to the chip amp.
Where are you in India?
If possible get Keltron, they are cheap and good, do not go for exotic Japanese.
What are the main amp chips? The quality possible from those will decide the performance.
But first remove the glue, I use a sharp paper cutter, that glue might have gone conductive.
After that, spray the pots and reflow the power in, input and speaker out solder connections.
Check for improvement.
Then, as this is a nice unit, and you have a spare, put new capacitors, and make holes in the cabinet if needed to ensure the heat sink area stays cool, high temperatures cause capacitors to fail early.
GR is an unknown brand for me.
Japanese capacitors are about 10 times Chinese price, and about 3 x Keltron in bulk.
Unless your amp is very good, and your source, you are wasting money on exotics, as Keltron is a licensee of Sprague Belgium. So good that fakes are available, buy from a reliable seller.
Put the next higher voltage value like 35 in place of 25, or go straight for 63, those seem to be easily available here.
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AudioTime
Member
Joined 2011
2021-07-14 6:02 am
#13
- 2021-07-14 6:02 am
- #13
Not sure which is the smoothing capacitors, seems to me that there is quite a number of them.
1) The big blue capacitor (photo 4)
2) the series of blue capacitors behind the heat sink (photo 2 and 3), and
3) the series of black capacitors (next to the heat sink).
I am from Singapore, and I am very noob to all this electronic stuffs, just my interest.
BTW, there is an external power adapter. so, I do not know if there is any issue with it, and will it have any impact or not.
I thought the glue can be removed easily using rubbing alcohol?
Are the 2 black big chips on the heatsink (photo 4) the main amp chips? Both from Philips. On the right, TDA8511J, and on the left is TDA8510J.
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NareshBrd
Member
Joined 2017
2021-07-14 12:39 pm
#14
- 2021-07-14 12:39 pm
- #14
I will check it out...the smoothing capacitors are there at the inlet from the power supply.
If you can, post a photo of the mains adapter name plate, if the details are visible.
Cut off the glue, alcohol will remove the printing om the components and PCB
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NareshBrd
Member
Joined 2017
2021-07-14 12:56 pm
#15
- 2021-07-14 12:56 pm
- #15
8510 is 4 single ended amps, 4 x 7W/ 4 ohms
8511 is 1 26W and 2 x 7W / 4 ohms
Distortion is 10% at full power.
Both are 15 Volts typical and 18 Volts max., you can use 25 V capacitors, 35 is preferable.
Both have 2200 uF as smoothing and 1000 uF as output coupling capacitors.
Change them to 105 degrees Japanese, German,American or Taiwan make capacitors, should be within 3 US for the lot.
Enjoy
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AudioTime
Member
Joined 2011
2021-07-15 4:51 am
#16
- 2021-07-15 4:51 am
- #16
Here is the photo of the nameplate (if I get it correctly).
IMG_20210715_111140[1] on Flickr
To link up the photos,
The power input will link to the left-most line on the PCB (Photo 1), passing through a 3A (if I interpret correctly) in the middle, to 2 of the black capacitors(?) at the lower right corner of Photo 4.
After that it should go to the big blue capacity, 6800uF, 25V on the right middle of the Photo 4.
Beyond that, I am lost.
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NareshBrd
Member
Joined 2017
2021-07-15 10:11 am
#17
- 2021-07-15 10:11 am
- #17
That is a bridge rectifier
4 diodes.
The 6800 is the common smoothing capacitor for both ICs
Cut off all the glue from capacitors and PCB using a knife. Then use a hair drier or heat gun to remove the excess left over.
Then see what happens.
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NareshBrd
Member
Joined 2017
2021-07-16 5:41 pm
#18
- 2021-07-16 5:41 pm
- #18
You have a multi meter?
If not, get one each analog and digital, they start about $5 US here for decent ones.
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AudioTime
Member
Joined 2011
2021-07-17 5:09 am
#19
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NareshBrd
Member
Joined 2017
2021-07-17 5:24 am
#20
- 2021-07-17 5:24 am
- #20
Sharp cutter, old tooth brush, iso alcohol and leaded solder 60/40 or 63/37 are also needed.
Start by removing all the glue, particularly off the tracks, and capacitor tops.
Spray all the pots, in the unit as well as remote volume, and the power in jack also. Contact cleaner, WD40 is dangerous to plastic at times.
Reflow all the joints, particularly at the in/out points, power connector too.
Sharp knife to cut glue, alcohol and brush for cleaning solder flux.
Leaded solder as lead free has a tendency to get dry joints, it is brittle compared to regular solder.
Then check and tell how it sounds.
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