How does the unit behave when you switch it to modes off and auto?
And until you are sure that the subwoofer is working, use signal from phone/mp3 player/laptop etc. (3.5mm to RCA connected to LINE/LFE ). You don't have to use both LINE and LFE inputs at the same time. For troubleshooting just switch between them.
To check if the sense circuit is working, while playing music, check pin 13 on ic109 - there should be +5V if a signal is detected.
madan1
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Last Activity: Today, 07:35 PM
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Location: Sofia
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Last edited by madan1; Today, 05:08 PM. -
This can't be right.
The power on that rail is generated from the feedback/bias winding on T102 and after rectified by d113 , if I remember correctly, should be around 20Vdc (measured on c127). Regulator IC102 makes the 12Vdc (measured on c184/c125) needed for the smps IC101...Leave a comment:
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For the twamp board, you have floating ground (KG +27.5 in reference to ground) which goes to pin2 on the TDA. TDA pin 1 should be -27.5 in reference to KG (pin2). TDA pin3 should be +27.5 in reference to KG.
TDA pin1 to pin3 should be +55.
On the same board is the oscillator for the TDA - IC503. Again it uses KG for ground. IC503 pin8 to pin16 should be +5V
p.s. check pin 6 MODE on the TDA - it should be >4.2V in reference to KG
Well not many places to lose the audio signal. Only a couple of caps and inductors between the connector and the TDA...Last edited by madan1; 09-17-2025, 03:18 PM.Leave a comment:
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If the original unit started working with another twamp board, this most likely means that all of the time there has been audio signal coming from the DSP. It will save you a lot of time (and nerves) if you make sure that you are testing correctly.. just a friendly advice
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SM page 108
The twamp is tda8922. Looks like the protection circuit of the IC is integrated with the rest of the system, so I guess if there is something wrong with its power supply (ig missing rail) the whole unit will be in protection mode. I bet the TDA failed, but still start with the standard procedure...Last edited by madan1; 09-17-2025, 10:24 AM.Leave a comment:
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SM page 101
T102 pins 9 and 11 are for the +/-55
The same transformer is used for the rest of the power rails, so if you have any power on the secondary side - the smps IC is doing its job.
If the 2x55V coil is not generating power, but the rest power rails are present, the coil might be gone....Leave a comment:
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Can you scope pin 10 (shut down) on KA3525A?...Leave a comment:
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Well, check the connection between pins 4 5 6 7 on u7 to the corresponding pins on u23.
Pin 3 (smute) should be pulled d̶o̶w̶n̶ UP when hp signel is used.
edit: my bad, mute should be high for enable...Last edited by madan1; 09-09-2025, 03:45 AM.Leave a comment:
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Can you upload the full service manual?Leave a comment:
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By the way, check for short to ground and audio/analog signal on pins 12 13 14 15 and 33 34 35 36 on IC702
Also check for audio/analog signal on pins 4 5 24 25 on IC703. Check same pins for short to ground.Last edited by madan1; 09-07-2025, 04:59 AM.Leave a comment:
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pin2 and pin4 might be pulled down through sw701 and/or r713 and r811. Switch off the unit and measure the resistance on each resistor of the array.. it should be 10k. If there are open resistors from array, try placing good ones just on their place.. it should not be hard - one end is on 3.3v power rail, the other on the slide switch.
p.s. if you insist on the exact part - just google "resistor array smd 4*10k"...Last edited by madan1; 09-06-2025, 04:41 PM.Leave a comment:
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Just noticed that the link for the pinout is corrupted. Here it is https://www.df7sx.de/wp-content/uploads/2014/08/radiowerkstatt_schema.pdf
In this case for enable/stand_by is used pin 13 and it goes to transistor Q4 that enables mosfet Q3. Q3 switches on the power supply for the power amp.. so I guess the easiest way for you will be to follow back the power supply for the amp. TDA2009A gets power on pin9 so follow it from there.
Anyways, in order to have enable/st_by signal, the board must have power - 1.2V and 3.3 on pins 1 and 2. If you do not have those rails when the unit is...Leave a comment:
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How about this https://www.onsemi.com/pdf/datasheet/ncp2811-d.pdf
ps: TBH I expected a more generic classD amplifier IC.. but anyways - go with the standard things - check the power rail, signal enable pin, input analog audio and audio output audio pins...Last edited by madan1; 09-05-2025, 11:54 AM.Leave a comment:
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What is the U18 ic?Leave a comment:
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It shouldn't be that hard.
From what I see, there are two analog audio outputs (rca and headphones) so there must be 2 analog audio amps, which should not be hard to find......Leave a comment:
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- Can anyone help identify the above ICs (especially FS1235)? ------------------ The Kino 3 baseband processor is the latest generation of integrated system-on-chip,
providing an optimised solution for WorldDMB Profile 1 DAB/DAB+/DMB-R and FM-RDS... https://www.electronicsdatasheets.co...d00.pdf?format
p.s. fun fact - According to this https://**************/dump/audio/ma.../73-1-0-100715 Makita dmr104 uses the same daughterboard/"brain".. unfortunately, still no schematics.
So I guess just start with...Last edited by madan1; 09-03-2025, 02:58 PM.Leave a comment:
- Can anyone help identify the above ICs (especially FS1235)? ------------------ The Kino 3 baseband processor is the latest generation of integrated system-on-chip,
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The same IC is used in other LG models, for which there are schematics. You can try extrapolating the value of the resistors based in on which pins they are connected to the IC.
For instance R5F7 R5G1 R503 seem to be connected to the caps next to them. Most likely those correspond to R5N9 R529 R528 on LG LAP250H....Leave a comment:
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Do you have to correct sw701 settings and "model type resister" value on pin30/ic701? I guess if the CPU thinks it is a subwoofer, it will not output any HF signal from the dsp..
Should work even without changing the switch settings....Last edited by madan1; 09-03-2025, 11:56 AM.Leave a comment:
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