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Trying to repair a bigscreen TV
- Thread starter strantor
- Start date
Ok, so I soldered leads to the input pins of the chip to make things easier. I cut the headphone jacks off my laptop speakers and verifed that I can get sound that way (with my working TV). I tested the broken TV in the same manner. I am not getting any signal to the input pins on the amplifier chip or to the AUX output jacks on the back. I verified the amplifier chip is working, as when I touch the leads, the speakers pop and make noise.
RCA R52WH74 52" projector. I am looking up 2 ICs I found near the amplifier I believe might be the switch you referred to many posts back or the DSP.
The first one is a tiny square Micronas (brand) SMD chip, 16 pins on each side, 64 total.
letters on the chip are so small I can barely make them out with a magnifying glass:
M(or 14)SP44400(or G) 0(or C)12
18(or G)8 430 100 R2LVF
6213 0500
the second chip is larger SMD, ST (brand) 14 pins each side, 28 total:
[st] (e4) ABQ
TEA6 422
9911C VH
MYS 99 620
sound processor (MSP4440G C12 ): http://www.datasheetarchive.com/dl/Datasheets-313/247411.pdf
If it's the DSP, it will be tricky. Doesn't look like there's a simple mute pin; it's controllled using I2C. Apart from the sound, is the TV fully working?
Try probing DACM_L and DACM_R: pins 20 and 21. Pin #1 is marked with a circle and pins are counted anticlockwise, I think. So pins 20 and 21 will be right of pin 1. Be very careful probing around here, shorting something could blow something up. For ground, clip the ground clip to the case.
Just read through the datasheet again. Saw STANDBYQ of DSP. This should be high. Pin #63, close to pin #1.
And supply voltage, on pin #10, should be about 5V.
Also try probing the crystal oscillator. Set your scope probe to 10X to avoid disturbing the oscillator. It should be 18.432 MHz.
Try probing DACM_L and DACM_R: pins 20 and 21. Pin #1 is marked with a circle and pins are counted anticlockwise, I think. So pins 20 and 21 will be right of pin 1. Be very careful probing around here, shorting something could blow something up. For ground, clip the ground clip to the case.
Just read through the datasheet again. Saw STANDBYQ of DSP. This should be high. Pin #63, close to pin #1.
And supply voltage, on pin #10, should be about 5V.
Also try probing the crystal oscillator. Set your scope probe to 10X to avoid disturbing the oscillator. It should be 18.432 MHz.
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No way to clip the ground to the case; it's a flat smd chip with pins on all sides of it. my o-scope probe is too wide to measure a pin without shorting it out to the next, but my multimeter probes are pointy; I can probe if I can hold my hand steady enough. I need a big magnifying glass just to see the pins.
Verified 5v supply on pin 10. verified 8V on 33/31 and 3.7V on 33/34.
I think there is no analog input. I rigged up my R!f@@ style speaker probe with my multimeter leads and probed 50/51 and 52/51, got no sound. it's almost like the pins are shorted together, as the speakers usually humm a little bit, but when i probe the humming stops. not quite sure what that means
OK, so the 2nd chip is a TEA6422 Bus-Controlled Audio Matrix. 6 inputs 3 outputs.
I have no sound on any of the inputs or outputs. I'm not sure, but I'm assuming this component is between the sound processor and the power amplifier in the circuit. In either case, what comes before the matrix and before the sound processor? whatever that component is, I think it's the one screwing me.
I have no sound on any of the inputs or outputs. I'm not sure, but I'm assuming this component is between the sound processor and the power amplifier in the circuit. In either case, what comes before the matrix and before the sound processor? whatever that component is, I think it's the one screwing me.
CORRECTION: I have sound on pins 6 & 23 (L & R input #3) of the matrix IC. The sound corresponds to the digital TV station. I have no other inputs to the matrix switch. I have my wii plugged into the aux sound jacks in the front, so I'm thinking I should be able to find the wii sound on one of those inputs, but I got nothing but input 3. No outputs. nothing ever outputs, even if I'm on digital TV
Aside from the time when I made the correction, I never had any inputs to the matrix switch. I didn't have any at first and now I don't have any again. I can't seem to find any connection between the 2 ICs. As previously stated, I never get any output from the matrix switch. I can't seem to find any connections from either IC to the inputs of the amplifier IC, and I can't seem to find where the signals come into the matrix switch from. Also can't figure out where the aux inputs go.
The way I assume it should work (keep in mind I have no idea what I'm talking about) is that all the inputs (digital TV, cable, DVD, front AUX jacks, rear AUX jacks) go to the matrix switch. So I should be able to read more than 1 sound signal at the matrix switch inputs, but I got nothing. The matrix switch then chooses an input and sends it to one of 3 outputs (sound processor IC, aux output, other IDK). So one of these outputs should be going to the sound processor IC, but I can't confirm that. I never read <50KΩ between any 2 pins between the two ICs.
Due to not being able to read anything at the inputs I assume there is another switch/switches somewhere but can't locate it.
I am pretty much at the end of my rope. If anyone could give me any pointers it would be nice. I am done for today.
The way I assume it should work (keep in mind I have no idea what I'm talking about) is that all the inputs (digital TV, cable, DVD, front AUX jacks, rear AUX jacks) go to the matrix switch. So I should be able to read more than 1 sound signal at the matrix switch inputs, but I got nothing. The matrix switch then chooses an input and sends it to one of 3 outputs (sound processor IC, aux output, other IDK). So one of these outputs should be going to the sound processor IC, but I can't confirm that. I never read <50KΩ between any 2 pins between the two ICs.
Due to not being able to read anything at the inputs I assume there is another switch/switches somewhere but can't locate it.
I am pretty much at the end of my rope. If anyone could give me any pointers it would be nice. I am done for today.
Connect it to the case of the TV not the chip.
Yeah I eventually figured out that there is a common ground in the TV. It's all plastic so there's not really a "case" but I found that I can clip onto the outside of the AUX barrel jacks and that ground is common to most things.
Anyway, I was past that part when I left off last night. I couldn't figure out where all my audio signals were ending up. they weren't making it to the matrix switch.
There was nothing on DACM_L or DACM_R, nor was there anything on the inputs
no sir, checked that, nothing. I think there may be multiple &/or intermittent problems. I think I should multiple inputs on the matrix switch, but I only have one, and it's not always there.
seecumulus
- Joined Jul 13, 2011
- 31
Hello Strantor -
IF you wanted and thought that it would be worthwhile financially and timewise . . .
I could take a look at the other Flat Screen that you posted which I think you said is beyond repair.
I would enjoy a Flat Screen project, presently.
IF you wanted and thought that it would be worthwhile financially and timewise . . .
I could take a look at the other Flat Screen that you posted which I think you said is beyond repair.
I would enjoy a Flat Screen project, presently.
Do you have any datasheet for the IC?
A picture would be helpful too, of the top and bottom layers, with both sound processor and mux switch in the same image, if possible.
The sound processor itself has multiple sound inputs, so the mux switch might only be used if more than the maximum inputs are used. I think it's 4 for that chip.
We've moved on from the video issues; that was a different TV, different problem. Right now I'm troubleshooting audio issues.
I'm not sure which one you're referring to. If it's this one, You can have it if you live in/ near houston. All 3 picture tubes are burt (literally, cooiling oil came out and they burned up, as in fire) + a good portion of the circuit board is burned/melted, cooling oil all over all of the components. I have removed components (brutally, no regard for preserving the TV; hacked through bundles of wires, twisted off metal pieces, broke off all the plasitc retaining clips, etc.). It's been severely molested. If you're still interested pm me. local pickup only. If you're talking about the one earlier in this thread, it's fixed, and is my current living room TV. if you are talking about the one I'm working on now, no, I haven't given up on it. You can't possibly be talking about the giant mitsubishi because I haven't even opened it up and assesed it yet.Hello Strantor -
IF you wanted and thought that it would be worthwhile financially and timewise . . .
I could take a look at the other Flat Screen that you posted which I think you said is beyond repair.
I would enjoy a Flat Screen project, presently.
I will post link and pics when I get home.
Sorry that I was away.
If you want I can see what I can do. I am now at north of Maldives.
To you guys it's like going to different states.
To me it's going to another island.
I am here to work. And to day I was able to get a descent connection.
I am at Ha. Hoarafushi. Does any one like to see..I got me cam
If you want I can see what I can do. I am now at north of Maldives.
To you guys it's like going to different states.
To me it's going to another island.
I am here to work. And to day I was able to get a descent connection.
I am at Ha. Hoarafushi. Does any one like to see..I got me cam
Ok thanks R!f@@
I made your sound speaker probe thing. worked great. did you read the posts about the sound IC problems?
I found the service manuals. I have posted datasheets for the ICs in question. I have not had a chance to review the service manuals yet. my TV repair hobby is only getting attention on sundays lately.
