Re: LG 47LB6100-UG Flashing on & off
Was it somewhat easy to get to the LED strip? I'm set up to do any job like that but if it's too time consuming, then its not worth the cost for me. Here is the CL post.
[url]https://pittsburgh.craigslist.org/ele/d/47-inch-lg-smart-tv-led-1080p/6646721165.html[/url]Re: LG 47LB6100-UG Flashing on & off...tps://pittsbur
Dgtech
E. Technician
Last Activity: 10-12-2022, 08:38 PM
Joined: 04-30-2009
Location: Pittsburgh
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Re: LG 47LB6100-UG Flashing on & off
Did you ever fix this problem somehow or just ditched it?
Theres one available on my local CL.Leave a comment:
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Re: My basic project - needs simplified - Digital TTL circuit maybe
That 74ls174 looks promising. The 74ls175 may work too as seen on the same datasheet.
This year marks 20 years since I've done my digital project in tech school so... my logic is rusty....Leave a comment:
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My basic project - needs simplified - Digital TTL circuit maybe
OK... this simple circuit idea is kinda like the show Jeopardy.
In this case:
There will be six contestants
One button per contestant - single pole single throw
Each contestant's button will correspond to a light - one light per contestant.
The light needs to stay on and lockout other contestants from ringing in until the master reset button is depressed.
Voltage has to be low voltage, 24VDC or lower.
I tried to solve this with a basic design from my experience with relay logic. (see picture). This design...Last edited by Dgtech; 04-16-2018, 08:47 AM. -
Re: Wavetek Model 130 Function Generator - Power supply problem
After I pulled this out of the board to diode check it. I saw the leg was tucked over the other one. Once installed CORRECTLY. 15VDC on TP2.
Put everything back together and hooked up the output to the scope - ALL IS WELL. All ranges of frequencies look good on my scope as well as the Fluke meter.
So to recap: The replacement of Q17 and 18 would have done the trick if some goofball (ME) would have installed it right the first time. And I used to work as a board inspector/tester....Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
zero volts on base of Q18.
-6.6 volts on anode of CR19
That R88 measures good out of circuit and point to point ohms out to its connections. 29 volts on one side. zero on the other. its not smoked either. I dont think its dropping the voltage.Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
I actually got an Idea. I'm just wondering if this would work. What if I simply bypass all this crap by eliminating this section of the power supply by implementing two 15 volt regulator IC's?
Here is my plan:
Pull Q17,18,and 19.
pull CR19
Input of 15V regulator at +29V, ground TP1, output to "J"point past TP2 leaving jumper open. I just have to heatsink it to something.
Do you guys think this could work or am I going too far? I just think this circuit...Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
Well, I removed both jumpers. I had to test a theory of that a friend had suggested that something downstream may have been loading down the circuit somehow.
With jumpers removed
TP3 shows -19VDC
TP2 shows -3.6VDC
The only clue that I gain now is not only that the problem is definitely in this area for sure but... why negative 3.6 at TP2?Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
I did check that R88, all is well there (resistively).
Ok, do we agree that if I lifted the jumper at TP2 and TP3, thus, in my mind, disconnecting the load from the power supply, I should have the rail voltages for sure. Please correct me if I'm wrong.
Just to refresh - what has been changed so far:
Q17
Q18
Q19
IC6
29VDC at Q17 and Q18 Collector (same point)
0.8VDC at Q17 emitterLeave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
ok. I replaced Q18 and Q19 Still no voltage on the positive 15V rail.
I pulled Q17. It tested good out of circuit but I replaced it anyways cause I had the new one and its kinda hard to get back in. Same problem.
So.... I pulled IC6 to see if it was pulling down the voltage somehow. Still no voltage for VCC with it removed.
Next I disconnected the jumper at TP2 separating R102 and R103. Still no voltage at TP2Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
I had to take a business trip to DC yesterday. Im back home and my parts are here now. Q18 showed no voltage when trying the diode test out of circuit. Q17 tests ok. I'm going to replace the two that I have out (Q18,19).Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
.8v directly on the solder side of IC6 pin 7
.8v on solder side of IC7 pin 7 too, which is weird if this side is working.
They are both can type of IC's so I can only get to the bottom/solder side of each - but directly on the pins themselves. Solder joints checked as well.
Q19 Out of circuit
620 ohms from C to E. Is this ok? Shouldnt it be open?
e to b 2 meg one direction and 330 K the other.
b to c 2 meg one direction and 343 K the other....Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
Q19 is not shorted. I checked. How about uA096? Is there a way to check this for correct operation? I ohmed out point to point of the components in question.Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
Thanks Longbow for your help. My component level troubleshooting skills sometimes are not where I'd like them to be. I saw that there was not that much difference between the +15 side and the -15 side component wise, thats why i resorted to comparison of one base voltage to the other base voltage, both to ground and so on.
I will check for Q19 and report back....Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
Here are some other voltages to work with as I do some comparative probing around. All of these voltages will be from TP1 to each location.
Cathode of CR 11 = 29VDC
Anode of CR 14 = -27 VDC
Cathode of CR19 = 6.4V Anode of CR19 = .05V
Anode of CR 20 = -17.9V Cathode of CR20 = - 11.3V
R93 side of base to Q22 = -15V
R92 side of base to Q19 = .79v
Where R91 and R90 come together = .8V
Where R94 and R95 come together = -16.6V
...Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
Just for the hell of it, I double checked the voltage on TP 2 and it shows .85 volts to TP1. Should be +15.Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
I measured wrong. I measured from the positive side of C48 instead of C49. Sorry, I was rushing. OK I have 6.1 volts on the cathode of CR19 to TP1.Leave a comment:
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Re: Wavetek Model 130 Function Generator - Power supply problem
Sorry guys that I took so long to get back to this.
So... on the cathode of CR19 with respect to TP1 there is -23Vdc using the correct polarity. Black on TP1Leave a comment:
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Wavetek Model 130 Function Generator - Power supply problem
I have this old function generator that I got recently and it has a power supply issue that I cant quit lock down.
Please view the schematic.
Incoming voltages 120VAC = OK
Fuse = OK
Using TP 1 as GND in this section;
TP2 = -2.7 to -4.8 varying with frequency knob\potentiometer. (Bad should be +15VDC
TP3 = -15VDC (Good)
Top of R116 = 26VDC
Bottom of R117 = -26VDC
I dont really know how to disect further to pinpoint the bad component. At this point I'd guess and just change out IC6 maybe?... -
Re: Changhong 50" LED tv, model LED50YC2000UA
On this video, this guy has similar symptoms and his problem ends up being a 3.3v regulator not regulating on the main board which overheats the processor. It may not be the same thing but its a good video to get you familiar with some of the set.Leave a comment:
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