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Search: Posts Made By: Howard_Woodard
Forum: Troubleshooting TVs and Video Sources 02-03-2020, 03:31 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Ha ha. No scopes or other electrical components - or engineers - were hurt in this effort. You're the second to offer such a warning on this thread. I guess I might have assumed too much -- I...
Forum: Troubleshooting TVs and Video Sources 02-03-2020, 02:43 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Just a final update in case others might have similar symptoms...

After being off for a couple days it came up and acted correctly as it has done before. But rather than turning it off, which has...
Forum: Troubleshooting TVs and Video Sources 01-11-2020, 11:21 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Yes, I understand the difference between power ground and signal ground -- my scope connections are correct and the readings are correct. I have it plugged into a GFI outlet and have popped it a few...
Forum: Troubleshooting TVs and Video Sources 01-11-2020, 10:46 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

In the pictures attached, the yellow trace is UP801S pin 1, the blue trace is pin 4 and the purple trace is pin 7 at the gate of QP802S.

When working correctly or while in the boot-loop the...
Forum: Troubleshooting TVs and Video Sources 01-11-2020, 08:05 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Ha ha. I'll have to wait until it fails to see what UP801S looks like when it is looping. When I first plugged the TV in it was looping and I clearly had two different signals going into pins 1 &...
Forum: Troubleshooting TVs and Video Sources 01-11-2020, 04:51 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Btw, when I first turned it on this morning it rebooted one time and then stayed up -- no auto-rebooting -- and everything worked like you would expect. I left it on and came back to it in about an...
Forum: Troubleshooting TVs and Video Sources 01-11-2020, 04:08 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Ok, just got back home and looked to confirm what I had done before responding to you.

(1) Inverter On/Off (pin 12) is grounded to signal (cold) ground on the PSU side.
(2) DET_5V wire between...
Forum: Troubleshooting TVs and Video Sources 01-11-2020, 03:39 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Yes, I did -- thanks for the link. Still pretty skimpy on mainboard info.

My wife sent me on a grocery errand. I'll follow-up on this when I get home.
Forum: Troubleshooting TVs and Video Sources 01-11-2020, 03:19 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Hi again Bud. I put a 1K pull-up to the 5V rail (pin 2) on the DET_5V line (pin 14). It still loops. On the scope it goes to 5V at about the same time that the BL comes on. Then, at approx 28...
Forum: Troubleshooting TVs and Video Sources 01-11-2020, 12:02 AM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Interesting. I think I read that one of the purposes of the DET_5V error line was to shut down the PSU if over-current conditions were detected in the inverter an/or CCFL bulbs. How would you know...
Forum: Troubleshooting TVs and Video Sources 01-10-2020, 08:15 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Got it - thanks.

Btw, is there any problem disconnecting the PSU from the CCFL sockets and powering it back up?
Forum: Troubleshooting TVs and Video Sources 01-10-2020, 07:30 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Thanks. I'll fiddle with what the DET_5V signal is telling me and where its coming from tomorrow.
Forum: Troubleshooting TVs and Video Sources 01-10-2020, 03:50 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Sorry to just now be getting on this but since I've been retired, "first thing tomorrow" has been getting later and later.

First I put probes on pins 12 & 14 (inverter on/off and DET_5V) and...
Forum: Troubleshooting TVs and Video Sources 01-09-2020, 10:29 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Thanks, I’ll try that first thing tomorrow.
Forum: Troubleshooting TVs and Video Sources 01-09-2020, 10:21 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Well, being the eternal optimist that I am, I think I may be getting close. The input to the gates of the two mosfets responsible for proving the switching input to the TI801S and TI802S primaries...
Forum: Troubleshooting TVs and Video Sources 01-09-2020, 09:28 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

This is the waveform at the yellow test point between high voltage MOSFETs QI820 & QI821.

This waveform looks confused but I don't know what a known-good board would show right here.

Anybody?
...
Forum: Troubleshooting TVs and Video Sources 01-09-2020, 07:15 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

I tried to reflow the processor's ball grid array -- had some luck in the past with graphics chips -- and at first thought it might have fixed the problem. Even though the set auto-booted, which it...
Forum: Troubleshooting TVs and Video Sources 01-09-2020, 01:21 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Ok, the heat gun on the main board had no discernible effect. Unless someone has a better idea for next step, I think it's time to remove the heat sink from the set-top processor (It's a Samsung...
Forum: Troubleshooting TVs and Video Sources 01-08-2020, 10:08 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Forum: Troubleshooting TVs and Video Sources 01-08-2020, 09:08 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Btw, there's a YT https://www.youtube.com/watch?v=RL5-GtwypiY by user NorCal715 on measuring the voltages for this set and I think he said that 0v on pin 14 (DET-5V) meant no problem which is the...
Forum: Troubleshooting TVs and Video Sources 01-08-2020, 08:52 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Ok, now I guess I can move on to heating the main board. When I plugged it in the BL came on and stayed on for the 4-5 minutes that I monitored it. Pins 12 (BL-On) & 14 (DET-5V) stayed steady for...
Forum: Troubleshooting TVs and Video Sources 01-08-2020, 08:34 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Removing connector CN802 and plugging in the power cord turns the BL on and it will stay like that forever. However, I wasn't monitoring the BL-On or DET-5V lines to see if it was doing anything...
Forum: Troubleshooting TVs and Video Sources 01-08-2020, 08:20 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

I see that I didn't answer one of your questions. Yes, I put my oscilloscope on the PS-On line to see if I could see anything that my VOM wouldn't detect. The PS-On line is a steady 1.7vdc. I also...
Forum: Troubleshooting TVs and Video Sources 01-08-2020, 08:13 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

DET-5V...

Plug power cord in and pin 14, DET-5V, goes to about .5vdc and after approx 1/2 sec it goes to .7vdc -- could be a diode or an emmiter-base junction. The startup Chime is heard and it...
Forum: Troubleshooting TVs and Video Sources 01-08-2020, 07:57 PM
Replies: 56
Views: 847
Posted By Howard_Woodard
Re: Samsung 32 inch (LN32B360C5D) in perpetual restart loop...

Ok, thanks. Before I try the heat I'll put my scope on DET-5V and see what it does through the cycle.
Showing results 1 to 25 of 47

 
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