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post #2401 of 2445 Old 11-08-2009, 10:48 AM
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Quote:
Originally Posted by QAM View Post

By forget, do you mean that the "virtual" channel number is no longer there, or does the channel no longer show a picture?

Even post digital transition date on June 2009, viewers are encouraged to rescan regularly as the stations will be upgrading their transmitters, changing antenna positions, and even changing back to their "original" channel frequency. The virtual channel number will not change, so a rescan is required.

I have not heard of the NVM losing it "memory". Do you have occasional power outages or surges in your area?

The rule of the day is to resan often... or until the digital dust settles.

Well, it requires a rescan to find those missing channels. They are using connected to rabbit ears antennae. Why rescan so often?

My computer's HDTV tuner cards and dTV Pal did not require rescans since they remember them. BTW, we live in Los Angeles area.
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post #2402 of 2445 Old 11-08-2009, 11:06 AM
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Don't know about your tuner card, but the DTV Pal picks up and adds in new channels automatically (I've heard of at least a few CECB's that doing that - both my Pal and CM7000 do). I don't recall the Zenith ever doing that when I had one.
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post #2403 of 2445 Old 11-08-2009, 12:35 PM
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Quote:
Originally Posted by QAM View Post

The rule of the day is to resan often... or until the digital dust settles.

No way ! I can't imagine going through the tedious pain of having to redo my user settings every time.

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post #2404 of 2445 Old 11-08-2009, 02:25 PM
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Quote:
Originally Posted by phildaant View Post

Hello.

Does anyone know why Zenith DTT900 (4/2008) converter boxes (have a few) like to forget channels and require rescans? This is in Los Angeles, CA, USA area.

Thank you in advance.

I had a similar thing happen with a Zenith DTT901 that I set up for someone else.

It only happened once during a day when I know that the station was off the air doing antenna work.

That channel disappeared from the channel list and required a rescan to get it back.
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post #2405 of 2445 Old 11-08-2009, 10:47 PM
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Quote:
Originally Posted by Floydage View Post

No way ! I can't imagine going through the tedious pain of having to redo my user settings every time.

A rescan does not undo your other settings, unless instead of a simple rescan you redo the initial setup.
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post #2406 of 2445 Old 11-09-2009, 11:38 AM
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Quote:
Originally Posted by dattier View Post

A rescan does not undo your other settings, unless instead of a simple rescan you redo the initial setup.

They said "rescan" which made me think of a total scan vs an update/add scan. They being the poster with the problem Zenith and the first replier.

Of course both scan methods will depend on the box*, some being more forgiving than others. My Zinwells add back my deleted channels and mess up my Favorites even on an update scan. My Artec is fairly new to me, I just tried the update and it did as you described (deleted channels stayed deleted but it has no favorites function); Artecs are thought to be Zentih clones. I think my CM brings back deleted channels on an update but keeps my Favorites intact.

*I know it's a Zenith thread but the replier was speaking in general terms.

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post #2407 of 2445 Old 11-20-2009, 08:10 PM
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Quote:
Originally Posted by Turbo DV8
Damn, the same DTT901 just did it again. It didn't respond to the initial power-on command. On second attempt when it turned on, it didn't lose it's channel memory, but all the zoom settings were once again panned out, forcing me to zoom every single channel again.


Quote:
Originally Posted by TalkingRat View Post

I think you can reset them all at once by selecting your preference in the menu. Then you'd just need to change the aspect ratio on any channels you want a different way.

Nope. It just did it again. When you go into the menu and change the aspect ration, it only changes it for the channel being viewed at the time. Real PITA, these things just keep spontaneously turning on/off by themselves, unlocking blocked channels and resetting zoom modes.
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post #2408 of 2445 Old 11-21-2009, 04:34 PM
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My Durabrand tv once misinterpreted very bad reception as encryption and therefore autodeleted the channel. A rescan (after adjusting the antenna) was required to get it back.

How can we say "the digital transition is complete" when thousands of low power stations are still broadcasting in analog?
LOW POWER ANALOG NEEDS TO DIE NOW!!!
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post #2409 of 2445 Old 05-07-2011, 12:47 PM
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My Dad's DTT-900 box stopped working a couple of days ago. Are there any ways for a user to diagnose and repair a "dead" DTT-900?
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post #2410 of 2445 Old 05-07-2011, 02:14 PM
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Quote:
Originally Posted by seatacboy View Post

Are there any ways for a user to diagnose and repair a "dead" DTT-900?

How dead?

1) If you are using RF out could it be as simple as the TVnot tuned to Channel 3/4?

2) Does the power light come on? If not probably bad power supply. Try plugging it into a know good outlet.

3) Could it just be the remote? Dead battery?


4) The box has both RF and composite outputs. Try the other one.
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post #2411 of 2445 Old 05-07-2011, 03:46 PM
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If you've tried all the above then I'd suspect either a fuse or electrolytic capacitor in the power supply. The fuse probably wouldn't be too bad to replace but the cap would require some soldering, generally caps are <$5 and closer to a couple bucks. Look for any bulging or leaking caps.
Wow, this thread hadn't been posted to for almost 1 1/2 years
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post #2412 of 2445 Old 05-08-2011, 07:32 AM
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Quote:
Originally Posted by jjeff View Post

If you've tried all the above then I'd suspect either a fuse or electrolytic capacitor in the power supply. The fuse probably wouldn't be too bad to replace but the cap would require some soldering, generally caps are <$5 and closer to a couple bucks. Look for any bulging or leaking caps.
Wow, this thread hadn't been posted to for almost 1 1/2 years

Here are photos of the power supply and main circuit boards found in a DTT900:
LL
LL

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post #2413 of 2445 Old 01-10-2012, 08:37 PM
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I just acquired two Zenith DTT900 (3/2008 & 4/2008) for my two old TiVo Series 2 connected to my old standard def CRT TV.
The Menu > Option settings have two prefs: "TV Aspect Ratio," which I set to "Normal TV (4:3)," and "Aspect Ratio," which can be set to one of four options:
- Set By Program
- Letter Box
- Cropped
- Squeezed
...when a widescreen program is broadcast, but when a 4:3 program is broadcast, it says "Aspect ratio cannot be changed on this channel."
My problem is that when it lands on a channel with a widescreen program being broadcast, it often, but not always, selects the wrong one, such as "Squeezed" instead of "Letter Box." I hate, hate, HATE the horizontally compressed distortion, and I'm usually not there to change it manually when my TiVo records. If I go into the Option settings and choose "Letter Box," it doesn't stick, and the next time, a channel with a widescreen program will go back to "Set By Program" and it'll often be wrong again. (Does the AFD signal from the local TV station distinguish a widescreen program between Letter Box and Squeezed?) In any event, how do I force my Zenith DTT900 to always use "Letter Box" for widescreen broadcasts?
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post #2414 of 2445 Old 01-11-2012, 04:13 AM
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With my Zenith DTT900's and their Best Buy twin from Insignia, if I set a channel on Letter Box (or Squeezed), it stays that way forever - UNTIL I do a complete rescan. At that point all channels scanned are reset to "Set By Program."

If I just "Add Digital Channels", the ones already scanned remain as I had set them.

Harry
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post #2415 of 2445 Old 01-11-2012, 06:25 AM
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I recently dusted off and used my DTT900 CECB while evaluating the Mohu Leaf antenna, and wanted to mention that this converter box really has a great combination of functionality and performance. The 480i picture quality is very good. If you are looking on the used market for a converter box, the Zenith DTT900 and DTT901 (and their Insignia counterparts) remain among the best performing units made.
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post #2416 of 2445 Old 01-11-2012, 08:29 AM
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Thanks, HGN2001, you seem to be saying that the Aspect Ratio setting is by individual channel, not overall. That didn't occur to me. I've just excruciatingly gone through all channels on both of my boxes and set the ones I could (widescreen programs at the time) to "Letter Box." It'll probably take at least a day to see if they hold in practice, and I'll come back here and report my findings. (Sheesh, the instruction manual is useless!) ...
Thanks again, HGN2001!
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post #2417 of 2445 Old 01-11-2012, 09:50 AM
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Quote:
Originally Posted by Schmye Bubbula View Post

Thanks, HGN2001, you seem to be saying that the Aspect Ratio setting is by individual channel, not overall.

I have an Artec which is a Zenith clone, from what I've seen on these forums the menus are identical. Having said that I've been able to make the aspect stick for all channels in the main menu. There was something weird about making it stick and I don't know exactly what it was but I do remember I had to try it in the main menu on a few different stations before it took hold (the different stations previously had different aspect settings using just the remote's aspect button so that may be clue). Afterwards I could go back and change individual stations without affecting the other stations by using the aspect button on the remote (i.e. don't go into the main menu on a station by station basis). The manual for the Artec was useless as well.

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post #2418 of 2445 Old 01-11-2012, 10:12 AM
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It would be greatly appreciated if anyone could come-up with what hoops must be jumped through to get the "Aspect Ratio" setting from the main Options menu to apply overall to all channels.

Right now, if you just set it, it only affects the single channel one happens to be on at the time, which really threw me for a loop because I naturally thought, being in the main settings menu, that it was a global setting, so I was setting it to "Set By Program" aaarrgghh! (And thereafter, as Floydage pointed out, the setting applied from the "Zoom" button on the remote control would stick only on a channel-by-channel basis.) This would greatly reduce the tedious burden after a full rescan as a starting point for reapplying the aspect ratios of the individual channels. What's the trick?
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post #2419 of 2445 Old 01-11-2012, 03:38 PM
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OK, the "Aspect Ratio" setting for sure gets remembered by individual channel, whether set in both the main Option settings or with the "Zoom" button on the remote control.

Still would like to know the trick how Floydage was somehow able to force an overall global setting for all channels in one fell swoop in the main Option dialog, e.g., set all channels to "Letter Box." But I guess I still would have to go through and set all the channels one-by-one, anyway.

Anyway, glad I've got it all working on a practical level now. Academically, however, I'm still curious as to why, when a channel's "Aspect Ratio" setting is set to "Set By Program," it often chooses the ugly "Squeezed" instead of "Letter Box" when a widescreen program is running. Does the AFD (Active Format Description) signal from the local TV station distinguish a widescreen program between Letter Box and Squeezed? Or does the Zenith DTT900 think it's "doing us a favor" by choosing the "Squeezed" setting for us so we don't have to "suffer" the black bars on the top & bottom of letterbox?
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post #2420 of 2445 Old 01-12-2012, 11:18 AM
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Quote:
Originally Posted by Schmye Bubbula View Post

Academically, however, I'm still curious as to why, when a channel's "Aspect Ratio" setting is set to "Set By Program," it often chooses the ugly "Squeezed" instead of "Letter Box" when a widescreen program is running. Does the AFD (Active Format Description) signal from the local TV station distinguish a widescreen program between Letter Box and Squeezed?

My guess is this is the case. Squeezed is 16:9 for a widescreen, it's just squeezed by the converter box. Letterbox is generated by the converter box, as well as all of the settings, to fit onto a 4:3 set (i.e. letterbox isn't a widescreen mode). I think the reason they did squeezed was because some widescreen monitors did not have ATSC tuners either (although I have seen a few movies on non-network stations that reformat properly when I used squeezed). I recently acquired a Panasonic widescreen CRT and the best fit I got was when I used squeezed and set the Panny to Full; letterbox works but I can't get as good a fit and geometry.

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post #2421 of 2445 Old 01-13-2012, 12:01 PM
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Aha, they had to make it fit the media:

http://en.wikipedia.org/wiki/Anamorphic_widescreen

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post #2422 of 2445 Old 08-16-2013, 08:30 AM
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I now have four DTT900 CECBs, three acquired from thrift stores (minus remotes) for about $13 each. There are some universal remotes (from RCA and other makers) which have the codes to control the DTT900 and its successor the DTT901. The tuner sensitivity of this model remains very impressive. The reason I'm stockpiling them is that there are some reports of these units dying after significant use.

The main drawback to MOST DTT900 models is the audio defect affecting models made up through May 2008. The audio at times has some annoying abberations during voice sibilants. Later models were fixed, but to my knowledge a firmware upgrade or repair of earlier DTT900s was not made available.

The other drawback, though a very minor one as of August 2013, is the lack of "analog pass-through" for low-power analog stations in metro areas and/or low-power analog translators serving rural "TV Reception Improvement Districts". An increasing number of those stations have either switched to digital transmission OR simply gone off the air. The last of the analog stations are being forced off the air by the FCC in 2015.

Although this model and the DTT901 have been out of production for four years, these are good choices on the used market. They are fairly common at thrift stores and yard sales at good prices, particularly the earlier DTT900. However, on Craiglist and Amazon, used DTT900 and DTT901 units sell for inflated prices.
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post #2423 of 2445 Old 08-16-2013, 10:00 AM
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Quote:
Originally Posted by seatacboy View Post

I now have four DTT900 CECBs, three acquired from thrift stores (minus remotes) for about $13 each. There are some universal remotes (from RCA and other makers) which have the codes to control the DTT900 and its successor the DTT901. The tuner sensitivity of this model remains very impressive. The reason I'm stockpiling them is that there are some reports of these units dying after significant use.

The main drawback to MOST DTT900 models is the audio defect affecting models made up through May 2008. The audio at times has some annoying abberations during voice sibilants. Later models were fixed, but to my knowledge a firmware upgrade or repair of earlier DTT900s was not made available...
My parents have April 2008 model from Circuit City with the coupon cards. I noticed their downstair's old huge projection TV make echo voices. Is this the one you're referring to? If so, then there is no way to fix it? BTW, their tuners still kick arse after five years!
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post #2424 of 2445 Old 08-20-2013, 09:01 AM
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>I now have four DTT900 CECBs, three acquired from thrift stores (minus remotes) for about $13 each. There are some universal remotes (from RCA and other makers) which have the codes to control the DTT900 and its successor the DTT901.

The Zenith/Insignia converters reused remote codes from a old LG/Zenith satellite receiver. Even if you have an older replacement remote, you should be able to get it to work by trying those codes until you find the right one.
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post #2425 of 2445 Old 11-10-2013, 11:19 AM
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I have one of these DTT900 that began failing a few weeks ago - shuts off for no apparent reason and would not come back on unless I unplugged from the wall (power button did not work).  It was so bad that it would not stay on for more than 2 minutes before shutting off again.

 

I have had this for about 4+ years - constantly on.

 

I managed to repair it by replacing 4 capacitors in the power supply


C121 and C123  1000uF, 10/16 Volt - replaced with 1000uF, 16 volt
C122 and C124  330 uF, 10 volt - replaced with 470uF, 25 volt

 

So far (2 days constant on) it is working great.

 

To begin, I took off the cover and inspected the boards - no obvious heat or other damage.
I then measured the power supply voltages at the connector P101.

 

Pin 1: 5.4 VDC (marked as 5.4VA )
Pin 2: GND
Pin 3: 2.9 VDC (marked as 3.2VA )
Pin 4: 2.2 VDC (marked as 2.4VA )
Pin 5: GND
Pin 6: 2.2 VDC (marked as 2.4VA )
Pin 7: GND
Pin 8: 0.4 VDC (marked as SMART)

 

So the voltages were lower than marked - suspicious.

 

I then removed and mapped out the connector on the power supply PCB (printed circuit board) and found:

 

Pins 4 and 6 are the same on the PCB and are fed thru a diode (HER202)
The input to this diode is the Pin 3 voltage.
Pin 8 goes nowhere on PCB (a wire jumper is missing)

 

So I then grabbed another bench power supply I had with 5 and 3.3 volt  (nominal) outputs.
I adjusted this supply to 5.4 V and 3.2 V to match the DTT900.

 

I then used alligator clip jumpers into 3 points on the bad power supply:

5.4 volt (after rectifier diode)
3.2 volt (after rectifier diode, which then feeds the 2.4 volt thru the HER202 diode)
Ground

 

Jumpering in after the rectifier diodes prevented any 'back feed' of power to the other power supply circuits.

 

I powered on my bench supply (the DTT power supply was unplugged) and the converter worked - stayed on for several minutes and the voltages were correct:

 

Pin 1:    5.4VDC when ON,  5.6 VDC when OFF
Pin 2:    3.2VDC when ON,  3.4 VDC when OFF
Pins 4/6: 2.4VDC when ON,  2.6 VDC when OFF

 

I also measured current draw:


5.4 volts:  0.38A ON,  0.08A OFF
3.2 Volts:  0.47A ON,  0.03A OFF (this was total current for both 3.2 and 2.4 volt feeds)

 

I took a guess that the associated electrolytic capacitors on the power supply were bad.  
There are 7 of them, but I only targeted the 4 on the output side:

C121  1000uF, 16 V
C123  1000uF, 10 V
C122  330uF, 10V
C124  330uF, 10V

 

If this repair doesn't hold,  I will need to try replacing the other 3 caps:
C103 47uF, 200V
C108  1uF, 50V
C109 33uF, 25V

 

(I didn't have these caps in my parts stash, so that is why I held off replacing them.)


Hopefully this may help others with bad DTT900 converters in getting them working again.

 

If anyone is interested, I could post a picture or two pointing out the parts I replaced.

 

Cheers,
Mike

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post #2426 of 2445 Old 11-10-2013, 11:37 AM
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Quote:
Originally Posted by mjkirk12 View Post

I have one of these DTT900 that began failing a few weeks ago - shuts off for no apparent reason and would not come back on unless I unplugged from the wall (power button did not work).  It was so bad that it would not stay on for more than 2 minutes before shutting off again.

I have had this for about 4+ years - constantly on.

I managed to repair it by replacing 4 capacitors in the power supply


C121 and C123  1000uF, 10/16 Volt - replaced with 1000uF, 16 volt

C122 and C124  330 uF, 10 volt - replaced with 470uF, 25 volt

So far (2 days constant on) it is working great.

To begin, I took off the cover and inspected the boards - no obvious heat or other damage.

I then measured the power supply voltages at the connector P101.

Pin 1: 5.4 VDC (marked as 5.4VA )

Pin 2: GND

Pin 3: 2.9 VDC (marked as 3.2VA )

Pin 4: 2.2 VDC (marked as 2.4VA )

Pin 5: GND

Pin 6: 2.2 VDC (marked as 2.4VA )

Pin 7: GND

Pin 8: 0.4 VDC (marked as SMART)

So the voltages were lower than marked - suspicious.

I then removed and mapped out the connector on the power supply PCB (printed circuit board) and found:

Pins 4 and 6 are the same on the PCB and are fed thru a diode (HER202)

The input to this diode is the Pin 3 voltage.

Pin 8 goes nowhere on PCB (a wire jumper is missing)

So I then grabbed another bench power supply I had with 5 and 3.3 volt  (nominal) outputs.

I adjusted this supply to 5.4 V and 3.2 V to match the DTT900.

I then used alligator clip jumpers into 3 points on the bad power supply:
5.4 volt (after rectifier diode)

3.2 volt (after rectifier diode, which then feeds the 2.4 volt thru the HER202 diode)

Ground

Jumpering in after the rectifier diodes prevented any 'back feed' of power to the other power supply circuits.

I powered on my bench supply (the DTT power supply was unplugged) and the converter worked - stayed on for several minutes and the voltages were correct:

Pin 1:    5.4VDC when ON,  5.6 VDC when OFF

Pin 2:    3.2VDC when ON,  3.4 VDC when OFF

Pins 4/6: 2.4VDC when ON,  2.6 VDC when OFF

I also measured current draw:


5.4 volts:  0.38A ON,  0.08A OFF

3.2 Volts:  0.47A ON,  0.03A OFF (this was total current for both 3.2 and 2.4 volt feeds)

I took a guess that the associated electrolytic capacitors on the power supply were bad.  

There are 7 of them, but I only targeted the 4 on the output side:
C121  1000uF, 16 V

C123  1000uF, 10 V

C122  330uF, 10V

C124  330uF, 10V

If this repair doesn't hold,  I will need to try replacing the other 3 caps:

C103 47uF, 200V

C108  1uF, 50V

C109 33uF, 25V

(I didn't have these caps in my parts stash, so that is why I held off replacing them.)


Hopefully this may help others with bad DTT900 converters in getting them working again.

If anyone is interested, I could post a picture or two pointing out the parts I replaced.

Cheers,

Mike
Nice! Images would be great to see for future references. Did it take long for you to figure these out?
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post #2427 of 2445 Old 11-10-2013, 01:23 PM
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Hi again,

 

This was the 2nd time I disassembled the unit in an attempt to repair it.  My wife was threatening to buy a new one to replace it.  :)

 

I have repaired other switching power supplies before (LCD monitors, PC mainboards) based on advice from other repair forums. 

Most of the time bad capacitors or switching diodes are the problem.   Took about 3 hours from start to finish on my 2nd attempt.

 

I replaced the 4 capacitors marked in RED circles (on right side of picture below).  The three marked in GREEN were not replaced. 

The PCB silkscreen shows the component ID (e.g. C121) as well as the marking for polarity (negative = white dot)

 

None of the caps were "bulging" on the top - which is typically a sign of capacitor failure. 

 

The DTT900 has been sitting on top of my other A/V gear - so the thermal heat probably did them in.

 

If this repair does not last (and replacing the other 3 caps does not help), I may find a "wal-wart" 9 - 12 volt DC supply and breadboard a 5.4 volt and 3.3 volt regulator inside the box to replace the DTT900 power module.

 

Cheers,

Mike

 

 

 

NOTE: image credit to https://nuxx.net/gallery/v/acquired_stuff/zenith_dtt900/IMG_0881.jpg.html

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post #2428 of 2445 Old 11-18-2013, 08:25 AM
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Follow up;   Repair is still working great after 9 days of operation (constant on).

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post #2429 of 2445 Old 11-18-2013, 11:42 AM
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Quote:
Originally Posted by mjkirk12 View Post


If this repair does not last (and replacing the other 3 caps does not help), I may find a "wal-wart" 9 - 12 volt DC supply and breadboard a 5.4 volt and 3.3 volt regulator inside the box to replace the DTT900 power module.

Or maybe a 'clean' 5 V wall-wart and a 3.3 V regulator? Of course if you make it 12 V-ish you can use it in your car too! wink.gif

Nice work, congrats, and hope those caps did the trick!

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post #2430 of 2445 Old 12-25-2013, 10:00 AM
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Early this morning, after returning from Christmas Eve observances, I happened to turn on a secondary CRT television still connected to the DTT900 and antenna. Although it is definitely limited to 480i, the SD PQ obtained from this set - even when set to the widescreen 16:9 aspect ratio - is pretty darned good.

This particular thread was started six years ago, and my DTT900 has a manufacture date of May 2008, which probably reflects the correction of audio sibilance problems found in the earlier units. I have another DTT900, which I bought with the NTIA's $40 rebate coupon, with a manufacture date of November 2007, and the audio sibilance issues occur periodically.

I have a couple of other CECB units, most of which are not in use as I am primarily using HD sets with built-in HD ATSC tuners, but for those of you looking for a CECB, I highly recommend this model. Because the Zenith CECBs sold in very large numbers at the time, they do show up fairly often on the used market including at thrift stores, although prices on e-Bay and Amazon are on the high side. It's too bad that LG completely stopped manufacturing this unit. The CECB program is long gone but the market for SD-compatible ATSC-to-NTSC converter boxes has continued, mostly with boxes bearing obscure brand names except for the RCA-branded box which is no longer manufactured by Audiovox (RCA's licensee) but by an obscure Canadian company.
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Reply Coupon Eligible Converter Box (CECB)

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