Zenith DTT901 & Insignia NS-DXA1-APT DTV converter box: Cold Power-Up Problem FIXED

[wb2mep]

This seems to be a common problem with these LG Zenith & Insignia DTV converters. Mine started failing when it was less than one year old: It was unplugged while I was on vacation in the winter, and when I got back, it was dead when I plugged it back in. Eventually I got it to come up by repeatedly plugging/unplugging until the red LED came on. Later on I had a problem where the
blue LED would come on for a few seconds then turn back to red, when it was cooler than usual in the living room. (< 78 degrees, I live in Florida) I had the problem again this weekend, so I dug into it. It has all the symptoms of a power supply capacitor problem, but the solution wasn't very obvious. The power supply puts out 5.4, 3.4, and 2.6 volts (voltages are labeled on the board at the output connector) The 5.4 V was good, but the 3.4 and 2.6 V were low and the box was dead. Eventually the voltages came up, and I got the red LED, but when I hit power, the blue LED came on for 2 seconds and went back red, and my voltages were low again. I pulled the power supply board and measured ESR on all the electrolytics. They seemed normal, so I put the board back in and the box powered up.
I got my can of freeze spray, and hit each of the 'lytics, and when I hit C123, the box shut down with a red LED and the 3.4 V dropped. C123 is a 1000 uF, 10 V electrolytic. Easy to find, the component numbers are printed on the board. This cap measured only 0.23 ohms ESR, which I wouldn't normally consider bad (it did go up to 0.42 ohms when I cooled it with the freeze spray).
It wasn't bulged or leaking, and looked brand new when I removed it from the board. It was a Chinese-made Sam Young brand cap. I replaced it with a Nichicon 1000 uF 10 V, 105 deg C, low-ESR cap and my box is working fine again.
These Zenith/Insignia DTV boxes were the best ones in my opinion, and definitely worth repairing, especially since you can't find new ones any more.

[Findm-Keepm]

My two both had the 1000uF/10V cap problem as well - one bakes atop a '86 Sony TV, and the other is inside a Commodore monitor, adapted to make it a TV. I replaced them with some Sanyo 1000uf/10v/105 degree caps, 14 cents each...
I recapped the Commodore monitor while I had it open as well - almost all 25V and 160V caps were high ESR....

[dieseljeep]

Originally Posted by Findm-Keepm

My two both had the 1000uF/10V cap problem as well - one bakes atop a '86 Sony TV, and the other is inside a Commodore monitor, adapted to make it a TV. I replaced them with some Sanyo 1000uf/10v/105 degree caps, 14 cents each...
I recapped the Commodore monitor while I had it open as well - almost all 25V and 160V caps were high ESR....

The first one I repaired, was probably three years ago. I'd leave it run continuously and when I went to use it, the sound was there, but the picture was froze up, plus no response from the remote or the top buttons.
I knew, it had to be a bad 'lytic.

[dieseljeep]

Originally Posted by dieseljeep

The first one I repaired, was probably three years ago. I'd leave it run continuously and when I went to use it, the sound was there, but the picture was froze up, plus no response from the remote or the top buttons.
I knew, it had to be a bad 'lytic.

I also found bad 'lytics in Digital Stream, Apex and RCA's.
Did you ever notice, if you tap gently on a Zenith or Insignia box, the sound glitches for a split second. Everyone I've owned, from the first one on, did it. Also, turning on or off, a light or another line operated item, on the same circuit does it. No matter, where I use them.
Please report what your findings are!

[Electronic M]

Originally Posted by dieseljeep

I also found bad 'lytics in Digital Stream, Apex and RCA's.
Did you ever notice, if you tap gently on a Zenith or Insignia box, the sound glitches for a split second. Everyone I've owned, from the first one on, did it. Also, turning on or off, a light or another line operated item, on the same circuit does it. No matter, where I use them.
Please report what your findings are!

I wonder it you powered it from a VRT isolation transformer if the lamp sensitivity would go away?

[dieseljeep]

Originally Posted by Electronic M

I wonder it you powered it from a VRT isolation transformer if the lamp sensitivity would go away?

Did you ever just tap it on top. Just a tap with your finger, not a heavy blow with your fist. Just setting the remote on top will do it. Outside of that, it works great, one of the better units.

[Electronic M]

Originally Posted by dieseljeep

Did you ever just tap it on top. Just a tap with your finger, not a heavy blow with your fist. Just setting the remote on top will do it. Outside of that, it works great, one of the better units.

I think so though I attributed it to antenna sway....I normally use my boxes with rabbit ears on them and when those are disturbed I loose sound and picture through pixelation....

[dieseljeep]

Originally Posted by Electronic M

I think so though I attributed it to antenna sway....I normally use my boxes with rabbit ears on them and when those are disturbed I loose sound and picture through pixelation....

Today, I had a strange problem with my Zenith/insignia boxes. I wanted to change the channel, for the Packer game. Pressed the channel down button on the remote. The box kept on changing the channels through the entire list, over and over. I thought the channel up/down button was stuck on the remote, so I removed the single AAA cell. Still kept it up. Probably bad 'lytics in that one too.
BTW, does anyone use the AM radio trick to test remotes. I checked the remote and the buttons weren't sticking.

[Ed in Tx]

Originally Posted by dieseljeep

Did you ever notice, if you tap gently on a Zenith or Insignia box, the sound glitches for a split second. Everyone I've owned, from the first one on, did it. Also, turning on or off, a light or another line operated item, on the same circuit does it. No matter, where I use them.
Please report what your findings are!

Mine does that too. Tapping on it, audio drops out, sensitive. Not sure about the powering on-off other things haven't tried it.
I haven't had to replace any caps yet, have one always plugged in out in the garage hooked to a little 9" Sony KV-9PT60.

One feature I really like on these Zenith boxes I haven't found anywhere else, is the memory for each channel's picture mode settings. There are a few channels here that have odd aspect ratio and to set and leave it for the particular channel is handy.

[Findm-Keepm]

Originally Posted by dieseljeep

BTW, does anyone use the AM radio trick to test remotes.

It used to be a valid test for most remotes - the resonator was either 450,455, or 500Khz, close enough to have the pulsing detected by the radio. Now, they use faster clock speeds. I've got one (a memorex learning remote) with a nice 4.5Mhz clock - it does nothing to an AM radio.

Now, the standard is to aim the IR remote at a CCD camera (any digital camera, camcorder, an iPad/tablet camera, or any smartphone or webcam) You can see the pulsing of the IR LED. RCA made a business-card sized IR sensitive tester - the remote would cause a little box on the card to glow.

We used an ultrasonic remote tester made by Zenith, a little metal box with an opamp and an LED to indicate operation of ultrasonic remotes. Zenith provided modification instructions at one of their service seminars on how to modify it to check IR remotes and to even check for drive signals on System 3 sets. That thing paid for itself in spades - we repaired remotes, mostly of the RCA ilk, as RCA rarely sold a "new" replacement remote, only selling rebuilt/remanufactured remotes that were cosmetically used. So we fixed the customers remotes to save them money, and kept their business.

Here's a pic of the tester.

[dieseljeep]

Originally Posted by Ed in Tx

Mine does that too. Tapping on it, audio drops out, sensitive. Not sure about the powering on-off other things haven't tried it.
I haven't had to replace any caps yet, have one always plugged in out in the garage hooked to a little 9" Sony KV-9PT60.

One feature I really like on these Zenith boxes I haven't found anywhere else, is the memory for each channel's picture mode settings. There are a few channels here that have odd aspect ratio and to set and leave it for the particular channel is handy.

Those 9" Sonys, nothing like them!
It's a little cold in my workshop, as I turn down the heat at night. The units probably don't like the temp extremes.

[init4fun]

In mention of testing IR remotes , I stumbled on a pretty cool trick one day while messing around in my workshop . I had a solar cell from one of those outdoor sunlight rechargeable garden lights and got the idea to hook it to a speaker and aim the remote at it . No amplifier , nothing , just the solar cell and a little 2" PM speaker farmed out of a dead transistor radio . Every different button gave a different tone in the speaker and there were variations in both pitch and duration of the tones with the different buttons i'd push . A cool experiment and I kept the solar cell and speaker together as a "quick & dirty" tester to see if a remote is working or not .

[Findm-Keepm]

Originally Posted by init4fun

In mention of testing IR remotes , I stumbled on a pretty cool trick one day while messing around in my workshop . I had a solar cell from one of those outdoor sunlight rechargeable garden lights and got the idea to hook it to a speaker and aim the remote at it . No amplifier , nothing , just the solar cell and a little 2" PM speaker farmed out of a dead transistor radio . Every different button gave a different tone in the speaker and there were variations in both pitch and duration of the tones with the different buttons i'd push . A cool experiment and I kept the solar cell and speaker together as a "quick & dirty" tester to see if a remote is working or not .

That would make for one cool prank - wire it up, and place the cell and speaker in a dark area near a TV for some fun!

[Ed in Tx]

Originally Posted by Findm-Keepm

... RCA made a business-card sized IR sensitive tester - the remote would cause a little box on the card to glow.

I have one of those! Still works. Picture with an IR laser pointer pointing at it.

"SK" for those who don't know was Thomson-RCA-GE's aftermarket repair parts brand. Most of which was actually OEM parts in SK packaging.