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.

[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.

[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.