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ATSC Converter Boxes (Non-HD, Non-Recording)

330656 Views 1036 Replies 266 Participants Last post by  roger1818
Will the samsung sir -t151 ota hdtv work on the sony 43in hdtv ready tv I live in Windsor ont have ota access
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RE: Access 1030d ventillation modification.

Ok, Saturday morning, back in the workshop in Kingston, here are the modifications made to the enclosure of the HD1030 to increase ventillation.

Unit disassembled, big hole cut out of the center of the top plastic enclosure. Metal screen installed inside with four tiny #4 x 1/4" machine screws that I had spare from other project. Taking great care that I choose the position of the screws so that when assembled they do not extend down and touch any components on the circuit board.

The metal screen is salvaged from a used car air filter. Those car air filter screens are handy for many things. They don't seem to rust, so I think they may be made of stainless steel. I've used other ones as a grill over the dryer outlet outside - to keep leaves and little animals out - good if SS - they don't rust with the hot moist wet air from the dryer. Same idea for some furnace outlets - maybe.

The little ventilllation slits on the sides of the unit seemed too small to me to work very well, so I very carefully drilled *MOST OF* those out to around 3/32", and added a series of more holes near the front w/the same pattern. Notice the first four columns of holes near the front - those I added. Some of the side slits were NOT* drilled out because they intruded into a square plastic support inside the sides. Choose carefully which ones to drill or *NOT* Drill.

Of course, the circuit board has been removed for this procedure. Pretty simple to take out. Undo the two nuts on the coax F-connectors at back. Make sure the one screw near the back connection area is removed. One plastic clip inside to spring with a little flat screwdriver, and the circuit board lifts up an slides forward and out. Simple.

Can't see this from this picture, but I have added two rows of holes on the bottom of the enclosure, same size as the other holes on the bottom, near the front of the unit. Extended the pattern forward two rows. They are larger than the side holes - for sure.

Why did I do this? There was space, and I noticed that all the other holes in the bottom are under the circuit board and do not allow direct airflow into the area above the circuit board - where the hot component with the heatsink is.

The silver sticker on the bottom, in that area, was carefully peeled off beforehand and put on again on the top after with some clear packing tape.

All reassembled, hooked up to a real antenna outside on the tower, powered up and tested. Rescanned, Works great, runs alot cooler, mostly because the heat from that heatsink can now go straight out the open screen I added. Also because air can flow in alot better from the sides and bottom now that I've opened it up a lot better.

I think the enclosure on this unit is too closed up. Needed to be opened up a fair bit more. It was holding the heat inside, probably affecting all the other components over time.

Simpler Modification ?
A much simpler modification, probably very effective as well, is just to carefully open up a hole on top as I did, and secure a screen from the outside with some glue or very small and very short screws. No need to disassemble the unit at all. Just cut or melt melt the plastic around those top holes very carefully and pop out the piece. Glue the screen and/or screw it in carefully - fit in in where the circular indentation is in the top. If drilling do so very carefully.

That one modification alone, cutting the hole in the top, allows the heat from that heatsink straight out the top much better. The plastic on top of that aluminum heatsink also acts like a sort of insulator, keeping the heat in the enclosure, rather than straight out the top. The metal screen instead is more open and does itself conduct heat right through it and straight out.

Unit runs alot cooler now.

I noticed that this unit does give a pretty nice SD - standard definition picture from a High Def sub channel - 16-3 WPBS-HD here.

As mentioned earlier:

Sound is still a little low, from the Composite outs Y R W - but ok.

Sound from RF out is a little noisy / white noise.

So with this unit, better to plan to use the Composite outs / not the RF out.

All in all, for the thirty bucks ( $30 + tax ) that I paid, Special Deal, on sale at Factory Direct store, seems like an ok deal.

But I think this unit needs a MOD to help with cooling.

Don't think it really needs a FAN now. Not sure. Will continue to test over time.

Same as ROGER1818 mentioned - it's is a very economical unit for the second TV in the other room.

I found the look ahead EPG menu, by doing the right arrow. It shows one program at a time on the screen. Seems to go ahead the full distance - like my other convertors - but just one program at a time on the screen.
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Getting A/C voltage on converter box's antenna input !

I need help to know if it's normal that i measure A/C voltage at the coax antenna inputs of my two converter boxes, one is the Zinwell ZAT 970A (measuring 47 volt)and the other is the Zenith DTT901 (measuring 56 volt).
When i made the test last week i went to the Zinwell and unplugged the coax cable from the wall and while connecting one voltmeter probe to the ground hole of the AC outlet and the other to the threads of the converter's antenna input connector ang getting 47 volt A/C.
My third TV is a Samsung Series 7 (LCD) and i get no voltage at all measuring the same way.
When everything is connected together to the antenna via a 3 way splitter,
this voltage must go to the ground because i have a ground block installed outside connected to a 5 foot copper grounding rod.
I wouldn't expect there to be voltage. However, if you're measuring that with only the volt meter connected, then there may be some stray voltage being induced by something. If there's any sort of a load, that voltage may likely disappear. Do those converters have external power supplies? Two wire AC cord? Grounded AC cord?
When i found out about that, i said my device is faulty but when i measured the second one i said maybe it's normal (??).
I'm not able to check in place cause i'm out of town now but i was able to zoom-in pictures from the internet and on the Zinwell, it looks like there's a switching adapter box that plug in the outlet and it's a 115 volt a/c to 5 volt d/c with no ground prong and on the Zenith, the 115 volt cord is going staight inside the box with no ground prong.
I'll be able to analyse this further soon and be even more specific. Thanks !
Equipment Leakage Current


The voltage that you measured between the threaded antenna connector and ground is caused by leakage current. All AC connected equipment, even when operating normally, has some leakage current. A 2-wire polarized plug power cord does not ground the equipment, it only ensures that the neutral of the equipment is connected to the neutral of the power system and the hot wire is connected to the switch. You need a 3-wire power cord to ground the equipment.

I have made many tests of equipment leakage current using my Simpson 229 Leakage Current Tester. I bought it because I had three close calls with electrical shock and I thought the expense of the tester was well worth it.

When I was calibrating the signal strength scale of an Apex DT502 to send to a friend, I had many pieces of equipment connected to AC:
2 Apex DT502s
2 Audiovox PLV16081 8" TVs used as monitors for the CECBs
1 Sony KDL22L5000 TV
1 CM 7777 preamp power supply
1 AC adapter for Sadelco signal level meter
1 AC adapter for RS preamp

During the tests I noticed a problem that I have seen before but couldn't track down until recently. When I touched a ground and the case of the equipment I felt a mild shock. My Fluke 25 DMM gave a reading of 58VAC. I hooked up my Simpson 229 Leakage Current Tester and found that the voltage reading was 40 volts and the leakage current was about 200 microamps; not enough to be dangerous but enough to give a tingle. (The difference in the voltage readings is because the input impedance of the two meters is not the same.) The reading of about 200 microamperes that you see in the above photo is the actual leakage current that I felt when I was shocked. It was not strong enough to be lethal, but it certainly got my attention. GFCIs are designed to trip at 5 mA, which is 25x as strong.

I then started unpluging each piece of equipment and noticed that the leakage current went down each time. The boxes have 2-wire cords so I grounded the coax shields at the splitter and the leakage current went to zero. With so many pieces of equipment connected to AC the normal equipment leakage currents were additive.

Most of the pieces of equipment use switchmode power supplies, which have more normal leakage current than the transformer power supplies for the signal level meter and RS preamp.

Even a good quality energized 3-wire extension cord will have some normal leakage current from the hot conductor to the ground and neutral conductors without any equipment being connected to it.

Since I was able to feel a leakage current of about 200 microamperes, my threshold of perception is considerably less than the mean value of 1.067 mA measured by Charles F. Dalziel as described in the 229 manual.

Since your pieces of equipment most likely have switchmode power supplies and they are interconnected through the shields of the cables between them, I suggest that the shields be connected to a ground. This demontrates the advisability of using a grounding block on the antenna downlead.

If you are able to borrow an appliance leakage current tester to see if your equipment is faulty, that would be ideal. It is also possible to assemble an inexpensive leakage current test circuit.

When setting up your equipment, turn all pieces off and remove their power plugs (or the power strip plug). Connect the cables between them, plug them into AC, and then turn them on.

For maximum safety:

1. Have an electrician install a properly wired 3-wire outlet for your equipment so that the equipment that has 3-wire plugs is grounded.
2. Test all pieces of equipment to be certain that the leakage current of each piece is below 500 microamperes (0.5 mA).
3. Interconnect the pieces of equipment as required.
4. Plug the 3-wire and polarized 2-wire plugs into the outlet strip.
5. Turn the power strip and then the equipment on.

There is another step that really needs to be done between no. 3 and no. 4, which is to ground the pieces of equipment that have 2-wire polarized plugs. This is the "dirty-little-secret" that is not often mentioned, but is important because the normal within-limit leakage current of equipment that has 2-wire polarized plugs is additive when connected together. Even though my Sony Bravia is in a plastic case and has leakage current within safe limits, there exists the potential for leakage from the antenna coax shield to ground.

I did my test setup in the kitchen and had two grounds available to drain the total equipment leakage current of about 200 microamperes: the grounding pin of the 3-wire outlet and a copper cold water pipe (same ground as for electrical panel). Either one reduced the total leakage current to zero.

Details of the tests are in the attachment PDF.


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I then tend to assume that the 2 "faulty" boxes are ok.
Even if the shields of all the coax cables connected together are grounded to the tower's copper ground rod, i will definitely connect the in-house three way splitter to the nearby copper pipe, that way i will connect the tower
ground to the one of the house which they aren't at the moment, that way i'll make shure there's no possible electric differences between them.
I have no piece of equipment with 3 wire cord but i can replace the 2 wire cords with 3 wire ones at least on the Zenith box and the HD TV and also run a third wire from the Zinwell box's coax. connector along the cord to the ground of the outlet.

By the way could you just tell me a tip or two on how to insert a picture from my HDD on a Reply on DigitalHome forum? I went on the FAQs and found the infos about it but the correlation between the tutorial and the reply page
doesn't seems to be correct, i've worked on it for quite a while with no succes.

Thanks you so much, i really appreciate your support.
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Do not use a 3 wire cord on a device that wasn't built for it. On many 2 wire devices, the chassis may be somewhere between ground and full line voltage, so connecting the ground to it could cause problems. There should be no problem grounding the coax though.

I agree with JamesK, don't change the power cords, just make sure that the coax is grounded to drain any leakage current.

I then tend to assume that the 2 "faulty" boxes are ok.
I get the same impression. The only way to know how much leakage current is on your boxes would be to measure it. But, whatever it is, grounding the coax would take care of it. If you have a voltmeter, you also probably have an ohmmeter, so you could make the checks in the drexel link given above without too much expense. Sam Goldwasser shows how to make a simple circuit consisting of a 1.5K ohm, 10 Watt resistor in parallel with a 0.15 uF, 150 V capacitor to use with your meter to measure leakage current.

The drexel link doesn't seem to be working now, maybe this one will:

By the way could you just tell me a tip or two on how to insert a picture from my HDD on a Reply on DigitalHome forum? I went on the FAQs and found the infos about it but the correlation between the tutorial and the reply page doesn't seems to be correct, i've worked on it for quite a while with no succes.
The two threads that have helped me are:

How to create a photo album for use on the Digital Forum

To show an image in your post you must put an image in your album. Then, before using the image, you must wait for the moderator to approve your image. When you then want to show the image in your post, heed the warning about using the BB Code.

An alternate way to show an image in your post would be to upload it to an image host like photobucket and then link to it in your post like I did with my image of the Simpson 229 Tester.

Post Pic or attachments

This thread gives some more tips on showing your image. In particular, note post #11 by downbeat that says you must have a check by show images in your CP:

You are not able to post images as an attachment unless you are a DHC Supporter.
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All right JamesK and rabbit73. I think i'll be able to get this TV systeme safe enough now, i should also be good to insert pics in my posts with your details rabbit. Thank you both very much. Merci beaucoup ! :D
Thank you both very much. Merci beaucoup ! :D
You are welcome!

I'm glad that I was able to help. I'm also glad that you asked about it, so that I would have a chance to talk about leakage current. It exists in all AC operated equipment, but not many people are aware of it. In equipment with a 3-wire power cord the leakage current goes to ground; in equipment with a 2-wire polarized plug cord the current can go through you to ground.

In your equipment, what is important is the strength of the leakage current. Most guidelines say the leakage current must be less than 500 microamperes (uA), (0.5 mA). A measurement of the voltage is not sufficient to let you know if the amount of leakage current is safe or not.

You said that you had a Zenith box, so I made some measurements of my boxes:

                 Simpson 229 Tester         Fluke 25 DMM
                 Voltage   Current             Voltage

Apex DT502       20 VAC    50 uA              46.6 VAC
Zenith DTT900    18 VAC    42 uA              46.2 VAC
Artec T3APro     42 VAC    48 uA              44.0 VAC
All three boxes pass the test for leakage current. The voltage readings with the Fluke DMM are higher because its input impedance is higher which means that it doesn't load the circuit as much. I also tried voltage measurements with an analog VOM; the voltage readings would vary according to the range used because of the changing input impedance.

The Apex and the Zenith have built-in power supplies, but the Artec has a separate AC adapter that is a switchmode power supply 100 - 240 VAC input to 12 VDC at 0.5 A output.

Some people think that a polarized 2-wire plug will ground the equipment, giving a false sense of security. It doesn't; it only connects the neutral wire in the equipment to the neutral wire in the electrical system. You can verify this for yourself by using an ohmmeter between the antenna jack threads and the wider blade of the polarized plug. It should show an open circuit.

In spite of the fact that a polarized plug doesn't ground the equipment, it has some safety advantages. In the case of a table lamp the threaded shell of the socket is connected to the neutral (white) wire and the hot (black) wire is connected to the switch. When a bulb burns out, most people don't unlug the lamp or even turn the switch off. The polarized plug keeps the voltage off the threaded shell so that you don't get a shock if you happen to touch it when changing the bulb.
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My third TV is a Samsung Series 7 (LCD) and i get no voltage at all measuring the same way.
I also have a Samsung TV. It is a 19-inch set with a 3-wire power cord and there is no voltage on the antenna jack. I was surprised that it had a 3-wire cord and thought they did that because it can also be used a computer monitor.

I made some measurements of the TV with the grounding pin not connected to ground to check its leakage current as mentioned in the manual. I didn't cut the pin off but used a 2-wire to 3-wire adapter:

Fluke 25 DMM: 58.1 VAC

Simpson 229: 32 VAC
Simpson 229: 85 uA

The input impedance of the Fluke 25 DMM on the AC Volts range is 10 Meg ohms.

The input impedance of the Simpson 229 Leakage Current Tester on the AC Volts range is 500K ohms.

If I put a 500K or 510K resistor in parallel with the input of the Fluke 25, the voltage readings would probably be similar.

So you see, even equipment with a 3-wire power cord has leakage current, but it is shunted to ground.
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RCA converter and Samsung LN-S3251 TV problems

Hi everyone. I use my RCA converter so I can record OTA programs on my Toshiba standard DVD recorder. It records great but I cannot use the my Samsung TV when it is recording.The reason I got it is so I can record one program and watch another on my TV .ie. I record Global on 29-1 on the DVD recorder from the RCA, but on the TV ,29 is blank as well as TVO 18-1. Ch 42 CTV is present but snowy. It seems all the digital channels are blank. When the RCA is off all my Tv channels return to normal. Could it be backfeeding into the TV antenna input somehow? Thanks.
It sounds like your signal is going through the RCA Converter. When the convertor is off, it passes through all the channels. When the convertor is on, it tunes to the digital channel and outputs on analog channel 3 or 4. My guess is that it doesn't pass the other channels through, so you can't see the digital channels.

Here's one way to connect your convertor to record 1 channel and use your TV's ATSC tuner to watch another.
Antenna-->Splitter-->|-->RCA Converter-->DVD Recorder-->TV Composite input
                     |-->TV coax input (ATSC)

You could get along with a 2 output splitter and an A-B switch.

___ Antenna >>> Splitter >>> Converter >>> Recorder >>> B-Input of the Switch

___ Other output of the Splitter >>> A-Input of Switch

___ Switch output >>> TV

B-position to watch the recorder on your TV

A-position to watch TV only (while the recorder does its job)
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Thanks everyone. I have the antenna going to the RCA converter , then the converter antenna out, to the tv. The converter video out is hooked up to the DVD recorder with the a video/L/R audio cable instead of CH3 or 4 .The instruction book says this is an option, but has no mention of it affecting the tv. Maybe Ill disconnect the video cable and switch to CH 3 or 4 and see if that helps. I figured the antenna in/out on the converter acts like a splitter just like the DVD recorder antenna in/outs did. Thanks.
Hi. Just an update. I used a splitter, one to the TV and one to the RCA unit. I did not want to split it at first because I was worried about Global 29-1 getting snowy.It works well now and the RCA does not interfere with the TV. One minor problem. Instead of the RCA outputting on CH3/4 with the antenna coax to the Toshiba DVD recorder, I used the Video/AudioL/R cable for a better picture but it wont pass the analog CH42 CTV now. I guess Ill just have use the coax. I wish Canada would get its act together and get everything digital!!
The converter video out is hooked up to the DVD recorder with the a video/L/R audio cable instead of CH3 or 4 .The instruction book says this is an option, but has no mention of it affecting the tv.
You would do this if your TV doesn't have an ATSC tuner so that you can use the digital box as a tuner and the RF modulate the signal it tunes onto ch3 or 4 if your TV doesn't have AV inputs.

I figured the antenna in/out on the converter acts like a splitter just like the DVD recorder antenna in/outs did.
No, it acts like a switch. Most likely your DVD recorder didn't have an RF modulator, and thus just split the signal for the output. FYI, some DTV boxes don't have a switch but instead will always block the signals from "passing through" (units that have the switch have a feature called "analog pass through").

One minor problem. Instead of the RCA outputting on CH3/4 with the antenna coax to the Toshiba DVD recorder, I used the Video/AudioL/R cable for a better picture but it wont pass the analog CH42 CTV now. I guess Ill just have use the coax.
Use both coax and AV connectors and use Video in for recording digital channels and the coax for recording the analog ones. Just make sure the digital box is off when recording in analog to prevent it from blocking the signals. Alternately you could use a 3-way splitter, but you will get additional signal loss that way.
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