Troubleshooting a Zenith PRO841X. Please help!

[DaiTotoro]

I was just given a Zenith PRO841X. I realize this is an old unit (1990), but it seems to have potential to still work. Unfortunately, it's not working at the moment. Here's what I've found:

-All lamps work and align. The setup menus look fine.
-Using the Y/C input, nothing is projected, however...
-Looking into the lamps, the outline of the material being viewed is dimly visible on the lamps
-Altering the video feed by hitting stop, fast fwd, etc, causes the "MUTED" tag to appear and/or change (steady vs wobbly)
-This is the strangest part! There is a setup menu item called "Teletext", I have no idea what it is for, but when I enter the adjustment mode for it, the video input is projected perfectly clearly, but for just 1 second!

That last bit makes me believe I can get this thing working with just some tweaking. Does anybody have any advice? I don't have a remote control, but I could probably order one if necessary. I haven't been able to find a copy of the manual online either, so if anyone knows a place where that might be found...

Any help would be greatly appreciated.

Thank you,
Sean

[JonMarsh]

Welcome to HT Guide.


These folks have manuals available for download at low prices:

http://freebrd.com/automanualSERVICE.html

Of course, be sure that your video source and cables are working OK, by testing them into a known good source. If you're seeing a very weak signal looking direct into the tubes, it's possible that it's just a video amplifier stage, OR an open cable- without test equipment and being there, it's hard to know.

The Pro-841X is a 480i video ONLY model, with manual controls for setup, no point convergence, etc., so I wouldn't recommend putting much money into this. If you have electronics experience and basic test equipment, or a friend that does, you can probably get this running fairly inexpensively - but beyond that, I wouldn't put much money into it.

If you're intrested in a primer on FPTV CRT technology, check out Curt's site here:

Curt Palme

As you can see, a video only projector in excellent shape is typically only worth about $500 in todays market. But there's lot of nice units you can get which will handle higher resolutions, with excellent performance.

Regards,

Jon

[Kevin P]

When you say Y/C input, is that S-video? Or composite? I've worked with the Pro851X, which I expect is a similar unit, but the one I worked with only had the composite input (no S-video, it was an add-on option), but the menus let you select the S-video or regular (composite) video. Maybe your menus are set to the wrong input.

Dang, I wish I could remember how to get into the Pro851X's service mode. I think it was Menu, 9, 8, 7, 6 or something similar. Of course you'd need a remote. It could be the service mode settings are messed up, or your basic settings (contrast, brightness etc.) are cranked all the way down.

[JonMarsh]

Very good suggestions, Kevin. Again, often you've got to remember to check the obvious, first.

The Zenith I used to have from the late 80's had a touch switch control pad which duplicated most of the functions on the remote. Did this series have that too? If not, then I'm sure he's out of luck without a remote.

~Jon

[DaiTotoro]

Thanks for the suggestions, guys.

The VCR/cables I'm running into this projector does work and I've tried the brightness settings at all available positions. So much for the utterly obvious.

Y/C is a composite (RCA) video input, this model does not appear to have component or S-Video capability. There are BNC connectors but I haven't made nearly as much progress with them as I have the Y/C jack.

The fact that it can show what I'm running into it for that brief second, is making me suspect there's an IC gate that is being kept closed erroneously most of the time (either from bad settings or just broken hardware). I may download the manual and look into that...

There are controls on the top of the unit (Power,Menu,Select,Adj+/-,Vol+/-,Enter), but there is definitely more that can be done using the remote (the help screen for the teletext feature shows use of the numbers and no analogous input from the buttons I have).

[George Bellefontaine]

The PRO 851 is a PJ I used to own. To get into the service menu you have to depress the MENU key for 5 seconds, then key in the digits 9876 and then hit ENTER. There is a whole list of things in there that could have been tampered with at one time or other and may have messed up the PJ.

On the 851 the YC ( Svhs input) only works if you have an adapter card, which I could never get my hands on, and without the adapter you won't get a signal, so I always used the BNC AUX input with an RCA adapter.

The Teletext thing doesn't have anything to do with how the projector functions. No one could ever explain this feature to me so I always just ignored it.

You know, though, even if this was only a video grade crt front projector, it gave an amazing picture. I believe I bought mine in '90 or '91 and I used it for several years. My son is still using it today.

[DaiTotoro]

:B WooHoo! :B
Thank you, George! Since you mentioned the Y/C might need an adapter card and mentioned BNC-RCA adapters, I decided to try running an RCA cable into the PJ through the BNC inputs. It worked! I had assumed since Coax-BNC was the only adapter Radio Shack had that I should be running from the Coax output on my VCR/DVD. Oops.

Now for the task of mounting this thing to the ceiling. I don't have the install directions, but it sounds like the PJ should be about 120"-140" from the screen for a 100" wide picture, right?

Last question (I hope): I'm planning on using the "Ceiling Mounting using an external plywood panel" technique from here, at the top of page 7. It recommends using 6 6"-3/8" lag screws. From the diagram it looks like those 6 will be distributed into 3 each in 2 joists. My question is, how far apart do each of those 3 screws in the same joist need to be (and as a side effect, how long does the plywood panel need to be)?

Once again, thanks for all your help. I couldn't have made it this far without your ideas.

Sean

[George Bellefontaine]

Sean, do you mean 100" diagonal ? Mine was set up for a 100" diagonal and if memory serves me correctly, the PJ has to be somewhere in the vicinity of 7 feet from the screen. Also you have to remove the cover and adjust the focus ring on each of the RG and B tubes. You then have to adjust the electronic focus for each of the crt tubes. The controls for the electronic focus are on a pad to the rear of the Pj on the right hand side. One set of buttons is the focus and the other is the RGB gains for adjusting the color temperature. Be careful back there as there is plenty of dangerous high voltage. If you don't know how to do this it might pay you to get a technician to come i9n, set it up and converge it for you.

Sorry, can't help on the ceiling install. Mine was floor mounted.

Good luck

George

[DaiTotoro]

The projector is now mounted and mostly focused/converged!

I have pulled off the back panel and adjusted the electronic focus controls back there. I was unable to determine how to get the rest of the case off to be able to adjust the ring on the tubes. Fortunately, the electronic focus seems to be sufficient. I assume it is possible to remove the case while the PJ is mounted to the ceiling, right?

The PJ emits a bit of a whine, it is louder when the picture is dark and gone when the picture is bright. Listening to the unit, it sounds like it is coming from the red tube. Does anyone know of a way to possibly quiet that whine, or would I have to replace the tube?

I owe you all my gratitude, since a few days ago I was not certain this thing could be made to work at all. Now we're planning to have some friends over and have our first screening tomorrow night!

[George Bellefontaine]

I don't know what that whine could be. This is one of those crt projectors that doesn't have an internal fan, so it must be some kind of electronic problem, but not necessarily a bad tube.

BTW, you can remove the entire case. After you take off the back panel you will see a series of nuts. Once you remove these the entire case comes off by pulling back and up ( or down if ceiling mounted).

Good viewing, my friend.