CurtPalme.com Home Theater Forum

[Brett]

Hi Guys,

Some of you already know me from the early days of the AV Science forum. I've chosen this forum to post to as it seems to be the refuge of the hard core CRT crowd.

You may remember that several years ago I was among the early experimenters in fan mods for the Sony 1292 which worked fine for quite a while:

http://archive.avsforum.com/avs-vb/showthread.php?s=&threadid=66669

However, despite the workaround of the projector's fan speed detection circuit, it has lately started causing me problems.

A year ago, the projector refused to boot up, showing the error code 01 meaning the fans were not running. This was with the projector open and all fans spinning up to speed perfectly during the first seconds before shut down.

Back then I was at a loss, as all the fan wiring and connector plugs looked good. Viewing my apparent despair, my wife started wiggling at random wires near the front of the tubes (good thing it was not running) and surprizingly it then fired up right away with NO error code. The projector then worked for a year, but recently went back into shut down mode with the same FAN error code, again with all fans running fine. This time jiggling wires didn't help...

Is there any way to remove or circumvent the fan detection circuit in this projector's main board or daughter card? I have the service manual with the circuitry, but can't read those graphs for the life of me. However I can solder quite precisely if you can point me to what and where.

Understandably this is not recommended, as there will no longer be any safety system to stop the projector if it is no longer cooling properly. However, this is a risk I'm willing to take after too many hours of projector mods and little heart to do it all over again.

TIA for any suggestions,

Brett

[tony359]

You can "disable" the fan control bypassing it on the fans itself. You should connect the fan control wire to +12V wire so that the projector see the fan rotating all the time. You probably have a bad fan or an intermittent contact on one of the control's wire.

Ciao
A

[Brett]

[dochlywd]

Brett,

Try messaging MP or going into his section of this forum where he talks about modding the 1292. He has done extensive research on the 1292 over the last 3 or 4 years. He's your best bet at getting the answer you are looking for.

Here's the link:

https://www.curtpalme.com/forum_archived/viewtopic.php@t=2131.html


Good Luck!

Doc

[tony359]

Sure, I understand. With 14 fans disabling the entire circuit perhaps is better!

Let us know

Antonio

[Atom]

Hi Brett
I'm glad to see you still have the 1292. I've had other projectors but I still keep coming back to the 1292
I have had problems with the male Fan connectors on the E and DC board The fan connector body was not flush with the circuit board and when inserting or removing the plug it caused the circuit traces to eventually crack. Re soldering fixed the problem.I also re soldered all of the power transistors and other power components on the E board , that cleared up some convergence and stability problems. I think that the E board is most susceptible to the problem with cracked solder joints because of the twisting motion that it get when that whole assembly is raised and lowered to get at the CRTs.
Andrew

[Brett]

[Brett]

[cooldog]

Hey Brett ... fancy finding you here!

I'll go fetch my reading glasses (we're all gettin' on, aren't we?) and the service manual and see if I can figure out an easy mod for you.

It really shouldn't be too hard ...

Be back in a few ...


Paul

[cooldog]

Brett,

Sheesh ... I'd forgotten how hellish it was working with the *copy* of a service manual that Sony sold me. Things that are supposed to be on a single fold-out page are split across several pages.

You'll need to cut a trace on the Y, or CPU board. If you have the service manual, the relevant page is 225. You'll see a signal called FAN PROT come in on pin 3a of the main connector where the Y board plugs into the motherboard. Then it goes through R59, a 300 ohm "chip resistor", then on to R123, a 10K "chip" pull-up to +5, with C63, a .01 uF cap to ground, and from there, on to pin 31 of the I/O and interrupt controller chip IC10.

Everything I see implies that the signal is actually active low, that is, if the fans stop, the signal is pulled to ground.

Simply cutting the trace somewhere between the connector pin 3a and R59, or between R59 and the R123/C63 junction should allow the R123 pull-up to keep the signal high.

Assuming you find and cut the right thing, this is safe, even if it somehow turns out to be ineffective. In that case, just patch the cut that you made and all returns to normal.

Paul

[Brett]

Hi Paul!

Great to see you again - time sure flies?

I thought there must be a way to trick the projector into thinking that the fans are working, even if they aren't. I'll bet other folks who have hooked up their hushboxes into air conditioned cooling could unplug their fans with your suggested circuit board mod. 8)

I'll give this a try if resoldering the boards doesn't provide a quick fix. As any normally constituted 9 incher who's ever bought a replacement tube, I'd rather have this safety feature active rather than short circuited. But if for some reason the shutdown keeps active with no valid reason, then by all means I'll cut those strips as you suggest.

Thanks a million for going to the trouble to decypher those boards. With your cristal clear instructions even I can dig into the circuitry and try out the mods. Of course, if resoldering doesn't fix it, I'll cut the ribbon strips and see if the trusty old 1292 starts back up and report back to others here.

All the best,

Brett