AVS Forum banner
Status
Not open for further replies.
1 - 8 of 8 Posts

·
Registered
Joined
·
85 Posts
Discussion Starter · #1 ·
I have had the 1209/2 now for about a year. It has been a great unit EXCEPT for this one RGB output amplifier (neckboard). It used to always give me a hard time but after cousin.it (another faithful forum member) gave it a good cleaning the problem was gone. For the last two weeks I have been getting a distortion on the left side of my screen that was easily fixed by slightly "jiggling" the neckboard (I love the technical terms). The problem has progressed to the point that after my unit has been on for about 5 minutes the red CRT (the one with the bad neckboard) goes very bright and stays that way. Since I have found out that the RGB output amplifier for the 1209/2 is one of the rarest pieces of eqipment to find, I am going to have to try and fix this thing or find somebody who can. What makes the problem even worse is that I am here in Dallas and the Cowboys are on Monday night football on the 15th of this month. If anyone has any suggestions on what I should look at please let me know. Curt, if you read this I know, I know, I shouold have sent the piece to you a long time ago. For those of you who may have some of these old giants laying around the part number is 1077118. Of course this particular piece of equipment is only found on the 1209/2 not the 1209s or the 1209. Any help would be AWESOME. I guess now I know the quickest fix is'nt always the best.
 

·
Registered
Joined
·
2,590 Posts
I am going to assume that the 1208/2 does not have the same borads, correct? I know that the 1208/2 and 1209/2 share most of the same boards, but I guess if one was going to be different it would be the board on the CRTs since they are obviously different across the two models. No, I don't have any spare 1208/2 boards but 1208/2 is a more common model. If you have some electronics troubleshooting experience, you could take a multimeter and measure different resistors and what have you across a known good board (on one of the other CRTs) and your bad board. If you find a difference between the two you might have identified the troublesome component. A friend of mine did that recently when my Barco 1208/2 went out and found an open resistor on my RGB Driver/Quad Decoder board. A new 4 cent part later and every was working! A guess resistors going bad are sort of common on Barco as my friend said there was another one on the power board that also causes a lot of problems. Of course if you are not comfortable troubleshooting like this or soldering you might want to leave it to experts.


secstate
 

·
Registered
Joined
·
85 Posts
Discussion Starter · #3 ·
secstate, thanks for the reply. Unfortunately I do not have any welding experience but cousin.it lives about 40 miles from me and he does. The neckboards are very different from the 1208/2 and the 1209/2 (I have a 1208/2 in the garage for spare parts). Since moving the board on the CRT used to work I am almost certain that the bad part has something to do with the piece that connects the CRT to the neckboard. Fixing it is most likely going to be a BEAR. I would love to find another neckboard so I could always have a spare. Thanks for the reply
 

·
Registered
Joined
·
968 Posts
Mike,


I still smile and laugh every time you refer to soldering as welding...


As I recall the problem we ran into was we couldn't find the exact correct service manual section for your neck boards. They're a newer version that can be built up with jumpers to support MEC or Sony tubes as far as the socket pinout goes.


By the way, the part number you gave above was actually the serial number off of the white sticker right? I think you have the 762292 boards which are just a bit different than the 7621195 older version.


Hmmm... maybe we just stopped working on it because it started working after cleaning up the glycol leak? Maybe we did find that section of the SM - I'll look again.


Mark
 

·
Registered
Joined
·
85 Posts
Discussion Starter · #5 ·
Mark, you know it is one of my missions in life to make you smile. Soldering, welding whats the difference, the results are the same. What are you an engineer? Yes you are right, I took the number off the white sticker and not the board itself. You are also correct that the board did work after cleaning the glycol leak.....but it still had to be "wiggled" from time to time to work correctly. The "wiggling" method became more and more frequent until yesterday. Not even the infamous wiggle manouver works anymore. I just get a bright burst of red (the crt the neckboard is connected to) until I turn off the projector. It is almost like the amplifier goes full bore and is no longer controlled by the settings on the G2 board. Maybe chewing gum and bailing wire will work......
 

·
Registered
Joined
·
85 Posts
Discussion Starter · #6 ·
bump
 

·
Registered
Joined
·
968 Posts
Well it appears Mike's BG1209/2 was bitten by an ethylene glycol coolant leak that caused circuit board damage. Both he and I had cleaned the glycol residue in this amp a while back, but a few drops had gone undetected underneath the tube socket. The glycol basically ate open a circuit trace at a solder joint. I ended up cleaning up the mess, flowing solder into each of the corroded joints and onto several of the traces, and the one circuit that had opened up I jumpered on the back side of the board. See attached picture...


In looking for this the clue we kept going back to the fact that he had previously been able to wiggle the amp block and sometimes it would heal itself. We couldn't find any bad solder joints or anything else mechanical, but notice a bit of blackish goop at one corner of the socket housing. That prompted the not-so-easy task of pulling the socket off the board.


After the repairs the board appears to be working now, but usage over time will tell for sure. The moral to the story is that ethylene glycol kills... circuit boards! If you've had a leak that managed to get on any of your electronics, pc boards, etc. clean it up very thoroughly and be wary of any inaccessible spots it might have dripped down in to.


Mark
 

·
Registered
Joined
·
85 Posts
Discussion Starter · #8 ·
I wanted to follow up. Cousin.it found the open circuit beneath the plastic socket on the board and repaired it. I ran the projector for 10 hours yesterday (NFL marathon) without one glitch. The bottom line is simple. Those of you who have projectors with CRT's that are liquid coupled or cooled beware of the evils of ethylene glycol. I have been fighting this battel about 9 months and it all stems from a leak I had around the seal of one of my CRT's. The leak ran down the CRT back into the neckboard, through the socket, down the board and out the pin hole used to short the board for G2 adjustments. The glycol along with the high temperature corroded every solder joint it encountered. We initially could not find the corrosion point beneath the plastic socket until it was removed. The "wiggle" that worked before was obviously closing the corroded circuit until it got so bad that not even that would help. Beware the circuit board evils of ethylene glycol and all praise cousin.it.
 
1 - 8 of 8 Posts
Status
Not open for further replies.
Top