|
 |
|
|
| View previous topic :: View next topic |
| Author |
Message |
tschaeikaei
Joined: 08 Apr 2013
Posts: 489
Location: Germany/Saarland
|
 Link Posted: Thu Apr 14, 2016 9:17 pm Post subject: |
 |
|
| Quote: | | Nobody's trying to demoralize anybody. We've made an attempt to keep you from blowing yourself up, OR your projector, that's all. |
Yes, and you've done that how many times? Get's quiet annoying over the weeks.
Blowing something up normally involves explosives. If you meant working on a live HV circuit, who did that (or advised someone to do it)?
| Quote: | | It was almost a "I'm having trouble with my transmission, can you tell me how to fix it?" scenario. |
That's an every day task for a technician. And what does the technician do? Asking about which gear makes problems,
taking a test ride and listening to the sound while driving.
Not wailing around that somethings gonna explode. That's what grandmas say, not technicians.
| Quote: |
This was not really all that different from someone with a computer problem saying "I think something's wrong with my computer and I'm sure it's one of those doohickeys on the motherboard. Can anyone tell me which one I need to replace, and how to do it?" . |
In that case, the friendly technician would ask if one of the diddely doo's is bulged and if not if the guy asking for advice has a multimeter.
I know enough strange (to me ) people replacing hundreds of good caps just because they don't know how to measure.
This forum is full of them.
| Quote: | | I'm a decent technician. |
Very good! Then you've understood what i wrote above and you certainly did know everything before.
But tell me something: What is the purpose of the circuit around Q20? What does it do? Drive H-yokes?
Will it destroy tubes if it fails?
| Quote: | | I'll toss the HDM in the trash and get another one before I'll mess with those high voltage deflection circuits. |
Yes, sure, that's what technicians are for. Repairing stuff is for idiots, a real technician throw stuff in the trash.
Because they have so much knowledge, they don't need to repair things.
The one asking questions doesn't have to be too knowledgeable. The person answering does. The guy standing aside
making comments no one asked for should realize he's in the wrong section.
I'm in the mood to believe that the average US-citizen wears gloves and eye protection filing his nails.
Safety is good, but overdoing it is ridiculous.
I'm not wearing any gloves or gas mask when i solder. And I'm still alive.
_________________
Marquee 9500U edgeblend P43 | NEC 9PG
|
|
| Back to top |
|
 |
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Link Posted: Thu Apr 14, 2016 9:59 pm Post subject: |
|
|
OK, fine, then I won't give you any more safety advice. Or ANY advice. You clearly have a high estimation of your technical abilities, so if I were to ask any question of you now, it would be "If you're so good why are you asking for help?" but I'm not going to ask.
BTW, the reason for replacing handfuls of caps that measure good is because they have limited lifespans and when some start to go, the odds are that others
are not far behind and they're cheap to replace so why not do them all in a batch?
But if you're such a hotshot technician, why am I even telling you that? Understanding the limited service life of electrolytics is not exactly a secret known only
by advanced technicians. It's pretty basic stuff, something you learn in first year electronics.
|
|
| Back to top |
|
|
tschaeikaei
Joined: 08 Apr 2013
Posts: 489
Location: Germany/Saarland
|
| Link Posted: Thu Apr 14, 2016 11:58 pm Post subject: |
|
|
| Quote: | | OK, fine, then I won't give you any more safety advice. |
You didn't in the past and either not today.
Well, I didn't ask for that, but well... ok.
| Quote: | | You clearly have a high estimation of your technical abilities, |
Where did you read this?
What i wrote was that i know about THIS repair. If someone asks something about another failure i may not be able to help him, but in this particular case I was. Ok?
| Quote: | the reason for replacing handfuls of caps that measure good is because they have limited lifespans and when some start to go, the odds are that others
are not far behind and they're cheap to replace so why not do them all in a batch? |
I'm ok with it, but let me add that you'll learn in the second year, it's not only time that makes caps go bad.
Heat, ripple, current. Only these three words, I'm not going into detail about this.
We both know.
| Quote: | | But if you're such a hotshot technician, |
Again, I did not write anywhere at all that I'm a technician.
Pretty basic stuff is to know what a circuit does. Repeatedly saying that he will blow his tubes is simply wrong.
That's what i wanted to point out. You can blow tubes fiddeling on other parts of the HDM but not at this one.
What i did is taking quotes from what you wrote and doing statements on them.
What you did is guessing. I think you should answer to what i wrote not to what you think i meant.
We're not getting to a point otherwise.
I hardly resisted on doing the above post, in fact i wrote a lot of alike things and simply stored them on my desktop for (maybe) future use and did not post it because i knew i was running into a fight.
What i claim about anyone who posted in the first two pages of this thread is the following:
I did this repair three times in the past (and i said that many times before) and it is perfectly safe.
It doesn't involve any work on a powered up projector, so it can harm no person.
Second: I looked into the schematic, understood, and replaced the parts. Oh and let me tell you that i got advice from someone else (not on this forum). You see i took some thoughts on this particular repair.
And since you repeatedly kept telling us that it could harm your life or tubes, that's enough evidence for me you did not look into the schematics.
If you had simply used your technical knowledge
(and I'm sure you're a well educated technician reading your posts from the past years)
and figured out what the circuit does, we would have never ended up like this.
That's the only thing that annnoys me.
I don't have no personal fight with you, i don't want to make you angry and i was happy if we could end this and
simply say that everything has been said.
If you want to add something, please do.
You see, I'm not godlike at all. I don't know much BUT i share what i know.
Regards, Julian
_________________
Marquee 9500U edgeblend P43 | NEC 9PG
|
|
| Back to top |
|
|
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Link Posted: Fri Apr 15, 2016 12:16 am Post subject: |
|
|
I'm OK with a peaceful and happy ending. That's best.
I didn't try to tell you about how that particular circuit worked because I didn't study it very deeply in the manual,
and in fact, I didn't even bother to look if you want to know the truth of it.
Why? Because there's very little about an HDM that I will fix. There isn't any NEED for me to do so because at last
count I have something like eight assorted HDMs and apparently they ALL work but some need some size coils replaced
due to being physically broken. Replacement HDMs are a dime a dozen, so learning to do repairs on them has not been
a priority for me. In fact, since I don't actually have one that has failed, there's not even an opportunity in there for me
to do some hands-on repairs.
Even then, I am very leery of attempting repairs in any circuit where failures can cause expensive damage (spot burned tubes
in thics case) unless I completely understand the circuit I'm working on and that includes accurate root cause analysis.
And if I don't know it well enough to teach it, then the prudent thing for me to do is to not attempt to teach it. I really do
know my limits. They're always expanding, but they're still there. Fundamentally, I don't want to give you BAD advice.
So, it is quite possible that at this point you may be MORE familiar with the operation of the HDM's circuits than I am, or at least,
some of them.
Chris
|
|
| Back to top |
|
|
mp20748
Joined: 12 Sep 2006
Posts: 5681
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
|
| Link Posted: Fri Apr 15, 2016 12:48 am Post subject: |
|
|
| tschaeikaei wrote: |
I did this repair three times in the past (and i said that many times before) and it is perfectly safe. |
I've been working at a component on Marquees for the past 21 years, and would not be able to recall the number of HDM's I've repaired and helped others to repair. The problem here is for ANY technician that understands these high current drive circuits, that are also critical to spot burn, should know that you NEVER tell anyone it's OK to simply swap out parts, without knowing first what else to check and what could also be defective. Also, it is VERY important to understand what are the "CRITICAL SAFETY" components in those stages. These are not parts you should easily replace (and that's why the manufacturers require you replace a bunch of parts for that one that failed - and they provide the parts in a kit).
Here's my experience and why I said it should NOT be serviced the way it was:
Whenever Q20 fails, it should be looked as a short on the Power Fets or associated circuitry. In the many of these that I have repaired, a Q20 failure was USUALLY the result of a shorted Power Fet or a defective other component on the final stage... you just CANNOT under estimate a TUNED (inductance/capacitance) stage. If any of those caps change value, that stage dies. You won't see a HDM failure where the horizontal shrinks on a Marquee, without you decreasing the size yourself. These circuits fail as a "Fail Safe" -- but when that final stage Fails, it's almost always a short, and what follows is a short or blown Q20.
Suggesting or recommending to someone to NOT work on that section of the projector, is based more on experience and many years of working on that and many other complex sweep circuits. A sweep circuit repair should always be looked at as a serious repair. And for anyone who has ever been to a manufacturers technician training on these projectors, they should already know this. It is consistent across the board in almost every manufacturer training class.
| Quote: | It doesn't involve any work on a powered up projector, so it can harm no person.
Second: I looked into the schematic, understood, and replaced the parts. Oh and let me tell you that i got advice from someone else (not on this forum). You see i took some thoughts on this particular repair |
I think what you say here should be fine if that's what you would want to do to your own set, but the problem here is advising someone else to take the risk.
Here's something you may not know. The HDM in a Marquee will most likely still operate if the cooling fans failed. We've had multi-projector commercial set-ups where these projectors operated in 24/7 operation in rear firing (behind the screen) equipment rooms. Sometimes these rooms would have an environmental control unit (air conditioner) fail. And at other times the fans would either fail or become clogged with dust. The Marquee in must cases just keep on operating. There were some problems with the very early HDM and heat failure, but the later ones held up very well, and that's why there was very little change in them over their more than two decades of existence.
So when you see one blow a power fet or Q20, it's not always heat related..............
No one is questioning your skills or your ability to repair anything. I just think when it comes to something that there are others who could have more experience working on the unit, that you should at least take heed to the warning. Curt by now should have more experience than me, and still I'll shoot him a question when I get certain problems.
| Quote: | | And since you repeatedly kept telling us that it could harm your life or tubes, that's enough evidence for me you did not look into the schematics |
There is no way of looking into the schematic and being able to understand how fast the protect circuit works on this particular HDM, and what and where all the triggers are. Somethings are only learned in time and with experience with the set.
But simply as a Rule, you should always be careful to not talk a novice into a DIY on certain sections on thee projectors and any other high current circuit in any of them.
|
|
| Back to top |
|
|
tschaeikaei
Joined: 08 Apr 2013
Posts: 489
Location: Germany/Saarland
|
| Link Posted: Fri Apr 15, 2016 1:03 am Post subject: |
|
|
Hey, we should have had this talk like two pages back.
| Quote: | | I didn't study it very deeply in the manual, |
I knew this reading your posts on the first and second page. But yes, no problem.
Being a tech doesn't involve to know everything about everything.
And I'm perfectly ok with you saying if you (or me or anyone else) does not know about a particular thing,
the best thing someone could do is asking and listening to advice. That's what haireez did and i gladly helped him
being proud of knowing about at least this one thing about the Marquee.
If i happen to know something else i will gladly help again and I'm sure you will do the same if someone asks about something you know.
You're surely aware of the fact that not everyone using a Marquee as 8 HDM laying around. I did not, so i made attempts to
repair mine. I had another working one in the second projector, but since i want to blend them i need two working HDM.
| Quote: | | that includes accurate root cause analysis. |
Straight out of my head 
We did this, it is clearly heat-related. Look onto your spare HDMs and compare Q20's heatsink to the big one the other transistors sit on.
If you play around with the cooling system, this is the first part of the whole projector to fail.
I hardly recommend to mount Q20 onto the big heat sink just to be safe (and maybe have less temperature drift).
| Quote: | I really do know my limits. They're always expanding, but they're still there.
Fundamentally, I don't want to give you BAD advice.
|
Like I said. And for me this was (i believe) the first time at all that i gave any advice on this forum.
Regards, Julian
_________________
Marquee 9500U edgeblend P43 | NEC 9PG
|
|
| Back to top |
|
|
mp20748
Joined: 12 Sep 2006
Posts: 5681
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
|
| Link Posted: Fri Apr 15, 2016 1:26 am Post subject: |
|
|
| tschaeikaei wrote: |
Like I said. And for me this was (i believe) the first time at all that i gave any advice on this forum.
Regards, Julian |
Its good that you're being helpful and wanting to help out. As well that you're very knowledgeable.
I only ask that you be more careful suggesting certain repairs to a novice..
There have been quite a few HDM repair attempts on this and AVS forums over the years, that were either sent to Curt or trashed for another one
Last edited by mp20748 on Fri Apr 15, 2016 3:51 am; edited 1 time in total
|
|
| Back to top |
|
|
cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
|
| Link Posted: Fri Apr 15, 2016 1:52 am Post subject: |
|
|
The only HDM repairs I've yet attempted were to replace broken adjustable inductors. (The H. size coils)
If I do encounter one that fails, I just put it in the spare parts bin and grab another one. I'm obviously acquiring spares faster
than they're failing.
Oh, does anyone have the cross-reference for which chip revisions on the HDM and CLM and DPB are compatible with each other?
If there are any firmware incompatibilities it'd be nice to know about them.
|
|
| Back to top |
|
|
|
|
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Forum powered by phpBB © phpBB Group
|
|
Forum FAQ
Search
Memberlist
Photo Albums
Register
Profile
Private Messages
Log in
