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Mike G.
Mike G., Technician
Category: TV
Satisfied Customers: 7355
Experience:  10 Years Audio Video Repair & Setup
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I have a JVC HD-70FH97. I have had it or seven years.

Customer Question

Hi Mike,
I have a JVC HD-70FH97. I have had it for six or seven years.
Recently I have noticed dark patches just left of top-center that run roughly diagonally down the full height of the screen. I replaced the bulb but the patches are still there. I found a dialog that you had with another customer and surmised that I have contamination on my projection lens and or mirror.
I removed the lamp and cleaned the optical iris. That had no effect on the dark patches. I unplugged the unit and waited for it to cool, then used a can of compressed air to blow out the intake and exhaust ports. That made the picture even worse. I believe instead of blowing the dust out, I blew it back into the unit and further contaminated the lens/mirror because I now see a splatter pattern of small spots that resemble rain/water drops on glass.
I procured a service manual for the unit, but am somewhat daunted by the instructions for gaining access to the components, i.e., removing the back cover. Is there a "path of least resistance" for accessing and cleaning the projection lens and mirror? That is, can I remove the back cover without removing the mirror, and clean the mirror "in place"?
PS - There are no authorized repair shops near me, and the unit is no longer under warranty. So, I am going to try this myself.
Submitted: 1 year ago.
Category: TV
Expert:  Mike G. replied 1 year ago.

Best bet is remove the entire front screen assembly. Use two people. Do not clean the screen assembly except very gentle wipe with DRY soft cloth. See service manual page 11 for screen assembly:

Customer: replied 1 year ago.
Hi Mike,I had already surmised as much, and I already have a copy of the service manual. What I was hoping to get from you was some details regarding the removal of the screen assembly. The diagrams are not completely intuitive and the supporting text appears to have been written by someone having English as a second language.How many screw MUST I remove to get the screen off? Surely I don't have to disassemble it completely to get it off ? Once I have the screen off, will I be able to access the mirror and projection lens for cleaning?VR,Fergie
Expert:  Mike G. replied 1 year ago.

This is the norm for tv service manuals. Manufacturers expect that the person who is performing service on their equipment has had professional training and certifications. These kind of procedures are not meant to be done by the general public. So the documents that are give out, are for technicians with experience who don't need every detail spelled out.

YES, once the screen is off, you will have access to clean the mirror and lens. Sorry, I cannot tell you how many screws. The diagram is VERY VERY detailed (compared to other service manuals I have seen). Dive in, just do it. You got this.

Customer: replied 1 year ago.
Not quite what I mean. I have had some electronics training. I can ohm out parts with the best of them. Not that one ever really needs to do that these days when vendors either swap out entire components or ICs or simply sell the customer an new unit altogether. When I said the service manual reads as if it was written by someone with English as a second language, I was referring to the incomplete sentences, convoluted sentences, subject-verb agreement issues, etc. The diagram is detailed, but it is not clear as to whether one needs to remove "every thing" to get to the mirror and projection lens to clean them. My goal is to remove only those parts, trim, components necessary to facilitate access to the mirror and lens for cleaning. I was looking for someone who had actually taken one of these televisions apart for maintenance/cleaning and could offer some guidance/suggestions in that regard.
Expert:  Mike G. replied 1 year ago.

I have taken the screens off hundreds of different projection TV's and maybe had to use a manual one time. If I had one of your model TV's in front of me, maybe I could give you a step by step, but I don't.