We have a bush set top box with no instruction book. one channell Win (9)is indicating ''no reception'' We were told by a local TV repairer to re tune our tv. How?

Different digital boxes and tv's have different levels of RF gain. Some need more signal and some need less to work efficiently.
Possibly your Bush pvr needs a much stronger signal than your tv so the available signal is permanently on the threshold of reception and atmospheric conditions will some of the time reduce the available signal when reception will become impossible for the box but still be above the threshold for the tv set.

Modern Bush is not reknown for being a high quality brand and the purchasers of budget brand pvr's often discover reception or performance problems in fringe signal areas. Because a single aerial must receive a very wide range of frequencies it will be more efficient for some channels than others and so one channel could be a fringe channel and another channel produce a very strong frequency.

The signal strength and quality can be checked for each channel by selecting options in the menu in order to check this theory.

The problem might be solved by replacing the Bush pvr with a premium brand or replacing your aerial for a more efficient type. One of my friends had five different boxes before he gained a satisfactory performance and another friend three boxes and still has problems.
My installation has a new high gain wideband aerial on top of my 3 storey house and a distribution amplifier in the loft to keep the input lead short and the whole lot connected by very good quality double-wrapped co-ax.
I had to add different amounts of attenuation for each box or tv set but in spite of the signal being on average too strong and needing attenuating there are still channels for which the aerial is not as efficient and providing only a weak signal.

Does this model of TV have a built in HD receiver? I've had a quick look at the instruction manual and it looks more or less the same as mine at home. I've not got HD tv reception built in but have to use a set top box. If you're in UK, it should have Freeview HD sticker from the box or manual somewhere but as this looks like an early model tv (only 1 HDMI socket) then you may need a HD set top box such as Sky HD or Freeview HD

You need to get a connection from a local cable or wireless service with a set top box to be connected to the input. Please check with your local operator and see if the set top box is needed for the digital feed.
Otherwise you might need a dish with the LNB to be used to the TV. Digital tuner means that the tuner is working to scan and memorising the full band width of the channels with digital processing and thus faster and crisp.
Check the details of the TV from a forum:
http://reviews.cnet.com/direct-view-tvs-crt/philips-32pt9100d-32-crt/1707-6481_7-31473699.html

Go into the user menu and reprogram the stations. Make sure that it is set to program digital channels only. Not analog.

If you just have over-the-air signals from local broadcast stations, you need a good VHF/UHF antenna connected to the RF input jack on the TV in order to get reception. If you have access to cable TV or satellite, you need to connect the box or receiver set-top-box to the TV using a HDMI cable. You need to select on the TV using the remote, (press the MENU button) setup for tuning channels. Do a scan after setting to AIR or CABLE so the TV picks up all available channels you can get. Once this is done you can change channels and see TV. If you reply back with specifics, I can help more...

Witout knowing your set up I can only guess at the set top box getting hot and failing.
Is the Teac box well ventillated? If not, put it somewhere where it can get cool air (ie not enclosed in a TV cabinet for instance).
I doubt it's your antenna if it works for a while, but you maty want to have your coax connection checked out. If you use a booster, that may be failing.
Sorry I can't be of any further use.

I have the Bush DFTA1A set top box and plugged the aerial into the back of it, then connected the 3 cables red,white & yellow also into the back of it and the other end of those cables into my DVD/TV. then follow onscreen prompts to install it. works fine.

I carried my Westinghouse TV to the basement. Unplugged the antenna from the digital converter box and connected it to my digital TV. I then re-scanned for channels and found channel 9. After carrying the Westinghouse TV back upstairs, I connected the original set-up and tuned to channel 9 which was now showing on the screen as no signal. From that point I moved my VHF dipoles until I had located the correct position for reception. A little labor intensive, but I was fortunate to have another antenna that was receiving channel 9.

I have a saterllite reciver just bought a bush hd freesat top box i am running my virgin cable tv through my samsung hd television i put my satallite cable in to my bush top box connect the hdmi cable to get the freesat turn my virgin box off source the hdmi cable on tv get the freesat logo but nothing else what am i doing wrong