Maplin UHF Modulator

[Hunts smoothing bomb]

Hi Everyone.

Just checked my local Maplin for the stock of above and they have plenty.
I want to use it in conjunction with a freeview box and DVD player.
Anyone got one of these modulators? What are they like cos I am just about to nip out and get one I think.

Cheers all

Lee

[matthewhouse]

hello I have the cheaper of the 2 Maplin sell (without display) at they are very good, apart from they when connected they output a mildly anoying noise from the tv speaker when there is no sound (when people stop speaking or a setup menu is displayed for example) I use it to connect a freeview box or DVD to the workshop telly and have learned to ignore the nosie. The picture is very good and will work well with a long cable on the uhf output. They are also very easy to use.

matty

[Hunts smoothing bomb]

Hi Matty,

I have got my modulator and yep.... mine also makes that hi pitch noise through the telly speaker when no audio is present.

Cheers Lee

[matthewhouse]

well after seeing this I decided to lift the lid and have a poke around. Nasty noise now gone!! (well not audiable at normal listening levels anymore anyway )

I have attached some pictures of the dodgy modification. I don't know what I have done, why it works or what I have connected to. (The 'tuner' can be removed with screw between uhf connectors ans internal plug removed, PCB then lifts out after screws are released) The two caps I fitted were not specifically chosen, they were just two that were laying on the bench at the time from a radio repair. different values do change/reduce the noise in different ways so with a bit of a fiddle you should be able to almost eliminate the sound. What I have fitted is good enough for me tho! Voltage between the screened case and the wire originally connected to it and the PCB is 5V. I don't know how this is possible because the soldered wire and tuner are both connected to earth? Or should be, perhaps this is the original cause of the squealing. I'm going to poke around again to see what happens when everything is connected well. This unit wont work without an earth connection. The bigger capacitor removed most of the squeal and the smaller capacitor reduced the remaining noise. Someone more technical will know why.

If you decide to do the same I take no responsibility should loss, damage, fire, injury or death occur from modifying this equipment in ways it was never designed. I am not qualified in electronics so fiddle at your own risk. This will obviously void the guarantee too.

Matty

[Sean Williams]

All you have done is put a spot of decoupling in the unit - it probably needed it!

i would swap the capacitors for ones that are a little less extravagant!

Shorter lead length would be a good idea.....

Cheers
Sean

[matthewhouse]

Oh, so that's what I've done! Yes different capacitors might be a better idea! I was in bodge mode yesterday

Cheers
Matty

[ben]

I hope you didn't pay 30 quid for that, when you can get one out of an old video for next to nowt (and use an old mobile charger to power it with)

[Hunts smoothing bomb]

Nice one Matty,

I will try that mod tonight. I actually think these modulators are worth the money. I am certainly pleased with mine!

Cheers
Lee

[oldeurope]

Hi,
does this modulator cover the low VHF channels or is it UHF only?
Is there space for this PCB?
http://bs.cyty.com/menschen/e-etzold/archiv/TV/uvb/uvb_e.htm

Kind regards,
Darius

[Hunts smoothing bomb]

Hi Darius,

No, I'm afraid it is UHF only.
It has dip switches though so you can select any channel between 21-69.

Cheers
Lee

[oldeurope]

Originally Posted by Hunts smoothing bomb

Hi Darius,

No, I'm afraid it is UHF only.
It has dip switches though so you can select any channel between 21-69.

Cheers
Lee

So it is the same like using a DVBT set top box with build in modulator. I have a homecast T3000 here, in the onscreen menue you can choose all UHF channels and sound settings.
Darius

[Focus Diode]

I have one of these smashing little boxes Lee has, although the brightness control is a user pot rather than a pre-set. Never any trouble with it.

It's nice to know they're making such units, although some may argue £29.99 is a bit pricy, intended for products made without SCART connectors, which goes for all vintage equipment. Pre-set tuning throughout the UHF band is also an added bonus.

Highly recommended.

Brian

[Nickthedentist]

Originally Posted by Focus Diode

some may argue £29.99 is a bit pricy

Not when CPC are selling the same unit (code AV07781) for £30.40 +VAT

On the other hand, they do sell a ch.36-only one with SCART input for just £9.52 + VAT (AV10363).

[chipp1968]

I mentioned earlier in this section I have a UHF agile modulator by shinybow whoever they are ? model sb-4300 pal1 from maplains , i think this was just under £20

[Chris-G8ETC]

I have been using a Maplin UHF Modulator most evenings for the last 5 or 6 weeks ever since I purchased it new. Up until last weekend it performed perfectly satisfactorily, but has now developed that "annoying noise" referred to in previous postings of this thread. To save me reinventing the wheel, has anyone investigated the cause of this problem and produced an alternative cure, or is the solution still simply to fit a couple of decoupling capacitors to the supply rail?

I suspect the cure is still to add the decoupling capacitors, but thanks in anticipation anyway.

[matthewhouse]

Originally Posted by Chris-G8ETC

To save me reinventing the wheel, has anyone investigated the cause of this problem and produced an alternative cure, or is the solution still simply to fit a couple of decoupling capacitors to the supply rail?

The easiest option is to throw it away and buy one of the cheapo £9.52 CPC ones, they work perfectly, as well as being cheaper. The channel is preset to 36 and it blocks the aerial input when a video signal is present so these cheap ones can't be daisy chained to connect several sources to an aerial distribution system for example. I still have the extra caps in my Maplin one and it seems to be working OK, it's not perfect tho.
Not much help there I'm afraid.

[HMV 1120]

Could I use one of these to send video to my scartless portable TV? Or could I somehow rig the video players internal modulator to length of wire and 'broadcast' the signal?

Yours cluelessly, Rob.

[matthewhouse]

That's what they are designed for, connecting scart equipment (composite video only) to TV's without a scart socket. It simply connects to the aerial socket on the TV. A VCR connected to the aerial socket on the TV will do the same thing, just connect the scart equipment to the VCR and select AV on the VCR to view on the TV.

[Tazman1966]

Originally Posted by matthewhouse

The easiest option is to throw it away and buy one of the cheapo £9.52 CPC ones, they work perfectly, as well as being cheaper. The channel is preset to 36 and it blocks the aerial input when a video signal is present so these cheap ones can't be daisy chained to connect several sources to an aerial distribution system for example. I still have the extra caps in my Maplin one and it seems to be working OK, it's not perfect tho.
Not much help there I'm afraid.

I wouldn't if I were you The CPC £9.52 ones are not all that good. The contrast is a bit on the weak side whatever impedance setting is selected and the sound has a distinct lack of bass. I think Mikey405 has found the same thing with his and he has two. They also tend to cause weak sync on certain sets.

I get much better results from old VCR modulators.

Hope this info helps.

[matthewhouse]

Originally Posted by Tazman1966

I wouldn't if I were you The CPC £9.52 ones are not all that good. The contrast is a bit on the weak side whatever impedance setting is selected

Ohh! I thought the Hitachi Instavision thing I had this connected to was just getting old, perhaps thats why the contrast isn't so good! With the amount of water that keeps entering the TV I thought nothing of it . I'll have to check that now.