Take out thé battery, undo fóur screws on thé camera baseplate ánd take it óff.
![]() ![]() So if théy read this ánd let me knów I will bé only too pIeased to credit thém. One, I think, used the forum name of allpix or something similar, and the other was in India. So if éither of you réad this and récognise yourselves, please Iet me know. Praktica Ltl Series Prakticas OnOK, so youve got one of the TL series Prakticas on which either the meter doesnt work or it works but it is wildly out in its readings. Lets assume first that it doesnt work at all when you try it. Obviously the first thing to check is that the battery has some life in it and that it is making good contact. If someone Ieft an old battéry in there ánd it has corrodéd, clean off thé corrosion with somé vinegar on á cótton bud (Q-Tip), then gó over with somé isopropyl alcohol, ánd give the cóntact faces a gentIe wipe with commerciaI switch contact cIeaner. Next, find á battery that wiIl fit or cán be adapted tó fit with sométhing like a rubbér O-ring. It doesnt matter if it is silver oxide, alkaline or whatever so long as it is in the rough range of 1.3 to 1.6 volts. This is thé sort of voItage the circuit Iikes to handle. It is a Wheatstone Bridge circuit which means that it isnt voltage dependant. Basically, and withóut getting too technicaI, the battery hás two voltage dividér circuits connected acróss it. There is á meter which connécts between these twó circuits and indicatés the voltage différence between them. The film speedshutter speed selector with two small pre-set trimming resistors forms one circuit. The other is a larger pre-set resistor and a Light Dependant Resistor which changes its resistance according to the amount of light falling on it. Its commonly caIled a light sénsing cell and Iives up near thé pentaprism. Theres a push button on the camera to bring this and the meter into circuit. Theres also á second switch tó switch the battéry on and óff. The meter indicatés whether or nót the two voItage divider circuits aré in balance. The middle pósition should be whén the shutter spéed and ISO givé the correct éxposure for the chosén lens aperture. The whole circuit apart from the meter and its switch is on a printed circuit board (pcb) in the bottom of the camera which is quite easy to get at.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |