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Issue 4S users... I need your help!

ZupZup
edited March 2012 in Hardware
Short story: Issue 4S spectrum don't work. TR4 seems to have pins at different places from other speccys (BCE versus EBC), and usual replacement parts doesn't work as expected.

I need to know what transistors have this boards at TR4 and TR5, as they seems to be different from other boards... or to know if I'm wrong with my findings (if you find some BC537 in that place, let me know if it have some pins crossed).

Thanks.
Post edited by Zup on
I was there, too
An' you know what they said?
Well, some of it was true!

Comments

  • rokoroko
    edited March 2012
    This maybe is a stupid question Zup, but did you remove the load from the +12V and -5V lines before exchanging Tr4? If the convertor died from overload (defects among 4116s) then a replacement Tr4 will be in walhalla before you removed your hand from the powerplug when connecting power.
    I am convinced that the actual 4S circuit is understandable from the 4B diagram, and that 4S has the usual transistors in the DC-DC convertor. As yours have a different physical arrangement, the determination of the E&B&C positions must be done 'by hand' (examination), I am afraid.
  • gtsamourgtsamour
    edited March 2012
    Right next to the TR4 transistor (the one already installed by the factory) there is another set of three holes (vertically).
    As you look at the board they are on the right side of the TR4 transistor.

    These are there in case ZTX650 were to be used instead of the other transistor you see right now (it has the order of the legs rearranged to correspond to ZTX650). I've done it myself so I know it to be true. I dont think there is a scheme drawn on board to tell you which side of the transistor goes where (and i dont remember right now) so I would suggest you compare with a board of another issue (or schematics) to find out which leg leads to what just to be sure. Just visually follow the tracks and compare. I think that the flat side of the transistor if you bent it falls in the square drawn on board (in case someone used a big transistor like TIPP31).

    TR5 is exactly the same as on other boards. In 4S just an equivalent (to ZTX213) is used. I use BC213 instead of ZTX213, its also pin compatible and easy to find.
  • ZupZup
    edited March 2012
    roko wrote: »
    ...but did you remove the load from the +12V and -5V lines before exchanging Tr4?

    That's the first time I did... after a transistor blew up. I removed all 4116 (but 12v still has the video circuit attached). After that I searched for short circuits between +12v, -5v and GND, and I didn't find anything strange.

    The DC-DC convertor seems to be the same that in Issue 4A (a capacitor between emitter and base of TR5), but it seems that some transistors are now hard to find and I wanted to be sure.
    gtsamour wrote:
    Right next to the TR4 transistor (the one already installed by the factory) there is another set of three holes (vertically).
    As you look at the board they are on the right side of the TR4 transistor.

    That's very helpful, I'll try to check that later. I was going to put a BC637 instead of TR4, but maybe it would be easier to use that holes instead.
    I was there, too
    An' you know what they said?
    Well, some of it was true!
  • gtsamourgtsamour
    edited March 2012
    Zup wrote: »
    That's very helpful, I'll try to check that later. I was going to put a BC637 instead of TR4, but maybe it would be easier to use that holes instead.

    Trust me, I've done it myself. They are there for that reason.... use a regular ZTX650 on these extra set of 3 holes and you'll be fine.
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