Tube-Town Forum
Technik => Tech-Talk Mesa Boogie => Thema gestartet von: rico am 26.04.2005 22:38
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Hi guys. Maybe someone can help me - for what LM3914 chip is used in the dual rectifier, where should i connect it?
Thx
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Look and read ... http://www.tube-town.de/ttforum/index.php?board=43;action=display;threadid=1303 (http://www.tube-town.de/ttforum/index.php?board=43;action=display;threadid=1303)
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i don't think this is corret, cause this chip is not even connected to any of the tubes, it's near the footswirch din.
it's for somethimg else and no one knows exactly fo what. i have already heard 5 different variants, and they're all wrong:(
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Hi, Rico!
Forget the stabilization - The Chip normally is used for LED-Dot-/-Bargraph-Displays. It contains a 10-step-voltage-divider and is probably working as a Converter for the footpedal!
The analogue signal from the footboard can be converted to a digital signal - its like a 10-step-comparator.
For further information look at the datasheet:
http://www.national.com/pf/LM/LM3914.html
PLAY LOUD!!
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Hmm
Sollte das nächste mal vielleicht zuerst den Plan ansehen ..,
Nichts für ungút :-\
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Okay, so is it in an AMP, or it is in a FOOTSWITCH?
Cause all i can see on the schemtic - only a few pins of LM chip are used and connected to somewhere... Is it normal? :-[
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Someone, please, HELP!!! :'(
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PEOPLE HEEEEEEEEEEEEEEEEEEEEEEEEEELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! SOS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'( :'(
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Hi Rico!
Have you already studied the supplied data sheet?
According to my schematic only Pin #1, #18 and #17 are used, these are LED-driver pins. They are connected to the FX-selector-switch and switching matrix fpr ch.-selection.
Pin #5 is used as input, Pin #4 and #6 are used for reference voltage.
Maybe the footswitch supplies a positive or negative voltage to Pin #5 according to the selected channel?
And by the way: If no one answers it's because no one knows the answer - so stop bugging.
Best regards
Hannes
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Hi,
wo bleiben denn hier eigentlich unsere vielen "Recto"-Spezialisten (u.a. Killigrew,Guido u.s.w.)? Oder trauen die sich vielleicht etwa nur nicht wg. der engl. Sprache? :o :-X :-[
Gruß
Günter
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Hallo!
Ich finde, dass der LM3914 sehr sonderlich eingebaut wurde - erscheint mir fast sinnfrei... ;)
Andererseits wäre es wohl kein Problem mit ein paar CMOS-Bausteinen das Switching neu zu bauen.
Grüße
Hannes
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Hi, Hannes.
Can youn tell me, the LM3914 chip is in a footsweitch, or it's on a PCBoard in an amp?
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Hi rico!
No, I can't tell you where the LM3914 is situated. But does it matter?
Best regards
Hannes
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I really dont' know, i'm asking because if it's not in an amp, i will forget about it untill i start making a footswitch, and if it IS in an amp, i need to have some place on a PCB for it. So...
I also wanted to know, how many contacts are connected to the footswitch DINm i know it's a 7pin connector with a 8-th in the center of it, but on the schematic u can only see that pin #7 is used.
And also, i can't find where to connect the 1'BUS wire.
Can ya help me with this? Thank you!
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HELLO?!??? ???
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Hi, Rico!
If we should help you, we need more information. Did you buy the amp or is it a homebrew model? Which schematic do you have? What do you want to do? We can't give you a "mod-manual", if we don't know what's up!!
PLAY LOUD!!
P.S.: Did you ever solder before?
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I have the schematic that is available on the Internet in *.pdf files, they are: 1BLK_DIA.PDF
2PWR.PDF
3PRE_PT1.PDF
4PRE_PT2.PDF
5PRE_PT3.PDF
6PWRAMP.PDF
NOTE.PDF
SWTCH_P1.PDF
VOICE_23.PDF
There u can see the LM394 chip. Maybe some parts of the schematic are missing, maybe not, but i can not see where should i connect this chip and some more traces, that i was asking about in "Need help - tracing PCB - dual rectifier 3-channel " here in this forum.
So, i need help on this questions. :'(