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TX9/10 IF modules.

 
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TX9/10 IF modules.

Post by Rebel Rafter » Fri Dec 04, 2015 3:59 pm

Hi, folks from RR. I have what is turning out to be a serious problem with an IF module that was in my 20" TX9, one day not so long ago it suddenly went very grainy, so I stuck in a spare one and this got the set working again, but I'm having a ridiculously difficult time trying to get the faulty one working again. No matter what I do with it it just absolutely flatly refuses to work. I've changed both chips with new ones, and these are not cmos chips, and I've checked the earth on my soldering iron which is fine, I've checked all the coils and there are no o/c windings, no s/c capacitors, all the resistors are ok, and I've even tried changing the SAW filter, but still it absolutely will not work, any ideas anyone? The only clue I've got is that the AGC voltage on pin 1 of the module is either too high at about 8 volts with one TDA2540 and far too low with another, but always far too grainy, you can barely see the picture, absolutely nothing makes any difference. It seems something is instantly killing off any TDA2540 that I fit, yet other older modules that I try work fine. The faulty one is the later third generation one with the SL1432 preamp chip, the 1531/001. Is it ok to use a DIL socket with these chips? I once read somewhere that they're supposed to be soldered in because of the high frequencies involved. And I'm not wearing any synthetic clothing when handling these chips, just cotton. I just can't understand how something so basic can be so ridiculously stubborn. Has anyone else had a similar problem with any of these modules? And I thoroughly scrutinise the soldering with a big magnifier before refitting the module and there are no shorting solder whiskers anywhere and no cracks in the print either. RR.

 
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Re: TX9/10 IF modules.

Post by Doz » Fri Dec 04, 2015 8:48 pm

Something's ringing a bell here... are the two modules compatible? Something's niggling in the back of my mind that says a later "plastic" module wasn't compatible with a "metal" one ...

 
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Re: TX9/10 IF modules.

Post by Rebel Rafter » Fri Dec 04, 2015 8:58 pm

Hi, they're all interchangeable, it's the preamp chips that are not interchangeable. The earlier ones, the PC991 and the PC1503 use the SL1430, which is very different from the SL1432 used on the later PC1531 which I'm having such stupid problems with. They all use the TDA2540 and the same SAW filter. The earlier ones have a preset control for the AGC but the PC1531 doesn't. Sometimes you find a different SAW filter but they're interchangeable, unlike the preamp chips which are not. RR.

 
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Re: TX9/10 IF modules.

Post by freya » Sat Dec 05, 2015 6:55 pm

This ones been in my box for a while, condition unknown but it was removed from a working tx9
Yours FOC if you would like it, PM me your address if required.
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