When i got my first cband dish last summer i noticed the guy had a pansat 2500 on the basement floor. i asked what was wrong and he said after flashing, it would no longer boot. (Later google told me why. how ironic to say the least.)
i asked him if he ever tried to jtag it and he said "what is that". So i gave him five bucks for it. i built a standard jtag cable from some resistors and db25 and an ide ribbon cable. i had it breathing in no time. For some reason though the 22khz never worked. which means no diseqc or USALS.
fast forward 6 months
I decided to take a whack at this. i knew it was not outputing 22khz tone because my ebay meter had a 22khz indicator light.
i figured the demod was producing this tone so i opened up the tuner and saw the zl10313. pin 4 is the 22khz ouput according to datasheet. http://www.datasheetcatalog.org/datasheet2/5/0qyrf5f2pzdgq6zgcal7g7gfl97y.pdf
Busted out the DMM, and started draw the circuit with this cool free app i found here:ExpressPCB - Free PCB layout software - Low cost circuit boards - Top quality PCB manufacturing
here is a finished screenshot of the circuit:
the expresspcb file is attached if anyone wants to open it with the app. please remove the .txt extension on the file after downloading.
13/18 switching was always working so i worked backwards from Q2. It didnt take long after that. Next in line is transistor Q3. i pulled it from the board and tested it.... and noticed it was open. must be the culprit. even better Q1 was an identical part, so i pulled Q1 and put it in Q3's place. fired up the pansat and like magic 22khz tone is back as indicated by the light on my meter.
Q1 and Q3 have the marking "sa928a" on it. So i just need to get a replacement now to fix what i disabled by removing Q1.
i asked him if he ever tried to jtag it and he said "what is that". So i gave him five bucks for it. i built a standard jtag cable from some resistors and db25 and an ide ribbon cable. i had it breathing in no time. For some reason though the 22khz never worked. which means no diseqc or USALS.
fast forward 6 months
I decided to take a whack at this. i knew it was not outputing 22khz tone because my ebay meter had a 22khz indicator light.
i figured the demod was producing this tone so i opened up the tuner and saw the zl10313. pin 4 is the 22khz ouput according to datasheet. http://www.datasheetcatalog.org/datasheet2/5/0qyrf5f2pzdgq6zgcal7g7gfl97y.pdf
Busted out the DMM, and started draw the circuit with this cool free app i found here:ExpressPCB - Free PCB layout software - Low cost circuit boards - Top quality PCB manufacturing
here is a finished screenshot of the circuit:
the expresspcb file is attached if anyone wants to open it with the app. please remove the .txt extension on the file after downloading.
13/18 switching was always working so i worked backwards from Q2. It didnt take long after that. Next in line is transistor Q3. i pulled it from the board and tested it.... and noticed it was open. must be the culprit. even better Q1 was an identical part, so i pulled Q1 and put it in Q3's place. fired up the pansat and like magic 22khz tone is back as indicated by the light on my meter.
Q1 and Q3 have the marking "sa928a" on it. So i just need to get a replacement now to fix what i disabled by removing Q1.
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