Quote:
Originally Posted by AndrewJ
Gday Allan
Just interested in how you interpreted the 2.2V from the pdf,
as its very light on other details ( ie like where ground is )
A mate wandered round today with a QHY8L that was/is showing problems.
When i stuck a CRO on it as per the instructions, i got a pulsetrain whilst processing but it was only about 0.3V pk-pk.
Adjusting the pot as per instructions appeared to adjust the DC bias only,
ie it stayed as a 0.3V pk-pk waveform, but adjusted its DC bias.
The pdf supplied says the upper edge of the waveform should be 2.2v but it doesnt clearly indicate whats zero.
If i assume a DC bias of zero is what is required for operation, then the waveform should be about 4.4V pk-pk and the pot merely sets the DC bias to zero.
What did you end up seeing?
Andrew
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Hi Andrew,
I haven't taken it apart yet.
It worries me that you didn't see what you expected.
I think the first thing to do is to try & re-create the fault indoors by
putting a lens in front of the QHY9 & using a LED as an artificial star.
I doubt I have the adapters to do that.
I'll have to get on to this job - & take pictures of waveforms etc to help others.
It annoys me that I always had this problem from brand new.
It tells me it was never adjusted correctly at the factory.
Also - what if I see spots on the CCD glass cover? - inside it or outside.
I would need Argon gas to replace what's inside to effect a repair.
I don't know what solvent to use to clean the glass.
All these doubts have made me think twice before opening it up.
One solution could be to put an external pot in place of the PCB mounted one
& adjust it while outdoors at night.
I don't know it's value so I would have to take it all apart twice.
It could be better to put a resistor in series each side of the pot -
& another one parallel to the pot to make for finer adjustments.
More research is needed.
cheers
Allan