I have been having non-stop problems with erratic TEC cooling function on my QHY8 Pro purchased here on IIS. It would appear that others may also have experienced this. My previous QHY8 was fine.
USB, power, close cables, drivers, PC, all the usual suspects tried to no avail.
To cut a long story short, after exhausting local avenues of assistance, including sending it to the sole Australian dealer, and eliminating as many potential causes as possible, I contacted the China QHYCCD help desk last night at 6pm. They had replied by 9pm, on a Friday night no less, with a fix that works! It's turned a cantankerous cow of a camera into a docile imaging delight.
They admitted there was a TEC (cable) problem on QHY8 Pro's made before May 2010, and gave me a fix (change two 10K resistor values on the rear connector board to 2.2K). Correspondence is attached, including their pdf resistor fix instructions.
TIP: I could not buy smd resistors on a Saturday morning, so in the hope that the function was not overly frequency sensitive, tried tacking two small 2.7K metal film resistors from Jaycar in parallel with the 10K smd's as per the pdf. Works just fine.
More than fine, just great. No overshoot, no hiccups, no glitches, just goes to set temp and sits there. Been running for two hours now at -21c 70% power from Ezcap 1.18 temp graph, after initial hour at -15c. Nebulosity works fine too.
Warning: needs a steady hand, a small soldering iron and a magnifying gadget. If you don't feel confident, contact Theo, ...he may even do it under warranty
..... or get your local electronics service shop (do they still exist?) to do it. The pdf instructions are quite clear.
Hope this helps any other frustrated souls out there.
