WOPL 700B Has more output on the left channel.

Mohawk said:
The blind leading the blind ? What's with that ? Apparently I have offended Mr Sniffer in some way ???
If you have no time for my questions and dont care to help then leave it at that.....
I'm only asking for some help and guidance in tracking down a problem......

I DO APPRECIATE any help from any of the other phoenix community members ....
To back this up a bit , the 700 was built maybe ,2 years ago and was just fine until
recently....
The plan was to ask lots of questions, get some ideas, take notes and then open it up
with a plan in mind......

M
Click to expand...

I can see in the middle foggy photo of the entire control board that R14L location appears to be installed. That has always been a DO NOT INSTALL location. I cannot see the right channel so cannot tell if that one is also installed in R14R. That by itself does not matter because C10L is not installed so that circuit is open (as it should be), just leaving a stub formed by that resistor. What does matter is where did that resistor come from and was it supposed to be installed somewhere else on the board??

Two to 3 high quality face shots of the control board showing close ups of various segments of the board so we can determine if the eagle eyes on this forum can pick out any misplaced values. Will also need high quality shots of the backplane boards with the control board swung out of the way.

That way we can stop guessing about any build errors that may have occurred along the way.

Can you help us out by taking those photos and posting?
 
The one segment of the backplane that is visible in the bottom most photo has some concerns for me. Usually on the PEM nut standoffs that are soldered into the backside of the board have vestiges of molten solder showing around the periphery of each PEM nut on the front side of the board. In the photo, I see none. That leads me to the concern that perhaps the joints on the back side were not reflowed enough and possibly are no longer attached. Something to check out. The meniscus around each of the socket cups for the 2 transistor leads shows evidence of cold solder. Those are relatively easy to solder, the PEM nuts are not easy to solder. The same type of cold solder is evidenced on the bus bar that has wires reflowed to it. It takes a lot of heat to solder joints like those properly and in this case, not enough was applied.

I am not trying to be critical. Rather trying to point out areas that concern me that you should investigate. May turn out be something, or may be nothing.

Last, the Backplane Kits are VERY DIFFICULT to assemble correctly due to the sheer mass of copper in each backplane board (for a reason). It says so in BOLD RED TYPE at the very start of the instructions.

The clear photos should help a bunch.
 
Can you take pics of how it is now?. That's what we are more interested in.
 
OK thanks, we will tune up our eagle eyes and wait for the better photos :-)
 
The Back planes as originally built .... Apparently that's all of his pics of the guts....
I will get it apart asap and get more pics up !
 
Me too, but I myself have left some in the past, regretfully..
 
Joe is the lead eagle eye. He designed the darn stuff so he can spot that stuff pretty quickly.
 
Incidental note, I don't know why the thick nylon washers remain on the upper standoff post. Those are only intended as an assembly aid during the early assembly steps of initially securing the backplanes to the chassis. Once you have all the output transistors in place, these washers are no longer needed and are to be removed. Not your current problem but unsure of whether it interferes with the chassis ground connection on the left side backplane.
 
I see that now.... The back planes ground to the chassis directly through those standoffs ? and then a single connection to the power supply buss bar correct ?
 
The present wiring looks correct. The 2 washers are not needed there is all that was pointed out.
 
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