Feature your business, services, products, events & news. Submit Website.
Breaking Top Featured Content:
ags TRIO / Kenwood KW-55A mag phono pre-amp weak channel
New power tubes from Jim McShane, all new electrolytic capacitors, all of the original gray capacitors and the wax coated ones are gone, replaced with new film caps.
In it’s present state it works and sounds quite good with a CD player at AUX but the right channel MAG PHONO input has a problem.
It is weak. For a time, it did not work at all but I eventually discovered a bad solder connection on one of the film capacitors I installed.
This morning, I was rotating the MODE selector while listening to PHONO. It may not have any bearing on the problem but when set to MONO, both left and right sides are evenly balanced.
Set to REV, the before mentioned weak right channel switches sides but when rotating the balance control lock to lock, there is audio on both.
This is not so when in STEREO mode. The balance control performs as it should.
Apolgies if the above description is vague, it’s what comes to mind.
I have swapped both 12AX7 tubes with no change so I am going to conclude that the tubes and sockets are OK.
I am obviously wrong though in my assumption that one 12AX7 is left channel and the other is right. I say that because removing either tube kills both sides.
Needless to say, there are a number of resistors associated with both tube sockets. Somewhere I got the notion those grey resistors do not necessarily deteriorate.
There has been work done to this receiver before I got it, a few electrolytic capacitors were installed. But I just now noticed a blue, presumably metal film 1.5K ohm resistor, connected to pin 8 of a 12AX7. There is no such resistor involved with the other 12AX7.
Would there be a recommendation or suggestion to start replacing resistors involved with those 12AX7 phono pre-amp tubes? Or something else?
Continue reading at DIYaudio.com: Click Here