Jeff Rowland Model 7 Please Help

rebank · 13th February 2009, 09:32 PM

I am a returning member of this forum, although it has been a while since I have last visited.

I have had my pair of Mod. 7 since 2000. Never had a problem, until now. Went to turn them on, one is OK, the other is dead. The relay is not clicking, making me think it is something in the input stage. Compared the voltage coming in between the good and bad amps, all check. What I have is probably the 2nd version, with potted modules and a PCB on top. This PCB has the fuses, circuit, 3 ICs, and a relay. The circuit appears to be a control of some kind (temperature, DC offset, ???). Since relay is not energizing, this PCB is the suspect. Have anyone experienced this problem? Suggestions?

JR recommends shipping the monster to them. I would prefer to fix it myself.

Thanks in advance.
Edward

Steve Dunlap · 13th February 2009, 09:40 PM

Most likely, when the relay does not engage it is because of DC on the output. Check for DC on the emitter resistors.

anatech · 13th February 2009, 09:44 PM

Hi Edward,
I have to agree with Steve here.

Jeff greatly prefers to service these things himself, and is helpful if you get to talk with him. His designs are fairly straight forward, but the devil is in the details. He does service the defective module by itself if that helps. It would certainly be a much lower shipping rate.

-Chris

13th February 2009, 09:32 PM	#1
rebank diyAudio Member Join Date: Sep 2005	Jeff Rowland Model 7 Please Help I am a returning member of this forum, although it has been a while since I have last visited. I have had my pair of Mod. 7 since 2000. Never had a problem, until now. Went to turn them on, one is OK, the other is dead. The relay is not clicking, making me think it is something in the input stage. Compared the voltage coming in between the good and bad amps, all check. What I have is probably the 2nd version, with potted modules and a PCB on top. This PCB has the fuses, circuit, 3 ICs, and a relay. The circuit appears to be a control of some kind (temperature, DC offset, ???). Since relay is not energizing, this PCB is the suspect. Have anyone experienced this problem? Suggestions? JR recommends shipping the monster to them. I would prefer to fix it myself. Thanks in advance. Edward

13th February 2009, 09:44 PM	#3
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Edward, I have to agree with Steve here. Jeff greatly prefers to service these things himself, and is helpful if you get to talk with him. His designs are fairly straight forward, but the devil is in the details. He does service the defective module by itself if that helps. It would certainly be a much lower shipping rate. -Chris __________________ "Just because you can, doesn't mean you should" © my Wife

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13th February 2009, 09:40 PM	#2
Steve Dunlap diyAudio Member Join Date: Sep 2008 Location: Here	Most likely, when the relay does not engage it is because of DC on the output. Check for DC on the emitter resistors.