# I hate days like this...



## nonreverb (Sep 19, 2006)

Every year or so, I have a strange repair experience.....The last couple of days are no exception.
Got a Reese Jimmy amp in. Very well built boutique amp albeit no output power when I received it. The amp was only 2 years old so a major fault was a remote possibility I concluded. Tested for all typical failures, tubes, fuses and switches....all perfect. Moved on to testing under power. First thing I notice is the B+ was low...like under 400 and seemed to be dropping. Tested the individual legs of the transformer. 390VAC on one side and 289VAC on the other! That's a problem! Pulled both wires from the circuit and unloaded the readings were the same. Now I'm thinking shorted winding in the power transformer. Redid my measurements and concluded the transformer might be bad. 
Contacted the customer and let him know what I found but that further testing was required and suggested to him to contact Reese to see if it was still under warranty. Discussed the problem with Bill at Reese and concluded that the transformer needed to go to them.
Feeling unsatisfied that the problem truly was the transformer, I redid all my testing....again. This time I unloaded all the secondary taps including the heaters and low voltage relay supply. To my amazement, all the voltages came back normal. I proceeded to reconnect all the taps back and try again. They were normal!
So now.....why was the amp still not working? I quickly narrowed it down to an open condition at the impedance selector switch and took al look at the selector itself. The selector is the blade type selector which uses a screwdriver to operate. Well, the customer had somehow turned it all the way around as the slot lined up but the tiny little red arrow was on the opposite side. Voila....back in biz.
My equipment tests OK...I made absolutely sure it was.
I guess we'll see what happens from now...... just when things get comfortable, something strange happens.


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## greco (Jul 15, 2007)

nonreverb said:


> Every year or so, I have a strange repair experience.....The last couple of days are no exception.
> 
> ............I quickly narrowed it down to an open condition at the impedance selector switch and took al look at the selector itself. The selector is the blade type selector which uses a screwdriver to operate. Well, the customer had somehow turned it all the way around as the slot lined up but the tiny little red arrow was on the opposite side. Voila....back in biz.



Very interesting!...Many thanks for the detailed post. 

Not wishing to sound like a smart a$$, but wouldn't a better designed selector switch (or at least one that only permits selection within the 3 choices) be something that the builder/manufacturer would want to consider changing to? Did the customer (unknowingly) force the switch? 

Please understand that my criticism here is ONLY of the design/construction of the switch and is not directed at the builder, the customer or yourself. 

It is likely something that only happens once in a million times and this is certainly not a perfect world.

Cheers

Dave


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## nonreverb (Sep 19, 2006)

The manufacturer makes it for several different uses. Having said that, certain types have an adjustable stopper that can be configured to only turn to certain positions....this is not one of them.


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## greco (Jul 15, 2007)

Thanks

Cheers

Dave


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## Lincoln (Jun 2, 2008)

Good find! Those are the kind of things that make you scream in your sleep.

He's lucky he brought his amp to you. The average tech would have replaced everything under the lid twice before finding the actual problem.


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## nonreverb (Sep 19, 2006)

Thanks for the kind words Lincoln, however, I'm still a little peeved that for whatever reason, I kinda got sent down the garden path for a while with the crazy transformer readings. Sometimes you just got to laugh at how things go in this game.



Lincoln said:


> Good find! Those are the kind of things that make you scream in your sleep.
> 
> He's lucky he brought his amp to you. The average tech would have replaced everything under the lid twice before finding the actual problem.


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## bluzfish (Mar 12, 2011)

I just goes to show you that no matter how bulletproof you try to design something, no matter how many hours you've contemplated every possible circumstance in which your design is going to be used and abused - give it to one user and they will inevitably find the flaw in your design that you never thought possible.

Once again, the real world rears it's ugly head.


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## greco (Jul 15, 2007)

bluzfish said:


> I just goes to show you that no matter how bulletproof you try to design something, no matter how many hours you've contemplated every possible circumstance in which your design is going to be used and abused - give it to one user and they will inevitably find the flaw in your design that you never thought possible.
> 
> Once again, the real world rears it's ugly head.


So true!

Cheers

Dave


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## jb welder (Sep 14, 2010)

Tough problem to find, so well done! Reminds me of the IEC sockets with the built in fuse holders (that are barely readable) that change the amp from 120 to 240V if you flip the fuse holder part upside down.


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