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Discussion Starter #1
Hi folks. Been having some bad luck with my fender blues jr cream board and was hoping somebody may have come across this problem already.

A while ago I started to hear a little electronic background noise when using the amp. Then one day I went to use the amp and I was getting very low volume output, with really crappy sound. I used to have both volumes turned up to around 4 or 5. That was usually loud enough. Now I have to turn both volumes past 7 to get any decent volume levels but the sound is horrible. I searched the net and found mention of the blues jr notorious tube sockets and connector ribbons. Perhaps a bad solder joint somewhere? Really crappy apparently. Got a new set of tubes, first set since new, so what the heck, gave them a try and no luck. Tried another set of extra tubes no difference. The amp has never left my house and has been gently used, never on for more than 2 or 3 hours at a time. I have no diagnostic equipment but would be willing to spend a little bit on such equipment as I do have other amps and I'm sure they will need some attention in the future and there are no amp techs in town.

Thanks for looking.
 

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you have tried the obvious tube swat with no results...
Having good diagnostic equipment and knowing what to do with it are 2 separate things.
Sometimes, a man has to know his limitations.
Its time for a good amp tech to have a look....
G.
 

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You might want to consider checking the BJ speaker and the connections to it through another amp.

At the very least that should eliminate the speaker and its connections as the cause. Just a thought and something easy to do.

Good Luck sorting it out.
 

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Discussion Starter #5
Thanks for the info guys. I'll try hooking it up to an extension cab and see what happens. I suppose I could ship it out for repair. I'm on the west coast, anybody know a good amp guru?
 

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@stringer I want to let you know that @nonreverb is a very experienced and well respected tech.
In comparison, I am just a guy interested in electronics (i.e., read not skilled and/or knowledgeable)

I have no real confidence in my suggestion about the speaker and/or connections because I think the presenting symptoms of this would be more 'all or nothing' in nature.

However, it is a safe and easy aspect of the amp to look into.

@stringer We just posted at the same time.
 

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Check out the website by Bill M. He shows you how to make a tester and how to test a Blues jr. He passed away a while back but his site is still up with tons of info on repairing and modding your amp. Just Google Bill M audio

Billm Audio » Billm Audio Blues Junior Mods
 

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Aren't Blues Jr's one of the models with the power supply resisitor problem? Like a single resistor and it burns out all the time. Happenned to my bud's amp and the result was as described by the OP; low volume and farty aneamic tone.

Sorry I don't recall the details, but I'm sure you can google it out. Also pretty likey you could tell what resistor it is by openning it up. Replacing it with the same value/rating will just blow again, I'm sure that google would give you the proper value to replace it with.
 

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open up the back, anything look burned out? swap some new tubes in, power separate from the preamp, anything sound better? no luck, maybe the for a pro
 

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From what I remember the weak link in the blues junior is the ribbon cable.
 

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Something I alway try first is cleaning the input jack, specially on an older amp. It can do all sorts of strange things.
 

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Discussion Starter #13
Thanks for the interest so far gang! A lot to look into. I've tried different guitar chords, hooked it up to an external cab but still same crappy low output. I've read about the ribbons, I may have come across the supply resistors info on another site. Unfortunately I have no diagnostic equipment other than my peepers and from what I can tell and smell there are no problems with any of the visible doo dads on the cream board. ( can't see any burns, leaking caps ) Looking more and more like I'll have to send it in for repair. A bit worried about shipping an amp. I wasn't very happy finding out about all the "common" problems with this amp as mentioned above. I'm thinking I'll get it fixed and try to sell it on, but I purchased a nice custom pine cab for it that I don't want to give away. I wonder if there is another tube amp that would fit in it.
 

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Yep, when me bud had the issue we tried diff speakers and changing all the tubes ( one at a time). None of that made a lick of a difference.
 

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Blues Jr's run the EL84's REALLY hard. This can cause two obvious problems. First, blown power tube and related screen resistor, the second is heat damage to the EL84 tube socket pins. Always a good idea to look for halo cracks there as it's a common problem. Remember...eliminate the obvious first.
Here's another potential problem to check which can affect the sound....the big filter caps (grey ones)...check to see if there is any brownish stuff surrounding the leg coming out of the black rubber part. If there is, they're toast. There have been batches of these along with the Deluxe/Deville series that had crappy B+ caps in them.
 

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Dave Vidal here in Vancouver works on all Fenders and owns a few Blues juniors so he probably knows what to look at. I don't want to give his number out over the web, but if you PM me I can send the number. He's been repairing stuff for a long time. Totally trust worthy.
 
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