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Post subject: USA Blues Deluxe Mystery
Posted: Tue Jan 16, 2018 4:34 pm
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Hi all
New here and hoping to find some wisdom.

I recently acquired a BD USA from a friend who advised 'it just stopped working' so I took the gamble as it was cheap.

I turned it on etc and sure enough - nothing. The power was turning on but no sound. Took the back off and theres no obvious loose connections.

I enquired at a local shop who advised it probs just needs new tubes so I got a kit and replaced them all.

Just turned it on and input into jack 1. There was a beautiful sound and I thought it was job done. However when I started to manipulate the sound i.e treble etc the sound got a little crackly then disappeared completely...

So I input into jack 2 and again I hear the beautiful sound. Similarly I continue to adjust eq etc then the sound fades away and thats it... its gone again.

Now I can't get a sound in either input regardless of any dial being changed. Ive turned the amp on and off and no change.

The tubes are all glowing correctly and are warm.

Just to mention the red 'dome' light next to the power and standby switch is not illuminated - both when it was making a sound and when it isn't.

Any help would be gladly appreciated.

Many thanks in advance

Chris

Just a quick edit...

I tried the old tubes back in and thought I’d not change any settings etc. The amp worked fine for around a minute before the volume faded to essentially nothing. If I crank the master volume to almost full I can hear the sound very quietly.
Equally it behaves the same when I swap out the tubes to the new ones again.

Thanks again for any help


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Sat Jan 20, 2018 1:31 pm
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Not claiming this will fix it but, try plugging a cord into the effects loops jacks a few times, both the send and return to exercise the connections. I believe the signal goes through both connections. Then try again using the guitar inputs.
Then try just a jumper into the effects loop, send and return, then try guitar in input.

Or another idea, try plugging your guitar into the effects return directly, I think you can do that. See if it works. If it’s not helping, maybe visually check for any cracked solder joints around the tube sockets. Just some ideas to try.

The pilot lamp may be a poor connection or a open bulb. See if you can unscrew the red lens and re-seat the bulb (with the pwr-off of course) or look to see if the bulb filament is open.


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Sun Jan 21, 2018 7:28 am
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Thanks for your suggestions mate - I’ll try them out tonight and post any results

Cheers


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Sun Jan 21, 2018 2:51 pm
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Ok I’ve tried all the suggestions above - thanks again.

When I plug the guitar direct in to the ‘power amp in’ I got a sound. A little louder than previously reported although none of the dials made any difference to the sound - the only noticeable thing was that when I strummed loudly there would be a very short burst of crackling and loudness then back to normal as above.

After noodling for maybe three minutes there was a kind of pop sound followed by the sound fading then nothing again. Dead.

I tried this several times after turning off the amp and back on again and it’s the same result every time.

I got nothing from plugging the guitar directly into inputs 1 or 2 with or without jumpers in as suggested.

Can’t see any problems with solder joints and yes it looks like the bulb is out.

Please again, any suggestions welcome but it looks like I’ll need to get it to a shop and bite the bullet.

Thanks again


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Sun Jan 21, 2018 7:22 pm
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Sounds like a trip to a trustworthy tech is in order, bad solder joint, etc.

UN


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Sun Jan 21, 2018 9:31 pm
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I agree with upnorth2, a trip to a tech would be good. You need more exacting tests with, test equipment dvm. If you could use a dvm, you could test things, lots of things. None of the dials working would be normal when you hear sound. Power supply might be a start or whatever the experts determine, faults. It's a worthwhile amp to own. At lease the lamp sounds fixed. (I wonder if you used the old tubes or new, ck those pwr supply caps).


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Mon Jan 22, 2018 9:23 am
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When you describe the pilot lamp not lighting and a fadeaway on the sound, that describes a loss of filament voltage or possibly a dc buildup on a preamp grid.
The grid can usually be smoked out by flipping the standby switch on and off. The sound will come back for a bit before fading again.
More likely is preamp tube soldering or at the spade lug on the transformer connections.
If it's more than 5 years old, I recommend resoldering the entire circuit board and the tube board.


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Mon Jan 22, 2018 3:39 pm
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Amazing thanks for all suggestions here - I’ll keep any updates posted.

Ps I do have and can use a dvm - can any recommend a link or video etc that demonstrates some testing you can do to begin diagnostics on an amp?

Thanks


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Mon Jan 22, 2018 10:00 pm
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Thanks to TimA, no doubt in my thinking excellent advice. If you could use a dvm, use some clip-on leads to clip on components, gets your hands away, then pwr-on, take measurement, pwr-off. Don't use some probes where you have to hold it on a junction or tp test-point, thats my approach. Meas AC & DC volts, as required.

It’s kind of involved, the process. Get some knowledge (schematic), formulate a plan, verify things that work and things that don't, then you'll be guided to a fault, repair. Lots of continuity measurements (Holmes, I mean Ohms, he was German) or testing components can be made with pwr-off in-circuit. No one right way to follow, but the end result will be a great Fender Blues Deluxe. Re-read Tim’s comments and value what he says, I would. Start with the lamp voltage, a great idea, spade lugs, there you go. I’ll say no more.


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Tue Jan 23, 2018 3:07 am
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Follow TimAudio advice ;

" If it's more than 5 years old, I recommend resoldering the entire circuit board and the tube board."
____________________________


- There is no way to use voltmeter here.


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Thu Jan 25, 2018 9:32 pm
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Yep, sounds like simply a bad solder joint, possibly in the power supply.

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Mon Jan 29, 2018 3:16 am
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I had one with almost exactly the symptoms your describing and it was indeed a bad connection, sadly it was the ribbon cable where it met the board and very close inspection revealed a nearly broken connection that was hanging on by a thread.

I ended up replacing that ribbon with individual wires and yes it was a pain in the keester ! LOL
I definitely did that work under a magnifying glass :lol:

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Post subject: Re: USA Blues Deluxe Mystery
Posted: Mon Jan 29, 2018 5:48 pm
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Hi again chaps

Once again many thanks for all your input on this one - much appreciated.

I’ve took out the board out etc and ran continuity tests across the whole thing - all spade connections, solders and ribbons etc appear to be fine.

I’ve noticed though that there are two white looking blocks which I believe to be 470w5 resistors which look super dried out and on the reverse of the board the soldiers are fine but the actual board around them looks blackened.

Is this normal or caused by arcing? Shall I replace these two components?

Many thanks

Chris


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Mon Jan 29, 2018 6:02 pm
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Those "sandbox" resistors are well known for causing all sorts of issues, Sorry I can't believe we missed that as it is so very common of an issue with any of the hot Rod amps.

They get very hot !

you can almost bet that they are your issue !

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Keepn' the Blues Alive

2004 50th Ann. Limited edition AMSE Stratocaster
2017 50's Baja Telecaster BSB

1968 Bandmaster with 2X12 cab C-rex speakers
VHT Special 6 Ultra combo

Visual Sound Route 66
Cmatmods Signa Drive


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Post subject: Re: USA Blues Deluxe Mystery
Posted: Mon Jan 29, 2018 9:08 pm
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It is normal for the board around those resistors to be black, from the heat generated by the resistors and zeners, for this +/- 16 volt supply. While this is a problem area for the BD and HRDlx, it wont keep your amp from working. The usual problems caused by this are channel switching and reverb issues. You likely have a bad connection somwhere else, and a continuity test may not uncover it. You have to inspect the solder joints closely with a magnifier to look for poor or cracked joints.

From your description, the amp works briefly and then quits, indicating a bad solder joint, likely in the connection(s) from the power transformer, where it connects to the circuit board, spade lugs and soldered connectors. A poor solder joint can work intermittantly, sometimes working until heated up.

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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