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Post subject: Re: Blues Deluxe - Original Issues (Distortion, Volume)
Posted: Sat Oct 05, 2013 4:24 pm
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" When playing chords and some lead lines there's break up on the G and B strings on the clean channel. Mostly present with higher guitar volume, and becomes more pronounced with higher tone pot. This is unwanted distortion. "

You only get this distortion on those two strings? How about when you play the same notes on other strings? Usually, it's the low or high notes that elicit amp distortion. Have you tried another guitar through the amp(s)?


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Post subject: Re: Blues Deluxe - Original Issues (Distortion, Volume)
Posted: Sat Oct 05, 2013 4:55 pm
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BMW2002Ti wrote:
" When playing chords and some lead lines there's break up on the G and B strings on the clean channel. Mostly present with higher guitar volume, and becomes more pronounced with higher tone pot. This is unwanted distortion. "

You only get this distortion on those two strings? How about when you play the same notes on other strings? Usually, it's the low or high notes that elicit amp distortion. Have you tried another guitar through the amp(s)?


BMW, did you listen to the two audio clips? It really sounds nasty all over (though it could be due to the unknown Samick guitar). I really think the seller and the seller's tech sold the OP a bad amp. Trying to troubleshoot this amp sight unseen will be a chore. All PCB so you can't really see if there are any mis-wirings or bad solder joints. This really needs a hands-on person.

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Post subject: Re: Blues Deluxe - Original Issues (Distortion, Volume)
Posted: Sat Oct 05, 2013 5:06 pm
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Here are pics of the circuitry.

http://imgur.com/a/SNoju

It's not the Samick doing things here. I've ran a Strat through it and a similar effect was produced. Also, I only have one of these amplifiers, my mistake on the initial sentences. I usually play my Hot Rod Deville and it doesn't give me these issues.

I decided I will take it to my professor and see if he will assist me in troubleshooting it, but I'd like to hear from you guys what I can do.


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Post subject: Re: Blues Deluxe - Original Issues (Distortion, Volume)
Posted: Sat Oct 05, 2013 5:38 pm
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I tried to DL the sound file, but got a warning statement about the voice001.mfa file. I'm afraid to proceed, as sometimes it lead to a bazillion generic VIAGRA pop-ups and emails.

And you know, us studly dudes don't need that sheet. :lol:

I'll take your work for the overall bad vibes, on all strings. If you are getting bad, under-powered tones with single-string or double-stops -> bad amp. You can try flip-flopping tubes around and see if that makes any difference. But, it sounds more systematic.

Can you get a refund?


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Post subject: Re: Blues Deluxe - Original Issues (Distortion, Volume)
Posted: Sat Oct 05, 2013 5:50 pm
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BMW in case this problem persists for more than 8 hours I will contact my doctor

I can totally get a refund, but I don't think that it's a good idea. Like I said as an audio engineering student this could afford a good opportunity to learn how to repair these kinds of issues.

Usually the sound comes through with harmonic content running.

Also this amplifier sat in storage for years, hopefully that will help with things.

Are electronic issues usually less than 200 or so?


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Post subject: Re: Blues Deluxe - Original Issues (Distortion, Volume)
Posted: Sat Oct 05, 2013 6:25 pm
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Hey! If the "condition" lasts for more than 4 hours --- call all my old girlfriends! :lol:

" Also this amplifier sat in storage for years, hopefully that will help with things. "

Ok, did you ramp up the amp on first fire-up? After years in storage? Those are kinda borderline cheesy caps, IMHO. Many moderate price IC caps are no longer being made in Illinois. They appear to be made in China and re-labeled. Anyhow, one or more may have failed on first fire-up.

If you want to do surgery on this amp... I'd first measure the DC voltage off those main filter caps. If you didn't ramp up the amp, may want to consider replacing the two 100mfd/350VDC and two 22mfd/500VDC caps. Get good F&T or Sprague Atoms. Similar value. Watch polarity!

Be sure to suck ALL the old solder off first and carefully remove the old caps. While you are at it you may want to suck ALL solder points and replace with good tin/lead solder.

For big caps, I "pig-tail" the new caps onto the old leads. Just cut the old cap right at the lead-cap entry point. Then wrap the new cap's leads onto the remaining old lead. Twist or pig-tail the two leads. Solder.

That way you aren't pulling old parts off delicate circuit boards & tracing pads. Be VERY CAREFUL with the circuit board. Esp the tracings.

Good luck.

PS: Really I think you ought to exchange the amp for a good one.


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Post subject: Re: Blues Deluxe - Original Issues (Distortion, Volume)
Posted: Sat Oct 05, 2013 6:33 pm
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Looks like I'll try testing and replacing the power filter caps. Would these be responsible for low volume on one input too?


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Post subject: Re: Blues Deluxe - Original Issues (Distortion, Volume)
Posted: Sat Oct 05, 2013 7:16 pm
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It may... without proper testing equipment it would be hard to narrow down the problem. You are going to have to empirically test the amp stage-by-stage to find the problem. Then, if it's major problem with the main board --- you may need to get a new amp, as I believe you can't buy a populated board from Fender.

Bad filter caps can lead to all kinds of symptoms. And replacing them is not too difficult & expensive.


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Post subject: Re: Blues Deluxe - Original Issues (Distortion, Volume)
Posted: Sat Oct 05, 2013 8:20 pm
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Right on, well Monday I'm going to take it to my electronics class and talk to the professor about doing a class project on it. Hopefully it will turn out alright.

Kind of funny that I was asking about exploring amp technology in class, and he said maybe. God has a way with arranging things, lol


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Post subject: Re: Blues Deluxe - Original Issues (Distortion, Volume)
Posted: Sat Oct 05, 2013 9:56 pm
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Bad filter caps was suggestion #4 in my original post where I advised you to check the power supply voltages.

The photos are really of little value. The power supply caps look good and there are no obvious burned components.

You need to understand that to remove/replace any components on the PCB, you will have to disassemble the amp and remove the PCB to gain access to the solder pads. The newer versions of this amp use through plated solder pads (there are pads on both sides of the PCB) which are easier to work with. The traces and solder pads in your amp are very delicate and can be easily damaged if you are not careful. The ribbon cabons are very fragile and prone to breaking if you are not careful.

If the power supply checks out OK, you then need to check the voltages at each tube. This includes both plate and screen voltages which are high voltage. If all the DC voltages check out OK, I would try replacing the tubes one at a time with new tubes. Yes, I know you said that you paid $80 for new tubes, but I question what you really got. You said in your second post that the power tubes were Russian 6L6WGCs. Those are most likely Sovteks which sell for about $30 per pair. Good, but not great (in my opinion) tubes. You also said that the preamp tubes were 7025/16s. I don't know what the "/16" represents, but there are no modern 7025s made today. 7025s were basically Mil-Spec, very low noise versions of the 12AX7. NOS versions cost over $100 each (if you can get them) today. A complete set of JJ tubes for your amp is $72 from Eurotubes (https://www.eurotubes.com/cart/index.ph ... gory_id=32).

Once all DC voltages have been checked and tubes verified, you will need to check out signal voltages through the amp using a signal generator and O-scope. The schematic link I provided shows all power supply voltages. DC voltages are shown in rectangular boxes. AC voltages are shown inside the ovals.

You are wise to take the amp to your class as I suggested. It is good to have an experienced person watching over you while probing inside of a live amp where the DC voltages are over 400 volts. You need to learn proper safety procedures when working on a live amp. You may want to read this before proceeding:

http://www.aikenamps.com/SafetyTips.html

This should make an excellent project. Good luck and let us know how things go.

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