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Post subject: Hotrod Deville 212 sounds disorted even on clean
Posted: Thu Jan 26, 2012 2:31 pm
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I got this amp (unknown age as it doesnt have a ser # sticker) used for $200.00 as it had a bad input jack. I replaced that, and it was fine, but now it sounds distorted even thru my tele at volume around 3-4. My blues jr gets way louder before breaking up now.

Where do I start to. Diagnose this. I have a multimeter and am not afraid to jump right in.

I sure will appreciate any help!!

Doug


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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Thu Jan 26, 2012 4:25 pm
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First, check all solder joints, especially on valve sockets and "big" white resistors.
8)
To know if the problem is in the preamp or the amp, use the preamp output that you connect on your blues junior for trial. You can also inject signal from a preamp in Amp In. With those trials, you will know in which area is the failure.
8)

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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Thu Jan 26, 2012 5:10 pm
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kawinut,

Have you ever worked on a tube amp before? If not, I suggest you read this:

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

You might also want to review this before you "jump right in".

http://support.fender.com/schematics/gu ... ematic.pdf

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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Thu Jan 26, 2012 7:20 pm
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Thanks for the input, guys. I'll do my research, tippee toe on in, and let y'all know how it works out.


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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Thu Jan 26, 2012 10:10 pm
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kawinut wrote:
Thanks for the input, guys. I'll do my research, tippee toe on in, and let y'all know how it works out.


Good plan. Come back if you need help. There are several of us here that know a lot about amps and are always willing to help others, but with an emphasis on safety. Some have learned the hard way. :lol:

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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Fri Jan 27, 2012 8:22 am
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LOL. Forgive my assumement, butthis is one of the several problems I've had with the Hot Rods I've owned. I agree first thing you should check out is the tubes. First;isolate if its in the preamp or power section. This is easy; you do it by plugging your guitar into the "preamp in" partof the "FX LOOP". It will be quiter because you're not running through the preamp, but; if you hear the disortion still when plugged into the preamp in; the problem is in your power section (where id bet $100 the problemlies if history is an judge). Then you decide if its the tubes, and while probably 80% of proklems like these arise from the tubes, on the HR series, its usually something else. Its going to be either the plate load resistors of screen filter resistors. If you're able to get the board off enough to see the back of it (after draining the excess electricty in the filtar caps; unplug the amp, turn it on &leave it for 10 minuts. Then take a piece of wire, preferably one w/ an alligator clip on one end to clamp onto the cchassis, but its not becessayr. You want to touch 1 end to the chassis for a ground, then take the other end and touch the positive leads on the filter caps, they're the large ones the look like grey shotgun shells.)
If/when you can see the back of the main board the one all the control pots are attached too; take a look at where the twolarge grey rectangular reistors are. These get hot as hell, and sometimes cause te solder to come loose, sometimes they will actually scortch the board. You're going to have to use a multi reader and chech if they show ressitance AND continuity.

The prolem most liekly is the plate load resistors for the phase invertor. The first 1 to check, and the 1 that goes the most is the 82K resistor (R57). Sometimes you can tell by just looking at it; it may have actually brak open, though most of the time this happens internally. When this happens it gives you "crossover. Distortion", thedistortion you're hearing if it is indeed a problem with the power section. A good thing to do is replace ALL the plate load resistors (Fender apparently had a bad batch of these resistors at one point in time). you'll need five; 1/2W 100K resistors, and one 82K(for the one I spoke of earlier; R57.

R57 & R58 should be replaceed together even if its only one that's bad; they're easy to fid, they're right next to V3.

Good luck


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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Fri Jan 27, 2012 3:54 pm
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I have a 410 DeVille Gen 3 for gigs and practice at home.
I use a 212 DeVille Gen 1 at our rehearsal hall.

The old DeVille has always sounded bad and got progressively worse so I took it home after rehearsal last night and put in all new tubes today.

It sounds GREAT now.


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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Tue Jan 31, 2012 6:23 am
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Been away for a couple of days, and have also been putting gibson p/us in an epi LP, and that's another story... This am I drained the caps, (showed zero on my multimeter) and plugged my American Deluxe strat with texas special p/us into the Pre Amp OUT. No sound in any channel. Then plugged into Power Amp IN, and though not loud, it didn't seem to break up. All the tubes are marked Fender (not GT) and are Slovtek. I reckon they're pretty old. My 10 year old blues jr has groove tubes and still sounds killer.

I also patched the input from the BJ to the power amp in, and just got feeble static, but patched BJ input to HRD Preamp out, and it sounded good.

So, the next step seems to be a pair of 6L6s, no? In my cursory research of these, seems there's a lot of options. Are GTs a safe bet. Thanks again for all the help!


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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Tue Jan 31, 2012 7:13 am
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A couple of missteps. No need to drain the caps unless you are shutting the power down in the amp to disassemble or test. If you are going to have power on the amp, draining the caps is a waste of time as they recharge when the amp is powered on.

You got it backwards, the "Preamp Out" is an output, not an input. You can plug your HRDvl "Preamp out" into the BJr input jack to test the preamp section of the HRDvl (although the HRDvl output section will still work, so you will still have sound from the HRDvl). The "Power Amp In" is an input, you can plug your guitar directly in here and it will bypass the HRDvl preamp section. This is what Tis-san describes (good advice).

You cannot "patch" the BJr input or output into the HRDvl, not sure what you are thinking here, you are connecting two inputs together, and nothing would happen there.

BTW, there is no such thing as a "Preamp In" on the HRDvl or BJr. Some people don't know what the heck they are talking about, and their feeble advice should be ignored. :roll:

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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Tue Jan 31, 2012 8:53 am
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in college course selections I went right past Engineering to English, and I continue to pay the price. From what I've tried and read, I'll try some new 6L6s if I can find some locally. Otherwise I'll have to go to Richmond and (yikes) GC.

One of my questions remains: Are there significant differences between russian, chinese, slovak tubes? I appears from MF site that all sorts are available. Am I safe with any GT branded tubes?

Continued, humble thanks y'all..


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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Tue Jan 31, 2012 9:03 am
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The fact that you plugged into the Power Amp In and didn't have the same distortion might mean that the problem is in the preamp section and possibly a bad tube, as you are only using the output section of the amp, which is the PI and output tubes.

The differences in tubes can be in both sound and/or quality depending on brand or type, and you might choose the tube to get the certain sound that you want. Even GTs have different ratings for output tubes, a color/number rating. Whenever changing output tubes, the bias should be checked and set for the particular type that you are using. If the bias is set correctly for the output tubes that you have, and you use the exact same brand and rating for replacement, then the bias should be good with the new tubes. Bias is not a concern when changing preamp and PI tubes.

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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Tue Jan 31, 2012 4:03 pm
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Quick update: I swapped the 12ax7s from my BJ into the preamp stages of the HRD, and no improvement. Next step is some research into the right 6l6s, which will have to be ordered. If that don't fix it, I'll dig behind the board. There was no visual evide ce of burning, but more to be learned....


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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Tue Jan 31, 2012 5:23 pm
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shimmilou wrote:
The fact that you plugged into the Power Amp In and didn't have the same distortion might mean that the problem is in the preamp section and possibly a bad tube, as you are only using the output section of the amp, which is the PI and output tubes.


I wouldn't jump to that conclusion too quickly. Don't forget that there is a significant difference in the output level of a guitar pickup compared to the output level of the preamp driving th phase inverter. I am not surprised that kawinut experienced a low level sound without breakup. The pickups by themselves do not have enough output to drive the phase inverter.

I would suggest using a clean boost if one is available, plug the guitar into the boost and the boost into the Power Amp input of the fx loop. Turn up the boost and see what happens. Most boosts supply 25 dB or more of gain which should be more than enough to drive the phase inverter.

You could also try plugging the preamp out of the Deville into the guitar INPUT of the BJr. You would have to juggle the volume controls on both amps to keep from overloading the BJr (you want the Deville preamp to distort, not the BJr), but that would be a pretty good indicator if the preamp tubes in the Devile are flakey.

Good luck.

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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Tue Jan 31, 2012 6:04 pm
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Kawinut (love that nom-de-plume :wink: Did you try replacing all of the 12AX7 with no luck? If so, try this crazy dumb trick (I assume you have no spare 6L6GC's). Pull one 6L6GC and listen to the tone. Then, replace it and pull the other. Try one 6L6GC in one socket and one in the other. Flip-flop tubes. Any difference? Kinda quick-&-dirty way to find a grossly bad output tube w/o subbing in a good one. Yes, the amp will work with one tube. Albeit with less volume plus worse bass & treble response. But, you should hear output.

If the tone is equally funky with either tube pulled or moved (the same funky tone). It may not be the 6L6GC's. Save you some $$$ and time. I have rarely seen both output tubes be equally bad. If this is the case, prolly need to dive into the guts of the amp. Maybe best left for a tech. However, if one tube is bad. Get a new matched pair. BTW... did you check the idle bias of the output tubes? Could be they are getting a bit too "cold" as they age. And you are dropping into crossover distortion area.

Anyhow, good luck with your amp.


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Post subject: Re: Hotrod Deville 212 sounds disorted even on clean
Posted: Tue Jan 31, 2012 7:15 pm
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Here's the tubes I put in mine:

http://www.guitarcenter.com/Sovtek-5881 ... 1387424.gc

http://www.guitarcenter.com/Sovtek-12AX ... 1387423.gc

$27.99 for a pair of power tubes and $9.99 each for preamp tubes is pretty reasonable.


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