SF '76 Fender Deluxe Reverb question

[hardie775]

I just picked up a '76 Fender deluxe reverb yesterday. got it home and couldn't turn it off I was so happy. When it wasn't powered up, I was thinkin about it. Anyway, today I started really running it through it's paces and I found that when I run any pedal through the vibrato jacks, I get alot of unwanted noise. True bypass or not, (well, I've only run a malello 616 and a analog alien fuzz bubble.) But I also got excessive noise with just a Boss TU2 tuner. Though, without any pedals, the noise is practically non existant. Through the main jacks I get no unwanted noise, just with pedals on the vibrato jacks, with or without the vib/rev functions on or off. Is this standard?
Appreciate ya'lls feedback here

[alnicopu]

When you say its "practically non-existant" without any pedals in the vibrato input does that mean it is still noisier than the normal input?

First thing I would do is eliminate a tube issue by swapping the vib and norm input preamps (V1 and V2) and see if the problem moves with the tube. If that doesn't do it, try subbing the rest with known good tubes.

Also, if its all original, a cap job is in order. I check all resistors for drift, when I'm performing a cap job, and replace the ones that are out of spec. Doesn't take long and you can check them all in circuit. I can think of at least 2 amps I repaired that had plate load resistors that had drifted upwards of 1 meg and found them both this way before I actually started trouble shooting.

BTW, When I retire, I'm going to open an amp repair shop next to a Chiropractors office and price this service as my "holistic" repair package. Maybe even hang crystals over my repair bench. Gotta make sure everything is healthy before trouble shooting.

[hardie775]

Glad you caught that, "practically non existent". Yes, it is a bit noisey-er than the normal input, even without any pedals. there is a slight "hum", which intensifies, x10 with a peddle in line. Still sounds way sweet, without the pedals that is, and I thought a tube might be the issue. Suppose to have had a relatively recent cap job. I've got a bunch of extra tubes here too, so I'll follow your suggestions here alnicopu, but am I to believe that when I get this sorted out, I should still be able to throw a fuzz pedal in line with the vibrato input with out any issues? That would be nice.

[alnicopu]

Originally Posted by hardie775

Glad you caught that, "practically non existent". Yes, it is a bit noisey-er than the normal input, even without any pedals. there is a slight "hum", which intensifies, x10 with a peddle in line. Still sounds way sweet, without the pedals that is, and I thought a tube might be the issue. Suppose to have had a relatively recent cap job. I've got a bunch of extra tubes here too, so I'll follow your suggestions here alnicopu, but am I to believe that when I get this sorted out, I should still be able to throw a fuzz pedal in line with the vibrato input with out any issues? That would be nice.

Most people I know don't use the normal channel. So yes, no more noise than is inherent in a fuzz pedal.

That being said, I had a Holy Grail reverb pedal I use to use with a vibro champ. Hated the thing, way too "hissy" when engaged. I also had a B.K. Butler Realtube overdrive that was nothing but noise when engaged. So a lot depends on the pedals themselves.

Interesting article about pedals and buffering and against true bypass.

http://www.petecornish.co.uk/case_ag...ue_bypass.html

[hardie775]

Weirdest god dam thing. Just went and replaced the 1st pre amp tube and the hum was not there any longer, however, with a pedal in line, while off, sound went through nice, with pedal on, no sound. Tried another pedal with the same result. I'm lettin it cool and am going to try a different preamp tube in this position.....sound right?

[hardie775]

Now with a pedal inline in the normal output or the vibrato output, I get silence with the pedal activated. Turn it off and I get sound. Switch cables. pedals and even put the original tube back in, still the same. Can't figure out what the heck happend here.

[alnicopu]

Originally Posted by hardie775

Now with a pedal inline in the normal output or the vibrato output, I get silence with the pedal activated. Turn it off and I get sound. Switch cables. pedals and even put the original tube back in, still the same. Can't figure out what the heck happend here.

How does it sound plugged straight in, no pedals?

[hardie775]

Bad tube. Switched the V1 and V2 and it's perfect in vibrato now. While I was workin on it I had a spaghetti like effect with cords at my feet and I'm ashamed to say that I had the in line pedal hooked up ass/backwards. appreciate the help. she's even that much sweeter now.

[alnicopu]

Originally Posted by hardie775

Bad tube. Switched the V1 and V2 and it's perfect in vibrato now. While I was workin on it I had a spaghetti like effect with cords at my feet and I'm ashamed to say that I had the in line pedal hooked up ass/backwards. appreciate the help. she's even that much sweeter now.

Good on ya. It sounded like a pedal issue thats why I asked about plugging straight in. Takes the pedals out of the equation.

BTW If it makes you feel any better. I was trouble shooting a missing voltage on one of my machines at work. I have those little doo-dads that meter lead ends plug into to make them able to clip onto test points on circuits boards. So, I'm looking for a missing 24vdc. The machine is on, no voltage. Well this output feeds about 10 other 24vdc inputs, so I'm disconnecting them 1 at a time thinking that when I find the faulty circuit and my meter jumps up to 24vdc. That technique has worked for me for about 25 years now. After about a 1/2 hour and another cup of coffee I happen to notice my doo-dad has unclipped and is resting, with the plastic insulation, right up against the test point.

Moral of my (long) story? Never panic, never let 'em see ya' sweat, and make em think your a friggin' genius for fixing it.

[adjason]

"I had the in line pedal hooked up ass/backwards." sounds familar to me too: who hasn't been there? congrats on a sweet amp-that is one I would love to own

[alnicopu]

Originally Posted by adjason

"I had the in line pedal hooked up ass/backwards." sounds familar to me too: who hasn't been there? congrats on a sweet amp-that is one I would love to own

I had a NS-2 noise suppressor pedal a few years back. To use it properly takes another cable or 2. Has an input, output, send and receive jack(s) on it. I bought it used so it took me about 30 minutes of googling a manual and flip-flopping cables to make it work only to realize I didn't want it. So yea, I been there.

[JDRNoPro]

Originally Posted by hardie775

I'm ashamed to say that I had the in line pedal hooked up ass/backwards.

Laughed when I read this..........not laughing at you, but with you - yeah, I've been there too.

That 76 SFDR should be a sweet machine - love my 74. And, although it may sound good as is, get the cap job done if it hasn't been done - you won't regret it!

[hardie775]

It's been re-tubed and re-capped, new reverb pan and a Weber Ferromax 12F150 added. But how about the blackface mod. Is this a good choice? Will it make that much of a differnce? And if so, which kit would ya'll recomend. I've seen a couple for sale on ebay.

[Ringo]

If it sounds good I'd leave it alone and play it, you might do the mods and find that you liked it better stock.
The SF DR's I've played usually have more clean headroom than at BF DR , which is not a bad thing IMO.

Here is some free info if you do want to try some mods

http://acruhl.freeshell.org/mga/main/sf_bf_mod.html
http://blueguitar.org/schems.htm

[telex76]

DR didn't change as much between Blackface and Silverface as the bigger amps.

You can Blackface it (I did my 78) but it won't be a big difference. Most change is in the phase inverter section.
Other than that, just a difference in value on a few resistors and 1 or 2 small caps, and removing the 1200 pico farad suppression caps (some amps will get an oscillation after removing them, some won't. If it does, you'll have to clean up the lead dress).

[hardie775]

OK, to get back to my original issue here, I'm still getting too much noise in the vibrato input jacks. Even with no pedals in line, there is more noise than the normal input jacks and with pedals in line, it's better having switched tubes, but still too much hiss and oscillating type sound.....Here's what I'm thinkin. I don't trust these tubes too much. I've got a sweet matching pair of 60's Motorola/RCA 6V6 power tubes I'm going to put in. Currently I've got EH 6V6's, with GT preamp tubes. I want to replace them all. I don't trust these cheap groove tubes. What's the best bang for my buck here? There alot of reissues out there, Mullard, stovek, Tung Sol, or I can even spring for some good NOS preamp tubes. I'd appreciate what ya'll think would run nice in this amp with these NOS RCA 6V6's. Also, Ive got a NOS GE 5AS4A rectifier tube. Will this run well with these tubes. With the new rectifier tube, I'll get the plate voltage and set the bias, but before I go here, I'd like to get the preamp tubes together.
appreciate your thoughts here.

[hardie775]

Guess I need a GZ34 rectifier

[alnicopu]

Try swapping V4 out with V1. V2 and V4 are the preamps for the vibrato channel.

Sorry it took so long to get back to you, I just got back from Seeing Tom Petty here in Atlanta. Great show. His wall of amps was like an advertisement for Fender. He even had a little tweed champ (or princeton) sitting right next to what looked like a Princeton Reverb. I spent the money on great seats but not close enough the amp names on the faceplates.

[telex76]

Originally Posted by hardie775

Guess I need a GZ34 rectifier

What's in it now, a 5U4? That's what it should say on the tube chart.
The previous owner of my 78 DR had put in a 5AR4/GZ34 and the plate voltage was way, way too high. I put a 5U4GB in and the plate voltage was back where it should be (still a little on the high side but not too bad).

[hardie775]

Thanks guys. Nice show alnicopu? I saw Tom Petty and the Heartbreakers as Bob Dylans band at Rich stadium in buffalo back in the mid '80's. The Greatful Dead was the opening act. Great show. I've got floor seats to Rodger Water doing The Wall at the Toyota Center here in Houston tomorrow night.....On the floor