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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Wed Jan 08, 2014 8:58 am
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" Just one more thing: there is a 220K resistor (in the 1972 Deluxe) soldered to the tip (reverb). Anyone knows its function and could it be that it has gone bad? "

The 220k-ohm resistor is the grid-to-ground resistor which help set the reverb recovery half of V4B (7025 or 12AX7) idle bias. The 2000 pico-farad cap in parallel to this resistor is a high frequency filter to help keep out high frequency induced instabilities in this stage.

The 220k-ohm resistor MUST be going from pin 2 of V4B to ground. I am not quite sure of your hook-up from the photos. The 2000 pico-farad cap in PARALLEL with the 220k-ohm resistor.




http://www.webphix.com/schematic%20heav ... _a1172.pdf


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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Wed Jan 08, 2014 10:41 am
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@BMW2002Ti - thanks for clearing out the fuction of the 220K resistor and 2000pF cap. Though, I can confirm they are hooked up correctly like you describe: from pin 2 there goes a yellow wire to the tip of the 1/4" chassis (the former "hot" of the reverb RCA of the footswitch). There, at the tip of the 1/4", the yellow wire meets the 220K resistor. This leads us to the 2000pF cap at the "hot" of the reverb pan output. The other sides of both the cap and resistor go to ground.

So in the end, I didn't change anything, I just brought the two footswitch RCA's together in one stereo 1/4" chassis. So still wondering where the "click" sound comes from...


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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Wed Jan 08, 2014 12:45 pm
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I did not look closely for now but I see your wires like the yellow one is too close from the heater green wires . All wire ( not heater ) must be close to the steel chassis

Push yellow wire and green wire on the bottom and /or side of the amp . If you are lucky this fix your "pop".


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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Wed Jan 08, 2014 3:07 pm
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stratele52 wrote:
I did not look closely for now but I see your wires like the yellow one is too close from the heater green wires . All wire ( not heater ) must be close to the steel chassis

Push yellow wire and green wire on the bottom and /or side of the amp . If you are lucky this fix your "pop".


+1

It very well could be something as simple as a lead-dress problem. Otherwise, the reconfigured footswitch jack looks entirely copacetic.

Arjay

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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Wed Jan 08, 2014 4:28 pm
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True 'bout the wires! Just pushed them away from the heaters, as close as possible to the steel chassis, but... no difference, the "click" sound is still there when I push the vibrato knob when the reverb is switched on.

Now I did notice something I didn't mention before: the "click" does get louder with the reverb volume pot higher. With reverb at 10 the "click" is very loud, with reverb knob at 1 the "click" is very silent, not gone, just silent. And like I said before, with the reverb switched off, the "click" sound is just gone. The strange thing is that the "click" occures when pushing the vibrato knob, but somehow the "click" is related to the reverb setting...

Some new theories?


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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Wed Jan 08, 2014 6:43 pm
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Did you check the solder points on the pots? I take it that this "click" is heard when you touch the Vibrato SPEED or INTENSITY control knob. Correct?

There is a 100k-ohm resistor on the SPEED pot. It goes from left tang (chassis out of cab, upside-down, looking from back of unit to front) to the pot metal housing. Maybe this resistor has a bad solder point or is cracked.

Check all the solder points to each pot. May want to resolder them. If the amp still makes the same noise --- you could have a bad pot.

Good luck! Keep us informed.


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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Wed Jan 08, 2014 8:59 pm
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I apologize for being somewhat late to this thread, but I have the following observations and questions:

Observation 1: The first one is what Stratele52 mentioned early on and is I find it curious that you have to re-solder the foot switch connections but not the reverb input and output connections every 10 gigs. These connections are immediately next to the foot switch connections, so I don't see why one set is a problem and the others are not.

Observation 2: You have a nice, shiny, new quarter inch jack in the chassis, but the plug in the pictures is not. How good of a ground connection are you getting from a sleeve connection that "floats" in that arrangement, given today's manufacturing tolerances. I'm all for simpler is better, but sometimes we overlook things that perhaps we shouldn't.

Lastly, I have a simple question, because I haven't been able to determine it so far, does this "click" occur when turning the vibrato on or off, or both?

I'm a "newb" here, and generally not that sociable when it comes to communicating via the internet, so please don't take this the wrong way, and I hope I haven't led you down any rabbit holes.

Thanks,
vinyl

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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Thu Jan 09, 2014 1:06 am
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OK... to get the facts straight... are we talking about "clicking" noise when tapping the Vibrato control knob(s) or when tapping the Vibrato foot switch?

If it's the foot switch, have you tried a different foot switch?


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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Thu Jan 09, 2014 3:05 am
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As vinyl write try a ground wire at the 1/4 jack to the chassis ground , Some photo of you solder/ work at the 1/4 plug too. The 1/4 plug you use is a very old model . I have some at home and sometimes they don't fit properly on the jack , and don't make good contact

Did you do any other work on the amp when you put 1/4 jack ? Move some wire with the drill bit.... anything you do in the amp you forget to tell ?

Show us a new photo of the green and yelow wire how they look now .

And photo with the plug IN the jack


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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Thu Jan 09, 2014 3:24 am
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@vinyl - I think you misred something, I never have to resolder the reverb's in- and output RCA jacks, I always have to resolder the RCA jacks at the end of the footswitch's cable because every gig I take out my footswitch the RCA connections get worn out a little bit more until they break. Imagine one would use such an RCA cable as a guitar cable you will understand the "cold" side will break very fast.

Concerning the plug, I already used several plugs, the problem stays the same, even with a brand new Neutrik plug...

The vibrato "clicks" when I push it on and off (please read the complete thread before asking such questions, I already described all these details), and this only with the reverb switched on.

@BMW2002Ti - no, the "click" doesn't occure when touching the pots, it only happens when I switch the vibrato on and off via the footswitch button. Nevertheless, I chopstick-checked for bad solder joints at the pot, but they turned out to be good.
I already used another footswitch (the same Fender switch from another Fender amp), but the problem stays the same...

@Stratele52 - I will take some new pictures this afternoon. And, no I didn't do anything else with the amp. The only thing I did was installing the 1/4" chassis and connecting it. I also measured the continuity of the 1/4" ground and it grounds perfect to the amp's chassis.

I also did a test: grounded the footswitch ground directly to the amp's chassis, just to eliminate a ground problem. The "click" was still their when hitting the vibrato button...

Has anyone seen my note about the "click" sound becoming louder when I turn up the reverb's volume pot? Any idea what this could mean?


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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Thu Jan 09, 2014 3:45 am
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bram9206 wrote:

@Stratele52 - I will take some new pictures this afternoon. And, no I didn't do anything else with the amp. The only thing I did was installing the 1/4" chassis and connecting it. I also measured the continuity of the 1/4" ground and it grounds perfect to the amp's chassis.

Ground might be good but Ohmeter test did not say all , try a wire .

I also did a test: grounded the footswitch ground directly to the amp's chassis, just to eliminate a ground problem. The "click" was still their when hitting the vibrato button...

Has anyone seen my note about the "click" sound becoming louder when I turn up the reverb's volume pot? Any idea what this could mean?

This do not mean a reverb problem , IMO its is normal . Reverb give more "headroom"

Chopstic a solder is only a 25% good test IMO . You must look ( need some experience and knowledge) to see suspicious solder or reheat solder.






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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Thu Jan 09, 2014 5:33 am
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I have a little break through! Someone studied the 1972 Deluxe schematic and concluded this:

It's a kick-start trem oscillator.

When "off", there's -60V applied to the AX7 grid. This holds it OFF.

When you switch "on", this -60V goes to zero. The 60V transient "kicks" the oscillator into life.

Most other ways of killing the trem, there is a long start-up because of the long time-constants in a low-frequency oscillator. This kickstart technique actually starts the first quarter-cycle of oscillation, so it starts-up at nearly full output and with consistent phase.

So we have a 60V switch-on transient. Meanwhile over in the reverb we are switching the tank output. Which is typically 10mV. 6,000 times weaker than the trem-start kick.

So even 1/6000 of sneak current or stray resistance or capacitance between trem and reverb WILL make a loud sound.

I think you have found why this amp used two connectors.

I don't see a no-drawback way to cure this.

Perhaps a JFET on the reverb point, turned off/on by a -10V feed from the reverb pedal switch. This also gets the reverb signal out of the pedal cable, reducing hum pickup.


So, I now changed the plug again to its former state of being: the old RCA plugs, everything soldered back to how it used to be before the mod.
So now I'm back at the very beginning and I still have a "click" sound, BUT it is a bit different and if I remember well it was there too before I started working on the Deluxe. Here's a detailed description of the current "click" sound:
with reverb switched on: still a "click", but it is much more silent now (I could live with it in a live setting, but couldn't live with it for studio work). Again the loudness of the "click" depends on the volume of the reverb.

Also what is different now, I ONLY have the "click" when I switch the vibrato ON. Whereas with the 1/4" plug I had it both when switching on AND off. Now I don't have a "click" when I switch the vibrato off.

Anyone? I must say the footswitch is a reissue footswitch and I've been told the switched in there are pretty cheap. Maybe that is it?


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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Thu Jan 09, 2014 5:58 am
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Didn't you say you tried another foot switch and still got the same "clicking" noise? That would most prolly rule-out the foot switch. As I would expect similar noise from whatever amp the test foot switch came from --- if I gather correctly.


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Post subject: Re: Fender footswitch: problems replacing old RCA plugs with
Posted: Thu Jan 09, 2014 6:19 am
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bram9206 wrote:

So now I'm back at the very beginning and I still have a "click" sound, BUT it is a bit different and if I remember well it was there too before I started working on the Deluxe.


Anyone? I must say the footswitch is a reissue footswitch and I've been told the switched in there are pretty cheap. Maybe that is it?


You must say that first , this change everything in trouble shooting
This happend so many time on forums .People forget to tell all the story. You are not the first one. It discourages me to help.

1-Your amp may have a "clik" whatever you do .

OR

2- There are many quality and specs on switch. With proper specs ,some may be quiet , some not

May be some caps between switch's contact may remove the "clikc". I don't know value of the cap.


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