Help! I tried to recap my amp!

[docz]

Please there is no need to apologize for giving advice. I am extremely grateful for all the advice and the amount of attention my little project has gotten! It is somewhat touching to see so many eagerly helpful people more than willing to spread their knowledge and experience. This is by far the most including community I have come across.

I try to the best of my (somwhat lacking) ability to follow your advice and study the concepts you present me with, it is a bit overwhelming at times, but utterly exciting and enjoyable!

I'm away on a gig right now, but I will be back in action tomorrow, and I'll give you all an update then.

Oh and a couple of questions: What is a "pop test"? and do I just hook up the end of the cap that connects to the power tube straight to ground?

DocZ

[Andy Le Blanc]

yes temporarily ground the signal input, the bias voltage is on the grid side of the cap,
dont ground G1, A pop test is like touching the end of your guitar cord.

you touch the signal path and make it go pop, the probe tip of a meter
screwdriver, etc.... REMEMBER THERE"S IS HIGH VOLTAGE BE SAFE

You need to know what your touching before you touch it. The pop puts a transient signal thru
the unit a tells you your getting signal to pass.

Simply poking around with your meter probes can tell you alot.

start with the power side and work backwards to the pre.

[docz]

Ok, disconnected the .01uF coupling cap from V1's second triode plate, and connected that end to ground. No hum but I get a faint version of the frying pan noise after a while, it fades out.

Touching pin 1 and 2 on the tube socket makes it pop, touching the side that is not grounded on the coupling cap also makes a pop.

If I hold the pop test probe in position I get a little hum, and after a while the noise gets a tiny bit louder, when I release the hum is imediatly gone, and the noise slowly fades away.

If I repeatedly push the 500k grid resistor the noise gets real bad!

Any ideas?

DocZ

[Andy Le Blanc]

replace the grid resistor, might be time to go to the happy resistor place in the trash.

check the solder joins around it first and also check the socket, might be corrosion or need to re-tension the socket clips

[docz]

Ok, I replaced the resistor, that helped a lot, after that the noise was barely audible, but still there. So I went over the bridge between pin 1 and 2 on the power tube, and the wire connecting to the coupling cap. Turns out the eyelet on the terminal strip was loose, and there was a bit of corrosion on the wire. So I replaced the wire, and moved it to the top of the terminal strip instead of connecting it to the eyelet. Now the noise is still there, but it is so low that I can only hear when not playing guitar, and it is reduced to the volume of a whisper, instead of a frying pan. The amp is much "hotter" now, by that I mean it starts to crunch at about 6 on the volume knob. To me this is cool, but if it is harmful to the amp or a sign that something is wrong I will investigate it further.

One thing that did trouble me a bit was that when tugging hard on the coupling cap loud pops and scratching appeared. Sometimes there was a crackling sound like a firecracker that slowly faded out, after releasing the cap. Does this mean something is loose or the cap is failing?

And how do I re-tension the socket clips? I have a couple that are really loose on the V2 socket.

DocZ

[Andy Le Blanc]

sounds like your on to it....

fenders usually just start break up around 4-5, its ok, tube substitution might get you more gain.

the leads on the cap might be coming loose, look around for bad solders joins
before you replace it.

the socket clips inside the there, you literally get in with something and push it a together.

TWO THINGS TO BE CAREFUL OF....

1: Make sure the amp is un-plugged from the wall

2: MAKE SURE THE FILTER CAPS ARE DISSCHARGED!!!!!!!!

YOU ARE GOING TO TOUCH A VERY DANGEROUS PART OF THE AMP

discharge with a 220k to 1M resistor unless you like the spark and pop with a screwdriver
the "soak" in the cap will return a voltage so leave it hooked to ground
with a resistor until your done and don't forget to remove it before you turn on the amp.

you also need to gentle, age can make those socket bits fragile, dont want to get stuck replacing the socket.

[Structo]

Yes it can be tricky to re-tension really old sockets as the metal can be brittle.
But it is worth a shot and at worse you have to replace the socket which is probably what you should do anyway.

I use a dental pick I bought at an electronics store.

Just bend the socket connector so it grips the tube pin tighter.

You can usually tell how tight a socket is by how hard it is to push a tube into the socket.

[Phil_S]

Socket retention. Like Andy said, make sure caps are discharged and you leave a bleed resistor on them before you try this. I select the size I want from a set of jewler's screw drivers. (I think the Brits call these spanners.) What I don't like is that they are all metal...bzzzzt.... what I like is that they go from quite small to fairly large and they can take the pressure. I use the small ones to just move the metal inside the socket enough to close the hole size some. A little bit of movement goes a long way.

[Structo]

Spanners = wrenches

Yes watch those caps.

[docz]

Ok, I've been poking around and fixing small stuff, lose connections, bad solder joints etc. Didn't quite get that tightening thing right, but at least the connections are not loose when the tube is in it's socket.

I notice that if I turn my guitar up to 10, the amp starts to distort at 6. If I turn my guitar to 7-8 distortion kicks in when amp is on 8. I'm not sure if this distortion is the right kind, sometimes it is a bit harsh and ugly on certain notes. But maybe that is the nature of the beast? I can't seem to get a nice smooth slight crunch....

Here are some sound clips, maybe they will give a better impression than my typing Amp is on 6 for all clips.

[Andy Le Blanc]

Its only a little SE amp, most likely a practice amp, they weren't designed for the distortion.
A low volume clean amp. Now that you got it going you can start to work on it to your taste.

New tubes will help, there is always a point where "it is what it is".
There will be a sweet spot on the volume where it just starts to break up.
Much past there you wont get any more output, just more dirt.

There's a reason they call it dirt.

Taste's change as far as style and genre as far as distortion goes.

Is this the first tube rig you've had the chance to get inside of?

I've spent a of time in fender champs, early on, the only thing I could afford to lay my
hands on besides boxes of blown junk from mil. surplus and yard sales.

[docz]

This is my first experience playing with anything with tubes. And my very first experience inside anything other than a computer. The tubes that are in there now are in fact new, or at least they are bought in 2010

I think I have learned a lot from this experience, the only thing left on the list of todos for this amp, is put in a new power cord socket. I think I'll donate from an old PC power supply.

Thank you for all your help guys, this has really been a great experience, and I will probably bother you with a lot more questions once I source the parts I need for my next project.

DocZ

[Andy Le Blanc]

PM the fellows on the pcl86 thread..... for more info on parts where you are.

[Structo]

Doc sounds like you have the hum and noise problems fixed.
Sounds good for a little amp.

If you want to give it some balls look up a Tubescreamer, they can really wake up a small SE amp.

And, now that you are in the land of tubes, maybe think about building a bigger, better tube amp that has the tone you have in your head.
Nothing more satisfying than playing a good sounding tube amp that you have made.

The knowledge you have gained from this forum in fixing your old amp is a great investment and starting point for you to do more.

[Phil_S]

Nice work, Doc! You're done!

See if you can build an amp from a kit. Keep searching. You'll eventually find what you need.