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(@demoetc)
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Joined: 19 years ago
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You guys are hardcore :)

Glad you're all on the board with us!


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(@hyperborea)
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Joined: 15 years ago
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Topic starter  

Ok, that's the amp finally re-"capacitated". :D

There was a big 2 month delay from Weber in getting the caps out to me. They were having big problems with their web server, billing system, and somebody there was pretty lax about letting me know that the billing system hadn't saved my payment info and that they needed me to send it again. Top that off with plenty of jobs around the house that needed done and there was a big delay.

Anyways, the re-cap job is done. On Sunday I replaced the power filter cap cans and put on a grounded plug (somebody in the past cut off the ground prong on the plug). Thanks to RaceTruck for the suggestions on holding down the cap cans - I ended up using some tin duct strap that I had lying around. So, I fired it up for a test and it sounded lots better but there was still a low volume motor boat sound.

Last night I went through it and replaced all of the rest of the electrolytic capacitors and the motorboating is gone, the reverb is really rich sounding but the amp volume is low and there's a fair amount of hiss that varies with the volume level. Probably the preamp tubes. I've ordered a full re-tube set from EuroTubes and they should be here by the end of the week. On EuroTube Bob's advice I ordered a current balanced 12AX7 for the phase inverter (an extra $3) and a matched pair of EL-84 power tubes (no extra charge).

I might think about a speaker replacement but I'll hold off until I get some time with the amp though most owners do seem to swap out the speaker. There's a place not too far from me (SVVVA - South Valley Vintage Amps) that has a good selection of speakers in cabs to try out with your amp and his prices are comparable to what others charge so I can always go try a few. The Celestion Greenback and the Weber Bluedog seem to be favourite pairings with the old Traynor combos.

Thanks to all for your help. I'll see about getting a picture up of the "new" innards.

Pop music is about stealing pocket money from children. - Ian Anderson


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(@ricochet)
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Joined: 19 years ago
Posts: 7850
 

Cool!

Motorboating is often due to insufficient capacitance in the filter nodes connected to the plates of various stages of an amp (dried up electrolytics being a common problem), or in the design of an amp where there's insufficient isolation between nodes by intervening resistance or inductance between the caps. Causes a low frequency feedback through the power supply.

"A cheerful heart is good medicine."


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(@hyperborea)
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Well, here are some pictures of the updated innards. The new cap cans are the big white tubes - Weber cap cans. You can see the pipe strapping that I used to fabricate a clamp for them. The other new electrolytics are the small (and in one case not so small) black tubes along the eyelet card. Those are also Weber.

Pop music is about stealing pocket money from children. - Ian Anderson


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(@ricochet)
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Joined: 19 years ago
Posts: 7850
 

Very nice!

I've used that same pipe strapping to hold filter caps in homemade amps. You can also buy conduit clamps of appropriate size, and places like http://tubesandmore.com/ sell proper clamps for cap cans.

"A cheerful heart is good medicine."


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(@hyperborea)
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Very nice!
Thanks. My soldering skills were a bit rusty and I did burn my right (offhand) thumb. There was one particularly troublesome solder joint where there were three wires, two capacitors, and a resistor coming in to one eyelet. It took forever to heat up enough to liquify the solder to get the caps out and the same to get it hot for a good solid joint. Too many wires were drawing the heat away.
places like http://tubesandmore.com/ sell proper clamps for cap cans.
I looked there and other places and they all seem to only have straps where the mounting screw will go in parallel to the axis of the cap can and not tangentially as the cans in the old Traynor are mounted. Did I miss those?

Pop music is about stealing pocket money from children. - Ian Anderson


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(@ricochet)
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They have had the old clamps with the tangential mounting screws, but I haven't looked in a good while. Triode Electronics used to carry stuff like that, too. Haven't looked there in a while, either. Angela Electronics is another dealer I've bought musical electronic stuff from in the past. There are a bunch of discount surplus electronics sites that you can find all sorts of stuff on, no telling what. The Electronics Goldmine is one I've patronized a good bit. http://www.goldmine-elec.com/ And Mouser's got just about everything.

"A cheerful heart is good medicine."


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 vink
(@vink)
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Joined: 17 years ago
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There was one particularly troublesome solder joint where there were three wires, two capacitors, and a resistor coming in to one eyelet. It took forever to heat up enough to liquify the solder to get the caps out and the same to get it hot for a good solid joint. Too many wires were drawing the heat away.

What's a good solution for that? I've had this problem, and I thought I just had a soldering iron that's too weak. Is it best just to be patient and wait for it to heat up enough?

(Most recently, I had this problem connecting to the input jack on my strat. I had a big soldering gun, I got that out and it worked fine, but I wasn't sure if that's what I should have done ..that one is kind of designed for cables and such, I think).

--vink
"Life is either an adventure or nothing" -- Helen Keller


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(@ricochet)
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Joined: 19 years ago
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Have a bigger soldering iron handy.

There's no substitute for adequate heat. Try not to burn anything up, of course.

"A cheerful heart is good medicine."


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(@vink)
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Joined: 17 years ago
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Have a bigger soldering iron handy.

There's no substitute for adequate heat. Try not to burn anything up, of course.

Ok, thanks!

--vink
"Life is either an adventure or nothing" -- Helen Keller


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(@hyperborea)
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Joined: 15 years ago
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Topic starter  

There was one particularly troublesome solder joint where there were three wires, two capacitors, and a resistor coming in to one eyelet. It took forever to heat up enough to liquify the solder to get the caps out and the same to get it hot for a good solid joint. Too many wires were drawing the heat away.

What's a good solution for that? I've had this problem, and I thought I just had a soldering iron that's too weak. Is it best just to be patient and wait for it to heat up enough?

Yeah, that's what I did and I was running a 48W soldering station.
(Most recently, I had this problem connecting to the input jack on my strat. I had a big soldering gun, I got that out and it worked fine, but I wasn't sure if that's what I should have done ..that one is kind of designed for cables and such, I think).

Some plugs and jacks can be really hard to solder depending on the design. If the soldering point is a big piece of metal attached to a bigger piece of metal then you have this massive heat sink that may drain away the heat almost as fast you add it. I've seen some right angle phono plugs from Radio Shack where the soldering pad is big and just about directly connected to body of the plug. It took forever to heat those up enough. In the factory where they make cables and do other soldering they use a big wave solder machine that heats it just about instantaneously to many hundreds of degree and it's soldered really quick before the heat can be conducted away.

Pop music is about stealing pocket money from children. - Ian Anderson


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(@hyperborea)
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Last night I went through it and replaced all of the rest of the electrolytic capacitors and the motorboating is gone, the reverb is really rich sounding but the amp volume is low and there's a fair amount of hiss that varies with the volume level. Probably the preamp tubes. I've ordered a full re-tube set from EuroTubes and they should be here by the end of the week.

Well, that's the new tubes here and they're in. The volume is now good but there's an annoying crackling sound coming through the speaker that takes some time to come on. When the amp is started up cold you get a couple of minutes before it starts and then a continuous crackling sound. The crackling is unaffected by volume or tone controls but is affected by tremolo and reverb. The tremolo is a bias wiggler so that is pretty much at the end of the line and everything gets affected by that. So, it's likely somewhere between the tone stack and the reinjection of the reverb signal or maybe in the reverb circuit. Also, if you switch to standby while the crackling is happening then you get a loud click sound through the speaker.

There is some hiss which you can only hear when the volume gets up to 9 or 10. This is probably there at lower volumes too but can't be heard over the crackling. This is likely to be normal hiss.

Any ideas on the crackling? Is this the plate load resistors? Perhaps the plate load resistor on valve 1B (the half of the preamp tube after the tone stack and before the reinjection of the reverb signal). Or maybe the plate load resistor on the post reverb tube half?

How about the B+ decoupling resistors? That might explain the crackling when the standby is switched.

I've tried tapping all of my recently soldered joints with a chopstick and this has no effect on the crackling.

Thanks for any help.

Pop music is about stealing pocket money from children. - Ian Anderson


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(@ricochet)
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Joined: 19 years ago
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Could be a plate load resistor or resistors, could be a cathode resistor too. (Could be a pot, for that matter.)

Carbon comp resistors deteriorate over time. Not only do they go crackly, resistance values change. Any that are suspect, just change 'em out for metal films and be done with it. I really don't like carbon comps, and their supposed "mojo" is just that hissy, crackly, frying bacon sound that comes from old amps with deteriorated resistors.

"A cheerful heart is good medicine."


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(@hyperborea)
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I think that most of the resistors in there are carbon film and not carbon comp - comp are usually smooth cylinders and the film have a curvier shape with bumps at each end. The amp is from 1977 so that's entirely possible. There appear to be only two carbon comp resistors and those are in the B+ decoupling line - a 470 ohm 2W and a 22K ohm 1W. Those are probably worth replacing for safety reasons alone - probably with flameproof.

Now, another interesting fact, as I was digging around looking for the various plate load resistors I found that the 10 nanofarad (.01 uF) ceramic disc coupling cap from the reverb section is microphonic. Tap it with a chopstick and you can hear the tapping coming out through the speaker. Probably should replace it (and the plate load resistor for the post-reverb tube half since they share the same well used eyelet).

Now, could that be the source of the noise? It's in the right place in the circuit - after the tone stack and before the reverb pot.

Thanks again for any help.

Pop music is about stealing pocket money from children. - Ian Anderson


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(@ricochet)
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I'd certainly replace it if it's microphonic.

"A cheerful heart is good medicine."


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