Jet City with cold joints - How hot can you go?

[LooseChange]

I have one of those Jet City (Cheap Soldano's) on my bench with some cold solder joints.

The amp is built on a PC board with PC mount sockets. I can't seem to get a shiny solder joint. I heat the board trace and the socket pin together and add solder. The joint cools off and goes cloudy.
I let it rest remove the solder and try again, keeping the iron there a bit longer.
Can't seem to get the joint to look right.

I've got the iron set at 725 degrees now and I'm afraid to go up any higher as I might lift the trace.

Suggestions, please??

[LooseChange]

I should add... I've soldered many times and I feel I am very experienced with the soldering process.

[birt]

don't just reheat it. remove the solder and add new solder.

[stratele52]

I agree with birt, IMO all the old solder must be removed before soldering. Probably the old solder contaminates the new solder you put ?

[John]

I let it rest remove the solder and try again,

I think he's doing that.

[Heinz]

The PCB was probably made with lead-free solder. It never becomes shiny and will always look like cold solder joints. For lead-free soldering you have to use higher temperatures (450°C I was told, you do the maths ) than with regular solder. I would suggest the same as everybody else. Remove the old solder carefully with a vacuum pump and replace it with your regular solder.

[Tiny_Daddy]

Probably some early and crappy version of high-tin lead-free. A solution is to touch up with 50/50 solder. Won't be shiny though.

[LooseChange]

Yeah. I removed the solder and replaced. No go.
Thanks!

[eleventeen]

Maybe you need some externally applied flux...usually applied from a plastic bottle with metal needle-type dropper.

[The_Gaz]

If you can, post a picture of what your "cold joint" looks like.

[DummyLoad]

use lead free solder. lead free solder doesn't shine like Sn/Pb solder. don't get the PCB too hot, don't roll the iron tip on the traces.

made in china.  

--DL

[LooseChange]

I do not use lead free solder.
I will try to get a picture up.

I really need to get some of that flux.

Thanks!

[Boots Deville]

I really need to get some of that flux.

Radio Shack might still carry it.  If not, let me know.  I have a tube you can use.

[kagliostro]

+ 1 for Flux use

Kagliostro

[stingray_65]

I like these pens better than the drops

Last time I bought mine from mouser for $5

the 951 is what I use and last a long time till you forget the cap.

We used them at my shop to solder the tabs on rear windows for the defroster.

951 is a no clean, alcohol carrier and non corrosive.

The fiber glass tip is mildly abrasive, so when I have to solder on the back of a pot, I just scrub it a bit with the tip, I suppose if I soldered on PCB's it would work the same.

[kagliostro]

Nice product Stingray

The fiber glass tip is mildly abrasive, so when I have to solder on the back of a pot, I just scrub it a bit with the tip,

hope I can find it here

Kagliostro

[frank57]

Which Jet city amp is it? It should have plated through holes.
On the 20 watt combo's I tried there was a noticeable loud hiss with the preamp on 2 or 3
and the master on 7 or so.(clean type setting)The hiss started around high noon and got progressively louder.
Does your amp do the same thing? I have no idea if that's normal. and never got an answer from jet city on it.

On one I had at the beginning of the year there were cold solder joints all around the diodes too and the amp was biased at just around 50%.

[LooseChange]

100H - 100 watter.  Not noticing too much hiss in clean mode.

[Tiny_Daddy]

Get yourself some Deoxit RSF-R80-2 rosin paste flux from Jameco or MCM. It's great for supercharging your solder wick too.

[The_Gaz]

Even real Soldano's hiss, and if this is typical SLO style circuit, there's a lot of gain in there, and the noise increasing with the master turned up is normal. Higher wattage plate load R's and low-noise 12AX7 in the first slot will too, but neither is worth it IMO considering the signal to noise ratio at that level. Never herad the particular amp in person, however.

Which Jet city amp is it? It should have plated through holes.
On the 20 watt combo's I tried there was a noticeable loud hiss with the preamp on 2 or 3
and the master on 7 or so.(clean type setting)The hiss started around high noon and got progressively louder.
Does your amp do the same thing? I have no idea if that's normal. and never got an answer from jet city on it.

On one I had at the beginning of the year there were cold solder joints all around the diodes too and the amp was biased at just around 50%.

[frank57]

It was a pretty loud hiss and single notes did not cover it.
That's the thing: a lot of guys say they don't have that issue.
The tubes are generic no name chinese tubes so maybe adding noise?
Not sure why jet city suggests using the amp with preamp low and master high for a clean sound.
It's pretty anemic at best and hissy .No hum though at all.

I couldn't get an answer from jet city as to whether it was normal so it left me in no man's land as far as buying it.
The overdrive was great on it. Not much clean headroom.
I'm going to check out another demo tomorrow.
It's all metal film in there and built rather well but made in china with no quality control going on at all.

It has less gain than the slo but it's a typical soldano type thing.
The combo's are basically atomic 16's with reverb.
The voltages all match the astroverb circuit.

The head is very similar to the combo and it's the only schematic I've seen.

[LooseChange]

Switch around the preamp tubes.  Replace a couple from a known quiet amp. Especially in the first couple of preamp tube positions.