Any tips on reflowing solder on PCB?

[mtlbasslad]

As if I haven't gotten myself into enough trouble with my B100R...

So, trouble now with wife Joanie's Peavey Minx 110. Many years ago the kids were roughhousing & the amp got knocked over on it's face - with a cable plugged in.When it first came to me last year, there was an elaborate rig involving much duct tape to keep the cable steady. It looked ugly to me so I figured 'i can fix this'. Pulled the head out & saw that the input jack (plastic of course, & soldered directly to the board) was cracked. I pulled it out & replaced it with a Swithcraft mono jack I had in stock, with short jumpers to the board. Yay, it works...

Lately it has been intermittently farting out. Another inspection & I discover if I wiggle any knob it farts. So, I'm thinking - cracked trace on the PCB?

Standard procedure would be to reflow the solder traces? Except I've never done that... any tips? Like iron temp or... ?

Thanks in advance

Lorne & Joanie

[Leo_Gnardo]

So, trouble now with wife Joanie's Peavey Minx 110. Many years ago the kids were roughhousing & the amp got knocked over on it's face - with a cable plugged in.When it first came to me last year, there was an elaborate rig involving much duct tape to keep the cable steady. It looked ugly to me so I figured 'i can fix this'. Pulled the head out & saw that the input jack (plastic of course, & soldered directly to the board) was cracked. I pulled it out & replaced it with a Swithcraft mono jack I had in stock, with short jumpers to the board. Yay, it works...

Lately it has been intermittently farting out. Another inspection & I discover if I wiggle any knob it farts. So, I'm thinking - cracked trace on the PCB?

Standard procedure would be to reflow the solder traces? Except I've never done that... any tips? Like iron temp or... ?

Good fix on the input jack Lorne! Could be dirty controls, need a shot of Caig D5 spray to each. If it was just one I'd say possibly the pot's wafer has cracked, or it's come unstuck from the circuit board, but since it's all of them that's unlikely. If you choose to reflow, first inspect the trace side of the board & maybe you'll see some part that's worked loose from the board saving you the effort of "shotgunning" aka reflow all connections. A good iron and old fashioned tin/lead 60/40 or similar solder recommended. Just go slow & careful, inspect all your touch ups, make sure you don't "bridge" connections by mistake, that is join up solder points that aren't supposed to be connected. A pointy "pencil tip" on the iron will help, good lighting & patience. But look for that loose connection first and don't rule out the ones you made to connect the new input jack.

Or Joanie's been slappin' that bass to the point the Minx speaker has worn out. I can tell you from experience, a Tone Tubby bass 10" speaker sounds marvelous in the Minx. And will make it about 5 kg heavier too. Even if the problem & solution work out to be something else a Tubby will make that amp sound way better. No I'm not an employee or owner of Tone Tubby, just a repair tech who stumbled onto the happy combination.

[mtlbasslad]

Thanks Leo - all controls got the D5 treatment first time around. Just pressing my finger anywhere on the front panel causes farting, that's why I suspect a cracked trace.

Nah, no 'over-slapping' on this amp, Joanie only uses it to rehearse at her sister's house. For serious slapping she uses her GK. The band is called 'Related' because its 3 sisters & a brother - I think there are some Ytube vids out there.

Ill check out that Tone Tubby though...

L & J

[Enzo]

Don't assume, FIND OUT. Cracked board? Maybe. Cracked solder somewhere? Way more likely.

Soldering is soldering, you take your hot iron, apply it to the joint, touch some solder to it from your roll of solder.

Go inside while it is running and use an insulated probe - a wooden chopstick - and gently nudge everything on it. Looking for anything sensitive. Before that, just make sure all the pot nuts and jack nuts are snug.

Nothing wrong with plastic jacks.

[mtlbasslad]

Hi Enzo

I was just wondering if there was something special about the reflow process - I guess not.

I wasn't thinking the board was cracked, just a trace perhaps. All pot & jack nuts are tight, did that the last time around.

About plastic jacks, you are probably right - I just liked when they were separate from the board, but I guess I'm showing my age.

So in we shall go, hot iron in hand. Guess I'll start around the input jack, as that was the one that took the original hit.

I'll let everyone know how that turns out.

L & J

[mtlbasslad]

So, pulled the little amp apart - couldn't see any obvious trace problems (of course my eyes have slumped a little)

Set up on the kitchen table, got the iron hot & hit every jack & pot with a touch of solder...

Put her back together and... it still works! LOL - even better, it's been plugged in for 2 hours now & when I wiggle the input jack all is good - yay

I'd call it a complete success but for one annoying detail - while tightening the nuts on the jacks the headphone one just broke off. Many bad words were uttered. Was I supposed to use a torque wrench on it? Plastic... looking for a replacement on DigiKey I see there are few choices, maybe go back to a panel mount type with jumpers... crap

I'll try to post some pics (crosses fingers)






Does the replacement jack have to be plastic so it won't make a connection to the panel?

It's so much fun being over my head...

Thanks all

[Jazz P Bass]

Plastic jacks are great until they are overtightened or the nut is crossthreaded.

I would call Peavey Parts & ask for the correct jack.

PHONE: 877-732-8391

[52 Bill]

Does the replacement jack have to be plastic so it won't make a connection to the panel?

Yes, I believe that there is a large resistor (5 watt) that is connected from the shield connection to the circuit ground. If this is the case with your amp, the sleeve must be insulated from the chassis.

Also, I couldn't tell in your photo if the replacement input jack has its' shorting switch connected to the circuit ground or not. If not, it should be.

[g1]

Was the input jack also a plastic type with ground insulated from front panel?
In both cases you can use the switchcraft type as you did, but with fiber insulating shoulder washers. This will avoid any issues such as 52Bill mentioned.

Plastic jacks and smaller pots are very easy to break when tightening. I try to hold the wrench no more that an inch or two away from the nut. The less leverage you have, the less likely to break them. They want inch/pounds, not foot/pounds.

[mtlbasslad]

Hmm, you guys pose interesting questions...

Best answer I can give is to post the schematic. Old input jack is long gone, I don't remember if the end was plastic or metal, but the replacement is all metal, no insulating washer.

MINX_110_95.pdf

Looks like the input jack is grounded to the chassis. Good thing, since I missed that when I installed it - oops! Any idea what the 2 switches in the input jack do? Noise thing when no plug is in?
I get what switches in the headphone jack do, yay I'm not completely stupid.

Good advice from all of you, many thanks for your patience.

L & J

[Leo_Gnardo]

Old input jack is long gone, I don't remember if the end was plastic or metal, but the replacement is all metal, no insulating washer.

Looks like the input jack is grounded to the chassis. Good thing, since I missed that when I installed it - oops! Any idea what the 2 switches in the input jack do? Noise thing when no plug is in?

A careful look at the input jack shows a stereo jack with switches on both tip and ring, BUT ring and its switch are all wired to ground. Peavey made sort of a waste of that fancy-dan jack, with only the shorting bar on the tip used to stop hum when nothing's plugged in. Also shows a local ground, presumably the chassis. Far as I can tell, your replacement with a Switchcraft 12A or its equivalent, bolted right to the chassis, is perfectly fine. That's not always the case - some amps will set up a ground loop and hum miserably, sometimes pick up radio, if the input jack isn't isolated from chassis ground. If yours isn't showing unexpected hum/buzz levels with the volume turned up, no problem. It's safe to rock, Joanie, yaaay!

G1, torque on the mounting nut - isn't that metric in Canada? Centimeter-kilograms or something like that? Where's my old slide rule... someday we'll catch up to metric in the USA. 'Til then we'll measure things in furlongs per fortnight.

[Enzo]

The part list says non-insulated jack at the input. Note the headphone jack is INSULATED, ie plastic, because the sleeve is not grounded.

I think the TRS jack was used because in addition to teh sleeve grounding, the ring contact also ground teh sleeve of the mono plug, making the jack grounding of the guitar cord a little more reliable.

[g1]

G1, torque on the mounting nut - isn't that metric in Canada? Centimeter-kilograms or something like that?

Newton-meters. But I can't visualize what a newton is so I stick with the one I can use. On occasion I'll hang my weight off a 6ft pipe extension on a wrench to simulate 600 ft/lbs.

someday we'll catch up to metric in the USA. 'Til then we'll measure things in furlongs per fortnight.

We changed over to metric mid '70s. It took me awhile to catch on to the whole "base 10" thing . "What do you mean it counts like money? What kind of idiot...? oh wait..."
But it's not just the USA, many here a little older than me just can't (or won't) convert. The fact that electronics uses the SI type system gives us electronics types all a head start.
The little problem up here is that the entire country is mapped out with a grid of square miles, including the roads .

[Jazz P Bass]

In the USA, Congress passed the Metric Conversion Act of 1975.

I am still waiting.