DC offset from pre-amp affects power amp how?

WOPL Sniffer

Veteran and General Yakker
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Aug 10, 2015
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Screw it
#21
Well....the sucker didn't suck and the wicker didn't wick all the solder out of those holes so the old fashioned way is what it was - but gently. There was a lot of solder in them thar holes. All new electrolytic capacitors are now in and it's working fine. During my brief dabblings, I've encountered a few non-polarized ones but not to the extent of what this pre-amp has. Most are bi-polar
Don't know what you got for soldering equipment but tip choice (if your tip hangs over the pad, it's too big) and heat setting for the iron IS CRITICAL. And, if you are on those pads for more than a couple seconds, TOO LATE...... the shitty CINA/Japanese CIRCUIT BOARDS are designed to go across the wave solder machine once and throw them out when they fail. I got this Carver amp sitting here and the runs on the board just fly away when you get within a foot with the soldering Iron. Here is the Old Fart Tricks you can use when getting ready to do some soldering.

1. Clean the board first (oxidation, conformal coating, shit, snot etc), you'll get the best "Heat Transfer" from iron to pad.
2. Clean it again
3. Put some FRESH FLUX on the area to be worked (if you have 5 year old flux hanging around, dump that shit).
4. Add a touch of FRESH Solder to the pads you will be unsoldering. Again, increased heat transfer so you can get on and off the pads QUICK.
5. Clean it again
6. If you are using "Solder Braid/Wick" put some flux on it, again, heat transfer.
7. If you are using "Solder Braid/Wick", don't apply too much pressure to the pads. The epoxy/adhesives used to attach the runs/traces to the board DO NOT LIKE HEAT, and pressure.
8. Clean it again.
9. Go back to step 1 and check your tip temperature. If you have your iron set to 800 degrees (Celsius OR Fahrenheit), you are killing your components and boards.
10. Believe it or not, solder choice is important. Go get yourself a fresh roll of 63/37 RMA solder. This is what you call [FONT=Oxygen, sans-serif]Eutectic and has the lowest melting point of all solders (about 400 degrees Fahrenheit). , [/FONT]Depending on the mass of the board and the component, Heat [FONT=Oxygen, sans-serif]will "WICK" away from the solder joint so you may have to kick up the heat a wee bit.
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[FONT=Oxygen, sans-serif]11. Many of the newer electronic devices use Lead Free solder to make the ROHS Compliance list ([/FONT][FONT=Roboto, arial, sans-serif]Restriction of Hazardous Substances) It takes different methods when soldering and unless you have to live in California, fuck "Lead Free". Hence why you want to add a little solder to the joint before you attack it. Lead free solder melts at up to 70 deg Fahrenheit higher that a Eutectic 63/37 (ratio of Tin/Lead) solder. Get the real stuff. If you tried using the solder your grandpa used out in the barn, throw it out. It could be cored different and eat up your beautiful WOPL boards.

[/FONT][FONT=Oxygen, sans-serif]TIP OF THE DAY: When soldering, sometimes it feels like you don't have enough hands...... If you are putting the solder in your mouth to feed it into a joint while you hold an iron and component, Save yourself the trouble and just shoot a lead .38 bullet in your head. Lead is poisonous and the heavy metal (not the band Ron) will concentrate in your body and rot your liver. WASH YOUR HANDS after soldering. I'm not kidding, lead WILL fuck you up. But it sure is easy to solder with.. Iffn ya don't believe me, take a piece of solder and wipe from one end to the other with a napkin, you'll see the lead rubbing off.

In the chart below, this shows the melting point of 63/37 solder. Obviously, the lower the melting point, the easier it is on EVERYTHING. Well, enough rambling. I just talk to hear my brains rattle. Go do some research and practice practice practice. They make kits just for that.

[/FONT] four-soldering-profiles.jpg [FONT=Oxygen, sans-serif]
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orange

Veteran and General Yakker
Joined
Jul 6, 2010
Messages
17,704
Tagline
Broken beyond repair but highly affable
#22
I remember being given a Yamaha pre and power amp that were known bad to sell and raise myself some funds (went to somebody on AK, it was that long ago). As long as I kept the bad pre channel off I could get one channel of the amp. Watching those red LED segments hop and the sheer volume of it was amazing, but I knew even then that was too much for my hearing (several nights at high school dances taught me that, along with tinnitus over three decades plus).

It was a badass amp.
 
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