Need help repairing HK 330C

[Sandman1221]

cesmith5600​

It’s been a while on this project and it has not ended well. In my attempt to replace transistors on the phono board I seem to have disrupted the board pads to the point where I can not get solder to stick. Any suggestions?​

Several options. You can use copper foil to reconstruct the traces and pads. Or if you're replacing the transistors you can leave the leads long and bend them along the trace that's left and solder to that. You may have to scrape away some solder mask to reveal the trace underneath.

Yeah, have done the same thing. I used a 10X loupe and a sharp angled Exacto knife blade to scape the the green coating off of the board to reveal the copper trace, and then used the soldering iron to drag a bead of solder back and forth between the leg and trace until it bridged both. That is a newbie fix job, and any expert can advise otherwise, but it did give a zero ohm reading between leg and nearest junction, so leg and trace was connected!

I fixed another broken trace using a thin copper wire, But then realized the problems with the integrated amplifier were far worse, and bailed and bought a new integrated amplifier, should be good for another 25 years, hopefully!

 

[cesmith5600]

Thank you. These are great options. I'll take a photo and let you look at it later this morning. I should be able to bend the leads on the transistor but I'd like your input first.

 

[Sandman1221]

Thank you. These are great options. I'll take a photo and let you look at it later this morning. I should be able to bend the leads on the transistor but I'd like your input first.

Be careful bending the transistor leg, it can break off. Short piece of solid copper wire to bridge the gap is easier/safer IMO.

 

[cesmith5600]

Be careful bending the transistor leg, it can break off. Short piece of solid copper wire to bridge the gap is easier/safer IMO.

Thank you

 

[cesmith5600]

Thank you

Here is my attempt at showing where I might bend the leads and solder to. The first three photos are just giving the lay of the land. Photo 4 shows where I might bend the leads or solder a coper wire to.

 

[Brian1970]

Hard to tell but looks like you might be bending them to the wrong places. Look at the board layout in the service manual. It shows the bottom side of the board so it should be a little easier to tell where the traces should be.

Looks like you've got some burned board there too. You'll probably want to scrape away the carbon. It can be conductive and you could get some current leaking where the burned parts are.

 

[cesmith5600]

Thanks. Again very helpful. I will scrape away as much of the burnt material as I can. Based on the trace figures in the manual I believe this is the way the leads should be bent.

 

[Sandman1221]

Thanks. Again very helpful. I will scrape away as much of the burnt material as I can. Based on the trace figures in the manual I believe this is the way the leads should be bent.

I would just use solder to join them, since that has been done elsewhere on the board and those solders look original.

With a fine tip on iron, drag solder bead back and forth from post to connecting soldered leg, until it bridges the gap, then pull iron away leaving the soldered bridge.

Just make sure to gently scrape off the burned material until you see the copper trace for both legs. A 10X loupe helps with that, trace is very thin, do not want to scrape it off.