morrissey007
Newbie
- Messages
- 12
So, having spent hours today with de-solder braid, continuity testing, reflowing solder joints on every single component etc, I finally nailed down the problem. The PCB is fine, no tracks broken and no solder pads detached from pads, and no dry joints. It was a faulty Volume Pot, one of the three solder lugs was ever so slightly loose on the brown fibre board, as if the rivet wasn't fully tight and the lug could move a miniscule amount and so was not making full contact with the potentiometer track, but it was intermittent, so when I moved the volume or slightly flexed the board it would disconnect/reconnect. I make guitar pedals for fun so luckily I had a replacement pot to hand. I soldered it in and now the amp is fully working, along with the satisfying outcome of the original work (following the replacement of the three TL084s with OPA 4227PAs) it isnow silent!
So, my observations/lessons learnt is;
Firstly; there should be a small but significant addition to the disassembly instructions and, in my opinion, it is a must: ๐๐ข ๐ก๐ข๐ง ๐๐ถ๐น๐ ๐๐ต๐ฒ ๐ฃ๐ฟ๐ฒ-๐ฎ๐บ๐ฝ ๐ฏ๐ผ๐ฎ๐ฟ๐ฑ ๐๐ผ ๐ฟ๐ฒ๐บ๐ผ๐๐ฒ ๐ถ๐, the slightest bend on the Pots will put a strain on them and could cause damage to them or the PCB, however, the good thing is that this is so simple to avoid and only adds 30 seconds to the work: undo the four screws holding the XLR board and connectors on and move it out of the way (don't even need to undo the earth cable that goes to pillar) this allows the Preamp board to slide in and out without any bend to the pots whatsoever.
Second lesson is; ๐ฑ๐ผ๐ป๐ ๐น๐ฒ๐ ๐๐ต๐ถ๐ ๐ฝ๐๐ ๐๐ผ๐ ๐ผ๐ณ๐ณ! If you have soldering experience then it really is a simple thing to do and reaps great results. It took me 30 minutes to remove the three TL084s and solder some turned pin sockets. I use turned pin as this prevents the chips coming loose when its in transit, which after all; its a guitar amp so its going to get moved, usually!
Finally: ๐ง๐ต๐ถ๐ ๐ถ๐ ๐ฎ๐ฏ๐๐ผ๐น๐๐๐ฒ๐น๐ ๐๐ผ๐ฟ๐๐ต ๐ฑ๐ผ๐ถ๐ป๐ด, the reducing is Hiss is phenomenal, its gone from annoying to me having to check if I have the amp switched on!
So, my observations/lessons learnt is;
Firstly; there should be a small but significant addition to the disassembly instructions and, in my opinion, it is a must: ๐๐ข ๐ก๐ข๐ง ๐๐ถ๐น๐ ๐๐ต๐ฒ ๐ฃ๐ฟ๐ฒ-๐ฎ๐บ๐ฝ ๐ฏ๐ผ๐ฎ๐ฟ๐ฑ ๐๐ผ ๐ฟ๐ฒ๐บ๐ผ๐๐ฒ ๐ถ๐, the slightest bend on the Pots will put a strain on them and could cause damage to them or the PCB, however, the good thing is that this is so simple to avoid and only adds 30 seconds to the work: undo the four screws holding the XLR board and connectors on and move it out of the way (don't even need to undo the earth cable that goes to pillar) this allows the Preamp board to slide in and out without any bend to the pots whatsoever.
Second lesson is; ๐ฑ๐ผ๐ป๐ ๐น๐ฒ๐ ๐๐ต๐ถ๐ ๐ฝ๐๐ ๐๐ผ๐ ๐ผ๐ณ๐ณ! If you have soldering experience then it really is a simple thing to do and reaps great results. It took me 30 minutes to remove the three TL084s and solder some turned pin sockets. I use turned pin as this prevents the chips coming loose when its in transit, which after all; its a guitar amp so its going to get moved, usually!
Finally: ๐ง๐ต๐ถ๐ ๐ถ๐ ๐ฎ๐ฏ๐๐ผ๐น๐๐๐ฒ๐น๐ ๐๐ผ๐ฟ๐๐ต ๐ฑ๐ผ๐ถ๐ป๐ด, the reducing is Hiss is phenomenal, its gone from annoying to me having to check if I have the amp switched on!
