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Topics - mattbianconi

Honey Amp / Power supply suggestions
May 20, 2021, 03:04:52 PM
I got the kit that came with the 8 ohm speaker.  All assembled and currently powered with a 9-volt battery.  It seems I have to have the volume absolutely cranked to be heard over the guitar strings themselves. Turning the gain up obviously gets past this a bit.
I tried to use a 12 volt DC wall plug but that introduced a ton of hum into the amp.
What are you using as power for this little guy? Would an A23 battery work?
TLDR: Where can I find the replacements for TIP147 and TIP142 in TO-218 cases now that those aren't made? Ones ordered from Amazon have shorted twice.

I have a Fender Performer 1000 that has been chugging along since I got it in '95.  Its always had the crazy loud "fizzt-POP" on shutting it off, and the background buzz whenever it is on. But these were mild issues for a 3 chord electric guitar player, I assumed all loud guitar amps just had that background fuzzy grumble and when you played notes on the clean channel they sounded clean, things on the two distortion channels sounded distorted and ncie. A friend brought over his newer amp though and it is quiet, doesn't bang when turning off.  So I read tons of forums and cracked it open to see what I could see. Since things were cheap and the Service Manual pdf going around for this amp included Tech Notes I thought maybe making those changes and replacing/cleaning pots would fix those issues. There was a cap at C68 that had broken its solder so I also fixed that.
During this work I saw that the darlington at Q14 looked super janky with leads soldered at right angles onto the existing leads so they could reach the board. The large caps at C71 and C72 were much skinnier than the white outlines on the board and taller than anything I could find online, which I assume means they had been replaced, and the resistors at R172 and R173 were 120ohms as opposed to 100ohms that the specs showed. So this means someone had worked on this thing within the year or two between manufacture and the time I got the amp!  I thought that while I had the board out I should replace these things since I like everything looking clean and to spec. I made all the tech note changes and replaced the caps and everything sounded... well fine, same as before. Oh well might as well replace the transistors. 
Well, those aren't made anymore.  I ordered some TIP147 in TO-218 size off Amazon since they aren't on mouser and it played well for about 60 seconds before blowing one.  I was getting -40 DC on the white output wire and it was reading as "two diodes" as opposed to "transistor" according to my little testing device.  The other three, the two TIP142, and the other TIP147 read as "transistors". Replaced with another from Amazon and same thing. Fine for a few seconds then blew.
So did I get bad transistors from Amazon?  Should I suck it up and put the original one back in?  Is it TO-247 I should buy? Maybe there is something I broke earlier in the circuit that's causing a coincidental fail of the transistors? It smelled hot when it was on so maybe lack of new thermal grease made them overheat and they were actually fine? Thanks for any help.