Recent content by bluebug

Thank you for confirming! :)

Thank you, I missed your post too sorry for not replying before. On V1 I already replaced the diodes by 1.5k resistors, and also the large orange filter cap, but did not replace the bypass caps yet. I ordered some waiting for the next bench time with the boogie. Right now what's on the bench are...

I'm sorry I missed your post, I too always wondered about that RCA jack, there is absolutely nothing tied to it inside the chassis. On yours, inside is there anything connected to that 1/4" jack?

Hello Mark, Oh, I forgot about that, right. So even if they are separated by a resistor this rule still stands? Thank you for highlighting that for me! Fred

Hi all, I came back to this thread to ask a question, but started by just re-reading the whole thing as I think I know a bit more now than I did back then, I'd like to say thanks again to everyone who helped me build up a bit more knowledge, little by little. An Happy New Year everyone too! So...

I’ve been taking apart a few old tube stereo consoles to convert them to guitar amp. Some old solid state stereos I took apart for parts too, so I can mod the tube ones. First one was a Sparton brand, with two single ended power amp channels (they are stereo, duh!) I kept one and built a JCM800...

Mine is an SP-3 and it is a 03/78. Maybe the use of the different boards depends on the options and not only the dates? I don’t have a reverb, and I saw some of the mark 1 preamp boards had an additional preamp tube compared to mine, I guess it was the reberb tube. Fred

Can see it a bit here, moslty hidden under all the wiring on the tube socket. From this angle it almost looks like the red wire is jumped with the point where the resistor ends. But that’s not how I saw it when I traced it... maybe a mistake, I might have a look tonight to confirm. Anything...

Hey Mark, the resistor is on the circuit board. I am on the phone now but will look at the pictures to try and find it when I’m on the computer a bit later. Glad the pictures and schematic notes of my Mark 1 can be useful for you guys! Fred

Hi there, Here is a picture where you see how it is wrapped, it’s the red wire around the three gray coax. I’ll see which other pictures show it from other angles. By the way here is the thread with all pictures (now that you see the wire it might be easier to spot in in the other pics...

Hello Mark, Here are the voltages at the documented points in the schematics. I have not taken the time yet to compare with your values though, you can see my measured voltages in blue.

I wondered that too about the 5 preamp tubes, maybe the EQ requires an additional tube? In mine there are 4 and it’s because of the fx loop. No reverb or eq.

Hey Jim, congrats on the nice score :) feel free to put some pics! What speakers does it have? Is it still running the fetron in V1 position? The options were available and you had to choose whatever you wanted and it was built to order. 60 or 100w, reverb, GEQ for instance were all options...

Hi Mark, Next time I have some bench time with mine I will measure, if you have not received answers by then. Frederik

No problem, you are welcome. I read somewhere when there are only two digits before a K it means the value is exactly in pF. But caps markings “conventions” are quite eclectic, if not cahotic lol