Help with Foreplay III troubleshooting

Bottlehead Forum

Welcome! Need support, you got it. Or share you ideas and experiences.

First of all, let me say that this was my first project ever and I came into it with no soldering experience (though I did have some guidance). The build was spread out over a month because had trouble finding even a few hours here and there to work on it. I had a good time with it, now I just need a little bit of direction and hopefully I can get the Foreplay up and running.
After completing the kit, the resistances looked ok for the most part, but the voltages were a little funny and it seemd like my DMM (Craftsman 82400) had a hard time ranging. All the tubes lit up when I took the readings. The readings were changing and funny for the most part, but it seemed like something in the ballpark of what I was looking for would flash on the screen temporarily.
I figured it was a problem with the DMM and tried out the Foreplay with my power amp and some junky speakers I had laying around. The sound I got had a loud buzz or hum in both channels no matter what input or if anything is connected to the input, I also tried a little bit of music which sounded extremely muffled. I turned the amp off and came back later and didn't think the tubes were glowing. I turned it on and off a few times, maybe too fast, and then checked the fuse, it was obviously blown (black scorch mark in the middle).
At this point I was pretty frustrated and confused, but based on what I read in the troubleshooting guide, I figured it was a grounding issue and possibly a voltage issue. I resoldered a few of the ground bus joints and terminal 28u, the joints on the power switch and socket, and a few on the power terminal. I then popped in a new fuse to try it again, I had the same problems as before.
I thought I'd check the resistances and voltages again before reporting back, since I didn't record them the first time. The Resistances were all ok except for at terminals 15, 22, and 31. I got a reading of 8k ohms at all of them instead of the desired readings of 22.1k, 33k, and 22.1k. After that I started to check the voltages again. I checked power transformer terminal 4 and I had the same trouble getting a reading. The DMM was going back and forth between 3.44, 27, and 98. I clipped the lead to terminal 5, and the reading slowly fell to almost zero (.003).
I noticed at this point the tubes were no longer glowing and checked the fuse again. This time it wasn't as obviously blown as the first fuse (there were no burn marks), but I think it was blown because I could no longer see the filament in it. This brings me to where I am now. How badly screwed up is my foreplay?? Any thought or suggestions on what I could do to fix it?
I'm really looking forward to hearing it, it was hard enough to be patient through the construction and now it's even harder now that it's complete. Hopefully I'll be able to listen to it soon.

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Topic - Help with Foreplay III troubleshooting - gfw 17:52:32 06/12/06 (3)

Re: Help with Foreplay III troubleshooting - gfw 20:29:38 06/17/06 (0)

Re: Help with Foreplay III troubleshooting - Paul Joppa 16:41:20 06/16/06 (1)

Checked diodes and capcitors again... - gfw 19:26:34 06/19/06 (0)

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