Mr. carl, Mr. Carl HEP

[Tilladude]

Carl, Dennis here in Tillamook and I'm having a little trouble getting my HH up and running. I've tried configuring both with & without R8 and the jumper inbetween Q2 & Q3 in either position but I keep roasting R10 (I had forgotten the smell of a burnt resistor--ICK.) This last time I thought it was going to hold, with R8 in and taking the Q3 gate in from between Rs 8 & 9. I was checking waveforms and poof and R10 toasted again, that's #3 and I only have 3 left.

Can you splain to me why this is happening and suggest a fix for this little conundrum.

Dennis

PS: Have you been up to visit The Tillamook Cheese Factory yet.

[Qiaozhi]

Carl, Dennis here in Tillamook and I'm having a little trouble getting my HH up and running. I've tried configuring both with & without R8 and the jumper inbetween Q2 & Q3 in either position but I keep roasting R10 (I had forgotten the smell of a burnt resistor--ICK.) This last time I thought it was going to hold, with R8 in and taking the Q3 gate in from between Rs 8 & 9. I was checking waveforms and poof and R10 toasted again, that's #3 and I only have 3 left.

Can you splain to me why this is happening and suggest a fix for this little conundrum.

Dennis

PS: Have you been up to visit The Tillamook Cheese Factory yet.

I know you addressed this to Carl, but here is my answer.

Short R7 and R8. Put the jumper in the lower position, as shown in the schematic. (i.e. the gate of Q3 connected directly to the emitter of Q2.) Check that IC5 is oscillating by monitoring pin 3 (TP1). If IC5 gets stuck in a low state, then Q1 is turned off and Q2 is on. In this case Q3 is permanently turned on, consequently roasting R10.