Bottlehead Forum

Bottlehead Kits => S.E.X. Kit => Topic started by: ksimmons on May 14, 2021, 07:31:45 AM

Title: Smokin' 5W resistor after successful resistance check
Post by: ksimmons on May 14, 2021, 07:31:45 AM: This is driving me a bit nuts, all the terminals look good for resistance, fuse wasn't blown, triple checked wiring and joints and they all look fine. Tubes don't glow and the "box resistor" gets hot to the touch. Glow test was successful so I'm not sure why it's smokin' now.
Title: Re: Smokin' 5W resistor after successful resistance check
Post by: Paul Birkeland on May 14, 2021, 07:32:14 AM: What is the DC voltage at pins 1 and 12 on each 12 pin socket?
Title: Re: Smokin' 5W resistor after successful resistance check
Post by: ksimmons on May 14, 2021, 12:05:24 PM: About 330v on socket A and -30mV on B. If they glowed on the glow test, shouldn't they be glowing now as well? Been staring at it for a few hours here...
Title: Re: Smokin' 5W resistor after successful resistance check
Post by: Paul Birkeland on May 14, 2021, 03:51:37 PM: You should post photos of your build. There's no way you should have 300V on those pins, something is very wrong here or you measured different terminals.
Title: Re: Smokin' 5W resistor after successful resistance check
Post by: ksimmons on May 14, 2021, 08:06:35 PM: there's a couple mistakes I made that I think have been corrected. The 15-22 strip is mounted backwards, and the OTs are swapped with the striped output wires wired in reverse on the headphone jack to correct the swap. Terminals 3 & 17 measure 880K instead of 880, and 11 & 25 measure 680K instead of 680 (seems like they read correctly). All other resistance checks passed. The IEC/relay twist looks ugly but passed PT-10 voltage checks and glow test, have enough wire to redo it.

Hoping a second set of eyes catches something I missed, I went over the manual 4 times and confirmed every wire is in the correct location. Thanks!
Title: Re: Smokin' 5W resistor after successful resistance check
Post by: ksimmons on May 14, 2021, 08:09:08 PM: more pics
Title: Re: Smokin' 5W resistor after successful resistance check
Post by: Paul Birkeland on May 15, 2021, 04:59:26 AM: What are the DC voltages on the H terminals?
Title: Re: Smokin' 5W resistor after successful resistance check
Post by: ksimmons on May 15, 2021, 06:20:15 AM: With negative connected to H1:

H2=20.5V
H3=8.2V
H4=-4.3V
H5=20.3V
H6=0.8V
H7=-4.5V
H8=0V
Title: Re: Smokin' 5W resistor after successful resistance check
Post by: Paul Birkeland on May 15, 2021, 06:33:57 AM: If you use your meter to measure a 9V battery, what does it display?

What is your incoming AC line voltage?

I notice that some of the wire leaving the IEC power entry module looks like it has jacketing that has melted off, do you know what happened there?

Whatever you do, don't try to listen to this amp until all the issues are settled.

I would also trim the leads of the MBRF diodes that are sticking out from the H terminal strip.
Title: Re: Smokin' 5W resistor after successful resistance check
Post by: Paul Birkeland on May 15, 2021, 06:39:02 AM: Your positioning of this resistor also looks off, maybe it's not connected to the correct terminal? Notice in the manual how it's perfectly parallel to the 680 ohm 3W resistor next to it and it's nowhere near touching pin 1 on the tube socket. This resistor in your build looks like it's running over tube socket pin 1, so that's worth investigating.