Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: Aldeon on March 07, 2023, 06:29:36 AM

Title: Xicon 270 OHM 5 W resistor split in half
Post by: Aldeon on March 07, 2023, 06:29:36 AM: Completed my Bottlehead Crack last week. I've been using it with the Sennheiser HD800s and so far it has exceeded my expectations. Looking forward to trying it with the Speedball sometime later this year.

I decided to install two STTH2R06 diodes in an attempt to remove some static interference. (as mentioned in this post: https://forum.bottlehead.com/index.php?topic=11676.0)

As I was desoldering the ground lug to prepare it for the new components I noticed the Xicon 270 ohm 5W resistor had split in half. Where would I go about ordering a new one? Would be very grateful if someone could link a part number should this one be incompatible: Mouser SQP500JB-270R

Also posting the completed wiring in case someone is able to spot a potential cause for the damaged resistor. Excuse the layman craftmanship.
Title: Re: Xicon 270 OHM 5 W resistor split in half
Post by: Paul Birkeland on March 07, 2023, 06:48:20 AM: That resistor will do that from a tremendous electrical fault being present in the amp.

Most all of the leads in your kit that are poking through tube sockets and terminals need to be bent up around the terminals, resoldered, then properly trimmed. I recommend the CHP-170 side cutters to get close to the terminals when trimming the leads.

The wire going into A4/A5 has too much jacket stripped off. If this touches the chassis, it will destroy your power transformer without the fuse blowing.

This build also looks like it was either done with lead-free solder or an iron not turned up all the way, so definitely remedy those issues if at all possible.
Title: Re: Xicon 270 OHM 5 W resistor split in half
Post by: Aldeon on March 07, 2023, 07:10:06 AM: Thank you for your response. I will certainly see to the issues you have informed me of.

As for replacing the resistor itself, would this specific component be sufficient? mouser.com/ProductDetail/YAGEO/SQP500JB-270R?qs=sGAEpiMZZMtlubZbdhIBIAik%252Bt0yKDKefNEvAIykC8Q%3D
Title: Re: Xicon 270 OHM 5 W resistor split in half
Post by: Paul Birkeland on March 07, 2023, 10:31:32 AM: I don't think those have long enough leads to span between the terminal strips.
https://www.mouser.com/ProductDetail/Xicon/280-CR5-250-RC?qs=meEoQE6dWKO3IwdGroF5sg%3D%3D (https://www.mouser.com/ProductDetail/Xicon/280-CR5-250-RC?qs=meEoQE6dWKO3IwdGroF5sg%3D%3D)

That's what I would use there.
Title: Re: Xicon 270 OHM 5 W resistor split in half
Post by: Larpy on March 07, 2023, 11:59:20 AM: Those look to be 270 microohms.

Try these Ohmites instead:

https://www.mouser.com/ProductDetail/Ohmite/25J270E?qs=jhoEV%252Bw5f595RpZRmEbunQ%3D%3D (https://www.mouser.com/ProductDetail/Ohmite/25J270E?qs=jhoEV%252Bw5f595RpZRmEbunQ%3D%3D)
Title: Re: Xicon 270 OHM 5 W resistor split in half
Post by: Paul Birkeland on March 07, 2023, 12:52:20 PM: Good call, I put in a link to the 250 ohm Xicon, which is also an acceptable substitute.
Title: Re: Xicon 270 OHM 5 W resistor split in half
Post by: Deluk on March 09, 2023, 03:28:36 AM: Interesting paint finish. 8)
Title: Re: Xicon 270 OHM 5 W resistor split in half
Post by: Karl5150 on March 10, 2023, 02:08:07 AM: Good looking take on the Crack, hope you get the technical issues sorted and can get back to the music. Is it a rattle-can marble finish or something more involved?
Karl
Title: Re: Xicon 270 OHM 5 W resistor split in half
Post by: Aldeon on March 10, 2023, 07:54:07 AM: I will hopefully have it in order soon. All components were removed and replacement and spare parts have been ordered.

Rattle-can marble finish is correct. Went for a black marble finish on the case and a silver marble finish on the plate.

Completed another build. So far everything appears to be in working order from what I can see, at least in regards to the voltage and resistance readings. Opposite colour scheme.