Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: randuin on August 20, 2014, 07:30:57 PM

Title: No right channel after Speedball install
Post by: randuin on August 20, 2014, 07:30:57 PM

First built the Crack, sounds beautiful. However, after installing the Speedball I have no right channel (left sounds great!). The LEDs on one of the small boards is not on and the voltage for Terminal 5 is way too high @ 170V ish

Title: Re: No right channel after Speedball install
Post by: Paul Birkeland on August 21, 2014, 07:11:47 AM

I would start by double checking that all the transistors are where they should be.

Often times this issue is resolved by reheating the solder joint of the MJE350 on the offending channel.

-PB

Title: Re: No right channel after Speedball install
Post by: randuin on August 21, 2014, 03:29:15 PM

I resoldered the points to the transistor and now the LEDs are on but Terminal 5 now has 0 voltage :(

Tested the MJE350. Voltage around 170 on 2 outer legs. 0V on the middle. solder joint looks fine. Was testing directly on the leg too. Is this blown?

Title: Re: No right channel after Speedball install
Post by: Paul Birkeland on August 21, 2014, 06:30:35 PM

Yeah, you still have flaky joints somewhere.

I'm guessing both LED's on the socket aren't yet lighting, and won't until all those joints are nice and toasty. 

0V on the collector of the MJE-350 would tell us that the transistor is completely open (turned off).  Generally when these blow, they blow shut. 

Title: Re: No right channel after Speedball install
Post by: randuin on August 22, 2014, 09:19:42 AM

Which spots would you suggest testing? The two LEDS on the socket are actually lit up.

Title: Re: No right channel after Speedball install
Post by: Paul Birkeland on August 22, 2014, 11:51:23 AM

Still having flaky solder joints means reheating the joints on the PC board.

Title: Re: No right channel after Speedball install
Post by: randuin on August 22, 2014, 04:57:03 PM

Relooking at things. It seems like the LEDs on the small boards are lit. But the LED that goes to A3 is off now.

Title: Re: No right channel after Speedball install
Post by: Paul Birkeland on August 22, 2014, 05:10:34 PM

Quote from: randuin on August 22, 2014, 04:57:03 PM

Relooking at things. It seems like the LEDs on the small boards are lit. But the LED that goes to A3 is off now.

Yup, flaky solder joint.

Title: Re: No right channel after Speedball install
Post by: randuin on August 22, 2014, 08:28:12 PM

After going through and testing what feels like everything. A socket is all good. Left board is good. Big board is good. However I'm back with the problem with the right board LEDs being off and lead 5 being 170 volts or so

EDIT: Just more info - same 170V at middle lead of the MJE350 and at the other transistor

Title: Re: No right channel after Speedball install
Post by: Paul Birkeland on August 23, 2014, 08:30:15 AM

Since you have 0V on the middle leg of the MJE350 on one test and 170V on the other test, I would still say that the center leg of the transistor needs to be reheated.

Title: Re: No right channel after Speedball install
Post by: randuin on August 23, 2014, 09:12:30 AM

Thanks so much for your patience but is there any simple continuity test I could do on the middle leg to try and figure this out? I feel like I've reheated this leg over and over again with no results.

Title: Re: No right channel after Speedball install
Post by: Paul Birkeland on August 23, 2014, 09:36:27 AM

Swap the little boards between sides and verify that the high voltage follows the board.

Also be sure there aren't solder blobs on the bottom of the board shorting out adjacent pads.

-PB