New guy from south louisiana - Page 1
Forum section: electronics / general

author: Donomite
author_rank: Contributor
timestamp: January 12, 2015, 04:20:15 pm
content: Hello and thanks for this great forum. Glad I stumbled across it. I am 44 years old and work as a technician in the gulf of mexico on oil and gas platforms. I work on fire and gas detection panels, nav-aid lights, fog horns and PA systems. I have a associate degree in electronics but haven't furthered my knowledge on the component level. I came across my fathers 80s Rotel stereo and it needed work. So here I am. I am really excited to learn. My solder skills are pretty good. Here is a pic of that stereoand here is a pic of the preamp I'm working on

author: zapta
author_rank: Super Contributor
timestamp: January 12, 2015, 04:33:27 pm
content: That's a real teardown. Good luck with it.

author: RobertoLG
author_rank: Frequent Contributor
timestamp: January 12, 2015, 05:08:19 pm
content: this is a nice looking setup, I hope you can get it fixed

author: nanofrog
author_rank: Super Contributor
timestamp: January 12, 2015, 08:57:22 pm
content: Welcome.Nice bit of gear there. Wish you well in getting it sorted.BTW, I'm also located in Louisiana (NE region).

author: dannyf
author_rank: Super Contributor
timestamp: January 12, 2015, 10:34:21 pm
content: Nice looking stereo. They don't make them like that anymore.

author: MacAttak
author_rank: Unknown
timestamp: January 13, 2015, 01:47:50 am
content: Not seen one like that in many years.St. John / St. Charles parish native here, though I moved away long ago. Also spent a few years up in NE during college (Monroe, Ruston).

author: Rory
author_rank: Frequent Contributor
timestamp: January 13, 2015, 03:10:49 am
content: I'm in St. Tammany...

author: Donomite
author_rank: Contributor
timestamp: January 13, 2015, 04:39:36 am
content: Thanks guys. I'm in Lafayette

author: atferrari
author_rank: Frequent Contributor
timestamp: January 13, 2015, 10:43:23 am
content: OK OK, the social part is done, I think. Let's talk business.What's the problem?BTW how long you stay in the platforms, in every period? I spent long hours avoiding them when reaching the Gulf with our vessel. So many of them...

author: Donomite
author_rank: Contributor
timestamp: January 13, 2015, 04:59:54 pm
content: The problem goes like this. I had the system up and running except for the EQ. I connected the EQ but did it wrong. I used the tape 1 loop on preamp to tie in EQ, I didn't loop it through tape 1 in and out. Played it a few minutes like this but the EQ wasn't actually being used. Decided to just go preamp out to EQ in then EQ out to amp in and it worked fine. Few min later the left or right ch...can't remember which one started to fade in and out. Then it quit all together. So I removed preamp and just used EQ and amp. Fed my phone music to input of EQ then to amp. Both channels working without preamp. So I knew problem was in preamp. Started taking preamp apart. Found two 2sa912 transistors with open emitter/base. They are on the mc/EQ amp board. Ordered some replacement transistors and decided to do a recap on preamp. 95% of caps done. Missed some caps when ordering so ordered remaining caps and transistors Sunday night. I am very new at this component level work so I probably am in over my head. I have a lot of wires that were wrapped around post that I cut, so I have to solder them back on. Oh I believe that 2aa912 is a pnp so I ordered its compliment npn so they will match. I learned that by research. So that's were I'm at.Sent from my iPad using Tapatalk

author: Donomite
author_rank: Contributor
timestamp: January 19, 2015, 09:56:13 pm
content: Got some really good news!! The recap and repair on my preamp was a success. I replaced 2 transistors with open emitter to base and touched over a lot of solder joints. Oh ya also 60 electrolytic caps. Just powered it up and got RUSH jamming. This was a lot of work for me.

author: nanofrog
author_rank: Super Contributor
timestamp: January 19, 2015, 10:03:31 pm
content: Nice! Glad you got it up and running again.