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qusp  
#1 Posted : Tuesday, March 23, 2010 1:10:10 AM(UTC)
qusp

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Joined: 7/22/2009(UTC)
Posts: 11
Location: Brisbane

Hi guys, some time ago my buffalo received a lethal overvoltage, my project box was left on and uncovered downstairs and it was knocked over, causing voltage death Boo hoo! for a while I didnt do anything about it, but about a month ago I decided I was going to attempt a repair. not one to do things by halves and thinking it was the best course of action, I bought parts to replace every active component on the board except for the relays, DAC and XO, plus some of the electrolytics. I figured there wasnt too much chance of these components being damaged by a short, because there was much in the road to fail before them, I just chipped away at it in my spare time until I was almost done, then I procrastinated about it, but this last week I decided I would finish it off. so I removed al the opamps, regs and 2 oscons that showed a 6R short across them (I have other spares too) lifting only one pad on the last thing I removed :( one of the shorted caps, but I carefully cut a piece of copper foil and folded it over a cpouple of times and soldered it in place, all was well. the job isnt as clean as I would like because of the glue, but its all rather neat and seems fine. today I powered it on for the first time Pray , I heard a reasuring click of the relays, no smoke and both LEDs flicked on and then off quickly (I cant remember if that is normal, there is no signal connected??)

so its now set up to receive SPDIF from the optical module, which has proven to work in the meantime with the MUX, which is also functional (or at least I get all the right frequencies with my meter I dont have a scope), but I have left it out of the equation along with the volumite to simplify trouble shooting.so after reading the manual again, I got to thinking that perhaps I should reset the dac after such a traumatic episode, would this be correct? and how is this done, I know there is a dip switch, but do I flick this before I turn it on, then wait, turn the dac off again and flick the switch back to the middle?, or do I do it while its on?

so I will hook up my iriver to the toslink module a little later, but wondered should I do the reset first. also if the automute LED should be on, can you guys think of something else I could check? it really does seem like its OK, or at least close to OK.

oh and i've replaced the FW with a new DIP as well

thanks for your time, I have a buff II which i'm gonna power up a little later, but was keen to get this done first.

Edited by user Tuesday, March 23, 2010 1:53:26 AM(UTC)  | Reason: Not specified

qusp  
#2 Posted : Tuesday, March 23, 2010 6:19:27 AM(UTC)
qusp

Rank: Member

Groups: Member
Joined: 7/22/2009(UTC)
Posts: 11
Location: Brisbane

well I connected up the toslink module and my iriver and I got lock!! all chips are warm/hot to the touch; with the LME94710 and LM4562 (cant remember for some reason the number) just warm and the OPA1632 quite hot. thats normal from what I understand of the 1632, I havent hooked up an amp yet, but is it safe to assume that the 9018 is OK since I have lock? or is that a function of the XO only? I wish I had a scope to put across the outputs. perhaps i'll hook up the volumite and just connect some crappy headphones instead of an amp. my meter is running low on battery and thus the readings are in general unreliable till I get some more. but I had the correct voltages on the placid BP before I connected to the analogue rails at+/-15VDC and 200ma. but just before, even though things seemed fine and I didnt have any smoke or undue heat, I was getting +27vdc and -2 or something on the right side, didnt check the left as I turned it off when I saw that. which seems odd, the connections are correct and there are no shorts at that point, there are no shorts on the board as far as I can tell unless one of the ceramics died as well (I only replaced the oscon and active components and they all seem to check out fine with no shorts or bridges as far as caps) but surely it would have been a bit more haywire after having it on for 10 minutes before that with constant lock?? just to double check, with you guys since tghere are no pics high enough rez, I just want to make sure I didnt mix the 2 national chips up (though they are sufficiently similar to not be the cause of this. its the 94710 first out from the dac and then the 4562 or the other way around. I made note, but thats the only thing I can think of there, guess i'll see what happens when I use volumite and crap headphones. in the meantime any ideas are welcome

any ideas on where to go now? am I going in the right direction ?

Edited by user Tuesday, March 23, 2010 6:23:13 AM(UTC)  | Reason: Not specified

Russ White  
#3 Posted : Tuesday, March 23, 2010 2:51:45 PM(UTC)
Russ White

Rank: Administration

Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,979
Location: Nashville, TN

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It's very difficult to help with things like this from a distance. It could as easily be an open net as a shorted one.
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