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redger

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  1. me too of course that's going to depend in part on how well I did the job 2 bonuses - No parts left over It started first time - so I didn't completely destroy it with dodgy soldering On the other hand the ribbon cables won't take much more manipulation so I hope I did enough to keep it going for a while Thanks again for all your help
  2. I think it's fixed !!! Spent lots of time resoldering yesterday ... Initially thought I'd spotted a few bad joins so re-flowed those ... but when i re-assembled and tested - "tap test" failed So disassembled again and re-flowed any join that looked at all doubtful, plus any others I could get to that looked "safe" to reflow. A couple i removed the solder and started again. I've no idea which was the problem join .... but on re-assembly it passed the "tap test" both on the board and the heat sink (and case) where it had previously failed. A few worries - I thought I had flowed 2 joins together in a couple of cases and in one removing solder to start again didn't help (still visibly flowed together) ... but in the end it all seems to work ok (whew) Will have to wait a week or 2 to see if it's stable ... but at the moment all looks good Thanks to those who advised .. particularly @Stevesie - your advice has been invaluable
  3. more "progress" Once the unit was able to start again I undid the screws holding the top Input board to the heat sink to eliminate "force transfer" effects, then went around tapping and stressing things on the top input board Couldn't get the unit to fail .... hmm BUT hitting the heat sink still ed to failure. And the only thing attached to that now is the bottom, Output board Started tapping and stressing the bottom Output board ... mostly by gently tapping a plastic road applied to the board. Found a point in the middle of the board which consistently leads to shut-down when tapped with relatively little force. Other points can cause shut-down but need much more force Looks like I need to remove the bottom board and have a look (I've marked the approximate spot). This is going to be tedious since everything will have to come apart to get to that board ... wouldn't you know it. I can just see myself left with a bunch of surplus screws and connectors once I've re-assembled it ... that'll be an interesting moment This darned amplifier has become quite a hobby / science experiment. Never bored Thanks again for your help and guidance
  4. thanks @stevesie. I'll let it run for a day or so to see what happens, then look at pulling it apart again over the weekend (all a bit stressful for the moment - those 5 ribbon cables are really delicate)
  5. hmmm .... curiouser and curiouser I replaced 10 * 10uF and 3 * 100uF capacitors and re-flowed solder on 4 400uF capacitors. Put everything back together, noting that the board is a REALLY tight fit between the heat sink and the back panel, needed quite a bit of force to install. The unit started ok when tested (heart stopping moment given this is my first time). Put it back in the cabinet and wired it up and .... FAIL ! grrr. Back on the bench ... it worked again ... double grr Remembering the tight fit I removed one mounting screw and "relaxed" another on the heat sink (they go thru the bottom panel). Tested and it worked on the bench. Restored to cabinet, rewired everything and ... it worked !!! We'll see what happens over the next few days. Does this suggest a break in the PCB ? That would explain response to changes in "pressure" and temperature. It may be that moving the heat sink slightly, to relax the stress on the PCB may be sufficient to "solve" the problem for the moment. Ever hopeful PS replacing capacitors is a really tedious job, particularly for the uninitiated. Thanks to youtube for instruction / guidance
  6. thx I've never re-soldered before ... but had a practice run on an old PC motherboard to try get a feel for it - after looking at examples on the web. Any advice ? Will give it a go tomorrow
  7. Fantastic .. that worked - thanks (restoring them is going to be "fun") After I removed the board I could see you're right there are a number of issues around that opamp ... and on the other side where the balanced sub-out connector is ... and further down the board (this one may just be a "spill" since parts don't look deformed, just some discolouration) What do you think ? R316 and R322 both appear discoloured and out of alignment. Possibly burned ? Discolouration around JZ2 and IC19 ... looks like a spill ? C324 area is all scratched and abused - this is the attachment for balanced sub connector out on the other side of the board Fourth picture is the other side from the first picture (roughly) ie. the back of R316 and R322. Looks like a dry joint ? Can only see this is a picture, not with glasses & magnifying glass. First step may be to address the "dry joint" and see if that helps at all. Then consider replacing R316 and R322 (somehow ... don't even know what to replace with let alone how) What do you recommend ?
  8. thanks @Stevesie I've attached some pics, attempting to show sufficient detail I've tried - - Pulling directly on the ribbon. It's a bit flimsy so have been careful. no sign of movement - Prying the middle of the plastic connector. There "may" be a line through the middle (longways looking down from top) ... but couldn't get any movement - Prying the "lid" up from the cable end. No movement - Prying the whole plastic connector off the board. No movement - Pushing or pulling the connector from the board. No movement running out of ideas thanks again for your help
  9. ummm well, progress - of a kind Summary - - By gently tapping the sides of the case noticed that a light tap on mid-right side consistently caused unit to turn off - Tapping right end of heat sink (large and runs left to right across the middle of the unit) also caused unit to turn off but tapping / moving wires down the right side of the case had no affect - Then more specifically - tapping the heat sink "arm" the top IO board is screwed to causes unit to turn off - but tapping lower board does not (not does tapping left end) - Tapping front right of the top IO board itself caused the unit to turn itself off .... NOW IT WILL NOT START (sort of) - Applying heat to upper IO board enables unit to start ! Will not start after cooling off ! Is it possible that there's a problem with the upper IO board, located at the back of the unit, which could prevent start-up ? Something about slight movement or heat expansion / contraction ? I can't see any discoloured or bulging capacitors etc - so nothing obvious. Any thoughts on how can I disconnect the ribbon cables on the upper IO board so I can remove and inspect it ? thanks for your help and advice
  10. hi Elf, my turn to apologise for tardiness circumstances have changed a bit so am holding back for the moment, (and for some reason I'm unable to send private messages (browser issues) ... hence posting to forum)
  11. that's interesting ... ok, so I should look "everywhere". Thanks for the heads up
  12. that's interesting ... ok, so I should look "everywhere". Thanks for the heads up
  13. ok, great thx. Will have a look-see. Not sure what values they all are ... will have to dig around a bit
  14. thanks @Rocky500 do you mean literally all the capacitors .... or just the electrolitics on the main power board ?
  15. fantastic, thanks for the feedback and advice. In the interim I have heard from Emotiva who advised me to replace 2 capacitors as outlined by Rocky (previous post). Emotiva sent an image showing the capacitors, what their original values were and what they should now be (unable to upload it for some reason. The same capacitors shown by Rocky are replaced by * C18 --> Nichicon Part No. UHE1C331MPD 330uF 16V 105 degrees (up from 220uF 16V @85 degrees) * C19 --> Nichicon Part No. UHE1C102MPD 1000uF 16V 105 degrees I replaced the capacitors as above and this seems to have made the unit more stable at high power/volume levels. HOWEVER it still fails to power up occasionally. Emotiva then advised me to monitor voltages at the connector just below the replaced capacitors (see picture above). The leads are numbered 1-5 from the left in the picture. Pins 2 and 3 should show 5V (MINIMUM, not even 0.1 less) at all times when main power is on ie. in standby and when operating. Note that pin 2 is ground/earth. If that voltage falls below 5V at any time the unit will power off. Also voltages at the connector "above" the replaced capacitors need to be measured, again pins are numbered from left to right in the picture. In this case there should be +12V on pins 1&2 and -12V on pins 2 and 3 where pin 2 is ground/earth BUT these should only be powered when the unit is powered up (not in standby) The next power connector to the left (2 pins only) should show +10V in pins 1 & 2 when unit is powered on. I ran a number of tests over several days of which only 1 test run led to failure (out of 18). There is an anomaly (?) on the top right connector. It shows +1.5V and +0.5V (pins 1&2, pins 2&3 respectively) when the unit is in standby vs. 0V expected. I've written to Emotiva and await their response. It sounds like it is worth replacing all the capacitors on this board ... is that correct ? Presumably that refers to the electrolitics not the others (tantalum, film ?) ... is that correct ? I take the point about heat (hot and cold) .. so will look into that. It may take a while since I've now lost my main amp ... it's died just this weekend ... so have pressed the Emotiva into service for the moment .. it works - just unreliable I must say I've been very impressed with Emotiva ... the unit is out of warranty and I bought it second hand, however they have responded to my request for help and remain enagged albeit with very slow turnaround times (fair enough since they are presumably also helping customers with "real" warranty issues) ... KUDOS to Emotiva. Thanks again for your interest and assistance
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