Sol
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Chief Technical Numpty
Posts: 135
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Post by Sol on May 9, 2007 14:04:41 GMT
Flummuxed - it's a word - but it's also a state of mind that I'm currently in!
So - I have a slight crackling in the left channel .. only occasionally and only when using Russian 61NEB tubes. These have been running a little hot .. and I've started to see some scorching underneath the board at each of the regulators.
So - I decided I'd stick some otehr valves in ... so I reached for my Nationals ... dead .. nothing ... nada. Both channles.
So I reached for the Mullards that arrived this morning ... dead, nothing nada!
So .. something says something has gone wrong between removing EBs and inserting otehr tubes.
I'll try my standard tubes later (busy right now), and the EBs back in
Also there's some known OK Nationals on the way from Mike I can try .. but are there any quick checks I can try to verify that tubes are OK? Is there a continuity check I can do?
I can hear a slight signal (unamplified I would guess) on full wack!
Thoughts anyone?
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Sol
100+
loves motorcycles !
Chief Technical Numpty
Posts: 135
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Post by Sol on May 9, 2007 14:34:37 GMT
Update: The tubes they glow ... but no sound .. so I guess we can rule out tubes!!
I'll try the 61NEBs again! Flummaxed will definately be a word if they work as before! Surley I can't have three sets of dead valves on both channels?
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Sol
100+
loves motorcycles !
Chief Technical Numpty
Posts: 135
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Post by Sol on May 9, 2007 16:08:37 GMT
Well bugger me if the EBs work, and all my other tubes don't!
Standard tubes - dead
Nationals - dead
Mullards - dead
Very bloody flummaxed! How can all of the tubes suddenly stop working. What is even more weird is that they all glow! Evry last one of them!
I need to go and have a lie down .. my head hurts!
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Post by PinkFloyd on May 9, 2007 16:41:08 GMT
Yeh, sounds like something has gone wrong. From my experience with these amps it's usually something pretty obscure (not obvious) and something totally unexpected such as a loose phono socket, a dry joint somewhere or the occasional wasted capacitor in the PSU section. You have power to the valves so not totally dead which is a good sign... I'd tend to look to the phono sockets first are you sure you didn't knock them or overly stress them plugging the leads in with the board removed from the housing?? If the amp works and then suddenly doesn't work after replacing both valves then very possible something has been disturbed when you've removed the PCB from the enclosure, look at the phono sockets first had a few apparantly dead amps and it was a broken ground lead inside the phono sockets both times  If not then we'll have to think about something else and then online diagnosis becomes VERY tricky indeed  |
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Post by PinkFloyd on May 9, 2007 16:42:57 GMT
Well bugger me if the EBs work, and all my other tubes don't! Standard tubes - dead Nationals - dead Mullards - dead Very bloody flummaxed! How can all of the tubes suddenly stop working. What is even more weird is that they all glow! Evry last one of them! I need to go and have a lie down .. my head hurts! Just noticed this after posting........ what to do is try one EB and one of the other valves (ie: EB on one channel and a Mullard on the other) let me know what happens  |
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Sol
100+
loves motorcycles !
Chief Technical Numpty
Posts: 135
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Post by Sol on May 9, 2007 17:19:34 GMT
Just noticed this after posting........ what to do is try one EB and one of the other valves (ie: EB on one channel and a Mullard on the other) let me know what happens I'll try that and report back .. .got my folks here so they'll be demanding food any second - break out the chilli, ginger, coriander, coconut milk, and fish suace ... a lavish amount of monk fish, and hey pretso, a resturante quality evening meal ... jeesh I'm hungry! Did you get the mail on parts BTW ... I have the bursons sitting here calling to me also! |
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Sol
100+
loves motorcycles !
Chief Technical Numpty
Posts: 135
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Post by Sol on May 9, 2007 23:31:52 GMT
Well ... what are the chances that every valve you possess is kaput. Has there been an EMP blast in Cambridge I'm not aware of? They were all perfectly fine on removal or bought from ebay!
Weirder than weird though .... when placed in a pair most of the valves glowed. When paired with a 61NEB they didn't! Likewise there was not sound (some in the 61NEB channel at full tilt)
Anyhow .. with a pair of Russian 61NEBs in, they both work, sound good, only they are running hot .. so back to fail safe, turn the appliance off while not in use.
On the good side ... while it's past midnight, I managed to get the bursons installed in the X-DAC V3 (fark me are those traces thin)... with limited opportunity to hit the volume, or listen to more than a couple of tracks (one each from Gladiator and Lord of the Rings soundtracks and a bit of opera) and acknowledging there's no supporting capacitors swoppped in, the bursons sound sweet and airy on first impression. More as my ears pick up the differences.
Up at 5.30! Bugger .. better hit the sack.
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Deleted
Deleted Member
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Post by Deleted on May 9, 2007 23:47:24 GMT
Seeing the new Russian tubes are running very hot, on top of your other troubles, have you checked your mains voltage ? It could be high at certain times of the day. If you have a circuit with values marked, it could also be worthwhile checking filament voltages and HT O/P voltage. Mike will undoubtedly be able to point you in the right direction in this area.
SandyK
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