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Post by (8^D) on Feb 5, 2007 22:40:05 GMT -7
Ok folks, put you to the test. Sr 212 w/verb died tonight during some quiet noodling while plugged into a Weber MiniMass set at 3. Ohm loads were set properly. Amp hasn't moved since 10/30/06 (Jr's been getting the gigs during the break). ---------- Pulled/replaced the 3/4 and 3 amp fuses (originals were fine but in case), replaced every tube, swapped input cables and nada. Speakers are fine, speaker cables are fine. After retube/fuse I plugged in & powered up the amp. The Power Tubes light up, but do not change when flipped off stand-by...they normally glow hotter when kicked off standby. All the pre-amp tubes look like they're getting juice. No sound, no pops, no hiss, nothing audible at all. Thoughts/suggestions/recommendations? Appreciate the help. Time to plug into the Jr. Thanks! DW.
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Post by John on Feb 6, 2007 4:10:51 GMT -7
Pop the hood. Take a look inside. Does anything look burnt or discolored? Stick your nose down there, does anything smell burnt?
If I remember correctly, the Doc has mentioned a bad grid resistor in this situation.
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Post by DRZ on Feb 6, 2007 5:39:13 GMT -7
If it doesn't change when you flip Stand-by on I would say your rectifier isn't suppling High Voltage to your tubes.
Swap it and pay CLOSE attention to the key way of the socket and the tube to get proper match.
I had one come threw that the Rectifier was twisted not keyed correctly didn't pop fuse but no High Voltage= no sound.
Easy fix but a lot of trouble and shipping for an incorrect tube placement.
Z
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Post by (8^D) on Feb 6, 2007 6:15:21 GMT -7
If it doesn't change when you flip Stand-by on I would say your rectifier isn't suppling High Voltage to your tubes. Swap it and pay CLOSE attention to the key way of the socket and the tube to get proper match. I had one come threw that the Rectifier was twisted not keyed correctly didn't pop fuse but no High Voltage= no sound. Easy fix but a lot of trouble and shipping for an incorrect tube placement. Z Hi Doc, Tried 2 different Rec tubes (after fuses, was my first thought) and neither made a difference. They were seated properly. Still wouldn't pass on power to the EL84's. Other thoughts? Dan
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Post by (8^D) on Feb 6, 2007 6:21:25 GMT -7
Pop the hood. Take a look inside. Does anything look burnt or discolored? Stick your nose down there, does anything smell burnt? If I remember correctly, the Doc has mentioned a bad grid resistor in this situation. Was another thought, but trying for the 'easy' stuff first. Will probably drop the chassis today and see what's up. If worse comes to worse, there's an authorized "Z" repair shop nearby. DW
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Post by billyguitar on Feb 6, 2007 8:27:25 GMT -7
Disconnect the attenuator first. Take it back to normal. Try it now.
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Post by (8^D) on Feb 6, 2007 8:59:46 GMT -7
Disconnect the attenuator first. Take it back to normal. Try it now. Appreciate the input, but I tried all the obvious/simple stuff (tubes, fuses, cables, wires, removing attenuator, checking knobs/settings, checking switches, checking connections to the speakers, looking for what's glowing/what's not, swapping things in/out and testing them in the Jr as well) before posting. Amp doesn't even make a sound with a cable and my thumb tapping the end...and I've even tried different cables..and different thumbs. Put the same gear on the Jr and it's fine. Sr is silent. I'm thinking something failed inside. It's been one of those weeks in the world of gear... Going to poke around inside the chassis this afternoon once the kiddo goes down for his nap (yes, I'll be careful . Any component suggestions to add to the grid resistor?
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Post by DRZ on Feb 6, 2007 9:13:51 GMT -7
Don't know what else to tell you, if no Hi Voltage either bad rectifier, bad fuse , or maybe fuse holder, or Stand-By switch it self.
All of these are pretty dangerous for a non-tech to deal with, so be careful and if it's not obvious just send the chassis back to me I'll fix it.
DR.Z
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Post by (8^D) on Feb 6, 2007 10:55:46 GMT -7
Don't know what else to tell you, if no Hi Voltage either bad rectifier, bad fuse , or maybe fuse holder, or Stand-By switch it self. All of these are pretty dangerous for a non-tech to deal with, so be careful and if it's not obvious just send the chassis back to me I'll fix it. DR.Z Will take a look. If I don't see anything I'll package up the chassis and send it your way. Appreciate it! Thanks! Dan
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Post by (8^D) on Feb 6, 2007 14:04:53 GMT -7
Hey Doc, The amp mysteriously came back to life...I flipped the amp forward, pulled the rectifier to double-triple-dog check it was in correctly (and was) and flipped the amp back upright and turned it on. Flipped it off stand-by and the speakers popped like they always had...quickly grabbed a handy cable and it's working. I hate electrical 'ghosts'. Think I should go ahead and pull the chassis to: 1. Tighten or clean the rec socket? 2. Look at and clean the stand-by switch? 3. Clean the fuse holders? The socket and fuse holder looked very clean during the trouble-shooting exam. It's setup the same again just idling to see if it will fail again. 60 minutes after it fired up and it's still running fine...
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Post by John on Feb 6, 2007 16:14:17 GMT -7
It worked because I had just removed the hex I put on your amp. But don't worry, it won't happen again, I'm all out of 'eye of newt' and chicken toes.
But seriously folks...
From my limited knowledge, that sounds like a rec socket. Not necessarily that it needs cleaning, but that the pin clamps...clamp down correctly.
From The Tube Amp Book by Aspen Pittman:
When tubes are changed again and again over time, the socket's female parts begin to stretch and not make good tight contact with the tube pins. This can lead to arcing and intermittent connections between the tube and the amp. This condition can be aggravated by the vibration from your speakers and so may occur on certain notes on your guitar. You can correct this by replacing the socket (last resort) or by retensioning the socket with a large safty pin, jeweler's screwdriver or small ice pick. Use a tool with an insulated handle if possible. First: disconnect the amp from the AC outlet and allow the amp to drain off any voltage by leaving your speakers hooked up to the amp with the standby "ON". This takes just a few minutes and could save an awful experience later. Now remove the tubes and notice the contacts located inside each pin hole of the socket. These contacts spread the pin hole--do not push the contacts in so far that the tube will not re-insert. After you've retensioned all the contacts, replace the tubes and notice how much tighter the tubes are held. You may also find corrosion on the contacts. Try spraying a little contact cleaner or WD-40 on a tube and inserting it into the socket a few times, This will improve the connection to the tube and prevent further corrosion.
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Post by hdahs143 on Feb 6, 2007 17:37:25 GMT -7
Hi Dan! When you get a chance, pull the chassis and take a look inside. It sounds like you might have a bad/cold solder connection at the rec tube socket, or the standby switch. There are wires that run from the rec tube socket to the standby switch, and from there usually to the rest of the amp. Just make sure the caps are discharged before poking around. You can use the method above, and check with a volt meter across the cap to make sure that it's still not storing high voltage. Hopefully the problem is in one of those couple of areas. If your amp is working fine now, you dont have a problem with grid/plate resistors, and even if you did, the amp would still make sound, albeit not very toneful, or until it blew a fuse. Good Luck and keep us posted. (pardon the pun). Harold
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Post by (8^D) on Feb 6, 2007 19:26:59 GMT -7
gtrman3, thanks for pulling the hex! Have one for curing bad note choice? I'm going to pull the chassis next day or two and check that and the standby switch/wiring/solder joints (thnx Harold and Doc). My Jr had an issue with the Rec socket tension but it faded in/out rather than just quitting. I'm just glad it's not a resistor...I won't own any newer Fender products because of those lil' buggers...WAY too many of them to troubleshoot when 1 fails...sounds like bacon frying when they go bad...tone's not good AND it makes me hungry. ;D
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