| Author | Message | ||
     DAVID ELLER |
I HAVE AN 212 130 HD I WAS PLAYING A GIG AND I HEARD A KRACKLE LIKE A LOOSE CABLE CONNECTION AND THAN NO SOUND THE TUBES (NEW) WERE EXTREMELY HOT AND EVEN ON STANDBY ARE GLOWING RED NOW THER IS AFAINT SOUND COMING OUT AND A HEAVY HUM . CAN ANYONE GIVE ME AN IDEA AS TO WHAT TO LOOK AT. THANX DAVE.}} | ||
| Michael Kaus |
Sounds like you either lost bias and cooked the tubes or they wer biased to hot anyway and cooked. The part about getting hot almost immediately worries mr though. THe only thing running on standby are the heaters, which shouldn't get hot, just glow and get red. That could be signs of a transformer taking a dump. I would have the biased checked first. Do you have a 12ax7 inverter tube or one of the solid state driver models? Mike. | ||
| DAVID |
I HAVE A SOLID STATE DRIVER | ||
| Michael Kaus |
The tubes should get WARM when on stand-by but shouldn't get scorching hot. If they do, with that driver, you either lost the driver bias or smoked a trans. Either way, sounds like a trip to the doctor is in order unless you're comfortable working around 700 volt!. Mike. | ||
| Dave Emminger |
First off, change the LM1458. This happened to me too, although without the glowing tubes (maybe because I shut it off soon as it quit). The 1458 can be replaced without shock hazard if you shut off the amp first and don't touch anything besides the 1458. | ||
| Terry |
Take a look at the JE1692 drivers replace them with 2N6488 if you can not set the bias. | ||
| Damien Trinkkeller |
I'm almost sure its a transistor problem, I had the same thing happen.... I'm having a hard time finding the motorola JE1692 drivers though, i tried NTE331 & NTE196 which are B C E NPN transistors.. doesn't sound quite right... I'll have to try that 2N6488... | ||
| TERRY |
YES GET THE 2N6488 AND DO NOT USE THE NTE YOU CAN GET BETTER ONES FROM MOUSER THE NTE ARE NOT A GOOD MATCH. IF YOU NEED THEM I HAVE THEM LET ME KNOW. | ||
| Terry |
What is the problem with the amp!!!! JE1692 are not Motorola ! | ||
| Paul Bradley |
I am in the middle of "snap crackle pop" crisis.(MM HD-130 head) At my last gig, it started. Loud crackle, then no sound. I put it to standby for a while, turned it back on and was able to play, but not push it or it would crackle. Sent it out for repair, tech went through it and pronounced it OK. Still crackles at higher volumes, higher bass settings etc (using amp for bass). Curious as to what David Eller might have found wrong with his unit - it sounded similar to my problem. Thanks...........Paul | ||
| Steve Kennedy |
This sort of symptom can be related to output tubes, cracked resistors or leaky/noisy solid-state devices. You will need to determine whether the noise is coming from the preamp, power section or BOTH (power supply). Steve |