ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Just a story from me....
I am in the process of restoring 2 Beolab 200 amplifiers, and got a complete service kit from Dillen(great service). I changed all caps and the op-amp, and went on adjusting the idle-currents...
Plugged the amp in, and measured and measured... Could not get any mV reading at all?? Testet if the amp actually worked, and it did. Disconnected the amp completely, gave it some time to cool down, plugged it back in, measured .. still nothing, nothing changed when adjusting the resistors.. nothing at all..
Gave up, went down to the local pub with one of my friends to have a few beers, we started talking, and I told him about this amp, and the second I told him I could not get a reading...... lightning struck :)
Would it maybe make difference if I actually powered the amp up ?? I have been doing all the measuring in std.by with red LED :) :) :)
Powered the amp up with no signal, and behold.... all was great and I could adjust the idle current...
Boy did I feel stupid :)
/Weebyx
To public a story like that takes a real man.
Glad to hear you work it out
Henrik
Don't feel like the Lone Ranger there, I've done that more than once. Got well into tearing something apart to realize it just wasn't plugged in!
I am still held in awe by my engineering and other male friends for this one, though it's not a screw up per se. I had an AV cabinet, pre B&O days for me, stuff to the gills with electronics, cable box, VCR, Laser Disc, surround processor, two power amps, etc. Just a complete blivet (a blivet is defined as 10 lb of excrement shoved in a 5 lb bag). Well, the VCR died, so I bought a new one since they were cheap. So I go to replace it, and find that the power cable is impossibly entangled with every other cable in the back of the cabinet. I'd have had to take everything out and spend the better part of a day untangling everything and putting it all back in.
So, I think, aren't there only one or two makers of these things now? I pull the cover off the new one and the old one, and yup, the power supply boards are nearly identical! The power cord plugs into the board using the same connector on both! So, I pull the cords on each, route the cord from the old one into the new one and plug it in, put the top back on, and slide it into the stack of gear! Problem solved, so, I went back to drinking beer instead of spending the day on my hands and knees swearing at the wires.
Laziness can be an art form!
Jeff
I'm afraid I'm recovering from the BeoVirus.
Rich:I broke the voice coil lead of an M70 tweeter once. Two years later I was able to fix it and send it down to Mexico for Soren. Hopefully it still works.
Still works Rich
Collecting Vintage B&O is not a hobby, its a lifestyle.
Adjusting idle current on my BM 901 I shorted to ground not one but 2 times, each time blowing diodes and a couple of transistors,
BL 5000 amp, wrong polarity on 2 transistors, only found it after buying a scope and learning how to use it, cost me 3-4 days, before I bought the scope.
When you start doing things you never done before it will cost some learning time/money
Søren Mexico: When you start doing things you never done before it will cost some learning time/money
Correct :)
I was beginning to look for a new multimeter since the old must be broken :)
The most annoying thing is that I just have adjusted idle current on my BM7000... And that didn't ring any bells.... Beer did though :)
/weebyx
Here's one I did. I had an over the counter microwave once, that had this huge collective solder joint where a lot of the power leads came together from the various boards. I'd repaired it once, reflowing the solder joint. I did just so so job, so it failed again several months later. So, I take my favorite soldering iron with a grounded tip, opened the front up, exposed the solder joint, stuck my iron on it and Kablam! I'd forgotten to pull the power plug, so my poor soldering iron got full 110V no limits on amperage outside the 20 amp breaker power. I dug out my old junk soldering iron after pulling power and fixed it (stayed fixed this time) and then looked at the board in my other iron to see if it was repairable.
Nope. It blew out a resistor, and a couple of diodes on the board that handled grounding of the tip. I couldn't replace them as I couldn't tell what they were, they weren't just bad, they were not even there, the current surge had just completely vaporized them and scorched the board under them. Had to replace it with a decent Weller, but I never have liked it as much as the original one I had.
Peter:Jeff's microwave storie reminds me of when I was 13 and my dad gave me a soldering iron and a beginners electronics kit so I could learn to fix electronics around the farm since he had no patience for it. Microwave, broken switch on the door, easy fix, if I could get the switch out. I skipped out on basic safety teachings like, discharging capacitors and unplugging appliances before sticking your hand in it. Result, woke up on the floor in our barn with a second degree burn on my right hand and a cramp that lasted days. I must have fainted when I got shocked. My parents used that microwave for another 10 years.
Microwave, broken switch on the door, easy fix, if I could get the switch out. I skipped out on basic safety teachings like, discharging capacitors and unplugging appliances before sticking your hand in it.
Result, woke up on the floor in our barn with a second degree burn on my right hand and a cramp that lasted days. I must have fainted when I got shocked.
My parents used that microwave for another 10 years.
Hehe, that reminded me of when I was 8, and one dark evening, decided to disassemble my alarm clock to see how it worked. One of those old with the "spinning digits"..
To see how it worked, I had it plugged in while looking at it go.... And somehow decided that it would be fun if I shorted the 220v wires with the screw driver. Big flash and the the circuit breaker went, the whole house went dark, and since it was totally dark outside, and because my eyes just got flashed, I really thought for a while that I was blind... Couldn't see anything for a minute or so, and when my parents got the light back on, they asked me if I knew what happened :)
Couldn't hide the totally fried screwdriver and badly scorched clock radio :)
Reminds me of my father. We had this huge, old Magnavox B&W TV, this is back far enough that the sides of the picture tube were curved, all tube set, no transistors. The whole thing ran on very high voltage, the B+ for the tubes was worse than the picture tube power as it had more current. So, dad decides to work on it, is laying under it, and apparently decides to just take a little nap.
My mother comes in, sees my dad laid out on the floor under the TV with the back of the set off, and immediately freaks and thinks he's electrocuted himself, especially as he's sound enough asleep he didn't respond to her initial "are you all right" queries. After she starts yelling at him he wakes up with "what are you screaming for?"
I still have his old electronics tool box, filled with old tubes and "condensers" and such. I periodically rediscover it and look thru it, the smell of old electronics alone reminds me of him, good memories.
Søren Mexico:Still works Rich Collecting Vintage B&O is not a hobby, its a lifestyle.
I just changed a shorted main capacitor on my MCL2P amp. Well, I just went and re-capped the whole thing while in there. After all that work, the amp would not come out of standby.
Yep, after much head scratching and measuring voltages.... you guessed it..... It was laying on it's face, pressing the "off" button. And I did this 3 times in a row, each time removing the whole board to check things! Nice!
Here's a cosmetic one for you all...
Got my hands on a Beogram 2400 with a really badly chipped side. I ripped off the wood, and stuck on a strip of wood-grain shelf liner.
Not sure if that qualifies... but seems pretty dumb to me now
Wish I had pictures!
TheTinman: I just changed a shorted main capacitor on my MCL2P amp. Well, I just went and re-capped the whole thing while in there. After all that work, the amp would not come out of standby. Yep, after much head scratching and measuring voltages.... you guessed it..... It was laying on it's face, pressing the "off" button. And I did this 3 times in a row, each time removing the whole board to check things! Nice!
Christ !!!! Last week I experienced issues with my ML/MCL converter and Powerlink cables. It would not turn on connected to my BS9000, tried lots of cables and one worked.
After reading your responce, tried all my cables last night, and all worked, so I bet that it was lying down when I tried it last week :) :) :)
Moving place in 1995 I found a cable sticking out of the wall in the corridor. I checked the voltage with a simple voltage tester embedded in a cheap screwdriver. Result: zero. OK I drove a nail into the wall. hooked up a small decorative piece of bronze thus covering the cable. One year later our caretaker, an electrician, checked with a real voltage tester. Result: 220 V (connected to the fuse box by someone without sense for safety, no FI, only 16 A fuse behind it).
No harm, much luck ...
1980s Beomaster 5000 - checking idle current - meter probe slipped - BANG!
On the upside, when I was confessing my sin to a certain Mr. Jarman, he admitted to having done exactly the same thing several years previously, which made me feel a bit better!
Peter the Biker: Moving place in 1995 I found a cable sticking out of the wall in the corridor. I checked the voltage with a simple voltage tester embedded in a cheap screwdriver. Result: zero. OK I drove a nail into the wall. hooked up a small decorative piece of bronze thus covering the cable. One year later our caretaker, an electrician, checked with a real voltage tester. Result: 220 V (connected to the fuse box by someone without sense for safety, no FI, only 16 A fuse behind it). No harm, much luck ...
You really have to watch how houses are wired, they are usually not wired the way you think. In my last house, I was going to put a ceiling fan up in the bedroom. So, I go off to the fusebox, find the breaker clearly labeled for that part of the house, and flip it off. Go in, lights won't turn on, so I figure I'm good. Climb up on the ladder and pull the preinstalled wires down, think to myself, well, I just better check. Grab my meter, 110v on the wires. Hmmm. So, I go back and start flipping other breakers, turns out the ceiling fan light in the bedroom was wired to the breaker for the front room and outside lights in front, not to the breaker for the back of the house. Always, always, always check.
Jeff:Climb up on the ladder and pull the preinstalled wires down, think to myself, well, I just better check. Grab my meter, 110v on the wires. Hmmm.
I always heard that getting an electrical shock is good for the treatment of rheumatoid arthritis without drugs
But you're right, there goes nothing above this wise saying: "measuring is knowing". In Europe, we have at home 230 volts and high-tension current 400 volts for the cooking plate or electrical motors.
Gives us an extra reason to be careful in working on any electrical systems in house and at industrial estates.
"Believe nothing you read and only half of what you see, let your ears tell you the truth."
I learned to be really careful both due to my career and my hobbies. As for hobbies, the B+ voltages on tube amps are very dangerous. On the career front, take all jewelry off, and keep your left hand in your pocket if you're right handed, so you don't accidentally make a path to ground across your heart.
Laser lab, the power supplies could be terrifying. We had a 2500 watt CO2 laser that used 25,000 volt power supply rails. The smaller CO2 lasers used 10,000 volt rails, all had high current capacity. We had one engineer accidentally touch the 10KV rail while adjusting the output coupler of the 100 watt CO2 laser. Blew him across the room, he hit the wall hard enough to put a man sized hole in the drywall. Blew his shoes off, and his ring and watch flew off he spasmed so hard. He survived, but got to spend 24+ hours in the emergency room to make sure the shock didn't cause him to dump enough electrolytes to cause heart problems or kidney failure.
The dumbest thing was NOT to check the 240V to 110V converter settings after moving to a new place: Bought a very nice Japan only machine from Sony plugged it in and the fuses of of the living room where gone within a second. The Sony didn't even have a chance to survive.
AdamS: 1980s Beomaster 5000 - checking idle current - meter probe slipped - BANG! On the upside, when I was confessing my sin to a certain Mr. Jarman, he admitted to having done exactly the same thing several years previously, which made me feel a bit better!
and I thought I was the only one ....