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I have to admit my err!...feelin' like a DORK!

wajobu

wajobu

Boing Boom Tschak
Well there I was this evening having a good time cleaning up a real DOG (WOOF!) of a Yamaha A-1 (before photo attached). I bought it from someone who retrieved it from a storage locker in TX (after an estate probated). It's missing the lower door, but if it sounds good...!

I had the lamps replaced, it's all clean again on the inside and I was setting the Idling Current and DC Offset (the test points aren't the easiest to access) when one of the probes of my DMM (Digital Meter) slipped at a DC test point and "ZZZTTT" with small spark and the amp went dead...blew the fuses so fast that the GFCI outlet didn't even have a chance to "trip"! :tears:

I need a third hand! The offending test points are at the right side of the photo near the light blue variable resistors.

In theory, all is well and hopefully it's nothing that a visit to the hardware store won't solve for a 125V 7A and two 250V 1A set of fuses.

DORK! :yes:
 
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Join the croud ! I think some great folks here a AK told me. :scratch2: last year when I murdered an otherwise perfectly functioning , cosmeticly perfect PIONEER SX-828 I aquired for FREE ! I was only replacing one little spent dial lamp and stupid me, Forgot to power her off , WTH ? and with a slip of the wrist POOOF ! Cream Puff unit was suddenly TOAST ! :tears: Yea, it can be repaired but it WAS NEAR MINT AND FREE ! Talk about a dork........ :yes:
 
It was suggested to me by our own Merrylander (thank you kind sir) that before I did this sort of exploratory surgery, that I buy myself a pair of micro-clip style test leads for my meter. I haven't yet, so I've been putting off the repair in question, but with my paws I know how easy it would be to "let the magic smoke out". Hope the fuses get you fixed right up buddy.
 
Mikeymax said:
Join the croud ! I think some great folks here a AK told me. :scratch2: last year when I murdered an otherwise perfectly functioning , cosmeticly perfect PIONEER SX-828 I aquired for FREE ! I was only replacing one little spent dial lamp and stupid me, Forgot to power her off , WTH ? and with a slip of the wrist POOOF ! Cream Puff unit was suddenly TOAST ! :tears: Yea, it can be repaired but it WAS NEAR MINT AND FREE ! Talk about a dork........ :yes:
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Tell me about it man. I learned my lesson last year when I left the power on to my machine as well. And boy, did I feel like the stupidest dork.

Say, for testing with hard to reach pins, wouldn't alligator clips on said pins work just as well? I am thinking that clipping the pins and then taking the wire out of the machine where it is easier to test might be a good idea. I havn't done this method yet because I havn't encountered hard placed pins yet, but I can see it as an idea.
 
Hey, are you hurt ? Is anyone else hurt ? No? Then don't sweat it. Any of this stuff can be fixed after a fashion, but sometimes people can't be fixed. And about everybody who fools around w/this stuff has had an "Ochit !" moment like you had. The ones who haven't just haven't been at it long enuff..
 
No one hurt!

No, no one hurt...I'm pretty careful--or try to be (even with the one hand in the back pocket trick sometimes). When I'm working on the amps (and I am still pretty new to this, but definitely NO electric conducting tools in my hands!)...THEY ARE OFF, but when setting the idling current and DC offset they need to be on, and I try to work carefully (with my wedding ring off too!). I also have everything plugged into Ground Fault outlets as well.

Merrylander also advised me on how to discharge the caps before working internally on an amp with a large resistor or a 60w light bulb in a rubber socket (with goggles!). So far, I'm using a heavy service (contractor type) light bulb and it seems to work.

The Yamaha A-1 also has convenient capacitor discharge points (with a suitable warning printed!) on the main Circuit Board.

Also, Merrylander has suggested some clip on probes available from "Mouser". I think that I will call them and order a catalog and place an order for some.

I'll report back after the new fuses are in place.

Sheesh!
 
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Fernzee said:
Say, for testing with hard to reach pins, wouldn't alligator clips on said pins work just as well? I am thinking that clipping the pins and then taking the wire out of the machine where it is easier to test might be a good idea. I havn't done this method yet because I havn't encountered hard placed pins yet, but I can see it as an idea.
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This is just what I did with my Yamaha amp. I took small alligator clips and soldered some wire between a pair of them to make some 8" jumpers. One end on the hard pin on the amp board, the other end gets clipped to the ends of my DMM probes. Any chance of any metal contacting? Just lay a small sheet of paper underneath. Works like a charm and frees both hands.
Tom
 
i hope you get it up and running again -- i have an A-1 amp that is super nice and sounds fantastic with ADS speakers....
 
shrinkboy said:
i hope you get it up and running again -- i have an A-1 amp that is super nice and sounds fantastic with ADS speakers....
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Fortunately for me I have another REAL A-1...a beauty (with all its parts) that too is hooked up to a pair of ADS L520s...oh, then one of my sons has another fixer-upper (no sparks on that one!).

I like this concept of an insulated jumper wire with a couple of small alligator clips (hardware store technology)...now that's something that I can make. :thmbsp:

This "Texas" (state where it came from) A-1 was a real mess when it arrived, so it's definitely a tinkering "project".

Thanks for all the input and stories of "Dork-dom" :D
 
Jeez you guys only killed one amp. I fried 2 of them at once. Talk about being a dork; well that makes me a super dork. I accidently touched the speaker wires together while my proton d1200 and adcom 555 were running. There was a horrible zzzzaappp and both amps went silent and immediately began smelling of fried electronics. The only noise coming from my listening room for a while after that was some horrible language; most of it directed at myself. Gotta turn those units off before making changes.
 
I Joined the ranks years ago

Fool that I am I believed my friend, the audio tech, that I should replace the heatsink compound on my five year oldSX-1280. After removing the transistors, cleaning the heatsink, and reseating the transistors properly (I thought), I fired up the receiver. Fired up would be the appropriate part of that statement. There was an explosion that sounded like a shotgun going off. The transistors were merely craters bolted to the heatsink. To this day I am uncertain what exactly I did, but I believe when I reinserted the transistors they were not properly centered and the leads were touching the heatsink. My best friend, the SX, stayed with me for two years afterwards because I could not afford to have it repaired but I couldn't bear to throw it away, but eventually the day came that I put it out on the curb with the trash can and I sadly watched as the trashman picked it up and threw it in the back of the truck. That was twenty years ago and I am still kicking myself in the butt for what I did. With what I have learned here at AK I know that it probably could have been repaired but back then I was poor, I had saved for 4 years to have the money to buy the SX in the first place, and did not think too far into the future. I think to call me a dork would be a kindness.

The only upside to this story is the fact that I found a G6000 at a pawnshop and due to a mixup of some kind the man sold it to me for $65. I walked out of that shop as fast as I could expecting someone to realize the mistake they made and come running after me. That G6000 is still my primary receiver today.
 
Hey guys, the only reason you would be a dork is if you didn't learn something from those experiences!

I've done my share of dumb things (Deoxit works great on switches; might as well put it on the tuner fins!) As long as I don't make the same mistake twice I consider it a cheap lesson.

Jim
 
Jim H B said:
Hey guys, the only reason you would be a dork is if you didn't learn something from those experiences!

I've done my share of dumb things (Deoxit works great on switches; might as well put it on the tuner fins!) As long as I don't make the same mistake twice I consider it a cheap lesson.

Jim
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True enough Jim. I learned to turn my sh*t off before working on it!
 
Yes, I did learn from my mistake...

Well, as always, I DID learn from my mistake...fell off the horse, but then got right back on...this time with a keeper...CR-2020. Over the weekend I popped the top (rather, slid the unit out of the box) and cleaned-up my fairly new (to me) CR-2020. I have wanted to check and adjust the Idling Current as recommended by Merrylander. This time, I had my newly made insulated wire jumpers with insulated aligator clips for a hands-free hook-up to the DMM. I hooked to the test points (double checked the connections!) and then performed the adjustments at the variable resistors. I got both channels to settle at 9.5mV (within the 10 +/- 1mV)...they started at 1.0 and 14.0 mV respectively.

I had shaky hands at first...I didn't want to screw THIS one up!...and in the end, it worked...all back together...hooked-up and music! :music: The DC offset (no adjustment for this in the 2020) seemed to improve a bit over the last check (I just don't know if the two values are inter-related).

I'll figure something out with the A-1...alas, I did put new fuses in and this time only the 125V 7A fuse blew :tears: (nice light show!), the two 250V 1A fuses did NOT blow. I'm not quite sure what that means, but I took the power supply board and drive circuit boards out and I don't yet see any visible signs of a short (or arc-welding!). I may send it to Merrylander later this year for a diagnosis, but for now it's all cleaned-up with no place to go. It is, however, an ugly duckling with missing external parts, but if I can get it working again it will be a good companion and back-up for my other A-1 (and THAT one is a beauty will all its parts!).
 
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Isn't it amazing how often we (or maybe just me!) don't take the time to turn the power off when working with speaker wire, interconnects, etc? Audio 101!

I f'd up a nice HK750 integrate amp while trying to adjust the bias.


Glad you got the 2020 adjusted. Those are great receivers.

Jim
 
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