NAD 7240 Receiver Totally dead part 1 troubleshooting
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- Опубліковано 17 чер 2020
- I would have liked to have finished this one, but NOOOOO. Even though the parts are local,I can no longer go and get them, because some idiot didn't follow the rules, a complaint was filed and the city shut down the parts counter. Mail order only now, so once the parts get here in a few weeks this one will be back on the bench.
- Наука та технологія
You are so lucky to have a local place to order parts, all the good old shops here are gone :-(.
You are spot on with the nasty glue, i've had to remove it from ham radio synth boards, it screws up the operation.
For sensitive synth parts i used soft brown wax instead.
Yeah same here in Southern Illinois absolutely nothing!
We have 2 retail shops that sell some parts, and 1 mail order shop that sells the more specialty parts.
Nice one sir. Thank you for the upload and keep up the good work. I really enjoy watching your videos and listen to the narration.
Here, same issue with local parts too. but at least, you still can get parts with a pre order, and pass by like a drivetrhu to get it.
Love the way you trace, you don't leave much if anything out, i follow the same rules/ways and it's served me well too, up to now!!! Great vids thanks, why thumbs down? is it because they're stupid and can't face it and just can't look in the mirror to see a dummy looking back! I.Q.'s about 20 if they're lucky, just ignore 'em, all the best from the UK
Yup lots of forreet gumps out there.
Sir your too good in your job. I learn a lot from your videos. Wish I was your nabour. Your just like my elder bro Greg who passed away recently. He worked for sony in dubai, then for the Abu Dhabi
aviation company for many years. He and I had many good times repairing all sort of equipments. I have lost him but feel comforted seeing you repair. Love people who bring things back in to life and to original. Appreciate highly the patience and process put by you in restoring equipment. Your years of experience is so useful, but very few people are left who are so generous enough to share their blood sweat / life's time experience to the general public. Love your work, u will always be remembered. Keep it going. By the way I'm Clayton from Mumbai (india).
You know what they say, we are a dying breed, literally. Once all the old guys are gone all that will be left is the videos that we make for the younger generation to see how this old vintage equipment worked. The golden age of consumer electronics made back when the quality went in before the name went on.
Bonus points to anyone old enough to know that slogan.
I feel your pain Dave....waiting for the parts!
Thanks for another great video! Happy midsummer.
That really sucks that your local parts guy got in trouble. I have a big bag of outputs and drivers I salvaged out of dead AVRs that I use for cheap repairs. The 90's units actually had nice silicon which makes them worth taking the time to part out. A Pioneer I parted actually had the exact same drivers and outputs as a friends blown up Yamaha M-60. Aside from a few resistors, diodes and small signal transistors, it was a free (but time consuming) repair. Those amps blow up good when they let go.
Well the mayor of Surrey is kind of a dick. When Uber and Lyft finally, after many years of waiting for a license by the government (previous government kept them out) Surrey would not give them a business license because the mayor was in bed with the taxi industry. Ride hailing falls under provincial transportation board, and they licensed them for the entire province. So the mayor ordered bylaw officers to book rides, and when the driver showed up, slapped them with a 500.00 fine for operating in the city without a business license. The thing is there is no business license in surrey for them. All the other areas signed on to a universal license that covers all the areas. So he is kind of a dick in that respect. It was so convenient back last year when I could call him up and drive over, park around the corner and walk to his place to get parts, but now there is the extra cost of freight which I am happy to pass along, but also the delay to get parts. That wastes my time because I have to put the unit back together so things don't get lost and then take it apart again to install the parts. Again this gets passed along.
Dave! check the two smaller capacitors beside the two main filter caps; I ran into the same situation you did, replaced the drivers and outputs on the right channel, ran fine for awhile and failed. After more extensive troubleshooting I found a bad cap on the right side of the main filter capacitor, it had a high ESR reading, "problem solved", that was years ago still running.
Careful when you see that only one transistor in a pair fails. I was working on an old sansui that had no output on one channel and none of the outputs tested shorted in circuit so I pulled them and they both checked out with diode test. There was one burned resistor connected to one of them so I replaced it and put it back together. Ran it on a dim bulb and it held up but on full ac the same resistor went up in smoke and that time the corresponding output transistor did test shorted. The original fusible resistor just went open so fast that the failing output didn't have a chance to fully blow while also protecting all the other nearby parts. Was a little annoying to figure out but the experience was educational.
Fine reworking skills there 12volt.
Hot melt glue can have a resistance of 20 - 45 Meg .
I chased that one for a hours & it was the glue holding a plug in place .
The plug had 70 volts ac on it .
The pcb link running under the glue when open had 10 V a/c on it !
Im lost without my desoldering pump,i use wick for some smd jobs...nte is used here also,keep up the good job 12volts...
That intro music makes me wanna Rob a bank in Atlanta.
@Vivian Stimpson
ua-cam.com/video/g4ouPGGLI6Q/v-deo.html
@@12voltvids Nice
That conductive glue has given me more than a headache. Some Mohms always appear on the surface
Awesome performance from Focus.
Jan Ackerman really butchered that performence.
No matter what anyone says brother you do greeat work thanks for the videos.
I have people all over the country sending me stuff to fix. I know how good I am.
Get a short length of Silicone tube and stick it on the end of the sucker. Lets it form around the lead while you're applying heat to the joint and makes them work a lot better.
Today i found a reputable electronic repair shop in switzerland. This i very very very seldom (the repair market in switzerland is nearly dead :-( . i brought him my Linn classik Movie 5 for repair and servicing. the shop is full with repaired high end audio equipment ;-)
I find the kickback from my solder sucker makes it jump off the target half the time.
Why do you think you seldom see it.
@@12voltvids Are you referring to solder cracks?
@@12voltvids I have an old pair of my grandfathers glasses. They are very powerful. I call them my microscope glasses. If I can't see any cracks with them, there aren't any. But maybe I'll take another poke at it and try measuring the voltages on the transistors like you did and see what I get. The only trouble is, the construction of those units makes it hard to get at everything with the power on.
I am always wondering why do you don't use a desoldering station like a cheap ZD-915 on your workbench.
Q438 & Q434 are set up as a darlington yes? maybe they drew to much power and the collapsed the rest down/up the line... if ya get me!!
P.S. is that an app you were looking up the transistors on??? and if it is whats it called?? Thanks!
and loads of stuff iv opened up to see inside had that shitty glue! sometimes pumped everywhere like little clock radios & always on those multi connectors like you said.. : )
A lot of these boards are wave soldered and all it takes is repeated heating and cooling to crack the solder connections. Doesn't matter if it's wave soldered in Japan or China, thermal cycling will take it's toll. ;-)
So does thermal expansion of dissimilar metals. Copper expands at a different rate than lead/tin alloy. Eventually they will crack. Wave soldered just adds to this because the solder is very thin. At least when you do it by hand you can put lots on to make it less prone to this problem.
Hi, Would you have any tips on the right channel not working on my NAD 7220? I opened it up (first time) and hoped it may be an easy repair like a speaker fuse (I assume two or more of the six fuses may be for the speakers?). I tired the extra speakers connection as well and right one not working there either. The wires to the speakers are ok. I have no experience with electronics but would like to keep this unit running. I've watched a few of your videos. Very interesting. Thanks!
Could be just about anything. Will need troubleshooting which is generally beyond a novice ability. Not something that can't be learned though as all of us started somewhere. I started when I was about 8 putting together those radio shack p-box kits and the 100 in 1 project boxes. Then moved onto more advanced heathkit. By the time I was 14 I was hanging around at the local TV repair shop trying not to electrocute myself.
Thank you!
HI there 12volt..Thanks for the video. I've had this receiver for >30 years and it went out last Christmas when I went to play our Christmas CDs. I would like to try and troubleshoot it...Any idea where I can safely obtain a service manual? Some of the download sites look a little sketchy.
SN A740 AK 26072
Regards--
John
I have this amp, the same problem. The output transistors were blown by a fault in the circuit board I have yet to find. without finding the fault,(a crack or loose solder joint) new transistors will blow if pressure is placed on the board, even picking up and moving the unit. I like the amp, so will try to fix it some day. at the moment the outputs have been removed. The tape out still functions, but when i press on the circuit board, it will cut out. This is what I use to find the fault, which I have not found yet. Until I do, there is no point in replacing the transistors, they will just blow again, The last time I worked on it i checked most of the solder connections, re-doing most of them, but still, when i press on the board, the sound in the right channel of the tape output cuts out. I am sure that if the outputs were replaced, they would blow when this happens. Do you have any suggestions where the fault causing this cut-out may be located? I have checked most everywhere, but no luck.
I bought one of these back when they were new, the 7240PE, and just inside warranty the same thing happened on it.
It blew the right channel, and not under any heavy load or anything. One day when i turned it on it went "pop".
Got it fixed and used it for a while, and then gave it away. Didn't think it sounded that great.
Why don't you like solder suckers? I love 'em if they are any good that is, lol
I'm on the other hand never used solder wick even though I got some laying around.
Because every one I have used is more work than it is worth. I had a real expensive station at the shop and every time I went to use it, it was all clogged up, or clogged up while using requiring disassemble and cleaning which wasted time.
KSHE played that record
back in the day.
People back here in Southern Illinois know nothing about KSHE in LA. :-)
Good old KSHE in St Louis.
Hey everyone, what's the best place to find schematics for older electronics?
hifiengine.com radiomuseum.org
Quick tip. If you use the reading mode on your phone it reduces the burn in significantly and is easier on your eyes.
I need to see during the day in the bright sun so turning down might solve the burn in problem but will create a usability problem :)
Modern displays don't suffer from "burn-in". That was for Plasma and CRT screens LOL
@@johncoops6897 OLED has burn in and I believe that's what he is using.
@@rickn3146 - Yeah, OK... however OLED Burn-in occurs when there's a STATIC image on the screen for a very long time. It seems that the phone used here is also used outdoors for other usage, so it's displaying varied content.
Furthermore, the videos shot at the work bench are what... an hour or two each week? At that rate it would take decades to accumulate enough hours for permanent burn-in (rather than temporary image retention) to occur.
I use the braid, the solder pullers send toner everywhere, glasses face, etc
You shouldn't be cleaning photocopiers with them. Use a vacuum.
When do you get the new output transistor?
When they get here.
Replacement parts is my biggest pain in the ass, makes me want to just give up at times, our throw away world!
" Hocus Pocus"
from 1973.
.....By Focus! Got this album in my collection!
Get yourself an Edsyn DS017 Soldapullt! Never again will you swear at one of those shitty solder suckers 😂 The Soldapullt sucks so well, it almost makes desoldering a joy!
I used to have one. Worked pretty good.
I had the same Weller solder pump but after a few decades of faithful service the spring broke. I'm annoyed by this as I can't find this one new. The cheap Chinese solder pumps are junk
i pickup up one of those electronic desoldering pump its a aoyue int474a from amazon has good reviews for its price
Many things on my wish list.
@@12voltvids indeed makes working on stuff a bit easier
The group is from
Denmark.
Actually Focus was Dutch
Part 2: ua-cam.com/video/BR-SfpLb1z8/v-deo.html
Hi Dave over the years I've come to really not like NAD gear like there casette decks are cheep and are not user friendly at all
Some people love NAD and others hate em.
Since I have never owned one until I was given a 7120 I have no opinion. I have fixed a number of them over the years, but then I have fixed all the other brands as well.
I have some parts to give you. Please let me know where to send them. USA address is best
Ha ha very funny. You do know the border is closed right.
@@12voltvids No i didn't . Let me know when they let you guys out. I have lots of stuff from repair business. I'm retired now.
Yes it is. We want to keep the virus out now that we have it under control here. Only 7 new cases yesterday and no deaths in past 7 days were I am. Unfortunately the numbers keep going up in the USA. So the border stays closed to non essential travel for at least another month. Goods still makes it across, as do essential workers like doctors and nurses but no casual travel.
@@12voltvids Unfortunately, the US isn't as smart as canada. I was there once in 2000. very beautiful