Sunday, 27 January 2013

A Smoking NAD Repair!

NAD 7020

The NAD 7020 I brought home to fix the other day was calling to me, so I started on it yesterday and finished it today. I almost finished it real good, but the smoke seems to have cleared.

I have always liked NAD equipment. The brand does have it's detractors with stories of cheap parts and poor quality control. I don't have much against them, as I have always liked the performance for the dollar being the cheapo that I am while still wanting good sound. I don't even mind the look which others put down. I have had more devices from NAD than just about all other brands, and kept them for longer on average. I do admit I've also had to fix more of them...

I used to have the NAD 3020 which was the integrated amplifier section of the 7020 receiver model. With that in mind I really wanted to play with this one from Clint.

Cosmetically this is in very good shape and has just a few minor scratches. It needed a good cleaning though. The usual dusting inside and cleaning of the switches and controls with contact cleaner I did yesterday. After plugging it it though I found another annoying issue.

NAD power switch 2

When turned on, even after another spray of contact cleaner in the switch area, the lights and also the sound to a degree sputtered and flickered. I've seen this before and decided to see if I could deal with it. It usually comes from electrical arcing in the switch and I saw it most seriously in a Pioneer SA-450 receiver, and I still have not fully addressed it there. The culprit in the Pioneer and as it turned out in the NAD was an ALPS brand switch.

It's a different model this time and appeared to be easier to access so I decided to go for it.

NAD power switch

Disassembly had to come after removing around 20 screws to get the cabinet and face plate out of the way, plus a number of wires to de-solder. The parts inside the switch of course decided to sproing out before I got a good look at how they went together. Figuring out how they went back together was trail and error...and trial and error...and so on, for about an hour until I had it right.

Anyway, age, dirt corrosion and so on lead to the arcing which blackens the switch contacts with soot or something similar. Taking things apart and scraping & sanding is just about the only way to address it. A simple spray cleaner does not do the job when it gets like this.

NAD switch parts

When I first saw it the round pad on the lower piece was as black or worse than the part above it that it had to make electrical contact with in order to turn on the receiver. There is another set inside the switch as well. Scraping with a screwdriver blade and sanding with emery paper cleaned things up quite well. This was the easy part. Now I had to put it back together.

NAD power switch 3

NAD power switch 4

Eventually I managed to figure it all out, had it reassembled and soldered together and had no flickering when I powered it on. So I reassembled the case, with the 20 screws of different lengths.

That's when the next problem arose. I had tested it before and the receiver had worked with headphones, tuning in AM & FM radio stations. Connecting a turntable and speakers came next... and so did the smoke!

It made sound, but a little curl came up from the cabinet in the tuner area. Powering it off and examining it, it looked like the smoke had come from a point on the main circuit board near one of the screws on the bottom panel. I am pretty sure I simply used a longer screw in that hole than it should have had and it must have contacted the foil side of the printed circuit board.

I moved some screws around, making sure the shortest ones were in those areas. I am only talking about a difference of 3 or 4 mm at most, but it was critical.

Anyway, no more smoke and it works great! No sparking, flickering, or scratchy sounds...just music!  

NAD 7020 2

Thursday, 24 January 2013

A Quick Kenwood Repair

I did a trip with my friend Clint out to Pure Sound today. We took in a Sansui amp, a Dynaco SCA-80Q and a Harman Kardon 630. I had had a look at the H/K and the Dynaco and they were both items that I did not want to take on trying to repair. The fellow there is a real audio technician; I'm just a hack.

Later I went back to Clint's shop and dropped off a Kenwood KD990 turntable which was one of my faster turntable repair turnarounds. Thankfully it was simple as the circuitry in this would have been tricky to work with. In fact it was not much worse than the best case scenario of a blow fuse, but it did not have fuses.

Kenwood KD990

It turned out to be (probably) just dirty contacts or sticky switches. It would not power on at first, and after opening it up and checking to see if it was getting power to the circuit board at the brown/red/black wires near the top, I simply detached the 2 circuit boards that the microswitches attach to and cleaned them with contact cleaner. I also pulled the black ribbon cables out of their sockets and cleaned those contacts.

Kenwood KD990 2

Back together it went and it worked!

It's a very nice and high quality turntable, weighing about 14 kilos. Unfortunately this one is a bit beat up which is quite the shame. The piano gloss black finish is not my favourite as it easily shows marks and this has more than a few of those. It also is missing a dustcover, and had an ugly Sansui headshell with an even uglier Stanton DJ cartridge on it.

Kenwwod KD990 3

When I took it back to Space Lab, I moved the cartridge to a better looking shell that was at least closer to the original model (not shown). I do like the tonearm with it's machined look. The antiskate is an interesting variation on the weight on a fishing line concept.

Kenwwod KD990 4

Anyway I did not get to to play with this one too much. It worked and sounded fine on the single record I played on it, but then it went back to the shop to go on display. And I am on to the next project, a NAD 7020!

NAD 7020

Sunday, 6 January 2013

Oh No! It's a new media format!

Sony Tapes

No it is not a new digital thing to take over from CD, Blu Ray MP3 or whatever. It's actually a very old format... Reel to Reel tapes. It's just new to me.

Even that is not quite true. I have used RtoR a lot but that was back in the 1970's either at home with cheezy portables or at CHSR radio at university where I used some very good gear and was pretty good recording and editing on it. I might have to relearn some of those skills.

I answered a Free ad on Craigslist and was not the first in line but the other guy could not make it in from Surrey right away and the owner called me back. The Akai 1730D-SS tape deck and the Akai AA-6100 amplifier that he gave me with it are still in the car (so no pics yet) but I got manuals, about 30 tapes, a tape head demagnetizer plus some Dual turntable parts and brochures too. Even the Puma sports bag was almost worth the trip.

Akai 1730D-SS

I don't know where I am going to put this but it should be fun to play with! At least it came with an instant music collection so I don't have to search that out right away.

Akai AA-6100

...I couldn't resist. I went down to the car and brought them up for a quick test before bed. I have Janis Joplin (backed with The Stones - Get Yer YaYa's Out) on the phones right now. It looks like the tapes were all recorded at 3 3/4ips and 2 sided. They are also about 40 years old, and the amp & tape deck have not been cleaned in any way so far so the fidelity and noise level is not the best, but they work!

Akai tape deck

Akai amp