CR-2020 static and possible refurbishing

[jlhi2001]

Hi,

I have a CR-2020 in what I would consider to be excellent condition. I purchased it used and was told by the seller that it had the service bulletin modifications done.

There is intermittent static in the right channel. It's not there when initially powered on and usually appears within 10 to 30 minutes. A slight knock to the case will often fix it temporarily. It seems to me that once the unit is on for about an hour the static disappears.

The static is audible through headphones and moves to the right channel (speakers or headphones) when the channels are reversed using the Mode dial. The static is also audible using an external preamp.

At one point the static started almost at startup and would cease if the one of the FM Mute or Blend buttons were pressed (I forget which one). I brought it for service and they fixed the static associated with the FM circuitry but they didn't address the remaining static issue. I'm going to have to bring it back to the technician for that.

The place I brought it to told me they don't do refurbishing--only repairs to obvious problems.

I've read that in order for these units to perform their best they likely need to be refurbished.

So, I'm wondering if this is something that I could possibly do on my own. I don't know much about working with electronics but I'm mechanically inclined and capable of researching what would need to be done.

I'm looking for opinions on this and wondering if there are an resources for learning how to go about planning refurbishing this receiver; i.e, conducting an inventory of parts to be replaced, identifying them and obtaining replacement parts.

On the other hand, I wonder if the necessity of refurbishing is overstated and whether there is any real potential for an audible difference to be heard?

To me this is a great sounding receiver. I think it compares favorably to most of the better equipment I've owned. I really want to keep this unit in good working order and take whatever steps I can to keep it that way. I'm really thinking of selling my other amps and preamps and sticking with the CR-2020.

I'd really like to find a way to do some work myself. I'd like to pick up a CA-1010 or CA-2010 at some point.

I suppose this is a good a place to ask for opinions on the best sounding vintage Yamaha receivers and integrated amplifiers.

Any thoughts appreciated.

Thanks

 

[avionic]

. A slight knock to the case will often fix it temporarily.

Cold solder connection,dirty relay contacts.Or possibly the speaker select switch is dirty.

 

[avionic]

Exercise the coupler switch on the rear panel a dozen times. They are notorious for being dirty.

 

[avionic]

Know how to use a multimeter ? Soldering / desoldering ? Follow a schematic diagram ?

 

[jlhi2001]

I've used a multimeter and have soldered. I don't read schematic diagrams. I can read mechanical drawings. I guess what I'm wondering is whether I can teach myself to replace parts that would call for replacement after 40 years. I'm also trying to distinguish between the skill necessary to identify the part and the skill necessary to execute the actual replacement.

 

[avionic]

Pull the bonnet off. Be very careful not to snag the dial cord. Using a non-metallic probe such as a chop stick or something. Lightly tap around on the various circuit boards and listen for the right channel to cut in and out. I've done this many times to help locate/isolate and cold solder connection. Inspect the solder connections on the circuit boards. I use a large magnifier and lots of bright light. Look for circular cracks in the old solder around the soldered component leads.

 

[jlhi2001]

Thanks for your suggestions. The repair I had done previously consisted of the following: replaced 2 x p/n 647-UPW1J101MPD6 with CAP. 100UF/63V HT; replaces 2 x p/n
647-UPW1J221MPD6 with CAP. 220UF/63V HT. The part numbers are from the service invoice I haven't figured out where they are located yet.

So far, what I've found is that the static cutting in and out seems to be associated with the power supply circuit board. I see a few capacitors that appear to have leaked. (there's some hardened brown resin type buildup at the bottom of the capacitors. I didn't find any obviously loose connections but tapping the board lightly with a chop stick affects the static. Lifting the board ever so slightly (1/16 of an inch) causes the static to disappear.

Any thoughts?

Thanks

John

 

[avionic]

(there's some hardened brown resin type buildup at the bottom of the capacitors

Thats most likely assembly glue.

 

[avionic]

Lifting the board ever so slightly (1/16 of an inch) causes the static to disappear.

Solder connection or loose wiring.

 

[MannyE]

I remember reading that before you open up the Cr-2020 you need to put the tuning indicator all the way to the right to avoid snagging it on a bracket and ruining it.

Here is the video:

 

[jlhi2001]

I saw that video too. Thanks for mentioning it. Surprisingly, the place that I brought the receiver to last September caught the tuner string on the cover when replacing the cover. When I got it home the tuner dial didn't turn. I now notice a frayed segment of the tuner string about a 1/4 inch long--not sure what to do about that.

Right now I have the power supply circuit board raised up slightly with a thin piece of cardboard--no static. Is this advisable?

I think it will take me quite a bit of time to locate the loose solder or wire--I've poked at all the capacitors and transistors but haven't been able to make the static occur. It's also difficult to see--even with glasses. I'm going to buy one of those bench/table magnifying lens/lights.

Much of the interior looks clean. The only wear and tear appears to be on the power supply circuit board. There's some discoloration around the two transistors that get hot--evidenced also by some blackening of the ventilation grill.

I'm amazed at how good this receiver sounds. I've used it with a pair of Klipsch KG2's and Proac Response 1sc's. To my ear it competes with my Naim Nait 5i-2 and Line Magnetic 216ia.