Yamaha cr-2020 refurb time

bktheking

Gitter Done!
Well 4seatpilot and I did some horse trading, more like - speakers, receivers and tube amp trading. Out of the deal I got this unit (plus a beautiful Marantz 1060 Engraved Face), it belonged to another ak'r who had it but due to health reasons never got around to working on it.
4seat was nice enough to double box the bloody thing and send it via family pony express.

I opened it up tonight , it's got minor dust and some cobwebs, nothing I can't clean up. I'm starting with the power board. It always amazes me on how you can tell a unit has been run/repaired. Previous owner to the AK owners got in there and replaced a bunch of caps, with crap caps- no name brand. I also discovered a cap was completely missing and relay is fried, no wonder it had issues. This thing is semi modular, I like it. Can't wait to hear it!

Tonight I recapped the one power board, replaced the relay. I've been so busy lately I accidently threw out the tip41c's I had to replace the 2 on the board. I'll keep the thread updated, take pics, until it's restored. I have all the caps less the monster caps, no need to replace.

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Welcome to the Yamaha section of the world... careful, you might get converted!


Something tells me he's going to be done that thing before I get done the one I started a couple months ago.
:rolleyes:
 
Pulled the relay apart and discovered this:

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Brought it up tonight after a recap of the power boards and amp boards. Right channel hearing snapping and popping, comes and goes. After an hour of playing off dim bulb the relay snaps open and begins the frying thing again. What the heck would cause that to happen???
 
Well- I vote for me being the bone head of the week. I'm still steaming over my f*ck up, it was a big one.

Right side amp board-

Chasing the snap crackle pop I replaced the 4 transistors in the DC offset circuit. OK- replaced, still getting the snap. So the next in line was the 458.
Well- the 458's in these here are the outhouse ones with the slope, the square ones. I thought they were ECB looking at the flat side, well as it turns out the flat side is BCE instead of ECB. So I installed the flatside of the ksc1845 out, whoops. I was running it on the dim bulb up until this point. I had unplugged it to the soldering and instead of plugging back into the dim, I plugged into the power bar. I throw the power switch, 5 seconds later- smoke show. The 470 ohm resistor blew as well as one of the small transistors. Oh shit what have I done.

Luckily I pulled the outputs to do this or I'd really be up shit creek. I decided to test all transistors in circuit, turns out everything from 5 on is smoked- 2 drivers, the oddball to-202 and everything else in the bias section.

A warning to all- if you replace the 458 the ROUND SIDE goes out, not the flat.

Anyways- ceitron has 6 of the 9 originals I need, the 2sc1628 (to-202 oddball) is being subbed with 2n6553, 2sc1624 driver is going to be subbed with 2SD351 and 2sc1918 subbed with 2sc1571. Costly mistake, I should have used the dim bulb.

Could have been worse, live and learn!
 
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Maybe Karma paid you back for your little photo-prank you pulled on me, as brilliant and successful as it was... ;)

So... just to be clear - KSC1845 is ECB looking at the flat side, (like you'd expect), and the SC458 is ECB looking at the sloped side. So Sloped side of the outhuse equates to the flat side of the TO92 package.

who'd have thunk one little backwards transistor could do so much damage... :dammit:
 
Knee deep in this unit this afternoon and snapped some pics. I redid the tuner board, this is an example of how many caps there are on it.

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I read where this unit to recap is not for "the faint of heart". Try recapping a marantz of equivalent size, this was a breeze compared to a 2270. At least this unit has all caps on one board for the tuner section, the marantz is split into 3 and some are difficult to access. That's why this unit is so wide, Marantz had a habit of mounting stuff on the bottom in an effort to safe on overall size whereas the Yamaha is quite bloated.
 
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I also recapped the pre amp sub boards today, pretty much finished the recap. Had to remove the faceplate and sub plate to gain access. Gave it a thorough deox while in there, it's the only way to gain access and do it properly.

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What amazes me is the cap size, old vs new.


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One benefit of the smaller size of modern caps is better ventilation, especially in a jam-pack powerhouse like this Yamaha.
 
Perhaps- the real heat as I found out comes from the power and cap boards, until I blew up the right channel :D. I just finished restringing it, thanks to Yamaha's clean instructions on how to do it- 15 minutes start to finish. I used 40lb trolling line from Can Tire.

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I think I'm gonna crack the 1060 not that I have nothing left to do and do some measuring!
 
<snip> I just finished restringing it, thanks to Yamaha's clean instructions on how to do it- 15 minutes start to finish. I used 40lb trolling line from Can Tire. <snip>

Looks like that did the trick! How well does it grab? I can never seem to find the right size "bead string" and then the stuff is still slippy. I might have to check out the local sporting goods store or walmart or whatever for that 40# line.
 
It's awesome, no slip whatsoever, stronger than dial string IMO. It's all I use, if a 35lb fish can be brought up on it a tuning cap won't be much of a fight :D. It's called northern braid #40, it was $8 for 100 yds. I've used it on tube radio's with double tuning caps, no problemo!
 
That is an awesome looking piece of gear. I had some Yamaha gear in the past, and I really enjoyed the looks and sound of that gear. I found a Yamaha receiver at the local used record store last year, but we couldn't agree on a price, so I walked away.
 
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