CR-1020 restore... "The Smokey One"

4seatPilot

"Broker"
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Getting started on restoring my pile of CR-1020 receivers... somehow I ended up with 5 of them. 3 were working, 2 not... This is one of the non-working ones (far right above - the other two are on the shelf, still in their case) - I figured I'd start with the one in the worst shape. I didn't even try turning it on... just dug right in. This one is tentatively sold to a local guy who will be using it in his warehouse, so his primary concern is power, and a good tuner. So I will not be touching the tone amp or phono amp sections.

It was quite dirty - a lot of nicotine staining inside, so I took the front frame right off and opened it up. ("Smokey one" refers to the smoke staining... not necessarily that it had actually "smoked," but who knows - it may well have at some point)

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The silver areas are clean from where parts were bolted to them... I went through a few paper towels soaked in alcohol - cleaned up quite nicely. (for some reason I didn't take any "after cleaning" pictures)

The bottom of the power & protection board:

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All cleaned up, there is a lot of damage here - not sure why.

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I discovered the following work has been done here already - 4 resistors changed on the cap board (the 10 & 22 ohm replaced with 3w), outputs replaced on one side of the amp, the wiring for the 234 transistors... I checked the resistors and found them in good order, outputs are good... so I set about re-capping and re-building.
 
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All the capacitors in the power section changed to Panasonic FM/FC, new relay, new transistors (since the SC234s were off anyway)... and I wanted to remote mount these to move the heat off the PCB.
A couple pig-tails off of computer fans, braided & shrink-wrapped:

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Put into place...

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the under-side:

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Fixed.

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All back together. :) I went through a lot of Q-tips & alcohol cleaning boards up as I went along, and I'm pleased with the result. I also re-capped the amp boards, found 2 blown fuses, replaced the SC458s with KSC1815s,

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Initial power-up on the dim-bulb was good, no shorts, relay closed. Not bad for a day's work, interrupted now and then by the kids... I had them sorting my caps into parts drawers behind me. :D

Will dial in the DC & scope it next week. :thmbsp:
 
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I like how you mounted those transistors. Nice trick with the pc wiring.

Some of those boards look they had been previously tortured. or maybe i should say torchered :)

that's great that you made such good progress.
 
I like how you mounted those transistors. Nice trick with the pc wiring.

Some of those boards look they had been previously tortured. or maybe i should say torchered :)

that's great that you made such good progress.

Thanks! :)

I debated where to put the transistors, and considered mounting right on the main heat-sink but I would need to tap a hole for the screw threads. I also thought about mounting them on their own separate re-purposed computer heatsink and securing somewhere, but for simplicity went with this. The idea is not my own... I borrowed this one from another post.

http://www.audiokarma.org/forums/showpost.php?p=6385188&postcount=91

And yes - torchered indeed. Ouch.
 
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Thanks! :)

I debated where to put the transistors, and considered mounting right on the main heat-sink but I would need to tap a hole for the screw threads. I also thought about mounting them on their own separate re-purposed computer heatsink and securing somewhere, but for simplicity went with this. The idea is not my own... I borrowed this one from another creative AKer (though I forget exactly who's post it was I saw it)

And yes - torchered indeed. Ouch.
I noticed you mentioned 1815's, these are from an old stash?

Was looking at your pics again, does the case cover fit OK over the fan lead attachments? They look like they are sticking up, hopefully not too high!
 
Thanks! :)

I debated where to put the transistors, and considered mounting right on the main heat-sink but I would need to tap a hole for the screw threads. I also thought about mounting them on their own separate re-purposed computer heatsink and securing somewhere, but for simplicity went with this. The idea is not my own... I borrowed this one from another creative AKer (though I forget exactly who's post it was I saw it)

And yes - torchered indeed. Ouch.

It wasn't an ak'r, it was a post from an ebay auction that an ak'r posted showing the mod- don't know if he was the seller.
 
I noticed you mentioned 1815's, these are from an old stash?

Was looking at your pics again, does the case cover fit OK over the fan lead attachments? They look like they are sticking up, hopefully not too high!

1815s are new... I bought a bunch from mouser.

the leads to the transistors are a bit high, I'll figure something out to get them to sit lower, won't be an issue. I kept them long as I wasn't sure exactly where they were going to end up, so I wanted the length for options... next time if I put them in the same spot I'll run them a bit shorter.
 
set the idle voltage last night - it adjusted perfectly and stable. The relocated transistors do not get over 100 deg F, and the leads were easy enough to secure out of the way of the cover.

Everything else works, except one issue in the tuner to chase down - it only works in Stereo. With the FM muting button "IN" there is no FM. A bit of a hum though. This one might be a challenge to find. OTOH, in stereo mode it pulls in all the local stations without an antenna and in my basement. So that's good...
 
set the idle voltage last night - it adjusted perfectly and stable. The relocated transistors do not get over 100 deg F, and the leads were easy enough to secure out of the way of the cover.

Everything else works, except one issue in the tuner to chase down - it only works in Stereo. With the FM muting button "IN" there is no FM. A bit of a hum though. This one might be a challenge to find. OTOH, in stereo mode it pulls in all the local stations without an antenna and in my basement. So that's good...
Glad to hear it all fits back inside the case :thmbsp:
Good luck with the FM...sounds like that mute button takes its job quite literally.
 
Yes indeed. The weird thing is, it mutes with the button in the un-mute position.

I've been searching for the cause... But no luck so far. A working sig-gen would be handy.

Sent from my GT-I9100 using Tapatalk 2
 
Good god!!! I hope that's not the one sold you. If it is I apologize for it being such a mess. Either way nice job and congratulations on getting it going again :thmbsp:.
 
Uhm... well... yep. it is. But no worries. The tuner is the only real mystery, and it's going to a guy for his warehouse - they won't be using the mono button to try and pull in distant stations. It gets the local ones just fine, benches at 98 watts (rated 80!), and I threw in an LED upgrade for him. He's getting it at a great price, I get to sell one that would otherwise be a bit of a hard sell... and everybody is happy!

:)

BK is thrilled with is 2020... I'll do fine with this 1020, much thanks Phil - I'm glad my friend happened to be vacationing in Nashville at the time. :thmbsp:

Are the SBs done on your new 2020? That one looks like a beaut... and the price! :nutz:
 
Sorry dude, well he did say he had trouble with performing the SBs on one of them. Never would have expected this much of a mess. I'm glad that BK's turned out nice and that you have a buyer. Not too bad I suppose for a couple of parts units. Yeah, that was nice timing. Thanks taking them off my hands and making something worthwhile out of them.

I've never had one with the box and I couldn't resist the price. It needs a good cleaning, but it's in great shape. I'm still waiting for the parts. Hopefully, I won't let this one sit for several years.
 
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