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So, pretty much following the other thread about PS 1770, we rebuilt some of it, but didn’t have the diodes. Upon testing the voltages are NOT where they should be, so we need to order the diodes, thanks for the links on the other thread.

Well, we pretty much rebuilt the amplifier, and one of the power supplies. Now we will focus on the protect circuit power supply. Hopefully the transformer stays up there where it should.

https://audiokarma.org/forums/index.php?threads/kenwood-kr-7600-protection-relay-not-clicking.822266/ Yep, found this, and this is where we are headed.

Yes, and we rebuilt Power supply C and Pin 1 and 2 went to plus 36 volts, pin 5 had about 5.5 volts, and I think that pin is the lighting section. The schematic doesn’t show, or I am blind what voltages I should have at the connections going in from the Control amp. Power supply A the 1770 on...

So, as an update, it will come out of protection with both channels unplugged. Checking the voltages, Pin 2 had -39 volts. Pin 5 had a trace. Checking the voltages from the red wires coming out of the PS, 30.6 volts, schematic says 37v. Two 10 ohm resistors seem to be open. There is a...

Thanks for that info. I will check that out. Gary

So, a newly acquired vintage stereo friend of mine has a KR 7600 which for the most part was butchered early by the person he bought it from. We went about basically rebuilding the entire amp board along with the amps themselves. What we didn’t replace were the variable resistors to set the...

Wondering if anybody has a schematic for the SONY TC-654-4 reel to reel. HiFiEngine does not. Unit looks nice, but the minute you turn it on, it goes into Fast Forward mode with the lights coming on for play and fast forward. I noticed it has a lot of card type electronics in the bottom...

Yeah, I recently picked up a Sansui 8080 NON DB and it worked on one side. I flipped the driver board and it moved to the other side. So kinda figuring it was on that board. The board is a mess, traces destroyed and wired up. There was kit put in with all the new parts, so I did...

Very good suggestion. So I was also wondering if I reflow, should I use air, or a pencil tip unit. Definitely will use your suggestion FIRST.

So I have been trying to see if I can find something that isn’t secured right, no luck so far. I need more light and patience. Here is a picture of what I am working with. When I was trying to find a unit to buy on Ebay, I would come across someone who made NEW boards for the 8080 and 9090...

So, I contacted @EastPoint and he did have a kit for the board. When I took the board out of the unit, it already had his parts in it. But the guy who did the work kind of butchered it, blew some traces I think, so we are kind of going over it. Switched it around and the problem moved to the...

Is there a part number for that trimmer? So know I have decided that maybe I need to rebuild this before trying to adjust anything. I guess I could check the voltages without moving anything. I haven’t explored this much since I got it yesterday. Yeah, I replaced transistors in my 6060, they...

Do a search within AudioKarma, or the Internet. I actually am aware of the trace issue and the fusible resistors. I already have the 5050, 6060, 7070 and now this one. I hope to collect the entire X0X0 series. I have been doing this for 35 years and just find it easier to ask questions...

I just got it yesterday afternoon, and it weighs like 45lbs. I need a bigger bench, LOL. I did try a Turntable to see if maybe the problem was in the FM, no change. I do have a small receiver that can fit in the space, I might try that from the preamp. Thanks.

Nope, but I will. Can’t hurt. So now I gotta go look to see if I can get to it. It isn’t going into protection, so far so good. I am also going to check the voltage and the bias now that I have the schematic, but not until tomorrow.

I picked up a Sansui 8080 and set it up when I got it, and it seems the left channel is somewhat muffled and low volume. Did all the switch and pot cleaning, which I would have done anyway, and there is no difference. So I thought I would come here and pick your brains. It’s not popping like...

I have used DEOXI-ID and I love it. Cleans better.

Yes, agreed. I just think that without the DBT, the excess current will blow those fuses again. That’s why I had it in the first place. Maybe he is going to attempt the repair himself.

So, as a final, I hooked up the receiver to my DBT, and it worked okay at low volume levels. When I started to turn the volume up, the bulb started to get brighter and brighter, so I did not go past 12 o'clock on the volume. I don’t think it would survive without the DBT, to much going on with...

I have been doing this hobby for 30 years. Got smart enough years ago to ask around because you can find a lot of good help and cut your time down by not having to do a lot of testing. I wish I had taken pictures of the Sansui 6060 I bought 30 years ago. Guy said it worked good. I got it...

I looked at the 330C I also have and the thermal paste looked messy to me on those too. So, it’s probably okay.

Did you manage to source all your parts from one vendor, like Digi-Key or Mouser? Other than the caps and the transistors, was there any other part you replaced? Some of these old electrolytics seem to be getting scarce. Thanks for the part number above, is that a OEM number made by many, or...

Well, when I opened the unit, on the amp board it kinda looked like somebody had tried to change the transistors. It is very messy looking. And you are talking a full recap of everything, not just pre-amp and amp boards. I guess I will have to ask him how much he wants to spend. I have taken...

The fuses are for the speakers. I have a DBT, but haven’t even tried it yet. Need to buy some fuses as well. But I do plan on putting fuses in it on the DBT. What I find troubling is there are no voltage test points on the schematics to test with.