Harman Kardon HK590i restoration
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The Fuxtor
Addicted Member
Hopefully you're not gonna replace small signal transistors? They are a pain to remove as they are packaged up with other transistors in small metal heatsink cases. Aggravating setup I thought.
As long as they still work correctly and there aren't any known problem transistors, I'll leave them in. I guess they may need new heatsink compound? I'll see when I get into it. It's a hobby so I don't mind a few things that take a little time.
I looked over the schematic and started thinking about what parts to order. I should have some of what I need already. Noticed the output transistors have a 30MHz fT so I guess they're pretty fast. Most of the TO-3P / TO-247's out there are around 3MHz. Hopefully mine will be good but checked to see if there's a suitable substitute out there. I found MJW3281AG and MJW1302AG but Mouser was out of the PNPs. Digikey has some but not a lot. I think those will work if I need them but if anyone has better ideas, I'm all ears.
The Fuxtor
Addicted Member
Why replace output transistors if they are good?
I'm not sure they are yet. Still don't have it to check. I'm just getting an idea what parts I have on hand already and what I don't, just in case I need them. And with the shortages of output transistors I wanted to have an idea if there are even good replacements available if I need them.
what about NJW0281G and NJW0302G? fT=30MHz
plenty of both in stock at mouser.
here's a thread on the 590i , post 11 has a couple other options that are available at mouser as well
Harman Kardon HK-590i high voltage output to right speaker terminal
Hi Everyone, I bought the receiver over the weekend and wanted to fire it up and hooked it to my Nova 6 speakers. I noticed a high pitched whine from the right channel and caught a whiff of that bad burning electronic smell. Checking into it I saw the crossover plastic cover had melted and...
audiokarma.org
Those look like they'd work. Thanks @painttoad I'm not sure why searching is so hard on both those websites. Just searching by specs didn't find those.
i use the search function on here to try to find a recommended replacement then use google to get the data sheets and to find out who has them in stock
digikey/mouser has a less than desirable search function. 1/2 the time it's worthless.
Well I got the 590i. Amazingly it arrived undamaged even though it was only shipped in packing peanuts and the box was pretty mangled. It's dirty and will need a lot of cleaning. There's some rust on the back panel that'll need some work. Brought it up on the dim bulb and all looked ok. Took out the dim bulb and touched up the offset and bias. Both were a little out. Played some music and it sounds decent. It's got the normal dirty switches and pots. When I get a chance later today, I'll hook up a signal generator and scope to get some real data but so far it's looking like mostly this will just be a cleaning job and pretty boring. Oh well, something will probably break.
It's rated for 45 WPC and putting out 60. The left channel cuts out with the balance pot centered so had to move that just a little off the detent and the channels are still pretty balanced. Looks like everything's working on it. Tuner seems pretty well aligned even. All the lights work. Guess I'll blow the dust out of it and clean pots/switches.
One thing I'll note for anyone who decides to tackle one of these in the future. Cleaning the dirty pots and switches requires quite a bit of disassembly. The pots are buried under a couple other boards that have to be moved to get at them and the front panels have to be removed. The tone and balance pots needed to be desoldered from the board to blast them out well enough. The switches are easy enough to clean by squirting some DeOxit in the holes on top or into the gaps on the front side. I didn't need to desolder or disassemble the switches at all.
Also, there's quite a bit of circuit board glue used and on mine it was turning dark and getting brittle. I don't think it was really causing any problems yet but probably would have turned conductive and corrosive soon. All that was removed with acetone, q-tips, and a screwdriver. Combined with how much disassembly I had to do, I decided to recap it while I was in there. All my caps seemed to be electrically fine and not leaking but lots of them had glue on them so it was easier to replace them than try to clean all that off. Those caps are 40 years old and I don't want to go through the disassembly again in a couple years if I can avoid it by just replacing the caps while I'm in there now. The only board I didn't recap was the logic control board. It's on top, is pretty easy to remove, and didn't have any glue on it so I figured it's easy enough to do in a few years if it's needed then.
Another benefit of recapping was that I was able to make a few small improvements. The HK schematics are really nice in that they show the signal path so it's pretty easy to know where you could improve things by using film caps or non-polars. For values above 10uF in the signal path I used non-polars and for 10uF and below, I used film. In the EQ board there are 2 22uF back-to-back in each channel. I was able to replace those with a 10uF film cap. Not sure I can hear a whole lot of difference since it wasn't really practical to re-assemble after cleaning the pots and switches before re-capping but I'm sure it makes at least a subtle difference.
There are a lot of fusible resistors in these units. I checked a bunch of them and they seemed to be holding up fine. Not drifting in value or anything so I just left them all in. I guess time will tell if that was a good idea or not.
It sounds great now after listening to it for a little while. These early 80's HK's seem to be pretty good values in my opinion. They don't have the looks of a Pioneer but if you're looking for great sound, they deliver.
Also, there's quite a bit of circuit board glue used and on mine it was turning dark and getting brittle. I don't think it was really causing any problems yet but probably would have turned conductive and corrosive soon. All that was removed with acetone, q-tips, and a screwdriver. Combined with how much disassembly I had to do, I decided to recap it while I was in there. All my caps seemed to be electrically fine and not leaking but lots of them had glue on them so it was easier to replace them than try to clean all that off. Those caps are 40 years old and I don't want to go through the disassembly again in a couple years if I can avoid it by just replacing the caps while I'm in there now. The only board I didn't recap was the logic control board. It's on top, is pretty easy to remove, and didn't have any glue on it so I figured it's easy enough to do in a few years if it's needed then.
Another benefit of recapping was that I was able to make a few small improvements. The HK schematics are really nice in that they show the signal path so it's pretty easy to know where you could improve things by using film caps or non-polars. For values above 10uF in the signal path I used non-polars and for 10uF and below, I used film. In the EQ board there are 2 22uF back-to-back in each channel. I was able to replace those with a 10uF film cap. Not sure I can hear a whole lot of difference since it wasn't really practical to re-assemble after cleaning the pots and switches before re-capping but I'm sure it makes at least a subtle difference.
There are a lot of fusible resistors in these units. I checked a bunch of them and they seemed to be holding up fine. Not drifting in value or anything so I just left them all in. I guess time will tell if that was a good idea or not.
It sounds great now after listening to it for a little while. These early 80's HK's seem to be pretty good values in my opinion. They don't have the looks of a Pioneer but if you're looking for great sound, they deliver.
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The Fuxtor
Addicted Member
Enjoy! Nice sounding receiver
I'm going to try to button this thing up over the weekend. Did some testing and it's performing well.
1 kHz sine wave - 56 WPC. Channels are tracking together very well.
Freq response - a little over 3db down at 2 Hz. Full power and very flat response from 3 Hz-40 kHz. Tried it at at 100 kHz and it was a little over 3db down.
I tried measuring slew rate with a square wave and it doesn't seem like the transistors are limiting it? I get about 2us of rise/fall time at low power levels all the way up to full power from 1kHz - 20kHz. Need to do some reading on how to measure this correctly. Looks fine though?
square wave testing showed all the tone controls working nicely with no noise. square wave still looks pretty square at 20kHz.
Still going to verify the RIAA Eq is good and align the tuner, although it seems pretty good and I don't think it needs much.
1 kHz sine wave - 56 WPC. Channels are tracking together very well.
Freq response - a little over 3db down at 2 Hz. Full power and very flat response from 3 Hz-40 kHz. Tried it at at 100 kHz and it was a little over 3db down.
I tried measuring slew rate with a square wave and it doesn't seem like the transistors are limiting it? I get about 2us of rise/fall time at low power levels all the way up to full power from 1kHz - 20kHz. Need to do some reading on how to measure this correctly. Looks fine though?
square wave testing showed all the tone controls working nicely with no noise. square wave still looks pretty square at 20kHz.
Still going to verify the RIAA Eq is good and align the tuner, although it seems pretty good and I don't think it needs much.
Thought I was about done but in testing the phono stage, it looks like it's getting a little noisy after it's turned on for a few minutes. Might have some transistors going bad in there. I don't have any canned air or freeze spray so need to get some. I checked the list of known problem transistors and don't see any of those in this unit.
I did get the tuner aligned. It didn't need much and was performing pretty well already.
I did get the tuner aligned. It didn't need much and was performing pretty well already.
The Fuxtor
Addicted Member
The phono board is easy to access . Shouldn't pose any significant problems!
Yeah, I already re-capped it. Just have to bend a tab and release a few connectors to remove it. Way easier than servicing the pots in this one.
Got a new toy / piece of test equipment. A QuantAsylum QA403 audio analyzer. Been learning how to use it on the HK590i. Here are a few screenshots. Looks like it's performing up to specs. The high freq roll off in the last pic might just be me not knowing how to use it yet. Still working on that. Wish I could have tested it before working on it but next project I will. Still need to figure out how to test the RIAA curve on the phono input.
