Thanks for this video; HK receivers don't get the love they deserve sometimes. Great little performer for 40-45 watt receiver. The design doesn't lend itself to the technician, but you made quick work of disassembly to access the good stuff internally. Your customer should be really happy putting this unit back in service. Have a great weekend.
Utility marking paint is excellent for painting meter needles. Just shake the can, spray it on a Q-tip and paint. The orange is somewhat florescent and the needle will stand out.
I have an HK 3500 and PM655. Bought Emotiva BASX TA-100. Couldn't believe the HK still sounded better . Much more lush and "thicker". The Emotiva sounded thin and lacking . It sounded like a Sony receiver . HK's have a nice sound signature .
A friend donated a HK560 to me. Upon powerup it has a strong hum audible over the speakers and the headphone amp, but disappears. Once on, there is LITTLE volume in the right channel. Left channel is fine. I don't think it's the output transistors since fuses look fine. Upon power down, i get horrible screeching on the right and left channel in equal volume, over the speakers and the headphones. I cleaned the pots as best as i could. I can check the bias, and the DC offset, but i wonder if this means bad filter caps, or a bad voltage regulator transistor?
Hi Anthony, On powerup the amps should be silent for the first 4-8 seconds until the power-on muting times out and sends a signal to Q405, Q406 to turn the amplifiers on. The power-on muting circuit is Q1 and associated parts. If the amp is making noise immediately after turning on there could be a problem within the power amplifier it self. One channel only suggests the problem is the amp and if the problem is in two channels it suggests the problem is in the power supply. Check fuses, both outputs for any DC, look for cracked solders on the transistors of the amplifiers
@@TrevorsBench I bypassed the preamp, and connected another preamp. All problems gone. I did this by unsoldering the wires from the amp board to the preamp. And connecting it to another source. All problems were gone. So it seems the problem is somewhere on the preamp board - which is quite hard to get to.
@@anthonypopovic7626 First, check the +/- 15v power supplies for the pre-amp. This is made from zeners D17 and D18. You should have close to 15v across caps C12, C13
Hi Trevor, thx for this video. I need help with this amp . I have a problem with the alimentation of the vu-metre only this ...all alim 's ok . Please help me .thx
Este prima dată când văd un radiator asa mare și rudimentar la un amplituner. S-a mers pe eficiență !!! Mulțumim pentru faptul că împărtășești cu noi toate lucrurile astea ! Enciclopedia amplitunerelor !!!! Încă o dată mulțumesc !!! Din curiozitate, ți-a trecut prin atelier modelul de la BASF D-6160 ?!?
You can fix UV stained plastic using UV light and hydrogen peroxide. I fixed up an 80s kitchen mixer using hydrogen peroxide (from a hair bleach kit, 12%) and sunlight. edit: I see someone mentioned it already.
Hi Trevor- subscriber here. Thks for the videos. I like your new carousel for the bench. Just checked Google and some good reasonable price options to buy something same / similar- had not thought about this before....... I am a DIY and learning all the time doing hobbyist repairs. I just want to confirm use of scope in some of the repairs you do. So connect AMP speaker output to good dummy load resistor - lets say 8 Ohm 100watt x 2 ( one for each channel) At same time connect scope leads across same resistors - channel 1 / channel 2 on scope Feed a signal / signals from frequency generator into INPUT of amp Then calculate potential watts from watts = volts² / ohms - correct? So questions. 1. I see you use sine way for above test = correct? 2. Assume AUX IN would be good for Frequency Gen signal input?- should I be concerned about voltage of input? 3. Assume good signal would be around 5 to 10Khz? Does this affect calculation of amp "Watts vs voltage / Resistance? 4. I see you have done additional test using square wave- what is purpose of this?- is it more for "soundstage" of amp vs Power of amp? Appreciate the assistance Thks Danny
Hi Danny. Good questions, I'm glad you asked because I don't always explain why I do things. 1. Yes, sine waves are the only pure tones of a single frequency. If I put a sine wave into a amplifier, I expect to see a clean sine wave for a output. Any distortion caused by a amplifier will show up as harmonics or tones that are not part of the pure input tone 2. Yes, AUX is a good port to insert signals. You can also inject signals into the tape monitors. The signal gen should have about 1v signal level which is the typical level for line audio signals. The phono stage has a pre-amplifier/equalizer so it expects to see a much smaller signal - 2 or 3 millivolts would be a good level to test phono inputs 3. The frequency I use for power tests is 1kHz only because it's a typical industry standard test freq. You can use any frequency you'd like. In fact, using the full spectrum is a good test for power bandwidth. The ohms law calculations assumes I'm using a purely resistive load. If we introduce inductance and capacitance into the load, things get complicated and will change at different frequencies. 4. The square wave test is a good indication of the amplifiers speed. The faster the transistors in the amplifier turn on or off, the better it will do amplifying a square wave. Square waves are the opposite of sine waves in that they are full of harmonics that can span very high up the frequency spectrum. A amplifier that is good at reproducing a square wave will also have a very high frequency response. The speed of a amplifier is measured by it's slew rate, higher numbers are better. So, as you guessed, using very fast transistors in a amplifier will give you a high slew rate but there is a limit to this goodness. If transistors are too fast the amplifier can break into oscillation which can destroy itself or it's load I hope that clears up your questions Danny, Thanks for watching
I was wondering if you might use nail polish to paint the needle. Also Trevor, are you looking for sponsorship from Popeye's? I have a subliminal urge for fried chicken ;)
Thanks for this video; HK receivers don't get the love they deserve sometimes. Great little performer for 40-45 watt receiver. The design doesn't lend itself to the technician, but you made quick work of disassembly to access the good stuff internally. Your customer should be really happy putting this unit back in service. Have a great weekend.
Thanks again Craig
Nice job Trevor. Enjoyed watching your attention to detail. Well done.
Angelo I.
Thanks Angelo, looking forward to working on that GX-230 soon
Super-useful video -- thanks! Was trying to locate the lamps behind the switches... the light assembly was a revelation for this newb.
Utility marking paint is excellent for painting meter needles. Just shake the can, spray it on a Q-tip and paint. The orange is somewhat florescent and the needle will stand out.
Hi Kimmi, I know the paint you're talking about. It's very bright colors.
I'll try in next time, thanks
I have an HK 3500 and PM655. Bought Emotiva BASX TA-100. Couldn't believe the HK still sounded better . Much more lush and "thicker". The Emotiva sounded thin and lacking . It sounded like a Sony receiver . HK's have a nice sound signature .
I had one of theses and the indicator lights behind the switches would burn out but they were not to bad to replace. Nice video.
Today I learned that Trevor hates my screwdriver :P
Hi i have noise in the right chanel without having tape etc working where might be the Problem?
How do i get these little switches off.....i mean the switch bank....
A friend donated a HK560 to me. Upon powerup it has a strong hum audible over the speakers and the headphone amp, but disappears. Once on, there is LITTLE volume in the right channel. Left channel is fine. I don't think it's the output transistors since fuses look fine.
Upon power down, i get horrible screeching on the right and left channel in equal volume, over the speakers and the headphones. I cleaned the pots as best as i could.
I can check the bias, and the DC offset, but i wonder if this means bad filter caps, or a bad voltage regulator transistor?
Hi Anthony, On powerup the amps should be silent for the first 4-8 seconds until the power-on muting times out and sends a signal to Q405, Q406 to turn the amplifiers on. The power-on muting circuit is Q1 and associated parts. If the amp is making noise immediately after turning on there could be a problem within the power amplifier it self. One channel only suggests the problem is the amp and if the problem is in two channels it suggests the problem is in the power supply.
Check fuses, both outputs for any DC, look for cracked solders on the transistors of the amplifiers
@@TrevorsBench I bypassed the preamp, and connected another preamp. All problems gone.
I did this by unsoldering the wires from the amp board to the preamp. And connecting it to another source. All problems were gone.
So it seems the problem is somewhere on the preamp board - which is quite hard to get to.
@@anthonypopovic7626 First, check the +/- 15v power supplies for the pre-amp. This is made from zeners D17 and D18. You should have close to 15v across caps C12, C13
Hi Trevor, thx for this video.
I need help with this amp .
I have a problem with the alimentation of the vu-metre only this ...all alim 's ok .
Please help me .thx
Este prima dată când văd un radiator asa mare și rudimentar la un amplituner. S-a mers pe eficiență !!! Mulțumim pentru faptul că împărtășești cu noi toate lucrurile astea ! Enciclopedia amplitunerelor !!!! Încă o dată mulțumesc !!! Din curiozitate, ți-a trecut prin atelier modelul de la BASF D-6160 ?!?
Thank you. I've never seen BASF audio gear here in America. It would be interesting to find one and have a look
You can fix UV stained plastic using UV light and hydrogen peroxide. I fixed up an 80s kitchen mixer using hydrogen peroxide (from a hair bleach kit, 12%) and sunlight. edit: I see someone mentioned it already.
For something small like this it's hardly noticeable. Good tips for badly discolored plastics tho
Thanks for another great video!
Nice video 😀 👍
Thanks, nice name!
Hi Trevor- subscriber here. Thks for the videos.
I like your new carousel for the bench. Just checked Google and some good reasonable price options to buy something same / similar- had not thought about this before.......
I am a DIY and learning all the time doing hobbyist repairs.
I just want to confirm use of scope in some of the repairs you do.
So connect AMP speaker output to good dummy load resistor - lets say 8 Ohm 100watt x 2 ( one for each channel)
At same time connect scope leads across same resistors - channel 1 / channel 2 on scope
Feed a signal / signals from frequency generator into INPUT of amp
Then calculate potential watts from watts = volts² / ohms - correct?
So questions.
1. I see you use sine way for above test = correct?
2. Assume AUX IN would be good for Frequency Gen signal input?- should I be concerned about voltage of input?
3. Assume good signal would be around 5 to 10Khz? Does this affect calculation of amp "Watts vs voltage / Resistance?
4. I see you have done additional test using square wave- what is purpose of this?- is it more for "soundstage" of amp vs Power of amp?
Appreciate the assistance
Thks Danny
Hi Danny. Good questions, I'm glad you asked because I don't always explain why I do things.
1. Yes, sine waves are the only pure tones of a single frequency. If I put a sine wave into a amplifier, I expect to see a clean sine wave for a output. Any distortion caused by a amplifier will show up as harmonics or tones that are not part of the pure input tone
2. Yes, AUX is a good port to insert signals. You can also inject signals into the tape monitors. The signal gen should have about 1v signal level which is the typical level for line audio signals. The phono stage has a pre-amplifier/equalizer so it expects to see a much smaller signal - 2 or 3 millivolts would be a good level to test phono inputs
3. The frequency I use for power tests is 1kHz only because it's a typical industry standard test freq. You can use any frequency you'd like. In fact, using the full spectrum is a good test for power bandwidth. The ohms law calculations assumes I'm using a purely resistive load. If we introduce inductance and capacitance into the load, things get complicated and will change at different frequencies.
4. The square wave test is a good indication of the amplifiers speed. The faster the transistors in the amplifier turn on or off, the better it will do amplifying a square wave.
Square waves are the opposite of sine waves in that they are full of harmonics that can span very high up the frequency spectrum. A amplifier that is good at reproducing a square wave will also have a very high frequency response. The speed of a amplifier is measured by it's slew rate, higher numbers are better. So, as you guessed, using very fast transistors in a amplifier will give you a high slew rate but there is a limit to this goodness. If transistors are too fast the amplifier can break into oscillation which can destroy itself or it's load
I hope that clears up your questions Danny, Thanks for watching
Yesterday I saw an ad that advertised radio for sale one dollar volume stuck on high thought I can't turn that
I don't know much about hk receivers but they made one of the best cassette recorders ever cd491 better recording then the Dragon .
I'm on the lookout for a CD491. Want to have one in my collection
Cd491 in good shape are not easy to find.
Hey, you can paint the meter needle florescent red and they will glow ln the dark*
The plastic .....peroxide and uv leds. The guys that rebuild video game systems use it to clean the cases.
I didn't get all the way to the switches etc, though, so it must be more than me
YAY
It's a great sounding receiver
I was wondering if you might use nail polish to paint the needle. Also Trevor, are you looking for sponsorship from Popeye's? I have a subliminal urge for fried chicken ;)
Strategic product brand placement that earns me absolutely sweet FA