Hi Tony, i have a G7500 and actually emailed you early this year.. i wanted to get my G7500 recapped... so i did... had it completely restored, and my master tech got mine bench tested to 125wpc... sounds fantastic, i use it everyday in my home office! was my Father's amp... he brought it a year before my birthdate...now its mine.. good for another 45 years!!
Thanks for another great video. I am teaching my partner about vintage audio gear and we love your channel. You are very thorough with everything and a great teacher. That receiver is gorgeous - the subtle blue lighting goes really nice with the incandescent light of the meters. Puts me in a music mood
Loved the Sansui G-7500 series. I just picked up a G-9000 that has a dead left channel - at least according to the description but I got it for a really good price considering what they are going for these days. I am hopeful it is a switch, or the Pre-Amp Connected switch or something simple. I am prepared to go through it. Interesting work on those output transistors. I wonder if thos same transistors would work in a G-9000 given you said they were good for 250 watts.
I had a very similar problem on a valve Sansui amp that had a bass boost in the flat response and loudness off. Turned out to be a faulty loudness switch! That was after I added some components to correct for the response hump.
These command some high value, on fleabay. I had a 1000A tube type (6v6) back in the early 70's great rig. They bring ridiculous prices, I see. Love watching you. You're more patient than I am.
I had a Dynaco PAS2 tube preamp and two Heathkit monoblock tube amplifiers back in the 70's. I sold the whole thing to my friend for $30 and had to beg him to take it.
Repair and maintenance is so time consuming, even if you're well capable of fixing equipment. I have often thought about repairing electronic apparatus for people, but the time involved makes it simply not viable. At least when you fix your own equipment, and if another problem crops up later, you can always deal with it, but that won't sit well for a paying customer? The problem with old stuff - all components are ageing in slow motion, and all at different rates. BTW @42:15 ... well spotted! Nice, clear videos!
I enjoyed watching you work once more. I stayed o to the end, glad to learn there wasn’t more damage to it. Wondering how those two bad resistors caused such screwy voltages. Maybe I missed your explanation, I’ll give it another listen. Edit: OK, three resistors were open and one was triple rated value. That would cause the symptoms exhibited earlier. Good job. 👍
Orange Hospital Grade AC outlet: Tony you're so smart using the outlet where the earth ground is totally isolated from the mounting ears to protect yourself from parallel grounds etc.
Tony i really appreciate all your videos. You've done tons of great videos to teach people from a very fundamental level how to work on electronics. I do have a suggestion for a future video. Could you go over entry level equipment for the beginner to put together a workbench? Including an inexpensive but decent oscilloscope? There are many cheap brand new Chinese ones, or a cheap used one. Hard to know what is the best option? The market is so wide open. What is the best option for a beginner? Easy to use, and not too expensive but reliable. Thanks so much!
See Blueglow Electronics channel here on UA-cam Oscilloscopes for audio part one. This is a 4 part series. I have 2 Hitachi scopes I got from eBay older model analog scopes. They sell for $100-$150. Try to find one that's shown powered on and look for broken or bent knobs.
buying pots for vintage gear constantly gives me a hard time, last time, i bought detented controls for an integrated amp and they were only center detent but i saw no indication on any pots on digikey on a stepped detent or center detent. maybe i'm missing something there but it is annoying everytime i bomb. great video tony!
The 4 electrolytics that are close to those 100 ohm resistors needs to be replaced, too.. I remember that from working on a G7000 and that board is exactly the same. Great video series and Merry Christmas.
Would love to see Toe Jam cranked up at full power on the scope, distortion meter. What a test! Thanks for the great instruction this past year, Tony. Wishing you and your family a Merry Christmas!
Why would one get up to about 65-70% volume, due to your video I went out and just unboxed a 40+ year old G7700 Pure Power DC receiver, was in its original box from a estate, still taped up new when I got it but never plugged in. Set it onto a pair of Realistic Mach 1 speakers tonight finally that looked new also but were in opened boxes I bought there too, and at a head bashing volume of about 65 to 70% it just clicked off till I dropped the volume to about 20% then would click back on after a few seconds (over load??) and had a little fault light come on near the dial. Running real copper 12/2 wire on it, good 300 ohm antenna ladder wire and weinguard FM 100 mile antenna dated oct 1977 from same collection of radios. Now wondering if its bad after sitting almost 45 years in its box. Bought 18 items from this estate all still in original boxes. 2 are REALLY heavy Sansui a G7700 and a 9090. Got 2 very old still in box Fisher 404 quad and 500tx. The rest are a Akai tape deck, speakers Sansui, Nivco and Foster and Ampex receiver amp. There was about 80 such items in his Dallas home but I ran out of money. Any idea on these?
Top Man Tony, great video, because I know Sansui's I would have gone for the fuse resistors first 😀 nevertheless very instructive for people just getting into this. 👍
Excellent job at saving this amp. Sansui are fantastic amps, this is a great model 90wrms/chan into 8 ohms. Freq Tes 5Hz -50 Khz. THD .025%. Excellent specs
Wow. The frequency response is impressive considering it is over UA-cam. Using Onkyo receiver and a really good Behringer studio headset. Very nice audio from this old Sansui 7500.
The F2852 phono pre-amp is used in a few different Sansui's, standard course of action is to replace the 4 x 100 ohm resistors from the power supply, in most cases they are out of spec...
23:50 - Tony, you tweaked TC-01 so the low end of the band tracked. Shouldn't you do the same for the high end of the band by tweaking the corresponding trim-cap?
42:12 I have a treble control in a Panasonic RX-5250 boom box that has become a volume attenuator when you turn the treble down. My guess is that the capacitor in the tone control has shorted and is taking all of the signal to ground.
In regards to the KSA replacement transistors, do you know the numbers, if any, for the 2SC1904? The driver transistors 2SC2238B and 2SA968B, do these have equivalent replacements? On the driver boards for the G-8700DB, they have that clipped center collector lead which is wired to the heatsink, and the base, emitter leads bent at 90 degrees.
As a collector of vintage hifi myself, that is a matter of personal taste and what you like. It is not a black and white answer, so many shades of grey. All have strengths, weaknesses, and personality. When you start collecting them they become like children, how can you say which one is more loved, or "best"? Tony's answer was more to the point.....
9:31 Must be some rounding, if ΔV = 6.168V, Δt = 7.6μs, then ΔV/Δt = 0.734V/μs; as it stand the rise time reported on screen is 0.811V/μs not 8.11V/μs.
0:15 Intro 1:20 THD test @ 1 kHz before clipping 2:37 Frequency Analysis Channel 1 (Fail) 5:03 Frequency Analysis Channel 2 6:04 Retry of Frequency Analysis Channel 1 (Yep, I screwed up on the first try) 7:40 1kHz Square Wave 8:45 Testing Slew Rate 9:45 Amplifier is running nice and cool :) 10:40 For your UA-cam Audio Library listening pleasure (No Twerking allowed during the viewing of this video) ;)=) 13:28 Testing the FM tuner (AM was done off camera) 13:44 Cleaning the tuning gang rotor contacts 18:02 Testing the tuning gang after cleaning 18:52 Testing MPX stereo and sensitivity using the Sencore SG-80 (quick test) 23:46 Well, I thought the video was over...... 24:47 We still have some problems.... 28:34 Testing the power supply to the phono stage 27:27 Power supply is good, now what? 27:40 Troubleshooting the phono stage 29:26 Checking the transistors in-circuit 34:16 Checking the JFETs 35:12 Finding & repairing the problem 40:05 Testing the phono stage, final tests and issue with the treble pot
11:55 Wow, this is really good😎 Just found this artist on SoundCloud: this artist knows how to throw a beat together; and it sounds like he's a Brit to boot. New artist discovered; thanks👍 Edit: well Soundcloud reports the artist as from Australia, but he's got what sounds like a Mancunian accent. Edit Edit Just found Slynk's UA-cam channel: boom 😲
A pleasure watching a true expert at work, hard to find these days.
Remember when every stereo shop had a repair shop?
Hi Tony, i have a G7500 and actually emailed you early this year.. i wanted to get my G7500 recapped... so i did... had it completely restored, and my master tech got mine bench tested to 125wpc... sounds fantastic, i use it everyday in my home office! was my Father's amp... he brought it a year before my birthdate...now its mine.. good for another 45 years!!
Thanks for another great video. I am teaching my partner about vintage audio gear and we love your channel. You are very thorough with everything and a great teacher. That receiver is gorgeous - the subtle blue lighting goes really nice with the incandescent light of the meters. Puts me in a music mood
Loved the Sansui G-7500 series. I just picked up a G-9000 that has a dead left channel - at least according to the description but I got it for a really good price considering what they are going for these days. I am hopeful it is a switch, or the Pre-Amp Connected switch or something simple. I am prepared to go through it.
Interesting work on those output transistors. I wonder if thos same transistors would work in a G-9000 given you said they were good for 250 watts.
I had a very similar problem on a valve Sansui amp that had a bass boost in the flat response and loudness off. Turned out to be a faulty loudness switch! That was after I added some components to correct for the response hump.
Love these troubleshooting and repair videos. Keep them coming!
These command some high value, on fleabay. I had a 1000A tube type (6v6) back in the early 70's great rig. They bring ridiculous prices, I see. Love watching you. You're more patient than I am.
I had a Dynaco PAS2 tube preamp and two Heathkit monoblock tube amplifiers back in the 70's. I sold the whole thing to my friend for $30 and had to beg him to take it.
The 1000A have 7591 tubes. They kinda look like 6v6gt but way more powerful (and nicer)
Great couple of videos Tony. Enjoy your honest down to earth commentary and standard of work. Seasons greetings from Down Under.
Repair and maintenance is so time consuming, even if you're well capable of fixing equipment. I have often thought about repairing electronic apparatus for people, but the time involved makes it simply not viable. At least when you fix your own equipment, and if another problem crops up later, you can always deal with it, but that won't sit well for a paying customer?
The problem with old stuff - all components are ageing in slow motion, and all at different rates.
BTW @42:15 ... well spotted!
Nice, clear videos!
I enjoyed watching you work once more. I stayed o to the end, glad to learn there wasn’t more damage to it. Wondering how those two bad resistors caused such screwy voltages. Maybe I missed your explanation, I’ll give it another listen.
Edit: OK, three resistors were open and one was triple rated value. That would cause the symptoms exhibited earlier. Good job. 👍
Woa awesome. I'm troubleshooting an amp right now and hadn't checked resistors yet but tonight it's going to happen. Thank you Tony !
Orange Hospital Grade AC outlet:
Tony you're so smart using the outlet where the earth ground is totally isolated from the mounting ears to protect yourself from parallel grounds etc.
Good catch ;)
Tony i really appreciate all your videos. You've done tons of great videos to teach people from a very fundamental level how to work on electronics. I do have a suggestion for a future video. Could you go over entry level equipment for the beginner to put together a workbench? Including an inexpensive but decent oscilloscope? There are many cheap brand new Chinese ones, or a cheap used one. Hard to know what is the best option? The market is so wide open. What is the best option for a beginner? Easy to use, and not too expensive but reliable. Thanks so much!
See Blueglow Electronics channel here on UA-cam Oscilloscopes for audio part one. This is a 4 part series. I have 2 Hitachi scopes I got from eBay older model analog scopes. They sell for $100-$150. Try to find one that's shown powered on and look for broken or bent knobs.
buying pots for vintage gear constantly gives me a hard time, last time, i bought detented controls for an integrated amp and they were only center detent but i saw no indication on any pots on digikey on a stepped detent or center detent. maybe i'm missing something there but it is annoying everytime i bomb. great video tony!
Thanks for posting Tony! This is a powerful machine now ready for its next life.
The 4 electrolytics that are close to those 100 ohm resistors needs to be replaced, too.. I remember that from working on a G7000 and that board is exactly the same. Great video series and Merry Christmas.
Would love to see Toe Jam cranked up at full power on the scope, distortion meter. What a test! Thanks for the great instruction this past year, Tony. Wishing you and your family a Merry Christmas!
You shouldve been a teacher or instructor. Learning so much from your videos.
I still have a lot to learn.
Why would one get up to about 65-70% volume, due to your video I went out and just unboxed a 40+ year old G7700 Pure Power DC receiver, was in its original box from a estate, still taped up new when I got it but never plugged in. Set it onto a pair of Realistic Mach 1 speakers tonight finally that looked new also but were in opened boxes I bought there too, and at a head bashing volume of about 65 to 70% it just clicked off till I dropped the volume to about 20% then would click back on after a few seconds (over load??) and had a little fault light come on near the dial. Running real copper 12/2 wire on it, good 300 ohm antenna ladder wire and weinguard FM 100 mile antenna dated oct 1977 from same collection of radios. Now wondering if its bad after sitting almost 45 years in its box. Bought 18 items from this estate all still in original boxes. 2 are REALLY heavy Sansui a G7700 and a 9090. Got 2 very old still in box Fisher 404 quad and 500tx. The rest are a Akai tape deck, speakers Sansui, Nivco and Foster and Ampex receiver amp. There was about 80 such items in his Dallas home but I ran out of money.
Any idea on these?
Go watch part 1 and especially about adjusting the bias voltage of the end amp transistors
Another well-done video. Thanks Tony.
Top Man Tony, great video, because I know Sansui's I would have gone for the fuse resistors first 😀 nevertheless very instructive for people just getting into this. 👍
Great job. Thank you for all the great videos this year. Mike,
Excellent job at saving this amp. Sansui are fantastic amps, this is a great model
90wrms/chan into 8 ohms. Freq Tes 5Hz -50 Khz. THD .025%. Excellent specs
90wrms/chan into 8 ohms. Freq Tes 5Hz -50 Khz. THD .025%. Excellent specs
Wow. The frequency response is impressive considering it is over UA-cam. Using Onkyo receiver and a really good Behringer studio headset. Very nice audio from this old Sansui 7500.
The F2852 phono pre-amp is used in a few different Sansui's, standard course of action is to replace the 4 x 100 ohm resistors from the power supply, in most cases they are out of spec...
I had this receiver, it's a very nice piece of gear..
Another reason for hearing that crunchy sound as you tune the dial… is too many cookie crumbs in the tuner - especially around Christmas!! 🤣😅😂
My friend's son put his peanut butter toast in the VCR. :)
@@xraytonyb I've seen an ice cream sandwich in a VCR. Goes right in, perfect size! ;-)
Nephew put a PB&J in the VCR...
Thanks Tony! And Happy Christmas to you and yours.
You can check/compare RDS on JFETs with the Ohm-meter when still on board
23:50 - Tony, you tweaked TC-01 so the low end of the band tracked. Shouldn't you do the same for the high end of the band by tweaking the corresponding trim-cap?
I have a G7700 that i got new in original sealed box. Not sure if its still even useful since its over 40 years old.
Ohhh that's very rare, have you test it ?
42:12 I have a treble control in a Panasonic RX-5250 boom box that has become a volume attenuator when you turn the treble down. My guess is that the capacitor in the tone control has shorted and is taking all of the signal to ground.
Awesome as usual! Thank you Tony.
16:00 Instead of the red D100, wouldn't it be better to use the green F100 in this application?
That wacky music put me in mind of the Zapp Band who I listened to in the 80s/90s.
Nice vid's. Tony, that Sansui Sounds great.
In regards to the KSA replacement transistors, do you know the numbers, if any, for the 2SC1904?
The driver transistors 2SC2238B and 2SA968B, do these have equivalent replacements? On the driver boards for the G-8700DB, they have that clipped center collector lead which is wired to the heatsink, and the base, emitter leads bent at 90 degrees.
Thanks again for super videos T.
,,ThumbsUp from scandinavia :)
Looked it up, Slynk is the name of the artist. They have their own channel here on YT.
What' the best vintage receiver in your opinion,sounding,options etc.
Same answer as my favorite underwear.....depends
As a collector of vintage hifi myself, that is a matter of personal taste and what you like. It is not a black and white answer, so many shades of grey. All have strengths, weaknesses, and personality. When you start collecting them they become like children, how can you say which one is more loved, or "best"?
Tony's answer was more to the point.....
Hi again , I did not find the Buzz sound on right side of my Sansui au20000, It is really killing me ;(((((((.
Huh?
@@xraytonyb
Let us hope that James does not find Mr Carlson's channel, eh?
@@poormanselectronicsbench2021 Thanks for your help....eh.
Hello good sir, can you please suggest one function generator, and thd analyzer for my audio workbench?
9:31 Must be some rounding, if ΔV = 6.168V, Δt = 7.6μs, then ΔV/Δt = 0.734V/μs; as it stand the rise time reported on screen is 0.811V/μs not 8.11V/μs.
Re your recent comment about your mic setup, your audio, is somewhat muffled. No treble. Sounds like there's nothing above 3k.
I forgot to put the mic on. It was hanging over the camera stand by the cord. I'm no recording artist. ;)
0:15 Intro
1:20 THD test @ 1 kHz before clipping
2:37 Frequency Analysis Channel 1 (Fail)
5:03 Frequency Analysis Channel 2
6:04 Retry of Frequency Analysis Channel 1 (Yep, I screwed up on the first try)
7:40 1kHz Square Wave
8:45 Testing Slew Rate
9:45 Amplifier is running nice and cool :)
10:40 For your UA-cam Audio Library listening pleasure (No Twerking allowed during the viewing of this video) ;)=)
13:28 Testing the FM tuner (AM was done off camera)
13:44 Cleaning the tuning gang rotor contacts
18:02 Testing the tuning gang after cleaning
18:52 Testing MPX stereo and sensitivity using the Sencore SG-80 (quick test)
23:46 Well, I thought the video was over......
24:47 We still have some problems....
28:34 Testing the power supply to the phono stage
27:27 Power supply is good, now what?
27:40 Troubleshooting the phono stage
29:26 Checking the transistors in-circuit
34:16 Checking the JFETs
35:12 Finding & repairing the problem
40:05 Testing the phono stage, final tests and issue with the treble pot
Does that 2204EX do the whole frequency analysis or are you using a function generator to pipe the sweep into the amp?
11:55 Wow, this is really good😎 Just found this artist on SoundCloud: this artist knows how to throw a beat together; and it sounds like he's a Brit to boot. New artist discovered; thanks👍 Edit: well Soundcloud reports the artist as from Australia, but he's got what sounds like a Mancunian accent. Edit Edit Just found Slynk's UA-cam channel: boom 😲
A Sansui with open or out of spec fusisters imagine that...
minute 13:00 , such bad 'music'. Not a single 'person' playing anything. Now back to the stereo gear...
Good clean work. Thanks for the look! Enjoyed.