Sansui QRX-9001 Restore and Mods

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schaale1969

New member
Joined
Nov 6, 2012
Messages
9
Location
Dover,Pa
Hi everyone! I'm new to quad but i'm going to jump in with both feet kicking. I picked up a QRX-9001and a 7001 to restore and mod for music and Movies. I've been going over the schematics making up my capacitor list and I have a question or two. I checked out QRXrestore web site and got some good info from there. I'm going to use the Nichicon UKW and UKT or maybe the FG caps in the signal path. I'll get the CDE brand 15000UF caps. Now on to my questions.
1. What type of caps should I get for the rest of the caps in the power supply section?
2.What caps for the tuner section?
3. Other than the 15000uf caps can I use the same kind of Nichicon caps for the rest or should I use differnt types in differnt places? Like the UKW in the signal path,something else on the tuner board,something else on the power supply filter boards. I find a lot of info on signal path caps but not much on the other areas. I have a schematic for the power supply section, one for the tuner section,one for the audio section,one for the 4-ch section.

So far on my list I have the UKW,bi-polars and I think its the KL for the BRN caps for the audio section. The CDE for the !5000UF caps. What type shpuld I use for the rest.

Thank You for any help I can get. After I get this straight i'll start with my mod questions
 
Hi everyone! I'm new to quad but i'm going to jump in with both feet kicking. I picked up a QRX-9001and a 7001 to restore and mod for music and Movies. I've been going over the schematics making up my capacitor list and I have a question or two. I checked out QRXrestore web site and got some good info from there. I'm going to use the Nichicon UKW and UKT or maybe the FG caps in the signal path. I'll get the CDE brand 15000UF caps. Now on to my questions.
1. What type of caps should I get for the rest of the caps in the power supply section?
2.What caps for the tuner section?
3. Other than the 15000uf caps can I use the same kind of Nichicon caps for the rest or should I use differnt types in differnt places? Like the UKW in the signal path,something else on the tuner board,something else on the power supply filter boards. I find a lot of info on signal path caps but not much on the other areas. I have a schematic for the power supply section, one for the tuner section,one for the audio section,one for the 4-ch section.

So far on my list I have the UKW,bi-polars and I think its the KL for the BRN caps for the audio section. The CDE for the !5000UF caps. What type shpuld I use for the rest.

For power supply use 105°C low ESR types.
For power supply inside the audio and tuner section use standart low ESR types. They can be 85°C types, unless you experience hot components in the vicinity. No need for expensive audio types here.
For signal paths use one of the audio types, but try to replace lower capacitance values 1µF to 10µF with modern foil capacitors if possible. The technology changed over the years making them now much smaller than 40 years ago. They can have spacings of 2,54mm these days.
In case of unavailability of "special audio capacitors" you can still use low ESR types of good quality.
Additional decoupling of ICs with 100nF ceramic capacitors soldered as close as possible to the supply pins of the component is often mandatory on old eqipment, and wasn't done way back then. I recommend to solder them on the solder side of the board.

-Kristian
 
For power supply use 105°C low ESR types.
For power supply inside the audio and tuner section use standart low ESR types. They can be 85°C types, unless you experience hot components in the vicinity. No need for expensive audio types here.
For signal paths use one of the audio types, but try to replace lower capacitance values 1µF to 10µF with modern foil capacitors if possible. The technology changed over the years making them now much smaller than 40 years ago. They can have spacings of 2,54mm these days.
In case of unavailability of "special audio capacitors" you can still use low ESR types of good quality.
Additional decoupling of ICs with 100nF ceramic capacitors soldered as close as possible to the supply pins of the component is often mandatory on old eqipment, and wasn't done way back then. I recommend to solder them on the solder side of the board.

-Kristian

What is the benefit of the foil caps? What does decoupling of the IC do? Whats your thoughts on adding the polypropylene caps in parallel with the electrolytic caps in the signal path? I'm going to send my boards to QRXrestore to have the diff mod done. That adds some circuitry that they didn't do back then either. I wonder if it's the same changes.
 
Welcome to the forum and good luck with your project. I envy folks like yourself with an aptitude for electronics. While I love all the vintage gear, my brain was not wired to understand the complexities of it all.
 
What is the benefit of the foil caps? What does decoupling of the IC do? Whats your thoughts on adding the polypropylene caps in parallel with the electrolytic caps in the signal path? I'm going to send my boards to QRXrestore to have the diff mod done. That adds some circuitry that they didn't do back then either. I wonder if it's the same changes.

QRXrestore? So you do not restore it by yourself?

Benefit of foil caps: They aren't prone to aging that much. Even at worst case conditions (temperature, ripple, etc) they have a durability of 100000 to 300000 hours. It's practically "use them and forget about them". Then they have lower tolerances compared to electrolytic capacitors, which is an advantage when the capacitor is used in a filter design. And then they show lower dissipation values, they act more like an ideal capacitor than electrolytics do.

Decoupling means that noise coming from other parts of the circuit is kept away as good as possible from the cirquit with decoupling. This in regard of supply voltage. For testing: Connect your oscilloscope AC-coupled to the supply pins of, say, an operational amplifier within your audio path. Turn it to 50mV/div, or maybe even 100mV/div. You will see a lot of noise coming from other parts of the circuit, i.e. the tuner section. Other type of noise is radiation from outside the apparatus, like AM or FM from your local radio or tv station visible on the supply. And, of course any noise generated by the circuit itself (radiation) influencing other parts. Electrolytic capacitors are good in supplying energy to the circuit in the lower frequency spectrum, but are in general pretty slow at high frequencies. So the ceramics help to supply the chip when the chip is requesting energy in short time frames if the IC is demanding it (think of FM demodulator chips who often have buit-in high frequency oscillators), and so keeps the supply lines more quiet. Regarding audio paths (think operatiional amplifiers, or quad decoder chips) they help to keep away this noise from the circuit itself.

Film capacitors in parallel to electrolytics: Often used to enhance the upper part of the audio spectrum when different audio circuits are connected via electrolytic coupling capacitors. A matter of taste, file this under "tweaking" rather than restoring. As I said, technology on capacitor development is more advanced today than forty years ago. I think you won't be disappointed with your audio type electrolytics.

-Kristian
 
QRXrestore? So you do not restore it by yourself?

Benefit of foil caps: They aren't prone to aging that much. Even at worst case conditions (temperature, ripple, etc) they have a durability of 100000 to 300000 hours. It's practically "use them and forget about them". Then they have lower tolerances compared to electrolytic capacitors, which is an advantage when the capacitor is used in a filter design. And then they show lower dissipation values, they act more like an ideal capacitor than electrolytics do.

Decoupling means that noise coming from other parts of the circuit is kept away as good as possible from the cirquit with decoupling. This in regard of supply voltage. For testing: Connect your oscilloscope AC-coupled to the supply pins of, say, an operational amplifier within your audio path. Turn it to 50mV/div, or maybe even 100mV/div. You will see a lot of noise coming from other parts of the circuit, i.e. the tuner section. Other type of noise is radiation from outside the apparatus, like AM or FM from your local radio or tv station visible on the supply. And, of course any noise generated by the circuit itself (radiation) influencing other parts. Electrolytic capacitors are good in supplying energy to the circuit in the lower frequency spectrum, but are in general pretty slow at high frequencies. So the ceramics help to supply the chip when the chip is requesting energy in short time frames if the IC is demanding it (think of FM demodulator chips who often have buit-in high frequency oscillators), and so keeps the supply lines more quiet. Regarding audio paths (think operatiional amplifiers, or quad decoder chips) they help to keep away this noise from the circuit itself.

Film capacitors in parallel to electrolytics: Often used to enhance the upper part of the audio spectrum when different audio circuits are connected via electrolytic coupling capacitors. A matter of taste, file this under "tweaking" rather than restoring. As I said, technology on capacitor development is more advanced today than forty years ago. I think you won't be disappointed with your audio type electrolytics.

-Kristian

Hi Kristian Thank you for the good info. Im doing the restore myself and i'm going to have QRXRESTORE do some mods for me. They do a Differential output mod that balances the current to the input transistors and add some circuitry. For the QRX-7001 i'm going to use Nichicon KW in the signal path, the KL's for the BRN caps, ES's for the bi-polar caps and the PW's for the low esr power supply caps. I'll use CDE brand caps at 15,000 for the main filter caps. For the QRX-9001 i'm going to use the Nichicon FG and foil caps and see if I can hear a differance. I'm doing research on adding the ceramics to the IC's. I haven't seen that mentioned in any other searches I did but it makes scence. For the other mods i'll do the holy grail alignment, 25v regulator, remove the blend resistors, change out the fusiable resistors with the metal film. On the 7001 i'm going to add inputs and outputs , and for the 9001 I will be using it for my home theater so I want to add outputs for a subwoofer. Are the audio circuits divided into different frequances then added together to go to the speakers or are they always together? I didn't know if I could get the lower frequency from some where in the audio circuit or if I had to add a parellel output to go to the sub. I'll be using a Heathkit aa-1640 amp thats moded. I'm up for any sugestions anyone might have.
 
Hi all Here is the capacitor list I came up with. There are a couple extra ones because the schematic called for one thing and the parts list called for something else so I got both.
AUDIO PATH
BRN's I went with the Nichicon UKL
2x 3.3uf 50v
14x 1uf 50v
8x 2.2uf 50v
Bi-polars I went with a Nichicon
2x 47uf 6.3v
1x 1uf 50v
2x 100uf 6.3v
The otheres I went with Nichicon UKW unless they weren't available in that size I went with the UKT
35x 1uf 50v
3x 100uf 50v
14x 100uf 6.3v
14x 4.7uf 25v
1x 33uf 50v
1x 470uf 6.3v
2x 47uf 16v
2x 220uf 25v
10x 10uf 16v
16x 3.3uf 50v
2x 4.7uf 50v
2x 100uf 25v
3x 47uf 6.3v
2x 33uf 10v
4x 10uf 25v
3x 47uf 10v
 
2x 100uf 10v
4x 33uf 25v
2x 2.2uf 50v
3x 100uf 16v
Power caps I went with nichicon PW
2x 470uf 10v
8x 1uf 50v
1x 330uf 10v
2x 100uf 10v
1x 47uf 50v 2x 220uf 25v
2x 10uf 25v
1x 220uf 16v
1x 100uf 16v
4x12uf polypropylene
Well theres my list. What do you think ,did I miss anything? For the QRX-9001 i'm going to go all out with ceramic decoupling caps for the IC's,Polypropylennes for the smaller caps and for parellel caps
 
Hi all When I was looking at the schematic for the 9001 audio section it was showing caps that where right after the transformer How can I tell which caps should be replaced with audio grade versus other ones? On the audio schematics for the 7001 it didn't show the transformer or the power coming in.
 
Hello schaale69 How are you doing with the recap on your 7001 and 9001? You are going to be impressed when complete. I have the QRX999 complete restore with the QBL100 remote modify by Jim Showker he also did the 9001. He sure is a helpfull and pleasant man to do bussiness with. I also have the 7001. Hope your restore is going well.
 
I ordered the caps and the parts to do the 25v regulator mod on the 7001 from Mouser, they should be here soon. I,m still researching on the 9001. I'm tring to find out which caps get the polyproplene bypass caps. Do all the caps in the signal path get them or just the ones that go to ground off the emitters? I can't decide which caps I want to use to replace the electrolytics with. Some guys replace them with polypropylenes where they fit, some people use oil caps. Looking for info to do the output diff mod myself. So while i'm redoing the 7001 i'll figure out what I want to do to the 9001 and get the parts ordered.
 
I ordered the caps and the parts to do the 25v regulator mod on the 7001 from Mouser, they should be here soon. I,m still researching on the 9001. I'm tring to find out which caps get the polyproplene bypass caps. Do all the caps in the signal path get them or just the ones that go to ground off the emitters? I can't decide which caps I want to use to replace the electrolytics with. Some guys replace them with polypropylenes where they fit, some people use oil caps. Looking for info to do the output diff mod myself. So while i'm redoing the 7001 i'll figure out what I want to do to the 9001 and get the parts ordered.

Hey there untitledmine.jpg QRX restore is detailed experts best
 
The top unit is a Sansui SE-9 motorized graphic equalizer spectrum anylizer pink noise generator whew
I ordered the caps and the parts to do the 25v regulator mod on the 7001 from Mouser, they should be here soon. I,m still researching on the 9001. I'm tring to find out which caps get the polyproplene bypass caps. Do all the caps in the signal path get them or just the ones that go to ground off the emitters? I can't decide which caps I want to use to replace the electrolytics with. Some guys replace them with polypropylenes where they fit, some people use oil caps. Looking for info to do the output diff mod myself. So while i'm redoing the 7001 i'll figure out what I want to do to the 9001 and get the parts ordered.
I ordered the caps and the parts to do the 25v regulator mod on the 7001 from Mouser, they should be here soon. I,m still researching on the 9001. I'm tring to find out which caps get the polyproplene bypass caps. Do all the caps in the signal path get them or just the ones that go to ground off the emitters? I can't decide which caps I want to use to replace the electrolytics with. Some guys replace them with polypropylenes where they fit, some people use oil caps. Looking for info to do the output diff mod myself. So while i'm redoing the 7001 i'll figure out what I want to do to the 9001 and get the parts ordered.
Ok so this post is 8 years old. How did it work out? I have a QRX6001 and an 8001 and am trying to psyche myself up to working on them. Itsa daunting task. Thanks for the capacitor list, that should save me a bit of time.i would really like to know how your experience went.
 
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