water on board
This morning I've surprised; my NAD board was wet. Not a very small drop, I thought "where this water was came from?". In a minute I recognise that a cap released water (or chemicals). Also, there was a some water stains on board. Now I know that it's come from caps.
Those are rectifier (decoupling) caps 50volts 2200uf's, 220uf/50 volt. Big capacitors have more water in it 🙂 Also, I want to say that after changing that capacitors I didn't absorbe any change in sound 🙂 This is also tragic.
For example 220uf/50v capacitor's last characteristics 210uf, esr 0.17ohm, vloss %2.2.
For example 220uf/50v capacitor's last characteristics 210uf, esr 0.17ohm, vloss %2.2.
a) I know white paste, I can say that I didn't measure (touching only) temp. of transistors, I look for the cooler temprature. Cooler was very hot. when I was changing transistors, I'm using white thermal paste.
b) my c352's volume control perfect, there is no noise 🙂
c) I couldn't solve the high temprature of rectifier transistors. output voltage is normal. preamplificators of c352's A-class, some transistors on it very hot. Perhaps, design is that much hot for c352. 5v rectifier chip is nearly 40-50C, 17V rectifier transistors much hotter then, some amplifier resistors as hot as you couldn't touch them. I will continue to absorbation about amp. I wrote to NAD, they said sent it to service 🙂 NAD serviceses are in ABD and in Canada. Not possible. Now sound is perfect, let's look what will happen in time.
Hi, I have a question about NAD C352;
In circuit bypassing elect. cap.s has a paralel 100nf poly. capacitors.A lot of amp. use this trick.
I changed the elect.caps. If I change that 100nf poly.caps with MKP2 caps. Is this an improvement in sound? thank you,
In circuit bypassing elect. cap.s has a paralel 100nf poly. capacitors.A lot of amp. use this trick.
I changed the elect.caps. If I change that 100nf poly.caps with MKP2 caps. Is this an improvement in sound? thank you,
Multible bypass capacitors
Multible bypass capacitors like 10uf+100nf, do you think quality of lower capacitor is important?
Multible bypass capacitors like 10uf+100nf, do you think quality of lower capacitor is important?
I don't know. Do the experiment. Install a polyester 10 uf, measure the distortion. Install a polyrophylene caps, measure the distortion. None of my amps or organs have this arrangement. See the John Curl cap article. He was measuring distortions in the 4th or 5th digit.
Thank you indianajo,
I have no any good oscilloscope, but if I find time, I will try to test with poly and mkp2 caps.
Here, I want to share my another theory; I think NAD uses heat in the amplifiers 🙄. Means, caps behave different (characteristics changing a little) when you heat them to perhaps 40C. Amplifier designed for 40-50C. Also, there are some coupled resistors for example (R153&R157, 1/2&2watts). If the resistor would be 20C, there was no interaction between the resistors. Here resistor R157 hotter than 50C. Some rectifier transistors (coolers. with changed termal paste) also hotter than 50C (means I couldn't touch them). They really heat the all amplificator. Thinking like that explain the heat 🙂
I have no any good oscilloscope, but if I find time, I will try to test with poly and mkp2 caps.
Here, I want to share my another theory; I think NAD uses heat in the amplifiers 🙄. Means, caps behave different (characteristics changing a little) when you heat them to perhaps 40C. Amplifier designed for 40-50C. Also, there are some coupled resistors for example (R153&R157, 1/2&2watts). If the resistor would be 20C, there was no interaction between the resistors. Here resistor R157 hotter than 50C. Some rectifier transistors (coolers. with changed termal paste) also hotter than 50C (means I couldn't touch them). They really heat the all amplificator. Thinking like that explain the heat 🙂
Polyester or polypropylene caps
Hi, I think I found a solution: In audio coupling caps, very important thing is dielectic obsorption. and this is
.
so, poly or polypropylene caps makes not much difference. Polypropylene is little better (for example I remember, heat response more linear). that's.. I will not change multible coupling capacitors.
Hi, I think I found a solution: In audio coupling caps, very important thing is dielectic obsorption. and this is
.so, poly or polypropylene caps makes not much difference. Polypropylene is little better (for example I remember, heat response more linear). that's.. I will not change multible coupling capacitors.
NAD caps change
Preamp stage I changed coupling capacitors with panasonic FC type caps. Result is very bad. I turn back to some original and Koshin (105C, M & KLH type; What I found) caps. It's surprised me
Caps C322-C321, C336-C335, C340-C339 and c139-C140 (feedback caps). C101-C102 are still FC type, I will test later.
Preamp stage I changed coupling capacitors with panasonic FC type caps. Result is very bad. I turn back to some original and Koshin (105C, M & KLH type; What I found) caps. It's surprised me
Caps C322-C321, C336-C335, C340-C339 and c139-C140 (feedback caps). C101-C102 are still FC type, I will test later.
C101-C102 Power amp. coupling cap.'s. I tried many caps. Coupling was 10uf elec. & 100nf polyester cap.
I tried instead of 10uf elec., 1uf MKS2 wima cap. I satisfied from the result. Now, I added one more parallel 10uf Rubycon YXJ series cap.. Perhaps, I will change with Pana., FC series (note that, I have no MKP2, 1uf caps or 10uf 🙂 ).
1uf mks2 changed the all colour of sound. I'm testing with violin sound, quartets...
I tried instead of 10uf elec., 1uf MKS2 wima cap. I satisfied from the result. Now, I added one more parallel 10uf Rubycon YXJ series cap.. Perhaps, I will change with Pana., FC series (note that, I have no MKP2, 1uf caps or 10uf 🙂 ).
1uf mks2 changed the all colour of sound. I'm testing with violin sound, quartets...