Always best to take components out for critical testing.
(having said that, I'd be surprised if you could notice anything by checking the diodes with anything, except maybe a 'curve tracer'. 
)
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Sansui AU-2200 Restore & Recap
- Thread starter Zeus12
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- recap sansui au-2200
(having said that, I'd be surprised if you could notice anything by checking the diodes with anything, except maybe a 'curve tracer'. )
Zeus12
Active Member
Hi Hyperion,
So basically, just replace them and don´t worry about testing them.
I tried to do it "in circuit" and this is what I got with the ES2PRO meter:
D601: pin 1 & 3 1.3 Ohms L = .01mH
pin 1 & 2 uf= 667 mV 768 mV
pin 2 & 3 uf = 779 mV 663 mV
D602: pin 1 & 3 1.2 Ohms L = .01mH
pin 1 & 2 uf=789 mV 647 mV
pin 2 & 3 uf=654 mV 781 mV
I can´t wait to get the new diodes!! It would be a shame to leave it and not give it a shot. I already invested quite a lot in all the tools and caps, so I might as well try and see if I can fix it MYSELF!!---with your invaluable help of course. Nothing beats that satisfaction!!!
Cheers!!!
So basically, just replace them and don´t worry about testing them.
I tried to do it "in circuit" and this is what I got with the ES2PRO meter:
D601: pin 1 & 3 1.3 Ohms L = .01mH
pin 1 & 2 uf= 667 mV 768 mV
pin 2 & 3 uf = 779 mV 663 mV
D602: pin 1 & 3 1.2 Ohms L = .01mH
pin 1 & 2 uf=789 mV 647 mV
pin 2 & 3 uf=654 mV 781 mV
I can´t wait to get the new diodes!! It would be a shame to leave it and not give it a shot. I already invested quite a lot in all the tools and caps, so I might as well try and see if I can fix it MYSELF!!---with your invaluable help of course. Nothing beats that satisfaction!!!
Cheers!!!
Zeus12
Active Member
Greetings Audiophiles,
Got some original diodes to replace the "tombstones" 10DC-1 & 10DC-1R at D601 and D602 respectively and unfortunately that didn´t fix the "windy/static" noise at the beginning.
.
This is what the 2 original diodes measured with the ESR2 Pro. Don´t know exactly what those measurements mean.
Such a bummer because I recapped the whole thing and after 1-2 minutes of that fricking ugly noise it works PERFECTLY!! What a sweet sounding little amp this is!! For only 10 watts, it can fill the whole house with that unmistakable Sansui balanced sound!!
From what I understand, it should be the STK-016B IC´s??? Why does it go away after a couple of minutes? How can a component fix itself? I always thought in electronics, it is either working or NOT. Is it worth the trouble to try and find a replacement? Perhaps keep it for parts till I find another Au-2200?
Cheers!!!
Got some original diodes to replace the "tombstones" 10DC-1 & 10DC-1R at D601 and D602 respectively and unfortunately that didn´t fix the "windy/static" noise at the beginning.
. This is what the 2 original diodes measured with the ESR2 Pro. Don´t know exactly what those measurements mean.
Such a bummer because I recapped the whole thing and after 1-2 minutes of that fricking ugly noise it works PERFECTLY!! What a sweet sounding little amp this is!! For only 10 watts, it can fill the whole house with that unmistakable Sansui balanced sound!!
From what I understand, it should be the STK-016B IC´s??? Why does it go away after a couple of minutes? How can a component fix itself? I always thought in electronics, it is either working or NOT. Is it worth the trouble to try and find a replacement? Perhaps keep it for parts till I find another Au-2200?
Cheers!!!
It looks like Uf - but I think it is supposed to be Vf - in other words Forward Voltage drop. This is the voltage difference between Anode & Cathode (of each rectifier diode) when conducting in the Forward direction. ~600mV or 0.6V or thereabouts is a very normal voltage for this type of rectifier.
The readings you have posted show no problem with those dual rectifiers - as you have now found out.
The readings you have posted show no problem with those dual rectifiers - as you have now found out.
Zeus12
Active Member
@Hyperion
Big thank you for your help. To be honest, I don´t understand very well what you mean by "forward voltage" drop.
The old diodes and new ones I replaced were more or less the same value at around 650mV, so yes, I figured that out.
If I leave things the way they are, could this mess up my speakers or DAC? I was using some cheap testing speakers before. I could just leave the amp ON ALL the time and not worry about it. Would that be OK?
As you mentioned in a previous post, maybe not a wise idea to put more money into this little amp. I kind of agree.
Cheers!!!
Big thank you for your help. To be honest, I don´t understand very well what you mean by "forward voltage" drop.
The old diodes and new ones I replaced were more or less the same value at around 650mV, so yes, I figured that out.
If I leave things the way they are, could this mess up my speakers or DAC? I was using some cheap testing speakers before. I could just leave the amp ON ALL the time and not worry about it. Would that be OK?
As you mentioned in a previous post, maybe not a wise idea to put more money into this little amp. I kind of agree.
Cheers!!!
The problem with that unit would be finding ICs.... Is this if my unit, I would look for BA311 or replacements, don't know how hard can it be, they are ancient chips. The STK amp modules, can be replaced.
Heck! on this kind of amp, even the NTE parts could work.
Heck! on this kind of amp, even the NTE parts could work.
Zeus12
Active Member
@Hipocrates
Big thank you for your tips. I will look into the BA311. I could also wait for another "beat-up" unit and cannabilize it. It would probably be cheaper than getting the replacements. Shame because this was my first "fully" recapped project. But, hey, "no hay mal que por bien no venga"-- Every cloud has a silver lining!
Love your nick and would love to visit Costa Rica!!
Let food be thy medicine and medicine be thy food.--Hippocrates
Costa Rica accounts for only 0.03 percent of the earth's surface (has only 51.100km2). However it contains nearly 6 percent of the world's biodiversity. source:http://www.costarica-embassy.org/in...r only,explained by its geographical position.
Cheers!!
Big thank you for your tips. I will look into the BA311. I could also wait for another "beat-up" unit and cannabilize it. It would probably be cheaper than getting the replacements. Shame because this was my first "fully" recapped project. But, hey, "no hay mal que por bien no venga"-- Every cloud has a silver lining!
Love your nick and would love to visit Costa Rica!!
Let food be thy medicine and medicine be thy food.--Hippocrates
Costa Rica accounts for only 0.03 percent of the earth's surface (has only 51.100km2). However it contains nearly 6 percent of the world's biodiversity. source:http://www.costarica-embassy.org/in...r only,explained by its geographical position.
Cheers!!
Asi se habla!
Yupe, very cool places to go if you like nature.
Ok some pointers.
./ Recapping usually do not fix much, but is a good thing to do.
They don't, what happens is that sometimes components get warm, expand and when that happens they make contact. Same happens with hairline cracks.
Think about audio units with 3 sections.
Input (preamp section)
Amplifier section (amplify the signal of your input section)
Power supply section. (gives power to the other sections).
First we need to find out with section is causing problems
Now, you have the same problem on both channels no matter what, what are the chances that ICs have the same failure on both channels? It can happen, but is not that common.
I would start measuring the power supply section, just to be sure it is ok.
You have some 12v zener glass diodes did you replaced them as John told you?
Did you check every solder with a magnifier glass looking for cracked solder? If any doubt re solder.
Do you have the same problem with headphones? volume down? loudness off/on
Do you have a multimeter? ( no need for something fancy) any anneng or so will do.
The big job here is the diagnostic not the parts, so I don't think you will spend much more
Homework.
Google.
How single and dual linear power supplies work.
How an amplifier works.
How a pre amp works.
How to read a schematic.
Study the service manual of your unit and this text from Conrad.
http://conradhoffman.com/troubleshoottut.htm
With some time, and analytical mindset you can fix this thing. Otherwise we would be throwing stuff to see what sticks.
Sorry not to be much more help, but the truth is that I've never seen an AU-2200 other than pictures... VERY good looking unit!.
Zeus12
Active Member
@Hipocrates
Thanks again for the nice tips. Made the "Troubleshooting Audio Electronics Without Tears" into a PDF and will print it tomorrow. Looks great!! Thanks for that link! I have a WHOLE stack of reading material, and I do my HOMEWORK everyday!
The 12v zener glass diodes, to be honest, I don´t remember anyone telling me to change those. I changed the "bridge rectifiers" diodes but that was not the issue.
I will TRIPLE CHECK and look for any cold or cracked solder joints. I already touched up and resoldered a few but never hurts to check again.
Yes I have a DMM and learning how to read Schematics.
Yes, I want to learn!! "Para aprender lo principal es querer". (The main thing to learning is to WANT to learn). I´m still a newbie and slowly getting the hang of things. Economics and Electronics are not very close,
.
Cheers!!
Thanks again for the nice tips. Made the "Troubleshooting Audio Electronics Without Tears" into a PDF and will print it tomorrow. Looks great!! Thanks for that link! I have a WHOLE stack of reading material, and I do my HOMEWORK everyday!
The 12v zener glass diodes, to be honest, I don´t remember anyone telling me to change those. I changed the "bridge rectifiers" diodes but that was not the issue.
I will TRIPLE CHECK and look for any cold or cracked solder joints. I already touched up and resoldered a few but never hurts to check again.
Yes I have a DMM and learning how to read Schematics.
Yes, I want to learn!! "Para aprender lo principal es querer". (The main thing to learning is to WANT to learn). I´m still a newbie and slowly getting the hang of things. Economics and Electronics are not very close,
. Cheers!!
Did you change the zeners? That has sometimes been the cause on my restores in the past. Did reflow any suspicion looking solder joints?
Did you ever find the cause of the cold start-up noise?
Did you ever find the cause of the cold start-up noise?