K-amps said:
Arif, the 70C that I am measuring is NOT the temperature of the output stage transistors but of the two predriver transistors on the input stage pcb, the ones that have little heatsinks attached to them which are right next to the green LED lamps (which I am also going to replace, since one is dead).
If you are routinely measuring 70C on the 555 1210 transistors, then I would assume that 70C is "normal" for these, but I could be wrong. I'm looking up the transistor chip online for environmental operating specifications. I'm probably still going to upgrade the heatsinks and perhaps design an active cooling solution.
Also, quoting woodman from a different thread:
Woodman said:
I tested my unit with these instructions and they measured very close to the correct values. ~100ohms, 112 ohms, and 12ohms
I think over 20 years, resistance values have changed, I remember when I had the amp disassembled I tested the resistance of the large 4.7ohm 20Watt Riken resistor on the soft start board and it was a little off. The other 6xx ohm resistor was about 20 ohns off too. Should be okay I think.
So, I think the grounding resistor is not open.
Also, I think you guys are right about not pursuing the quick-connectors. While it would simplify things, especially in the testing phase after I clean the boards and affix new caps, I will have to sacrifice ease in favor of quality here. While I have the board out I want to rewire the amp with higher quality milspec copper with teflon dielectric wire. I need to start searching for those predriver transistors on alliedelec.com
Oh and one more thing, I liked Chris' method of using an ultrasonic cleaner to clean the PCBs. In addition, I have a lot of small items that need special cleaning, so I just got this:
An externally hosted image should be here but it was not working when we last tested it.
Yeah I know it looks like a little funky toilet, but it will soon be a little electrolyte toilet. 😀
MJR, 70c for the pre-pre driver seems normal. Operating temps of the substrate is 150-250c, of course further away from the substrate you derate... worst case even a steady 80c is ok for a constant current device... though not ideal.....
for OP's best to keep them under 55c as the current demands on them can suddenly cause hotspots.
for OP's best to keep them under 55c as the current demands on them can suddenly cause hotspots.
Sorry my threads tend to be lengthy. 
Thank you Arif, you are right. Here is the specsheet for the two Sanyo Predriver Transistors on the 565 input stage.
Q111 (2SA1210)
Q112 (2SC2912) {variation of the 2SA1210}
Sanyo 2SA1210/2SC2912 150W Predriver Transistors
So it has been operating at about half (70 degrees C) of the absolute max rating. I'll take the temperature after the input stage rebuild and see if it changes. If it doesn't I will consider upgrading heatsinks if I can find a surplus heatsink that fits.
Okay, now onto selection of new op-amp chips. I want a good quality OP97 as Walt Jung suggested. Does anyone have any experience with a specific model?
K-amps said:
Thank you Arif, you are right. Here is the specsheet for the two Sanyo Predriver Transistors on the 565 input stage.
Q111 (2SA1210)
Q112 (2SC2912) {variation of the 2SA1210}
Sanyo 2SA1210/2SC2912 150W Predriver Transistors
So it has been operating at about half (70 degrees C) of the absolute max rating. I'll take the temperature after the input stage rebuild and see if it changes. If it doesn't I will consider upgrading heatsinks if I can find a surplus heatsink that fits.
Okay, now onto selection of new op-amp chips. I want a good quality OP97 as Walt Jung suggested. Does anyone have any experience with a specific model?
I have little idea what I am talking about but seem to have somehow been correct. 🙂 When you said both were at 70c it was pretty obvious though.. 🙂
So whats up with the RF issue? Have you gotten some beads?
So whats up with the RF issue? Have you gotten some beads?
Re: PROBLEM FOUND! Fixed!
Didn't need them barchetta, it was some weird grounding issue. Chris suggested testing the 220V connections downstairs for my washer/dryer, because there could be some sort of phase alignment issue. I don't completely understand it and don't want to get shocked! I grew up abroad in a British colony where 220V is standard and one day I decided to stick my pinky into the socket and it hurt! I was under 10 yo and it is the earliest thing I can remember from my childhood.
Hmm, thinking about it now, maybe that explains why I am always looking to modify any electronics I can get my hands on. 😉
mjraudio said:
Didn't need them barchetta, it was some weird grounding issue. Chris suggested testing the 220V connections downstairs for my washer/dryer, because there could be some sort of phase alignment issue. I don't completely understand it and don't want to get shocked! I grew up abroad in a British colony where 220V is standard and one day I decided to stick my pinky into the socket and it hurt! I was under 10 yo and it is the earliest thing I can remember from my childhood.
Hmm, thinking about it now, maybe that explains why I am always looking to modify any electronics I can get my hands on. 😉
Re: Re: PROBLEM FOUND! Fixed!
You aren't going to get off that easy.. you need to tell us all how you fixed it.. or did you? I will scroll back and look but if its not here you need to help others with this information.
Edit: Okay; I see you didn't solve the problem but came up with a workaround.. You moved one amp to the same phase as the other as it seems.. so I am not sure why you think its a grounding problem. BUT if you do actually solve this let us know.. maybe its just "bad" (like crossing the streams) to have equipment on 2 different phases? Did you figure out that each outlet is INDEED on a different phase? I didnt see where you had determined that.. youd hav eto of course figure out which breaker each one is on and then physically look and see which "side" each one is on..
I am really curious.. anyone could run into this hair puller.
mjraudio said:
You aren't going to get off that easy.. you need to tell us all how you fixed it.. or did you? I will scroll back and look but if its not here you need to help others with this information.
Edit: Okay; I see you didn't solve the problem but came up with a workaround.. You moved one amp to the same phase as the other as it seems.. so I am not sure why you think its a grounding problem. BUT if you do actually solve this let us know.. maybe its just "bad" (like crossing the streams) to have equipment on 2 different phases? Did you figure out that each outlet is INDEED on a different phase? I didnt see where you had determined that.. youd hav eto of course figure out which breaker each one is on and then physically look and see which "side" each one is on..
I am really curious.. anyone could run into this hair puller.
Hi Joe,
Those do run around 70 ° C normally. A larger heatsink will help here. Originally I thought you were talking about the diff pairs.
Ultrasonic cleaners are great. Your wife will love it for cleaning jewelry. Mine does that a lot.
-Chris
Yes. I've had to troubleshoot these issues before.
Those do run around 70 ° C normally. A larger heatsink will help here. Originally I thought you were talking about the diff pairs.
Ultrasonic cleaners are great. Your wife will love it for cleaning jewelry. Mine does that a lot.
If Walt suggested this, then just do it. This man knows his op amps.
-Chris
I don't have a wife. 🙁 ...actually i should be putting this smiley: 😀
This is the op-amp I am going to be using to replace the LT1012. I ordered two of them two weeks ago, but accidentally ordered the wrong packaging, I have the small SOIC package ones for use with printed circuit boards, but I need the larger PDIP sized op-amps.
It says in the product description for the Analog Devices OP97 that:
THIS is the packaging specification for the LT1012 (ADCOM 2A) op-amp IC.
I'm going to place an order sometime this weekend for the Analog Devices OP97 PDIP equivalent: Analog Devices OP97FPZ
Adcom 2A Thread (for reference)
This is the op-amp I am going to be using to replace the LT1012. I ordered two of them two weeks ago, but accidentally ordered the wrong packaging, I have the small SOIC package ones for use with printed circuit boards, but I need the larger PDIP sized op-amps.
It says in the product description for the Analog Devices OP97 that:
THIS is the packaging specification for the LT1012 (ADCOM 2A) op-amp IC.
I'm going to place an order sometime this weekend for the Analog Devices OP97 PDIP equivalent: Analog Devices OP97FPZ
Adcom 2A Thread (for reference)
Hi mjraudio,
The OP97 looks good. I expected no less from a suggestion that Walt has made.
No wife? Too bad. Good ones are great, a bad relationship is terrible.
-Chris
The OP97 looks good. I expected no less from a suggestion that Walt has made.
No wife? Too bad. Good ones are great, a bad relationship is terrible.
-Chris
Op-amp AND relationship advice: I'm impressed Cris! 🙂 hehe
I have asked you this question before...on the input board, according to the service manual "C101 is an extremely high quality capacitor and serves to protect the amplifier and the speakers connected to it from DC faults at the output of the preamplifier."
The Roederstein MKC1862 or Electronic Concepts 5MC22B505K can be used for it. I looked up the specification sheet for the MKC1862; which reports that it is an Axial Metalized Polycarbonate Film Capacitor rated at 100V with a capacitance value of 4.7uF.
Since the input signal goes through it, if one will fit, can I upgrade it to an "audiophile" capacitor? Will upgrading it give me any tangible or audible benefits? I figure since that original part (even if it is a good model) is 20yrs old, it would be nice to give the circuit a fresh cap while I have the boards out...
Sonicaps 4.7µF / 200VDC / 0.74 x 1.80" / $11.20
Auricaps 4.7µF / 200VDC / 1.05 x 1.17" / $15.75
I guess I just want to know if this would be the equivalent of putting a Mercedes engine into a Chevy Impala.
Maybe the capacitor below is getting there,🙂
Mundorf Silver/Gold Capacitors 4.7µF / 1200VDC / 40 x 69" / $126.13!
I have asked you this question before...on the input board, according to the service manual "C101 is an extremely high quality capacitor and serves to protect the amplifier and the speakers connected to it from DC faults at the output of the preamplifier."
The Roederstein MKC1862 or Electronic Concepts 5MC22B505K can be used for it. I looked up the specification sheet for the MKC1862; which reports that it is an Axial Metalized Polycarbonate Film Capacitor rated at 100V with a capacitance value of 4.7uF.
Since the input signal goes through it, if one will fit, can I upgrade it to an "audiophile" capacitor? Will upgrading it give me any tangible or audible benefits? I figure since that original part (even if it is a good model) is 20yrs old, it would be nice to give the circuit a fresh cap while I have the boards out...
Sonicaps 4.7µF / 200VDC / 0.74 x 1.80" / $11.20
Auricaps 4.7µF / 200VDC / 1.05 x 1.17" / $15.75
I guess I just want to know if this would be the equivalent of putting a Mercedes engine into a Chevy Impala.
Maybe the capacitor below is getting there,🙂
Mundorf Silver/Gold Capacitors 4.7µF / 1200VDC / 40 x 69" / $126.13!
I have seen old 555's sound better than 555ii's.
However the new 555ii's sounded better than the 555's.
Also... caps age and change sound...
Also the 555 never had an input coupling cap but the 555ii did.
I will not draw conclusions for you... 😉
I know Chris will be upset with me.... but if this were my amp... I'd go with NO caps...
But if you have to choose, audition a few before settling down on the one u like sonically even if it is a surplus part from ApexJr (i have a few of his 😉 polyprops.... not bad )
However the new 555ii's sounded better than the 555's.
Also... caps age and change sound...
Also the 555 never had an input coupling cap but the 555ii did.
I will not draw conclusions for you... 😉
I know Chris will be upset with me.... but if this were my amp... I'd go with NO caps...
But if you have to choose, audition a few before settling down on the one u like sonically even if it is a surplus part from ApexJr (i have a few of his 😉 polyprops.... not bad )
Hi Arif,
I have seen DC offset from preamps. One was connected to an amp with no blocking caps. Bye bye PSB Stratus Gold i. It was a Krell (what's that smell?
). I don't think it's worth while. Use an input cap.
Some audiopile (intentional) capacitors are too large to fit in the original holes. That rules them out. I honestly don't thinl you will better the originals.
BTW, electrolytics are the ones that age. Plastic is inert. Tantalum and electrolytics don't sound good. Electrolytics suck less than tantalums these days.
-Chris 😉
Yup, I am.
I have seen DC offset from preamps. One was connected to an amp with no blocking caps. Bye bye PSB Stratus Gold i. It was a Krell (what's that smell?
). I don't think it's worth while. Use an input cap.Some audiopile (intentional) capacitors are too large to fit in the original holes. That rules them out. I honestly don't thinl you will better the originals.
BTW, electrolytics are the ones that age. Plastic is inert. Tantalum and electrolytics don't sound good. Electrolytics suck less than tantalums these days.
-Chris 😉
The ones in the 555ii were supposed to be paper in Oils... whtever they are something (heat?) made them sound bad over a period of 20 years... Weirdly the 545ii does not suffer the same fate. It still sounds better than the 545... maybe it's input cap remains unaffected.
Lytics and tants both bad in the signal path IMHO... Metallized polyprops much better (though not the end all).
Chris... you take a risk everytime you take your NSX on the road... so is life, I'd rather take a risk and enjoy myself then let life pass safely and then die in the end anyway... 😉
Lytics and tants both bad in the signal path IMHO... Metallized polyprops much better (though not the end all).
Chris... you take a risk everytime you take your NSX on the road... so is life, I'd rather take a risk and enjoy myself then let life pass safely and then die in the end anyway... 😉
Hi Arif,
Whether to risk this or not is an individual choice, make sure you are well read on the possibilities before connecting naked.
-Chris 😉
Yeah, and I did get creamed on the road about a year and a half ago. Enough excitement for me.
Whether to risk this or not is an individual choice, make sure you are well read on the possibilities before connecting naked.
-Chris 😉
Non-functioning fans
Thanks for your guys' input.
Back to temperature issues, but this time not with the predriver transistors but with the output transistors and my optional fan top covers.
Both my amps are now biased correctly, hovering at 24mV (or 25mV occassionally) and the temperatures of the output stage transistors are in a decent operating range (35-40 degrees C).
But I have a problem with the fan, it has NEVER turned on no matter how long I keep the amp on or even how hot the output stage gets.
I just conducted a little test by taking a blow dryer and aiming it directly at the thermistor attached to one of the output stage heatsinks. I put the blowdryer on high heat and low airflow, and heated up that thermistor to 85 degrees C (crazy unnormal temp) for 1 minute (then cooled it back down to below 34 degrees in a matter of minutes). At no point did the fan engage!
Once again, I my speakers are 8ohms, during operation I took a DMM and measured the speaker resistance, seeing it fluctuate from anywhere between 4 and 6, and averaging 5ohms. Now Adcom says that with the fan upgrade the 565 is possible of 800watts @ 2ohms. So my question is, are the fan systems in the amps broken or do I have to drive the amps @ 2 ohms for them to actually turn on?
Something is wrong with the amps if that "continuously variable cooling fan" doesn't even budge when the output stage thermistor is at 85 degrees Celsius! HELP!
Thanks for your guys' input.
Back to temperature issues, but this time not with the predriver transistors but with the output transistors and my optional fan top covers.
Both my amps are now biased correctly, hovering at 24mV (or 25mV occassionally) and the temperatures of the output stage transistors are in a decent operating range (35-40 degrees C).
But I have a problem with the fan, it has NEVER turned on no matter how long I keep the amp on or even how hot the output stage gets.
I just conducted a little test by taking a blow dryer and aiming it directly at the thermistor attached to one of the output stage heatsinks. I put the blowdryer on high heat and low airflow, and heated up that thermistor to 85 degrees C (crazy unnormal temp) for 1 minute (then cooled it back down to below 34 degrees in a matter of minutes). At no point did the fan engage!
Once again, I my speakers are 8ohms, during operation I took a DMM and measured the speaker resistance, seeing it fluctuate from anywhere between 4 and 6, and averaging 5ohms. Now Adcom says that with the fan upgrade the 565 is possible of 800watts @ 2ohms. So my question is, are the fan systems in the amps broken or do I have to drive the amps @ 2 ohms for them to actually turn on?
Something is wrong with the amps if that "continuously variable cooling fan" doesn't even budge when the output stage thermistor is at 85 degrees Celsius! HELP!
Chris I have made a mistake. I pulled out the input board on the amp with the 270mV offset and removed the electrolytic capacitors, LEDs (one is busted so I will replace both), variable resistor, and opamp IC.
Unforunately, when I removed the variable resistor, I heated up the solder for too long and one of the leads from the resistor was pulled slightly out of the variable resistor plastic housing (it is still there, but dislodged)...Ideally I would like to just replace that variable resistor.
Here is the appropriate info on the part:
R143
41-7122-0
PK502H101H0
I searched for PK502H101H0 on the internet but could not find the manufacturer or any datasheets, only some out-of-production part suppliers in China which have no information on it.
My question is, what can I use to replace it? I assume I would need a PCB Mount Trimmer. Should I get a single-turn or multi-turn? And also what WATT rating and value?
TRIMMERS
Thank you! 🙂
BTW: I took pics of the board, and I also found out that the input film capacitor (C101) is the WRONG value! The one installed was a 50VDC 5.0uF capacitor, when the service manual calls for a 100V 4.7uF capacitor! I will surely be replacing it. Also, some of the resistors are significantly below their rated resistance value. I will publish a complete listing of the resistance values that deviate noticeably from spec. later this weekend. Also, regarding the fan circuit, I haven't looked into it in depth, but I am going to replace the capacitors on the fan PCB assembly, which also use the light blue SHOEI capacitors like on the input stage (that were dried up). I took a pair of pliers and squeezed the old electrolytic caps. and barely any electrolyte came out. To think after 20 years of operation at high heat levels, this comes as no surprise.
Picture of Input Stage
I'm going to try to replace the incorrect-valued C101 input capacitor with an Auricap or better.
Unforunately, when I removed the variable resistor, I heated up the solder for too long and one of the leads from the resistor was pulled slightly out of the variable resistor plastic housing (it is still there, but dislodged)...Ideally I would like to just replace that variable resistor.
Here is the appropriate info on the part:
R143
41-7122-0
PK502H101H0
I searched for PK502H101H0 on the internet but could not find the manufacturer or any datasheets, only some out-of-production part suppliers in China which have no information on it.
My question is, what can I use to replace it? I assume I would need a PCB Mount Trimmer. Should I get a single-turn or multi-turn? And also what WATT rating and value?
TRIMMERS
Thank you! 🙂
BTW: I took pics of the board, and I also found out that the input film capacitor (C101) is the WRONG value! The one installed was a 50VDC 5.0uF capacitor, when the service manual calls for a 100V 4.7uF capacitor! I will surely be replacing it. Also, some of the resistors are significantly below their rated resistance value. I will publish a complete listing of the resistance values that deviate noticeably from spec. later this weekend. Also, regarding the fan circuit, I haven't looked into it in depth, but I am going to replace the capacitors on the fan PCB assembly, which also use the light blue SHOEI capacitors like on the input stage (that were dried up). I took a pair of pliers and squeezed the old electrolytic caps. and barely any electrolyte came out. To think after 20 years of operation at high heat levels, this comes as no surprise.
Picture of Input Stage
I'm going to try to replace the incorrect-valued C101 input capacitor with an Auricap or better.
5uF is still within spec. However I'd use a non-polar cap (which I assume it is, but then why rate it vDC? ) Non-Polars are usually rated v not vdc.
Hi mjraudio,
Arif is right. Your input cap is fine. Do not use large components that do not fit properly. An Auracap will not buy you anything at all.
Your trimmer part number suggests a 5K pot. Just measure the old one and buy a similar new single turn control. Multiturns do not belong in an amp as far as I'm concerned.
Your input PCB needs a very good cleansing indeed. Several rounds of Simple Green, followed by some clean water washes. An ultrasonic cleaner is called for. Failing that, strip and clean with a toothbrush a few times. I vote for an ultrasonic cleaner (I bought one).
-Chris
Arif is right. Your input cap is fine. Do not use large components that do not fit properly. An Auracap will not buy you anything at all.
Your trimmer part number suggests a 5K pot. Just measure the old one and buy a similar new single turn control. Multiturns do not belong in an amp as far as I'm concerned.
Your input PCB needs a very good cleansing indeed. Several rounds of Simple Green, followed by some clean water washes. An ultrasonic cleaner is called for. Failing that, strip and clean with a toothbrush a few times. I vote for an ultrasonic cleaner (I bought one).
-Chris
Thanks Arif & Chris,
As per the service manual, "the input signal pases through network C101 [input capacitor], C102, R102, and R103 which provides a 3db bandwidth of 0.7hZ to 700kHz to the input of the amplifier. C101 is an extremely high quality capacitor and serves to protect the amplifier and the speakers connected ot it from DC faults at the output of the preamplifier [or source]."
Now, because of the inherent use of capacitors as high-pass filters in speaker crossover circuits, will the use of a specific value of capacitor in this input stage yield a particular frequency rolloff to the input of the amplifier? Could I decrease the capacitance value of C101 and change the bandwidth and frequency response of the amplifier? Ideally I would want as wide a bandwidth as possible, so that I can take full advantage of the 1Hz-100kHz frequency range of SACD (when I buy my Sony SCD-1 SACD player someday
$$$)
Hehe, I bought one too 🙂. I will go searching for Simple Green at the department stores now. One quick clarification on your bathing technique Chris (for the boards, not you): the ratio of 10:1 that you suggest for the input stage bath...is it 10:1 (Water:Simple Green?) or 10:1 (Simple Green:Water)?
Thanks in advance...
Also, I'm also going to upgrade some of the wires in the amp with the same guage, but silver plated copper conductors with teflon dielectric! Can't wait to hear it when it's all done.😀
Ohhh, BTW Chris, Thanks so much for the info on the trimmer, I can now place my order for parts from alliedelec.com (great service btw, they always ship the same day).
As per the service manual, "the input signal pases through network C101 [input capacitor], C102, R102, and R103 which provides a 3db bandwidth of 0.7hZ to 700kHz to the input of the amplifier. C101 is an extremely high quality capacitor and serves to protect the amplifier and the speakers connected ot it from DC faults at the output of the preamplifier [or source]."
Now, because of the inherent use of capacitors as high-pass filters in speaker crossover circuits, will the use of a specific value of capacitor in this input stage yield a particular frequency rolloff to the input of the amplifier? Could I decrease the capacitance value of C101 and change the bandwidth and frequency response of the amplifier? Ideally I would want as wide a bandwidth as possible, so that I can take full advantage of the 1Hz-100kHz frequency range of SACD (when I buy my Sony SCD-1 SACD player someday
$$$)anatech said:
Hehe, I bought one too 🙂. I will go searching for Simple Green at the department stores now. One quick clarification on your bathing technique Chris (for the boards, not you): the ratio of 10:1 that you suggest for the input stage bath...is it 10:1 (Water:Simple Green?) or 10:1 (Simple Green:Water)?
Thanks in advance...
Also, I'm also going to upgrade some of the wires in the amp with the same guage, but silver plated copper conductors with teflon dielectric! Can't wait to hear it when it's all done.😀
Ohhh, BTW Chris, Thanks so much for the info on the trimmer, I can now place my order for parts from alliedelec.com (great service btw, they always ship the same day).
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