yes chris
you are very correct about this ....true he will not learn anything but at least he will get somewhere ....
cause this isnt getting anywhere i think .....paco doesnt have a stracture in what he wants to do .....step1 step 2 step 3 and so on .....
he is tapping here and tapping there ....trying to listen from me from you and others probably .....and as my friend fotios said .....opinions are like ***----holes .....everybody has one !!!!!
you know i am a member in a similar greek forum .....in this forum i make also repairs for forum members for free ..... but in this case i ask the members to come , bring the device in, and start to fix it .....and then i just guide them through and or provide some help to them ....
for forum members i dont charge anything ( except parts ofcourse )
i actually made quiet a lot of internet repairs ( guide through e mails ) often gifts and drinks arrive to my shop from this people
(one sent to me home made drink also ....or may be home made dynamite ha ha ha )
i wish i could do the same with paco ....i will be very happy to do so actually
you are very correct about this ....true he will not learn anything but at least he will get somewhere ....
cause this isnt getting anywhere i think .....paco doesnt have a stracture in what he wants to do .....step1 step 2 step 3 and so on .....
he is tapping here and tapping there ....trying to listen from me from you and others probably .....and as my friend fotios said .....opinions are like ***----holes .....everybody has one !!!!!
you know i am a member in a similar greek forum .....in this forum i make also repairs for forum members for free ..... but in this case i ask the members to come , bring the device in, and start to fix it .....and then i just guide them through and or provide some help to them ....
for forum members i dont charge anything ( except parts ofcourse )
i actually made quiet a lot of internet repairs ( guide through e mails ) often gifts and drinks arrive to my shop from this people
(one sent to me home made drink also ....or may be home made dynamite ha ha ha )
i wish i could do the same with paco ....i will be very happy to do so actually
Hi sakis,
People must be able to learn, but in a safe way. Some people should never try to fix things, others should never drive and still others should not pretend to be a doctor. We all have our own abilities. One of my goals is to have people either learn how to do something, or at least appreciate the skills that others have.
If you say that something is easy, then perform the job at no charge, what have your clients learned?
I'll tell you.
They have learned that what you do has no value (they believe you). That is not fair to you, or anyone else in the field. Look at every profession. All these things are "easy" for experienced people, however you do respect their skills because you have to pay for it. Every single time.
I have no problem with barter or trading work. I have no problem with helping people out as I do a lot of that myself. Just not your way. Do not devalue the skills that professional servicer's have. That is equivalent to "taking the bread from their mouths". What you do does take skill, practice and requires equipment. You have a skill that is worth something.
All I ask is that you think about this. Think about supporting your family by doing a job that has no value.
-Chris
I disagree with you. Paco has discovered something, and he will learn.
People must be able to learn, but in a safe way. Some people should never try to fix things, others should never drive and still others should not pretend to be a doctor. We all have our own abilities. One of my goals is to have people either learn how to do something, or at least appreciate the skills that others have.
If you say that something is easy, then perform the job at no charge, what have your clients learned?
I'll tell you.
They have learned that what you do has no value (they believe you). That is not fair to you, or anyone else in the field. Look at every profession. All these things are "easy" for experienced people, however you do respect their skills because you have to pay for it. Every single time.
I have no problem with barter or trading work. I have no problem with helping people out as I do a lot of that myself. Just not your way. Do not devalue the skills that professional servicer's have. That is equivalent to "taking the bread from their mouths". What you do does take skill, practice and requires equipment. You have a skill that is worth something.
All I ask is that you think about this. Think about supporting your family by doing a job that has no value.
-Chris
I'm not sure why I even mentioned it in the first place, but I was using the eraser. Sorry for not specifying.
About the transistor; are you saying to not use anything but HK parts, or am I misunderstanding something???
About the transistor; are you saying to not use anything but HK parts, or am I misunderstanding something???
Hi Paco,
I'm trying to make sure you use a transistor that has the same number or is a proper replacement for the one you have. What is the part number?
-Chris
No, not at all.
I'm trying to make sure you use a transistor that has the same number or is a proper replacement for the one you have. What is the part number?
-Chris
harman kardon part number is 43024218
Actual label on the part itself says RCA 4218 ID (or 1D, not sure which) CC, whatever all of that means...
Did a little extra research and found that the RCA equivalent part # is supposedly RCA 40594. Here's the URL to the Google cache so you can find the terms easily.
http://74.125.47.132/search?q=cache...part+number+43024218&hl=en&ct=clnk&cd=2&gl=us
And another handy link too. I believe you asked about schematics earlier Chris, but I have no way of uploading the ones I have which, amazingly, all were there with the amp when I bought it...Anyways, here's a link to a PDF of all the schematics:
LINK
Actual label on the part itself says RCA 4218 ID (or 1D, not sure which) CC, whatever all of that means...
Did a little extra research and found that the RCA equivalent part # is supposedly RCA 40594. Here's the URL to the Google cache so you can find the terms easily.
http://74.125.47.132/search?q=cache...part+number+43024218&hl=en&ct=clnk&cd=2&gl=us
And another handy link too. I believe you asked about schematics earlier Chris, but I have no way of uploading the ones I have which, amazingly, all were there with the amp when I bought it...Anyways, here's a link to a PDF of all the schematics:
LINK
The data sheet I found says that's equivalent to a 2N5320, which is in current production... $1.43 for a Central Semiconductor brand one from Mouser. Not sure about Central Semi... others here may have some better suggestions.
Funny that that thread you linked to covers platen cleaning with odd chemicals. When I was a printer tech we used oil of wintergreen to clean platens. We bought a big case of it when the local pharmacy told us it was being discontinued.
Funny that that thread you linked to covers platen cleaning with odd chemicals. When I was a printer tech we used oil of wintergreen to clean platens. We bought a big case of it when the local pharmacy told us it was being discontinued.
Just was doing even more research (am honestly beginning to find all of this very enjoyable) and came across an old diyaudio thread http://74.125.47.132/search?q=cache...RCA+40594+transistor&hl=en&ct=clnk&cd=3&gl=us where a guy was asking about transistors for the C12 blah blah blah, but what caught my eye was that someone mentioned the input diff pairs going noisy and dying after years because of bad voltages. Could that be it? I thought someone mentioned that earlier, but couldn't find anything...
The transistor I've been looking at is Q709 if you look on the schematics, not Q701, which is the input pair for the right channel. If I have time tonight even I'll go remove, clean, and reseat the thing since doing so can't hurt much and it's worth a shot. Besides, in all my reading, I read from on a shop's website that often all that is needed to get a Citation amp working right again is to clean and resolder everything, so it might be worth a try this weekend.
The transistor I've been looking at is Q709 if you look on the schematics, not Q701, which is the input pair for the right channel. If I have time tonight even I'll go remove, clean, and reseat the thing since doing so can't hurt much and it's worth a shot. Besides, in all my reading, I read from on a shop's website that often all that is needed to get a Citation amp working right again is to clean and resolder everything, so it might be worth a try this weekend.
I think I might have answered my own question. I cleaned and reseated the right channel diff pair just now and VIOLA! Great success! though not completely. On my bench, I checked, double checked, and triple checked plugging in a crappy speaker and unplugging and replugging in the power and the noise has been reduced significantly. In the basement where I work, it was essentially gone, so of course once I move the amp to my room and plug in my speakers, it comes back, but not at all badly. The amp is usable about 45 seconds after I plug it in here upstairs, I guess after the inrush has leveled off. There are still faint clicks and pops, but after about a minute, they're not at all significant and the loud, speaker destroying bangs are gone after about a minute too. They're still there when I first plug it in, but again, I think that might have to do with the initial current draw...
I think I may have found the problem at last...I hope.
I think I may have found the problem at last...I hope.
Hi Paco,
The link for your driver transistors can be found here.
Thank you very much for the link to the manual.
You are replacing that one six legged thing with two three legged things. Transistors that might work well in a pair are 2N5087 (close to supply on Vce at 50 VDC), 2N5401, MPS8599 or BC556B. There are probably others as well. Most good signal transistors with high gain have Vce breakdown voltages of 40 VDC or lower. You also have to confirm the lead pinouts in case the new transistor is different. Once you have a pair that match, poke their leads through the holes and apply some thermal compound in between them. Bend the leads so that the two cases are touching and parallel. Put a piece of heat shrink tubing over the bodies of the transistors and heat it up to hold the two parts together. Now you can solder the leads into the holes. Done.
-Chris
Note: Looking further down in the manual, I see that they replaced that dual transistor with a pair of 2N5087. Cool! 😎 What a guess!
The link for your driver transistors can be found here.
Thank you very much for the link to the manual.
I did, earlier. Your diff pair is faulty and may fail completely at some point. Given that these are inexpensive, why not buy 10 and pick the closest pair? That means you will need to measure them. You should measure the original pair to see what the beta was.
You are replacing that one six legged thing with two three legged things. Transistors that might work well in a pair are 2N5087 (close to supply on Vce at 50 VDC), 2N5401, MPS8599 or BC556B. There are probably others as well. Most good signal transistors with high gain have Vce breakdown voltages of 40 VDC or lower. You also have to confirm the lead pinouts in case the new transistor is different. Once you have a pair that match, poke their leads through the holes and apply some thermal compound in between them. Bend the leads so that the two cases are touching and parallel. Put a piece of heat shrink tubing over the bodies of the transistors and heat it up to hold the two parts together. Now you can solder the leads into the holes. Done.
-Chris
Note: Looking further down in the manual, I see that they replaced that dual transistor with a pair of 2N5087. Cool! 😎 What a guess!
I'll definitely look into getting that done ASAP. I guess, in order to match the transistors, I should build that jig you suggested earlier right?
Hi Paco,
Not really required. It's just that the jig made my life a great deal easier and I ended up with true matches. Remember that transistors are extremely temperature sensitive, so there are a lot of inaccuracies in measuring a beta one at a time. It really does take a jig like the one I made to be able to match transistors easily. Both test transistors will be about the same temperature and have to share emitter current evenly.
This is a terribly easy project (the matcher). It didn't take me very long to design and build it. The bonus was that I has all the parts on hand. The transistor used in the current sources does not have to be that exact part number. Look for a transistor with gain over 100, the higher the better within reason. You do not want a darlington transistor there. Matching the resistors would be the only critical part. Mismatches here will affect your matches and beta readings if you choose to try that. This thing is one of those little projects that you may possibly use far more than you figured you might.
Don't forget to order 10 each metal film resistors, 1 %, 1/2 watt should be fine. You can power it with a pair of 9 V batteries. Bypass both supplies with capacitors to avoid other problems.
-Chris
Not really required. It's just that the jig made my life a great deal easier and I ended up with true matches. Remember that transistors are extremely temperature sensitive, so there are a lot of inaccuracies in measuring a beta one at a time. It really does take a jig like the one I made to be able to match transistors easily. Both test transistors will be about the same temperature and have to share emitter current evenly.
This is a terribly easy project (the matcher). It didn't take me very long to design and build it. The bonus was that I has all the parts on hand. The transistor used in the current sources does not have to be that exact part number. Look for a transistor with gain over 100, the higher the better within reason. You do not want a darlington transistor there. Matching the resistors would be the only critical part. Mismatches here will affect your matches and beta readings if you choose to try that. This thing is one of those little projects that you may possibly use far more than you figured you might.
Don't forget to order 10 each metal film resistors, 1 %, 1/2 watt should be fine. You can power it with a pair of 9 V batteries. Bypass both supplies with capacitors to avoid other problems.
-Chris
Ok. Since I'll be replacing the pair for the right channel, would it be a good idea to do so for the left too? I would think so yes personally...
Yea Thanks.
I second the Thanks for the Service Manual. I just
picked up a clean Citation 12 today. Boy this thing is
Heavy!
jagtek
I second the Thanks for the Service Manual. I just
picked up a clean Citation 12 today. Boy this thing is
Heavy!
jagtek
Yeah. I was lucky to come across that link. And yes, these little amps are like boat anchors. Even though I have the case off of mine right now, it still is deceptively heavy! Congrats on the amp too! Mine is behaving well right now, enough to allow me to enjoy Jazz Classics on NPR, so things are good for the time being 😀 Still trying to figure out what new transistors to look for though...
Hi Paco,
Yes, if you can match for both channels, do so. You can even check the original devices to see how well they were matched. The closer the matching you end up with, the better performance and lower the drift you will end up with.
Hi jagtek,
I killed your duplicate post for you. Don't worry as this happens to everyone now and again.
Enjoy the site and welcome!
-Chris
Yes, if you can match for both channels, do so. You can even check the original devices to see how well they were matched. The closer the matching you end up with, the better performance and lower the drift you will end up with.
Hi jagtek,
I killed your duplicate post for you. Don't worry as this happens to everyone now and again.
Enjoy the site and welcome!
-Chris
Well, the original diff pairs were dual transistors, so they're naturally matched perfectly between each pair. As far as between the two parts themselves, I don't know. I haven't taken the amp apart yet since i haven't ordered any transistors yet either. Will do that hopefully tonight and be able to get to them next weekend since it's too late to do anything this weekend...
Hi Paco,
These were assembled at the factory and may be a sloppy match. They could also be an excellent match. Never assume anything.
-Chris
A reasonable assumption - but untrue.
These were assembled at the factory and may be a sloppy match. They could also be an excellent match. Never assume anything.
-Chris
Oh, woopsy daisy. I thought I read somewhere that dual transistors were matched perfectly within the part itself...
- Status
- Not open for further replies.