Sansui 6060 popping noise

jabski

Vintage gear noob
I recently bought a Sansei 6060 at a local thrift store.
All the functions work, but there are light to very loud popping noises, whether at zero volume, or higher.
It does seem to diminish somewhat as it plays for a bit, but then ill get another loud pop every so often.
in another thread, it was suggested that "" this will be due to either one or more of the 2SA726 (differential input pair on the F-2647 board) or 2SC1313 (F-2646 board) small signal transistors going noisy. These are both known trouble makers in terms of noise (pops and hiss). I beleive that the standard replacements for these are the KSA992 and KSC1845. Note that the KSA992 pair would need to be gain matched, and the pin out checked against the original transistors (I beleive that they need to be installed 180 degrees with respect to the orientation of the originals )""
i have basic understanding of circuits, but have not done detailed work before, like what is suggested here.
The gain matched part is a bit puzzling to me at this point,along with the orientation..... I'll have to do some digging!!
The schematic,http://www.hifiengine.com/manual_library/sansui/6060.shtml will surely help.
Any tips on removing boards will be greatly appreciated, as i've never done this before.
I have a decent Hakko 888d soldering station, and solder suckers and wicks, but I would greatly appreciate any tips regarding this.
I have a local electronics store, where the owner is very patient with dumb questions,and he has darn near anything needed. Plus the guy is damn near standup comedian caliber!! I always leave there laughing.
Thanks for any help.
 
I recently bought a Sansei 6060 at a local thrift store.
All the functions work, but there are light to very loud popping noises, whether at zero volume, or higher.
It does seem to diminish somewhat as it plays for a bit, but then ill get another loud pop every so often.

....

Very good.

I think folks that have worked previously on this receiver will chime in soon.

But, other than the faulty transistors in it, I think the receiver's boards may have cold solder joints throughout them. With a magnifier glass, try to see if components are properly soldered, and also the main big capacitors.
95pob8.gif


If you can take some shots (and macro shots too, from bottom side where the joints are) and post them here.

Try it. :thmbsp:

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Those symptoms indicate bad capacitor.

Noisy transisters are noisy, as in hiss.

Popping is an intermittent type problem and those are the most difficult to find.
Even with a scope, a pop is a sudden electrical surge in a circuit and the whole circuit will show a spike on the scope.

Since you are inclined to work on it and have some tools, this is a good opportunity to do a re-cap.

There is no guarantee that it is a cap, but every time I've had popping problems, caps were the issue.

I'd replace the power supply, pre-amp and amp caps as a minimum and the reason to do the power supply caps is just because I'm in there and getting parts anyway and without a healthy power supply it's just polishing a brick. You can skip the large filter caps. When I've seen those go bad (once) the problem was so bad you wouldn't play it at all.

I suspect either electrolytic or tantalum caps.

But, it could be a diode too. I have seen that, but in my repair experience, it's much less often than a cap.

Recapping is much easier for a noob. Two legs instead of three. Easier to get the right parts, just match uf and v. Do one at a time and watch +\- orientation. Physically look at what is in there to make an order list. Service manuals are not always correct.

So far I've never seen a bad transister cause popping.
I have never seen bad solder joint cause popping.
 
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I had a 1998 Denon PMA-1500R (UHC-MOS), that, due to intense heat, caused to dry many solder joints in the main board, giving loads of "pops" and crack sounds every so often. Similar situation - with pictures - here.

Not being a high current receiver, most likely it's bad capacitors in his 6060 indeed. However, it is still a 1976 receiver...

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Sounds like you are going down the right track with getting the schematic and some local advice. I am working on a popping sound on my 9090DB right now and have a couple of tips.

1. When the pop occurs does the speaker protection relay kick in and dump the signal from the speakers? You would notice this by noticing that just after the pop the sound from the speakers cuts out for a moment and then the relay pulls in and the sound is restored.

2. Have you used a volt meter to check the DC on the speaker terminals. This should be very nearly 0V +/- 10mV. Get the 9090DB service manual and follow the measurement instruction. You do not have the adjustment potentiometer on the 6060 but the measurement shows how well the driver circuit is "tuned" for a low DC offset.

The popping sound is quite probably a large DC signal on the F2647 board points 5 or 6. If you can monitor these points during a pop you may be able to narrow down which channel is causing the difficulty.

I would avoid a full recap until you have solved this problem specifically.
 
Thanks for that. The local shop I went to was wanting to sell me the NTE 199, and NTE 234 as replacements for the 2SA726 and to SC 1313. Yet I see people here talk bad about NTE, and was told to get KSA 992 and KSC 1845 as replacements.
I'm ashamed to say that I'm not sure which is the pre-amp power supply and amp.
I have already replaced all but six of the original caps on the 2647 board in the picture. So are you saying the very large black cans don't need to be replaced, or are those usually always replaced?
Sorry for the dumb questions, that's how I learned, right?
I don't remember if that symptom occurred regarding the popping. I have everything apart now, and no, I did not measure at the speaker terminals. I tried to post a picture of the 2647 board....I don't remember if that symptom occurred regarding the popping.if the sound did stop, it was very quick, from what I remember. I don't think it's what you were referring to. I have everything apart now, and no, I did not measure at the speaker terminals. I tried to post a picture of the 2647 board but I am still new at this and the wrong picture showed up.
 

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Grrrr..... Now I can't seem to upload the picture of the main board. I hate being new at stuff!
 

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I can't really put it back together as of yet. Last night, I started replacing some of the old 726 transistors with the NTE 234s.
For laughs and giggles, I wrote down some of the other transistors on the 2647 board, and the local guy gave me some NTE 382 and 383s that he said cross referenced. So I have a few replaced, but not all, as he only had 3 of the 234s
THEN, I started getting cold feet because, after the fact, I saw where people were bad mouthing the NTEs. AND, this morning, I realized that instead of paying attention to the layout, I just replaced them in the same orientation as the originals .
AND, I wasn't really cognizant of using heat sinks on the transistor legs, so I probably got them too hot.
At this point, I'll probably remove what I installed, and order what was recommended from the other thread!!!!
The only thing about that, when I went to digikey, it showed different variations of that transistor. I'm assuming that I need to completely study the specs of the originals, then choose from the many variations of the replacements?
So by now it's completely obvious that I have only a small grasp of what I need, but I'm up for a challenge.
But I did feel the top of that cap that you had circled, and I THINK it felt a little high on top. And according to Murphys Law, that one is glued down. I was hoping to replace it without taking that front panel off, as I can't see how to do that without the string getting slack, and falling off of the guide wheels..... Tape?
Lol, again, I appreciate the help.......
 

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Not sure why I only seem able to post one pic at a time...
 

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OK, Take a deep breath.

If you have an ohmeter test the transistors you pulled out. If they test good. Put them back in.

Meanwhile tell me what transistors you are looking at from DigiKey. Sometimes the letters at the end just specify the packaging (i.e., bulk, ammo, tape, etc...) and any of these will do.

Look at the resistors near the connector on the driver board you have. One is chipped and the others are pushed up against the connectors. Probably should order some new ones just in case. I think they are 220 Ohm R31,32,33,34.

If you dont know how to test the transistors. Speak up and we can walk you through it.

Be calm, work slow......
 
The 2SD438(E,F) and 2SB560(E,F)are going to give you a gain between E 100-200 and F 160-320 see data sheet on the web at http://www.classiccmp.org/rtellason/transdata/2sd438.pdf

The 2SD438 replacement is KSC2383(O,Y) and is going to give you a gain between O 100-200 Y 160-320

The 2SB560 replacement is KSA916(O,Y) is going to give you a gain between O 80-160 Y 120-240

Probably a good idea to use either O’s or Y’s but keep them the same. Mouser has stock of Y’s on hand.
 
SansuiSteve,
Good eye regarding those resistors.
The digikey trans were the ksa992 and ksc1845.
I see the 2383 and 916 y at mouser, if I order the ksa992 and ksc1845, which ones should I get?
I'm not sure what the differences are, and while I'll learn this in due time, for now it's just easier to ask your opinion.
Yes, regarding the take a breath and step back! Lol I do have a tendency to rush things at times!
I appreciate the help you guys are sending my way.
This forum is priceless....
Terry
 
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...

Where did you get your substitution references from?

Hi Steve. I think the thread actually started here (a Sansui AU-217 thread) for TO-3 outputs and went on on page two where John (skippy124) gently advised him (post #27) for the KSA992 as subs for 2SA726 at differential input pair on the F-2647 board, and KSC1845 as subs for stock 2SC1313 (F-2646 board) small signal transistors going noisy. Then, this thread was created for the 6060.

I see the 2383 and 916 y at mouser, if I order the ksa992 and ksc1845, which ones should I get?
I'm not sure what the differences are, and while I'll learn this in due time, for now it's just easier to ask your opinion.
Terry

Hi Terry. Complementary KSA992/KSC1845, the 2SA916(Y) and 2SC2383(Y) transistors have different parameters and may serve for different purposes in this case. You probably need both pairs. Steve and others will guide you here as they know the 6060. I put here briefly their numbers so you can have an idea on how they work in different parts of circuit.

Code:
KSA992/[URL="https://www.fairchildsemi.com/datasheets/KS/KSC1845.pdf"]KSC1845[/URL]  > 120V - 50mA - 500mW - 110MHz - min. 200 max. 1200 hFE - T0-92

[B][U]2SA916[/U][/B]/2SC1941  > 160V - 50mA -  1W   -  80MHz - min. 90  max. 400 hFE  - NEC pack.

2SA1013/[URL="http://www.romstore.ru/pdf/2SC2383TOS.pdf"]2SC2383[/URL] > 160V -  1A  - 900mW - 100MHz - min. 60  max. 320 hFE  - TO-92L

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Unfortunately, Karl, the last time I had any circuit theory was in '86 or so. I've not really thought about Kirchhoff or Thevenin since then, and I was just barely making passing grades. it bugs me that I never persevered and finished.
So, 2SA726/ KSA992, 2SCC1313/KSC1845
2AD438/KSC2383Y, 2SB560/KSA916
Does this work?
Lastly, there's 2 remaining original transistors on the F-2647 board.... The C1951. I may as well replace those too as long as I'm bastardizing this board,Right?
The local guy gave me the NTE382 as a cross for the C1951. Would that work, or are the NTEs just not that good? I tried to cross reference that one, but all that came up was a BSS38, and a 2N5058
My head's spinning right about now. I wish I would have finished my circuits classes....
 
After some research during my morning breakfast this is what I could find on the AK ES forum....

2647 board
TR01 2SA726 (F,G) Input Diff pair - KSA992FTA/-FBU or BC560 - (AK member TonyCH)
TR02 2SA726 (F,G) Input Diff pair - KSA992FTA/-FBU or BC560 - (AK member TonyCH)
TR03 2SA726 (F,G) Input Diff pair - KSA992FTA/-FBU or BC560 - (AK member TonyCH)
TR04 2SA726 (F,G) Input Diff pair - KSA992FTA/-FBU or BC560 - (AK member TonyCH)
TR05 2SC1951 Constant current source - ZTX694B - (AK member LBPete)
TR06 2SC1951 Constant current source - ZTX694B - (AK member LBPete)
TR07 2SD438 (E, F) Audio output driver - KSC2383(O,Y) - (AK member FootFungus)
TR08 2SB560 (E, F) Audio output driver - KSA916(O,Y) - (AK member FootFungus)
TR09 2SD438 (E, F) Audio output driver - KSC2383(O,Y) - (AK member FootFungus)
TR010 2SB560 (E, F) Audio output driver - KSA916(O,Y) - (AK member FootFungus)

F2648 board
TR05 2SC711 (E) Bias adjust – KSC945 (G) (from AK member Avionic)
TR06 2SC711 (E) Bias adjust – KSC945 (G) (from AK member Avionic)

F2648 board
TR01 2SD188A (R, Q) Audio Output - MJ21194G - (AK member LBPete)
TR02 2SD188A (R, Q) Audio Output - MJ21194G- (AK member LBPete)
TR03 2SA545A (R,Q) Audio Output – MJ21193G - (AK member LBPete)
TR04 2SA545A (R,Q) Audio Output - MJ21193G - (AK member LBPete)

It is a good idea to gain match the input diff pairs. They are cheap and if you buy 20 or so you should be able to get 4 that are pretty close.
 
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