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Tiger1967
Reply with quote  #1 
Hi everybody,

I have had my BA5k+C2301 for about 2 years by now and has been nothing but a pure joy until recently the noise produced by a working fan on my BA5K became audible and very annoying.  In addition there is now a click in the speakers when the fan goes off.   Has anyone had similar problem and could kindly explain how to fix it?

Thanks in advance,
Evgeny
BeatleFred
Reply with quote  #2 
Hi Evgeny,
 
I think the fan should not come on unless the BA-5000 is really driven hard. How soon does the fan come on when you are using the amp? And are you really pushing the amp hard- playing music VERY loud?  And what speakers are you using, are they 8 or 4 ohms, or are you using multiple speakers? When you place your hand on the amp, is the cover very hot to touch?
 
The BA-5K might need some adjustments to run cooler so that the fan doesnt even come on at all.
 
Interesting that you have a C-2301 preamp- I also have one. I'm curious- is your 2301 pre-'87- with the classic Sansui logo, are made after the logo change?  And what year is your BA-5K? ('75, '76, '77?  the serial # in the back will indicate the manufacturing date).  How did you acquire your 2301, and did you prefer it over a CA-3000?
 
Fred
Tiger1967
Reply with quote  #3 
Hi Fred, thanks for responding.  My speaker are JBL K2 5500 4 Ohm.  The cover of BA5k becomes hot after 2-3 hours of continuing use but it is not extreme. 

About C-2301, I am not sure when it was made, and I am not sure i know the Logo thing well to say whether it was made before or after.  What is the story about the logo?  Mine is simple gold printed Sansui logo (like this one http://audio-database.com/SANSUI/amp/c-2301vintage-e.html).  The serial number for C-2301 is 216020005 (Jan-Feb 1986).

The serial number for BA-5k is 235100093, seems like it was made between Sept and Dec 1975.

Both BA5k and C2301 were acquired in Japan.   I did not have a chance to compare with CA-3k.

I would appreciate if you could give some advice to adjust BA5k to run cooler and quieter. 

Evgeny
BeatleFred
Reply with quote  #4 
Wow, my C-2301 is very close to yours, # 216020007.  Thus its also a February '86 unit. (your BA-5000 is an October '75 unit).
 
The BA-5000 service manual would indicate the settings needed to be made for bias & offset. You would need a meter to make the measurment.
 
I think its normal for the amp to get warm, but not super-burning-hot. The fan is designed not to come on until the temperature reaches almost 160 degrees F.  I think the BA-5000 should be able to run without the fan ever needing to come on at all, unless it was powering the sound system at Woodstock, or something like that
 
Happy holidays,
 
Fred
Dallas
Reply with quote  #5 
How do you guys get the info out of the serial number? My BA5K has a serial number of 247040029. Could you figure that out for me?
Keeper
Reply with quote  #6 
Quote:
Originally Posted by Dallas
How do you guys get the info out of the serial number? My BA5K has a serial number of 247040029. Could you figure that out for me?
Your BA-5000 is made in April 1977 at factory assembling line 24 as No  29
Dallas
Reply with quote  #7 

Thats great Thanks!

Warren
Reply with quote  #8 
It may be that the fan has dust built up in and around it and just needs to be cleaned.
BeatleFred
Reply with quote  #9 
(Hi Warren, happy belated holidays!, always nice to see a message from you).

Its possible that the fan may be dusty and a can of compressed air would be useful. But I imagine if the amp seems to be running too hot, given its age and perhaps never having any service work done, its likely some components are long overdue for replacement/upgrade.  I'm sure the BA-5000 has a few common issues that are known, such as the "twitchy" meters which can be corrected by a diode upgrade. I suppose the original fan's bearing would probably contribute to excess noise, but there is likely some way of quieting it down.

Having an infra-red temperature-measuring device might also be useful, such as the Tenma 78-820, to see how hot the BA-5000 actually gets. The best way to begin improving the situation is probably to check the bias/offset and adjust it if its out of spec.
BeatleFred
Reply with quote  #10 
ps: here is a bias adjustment pic:


Tiger1967
Reply with quote  #11 

Fred, could you repost the picture, please.

BeatleFred
Reply with quote  #12 

Does the photo appear on your computer monitor?  The pic I posted still shows on the screen.

Rick
Reply with quote  #13 
My BA-5000 runs very, very cool. Not sure why. My BA-2000 runs much warmer.

Could this mean something is not right? The unit sounds very good, but I've only had it about 2 weeks.
BeatleFred
Reply with quote  #14 
Does the fan on your BA-5000 turn on automatically when you turn the amp on? Some BA-5000's have been re-wired to have the fan come on
and stay on at all times, which would keep the amp cool. Otherwise, the amp was originally designed to have the fan only come on when
the amp got very hot.
Rick
Reply with quote  #15 
No, the fan does not come on when the amp is switched on, in fact, I was concerned about fan noise, but have discovered it never comes on. I have read about the mod to have it come on with the power switch, and perhaps that is why the issue of heat is one that concerns me.

The transformers stay cool, the top of the cabinet remains extremely cool, just a tad above room temperature.

I'm tempted to take the lid off the cabinet, and see if anything inside gets warm to the touch.

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