Kenwood KA-3500 Integrated Amplifier

[peace_sells]

Hi guys. I came back home from Patna a few weeks ago (my grandparents' home). When i went there, I noticed (for the the first time) a vintage Kenwood stereo amplifier on one of the shelves. I think I'd seen that before (4 years ago when i last went) but never realised what it was . My uncle plugged it in with the Philips Turntable and some vintage floorstanders. It sounded really impressive and warm. Realising my interest and recent record collection mania, my uncle forced me to take it along with me to Bangalore (it was never used there since there's another radiogram with a turntable. Also nobody there now listens to too much music ever since my grandfather passed away).

So i packed it nicely with the help of my uncle and brought it to Bangalore (was coming by flight so I wasn't too sure if they'd allow me to carry the amp separately. Plus I dint want to check in the amp separately. So i packed the amp securely in one of my suitcases. With clothes around. I dint want to do it but couldn't think of any other way).

So when i landed in Bangalore, the suitcase also arrived alright. But i badly wanted to get home asap and check the amp myself. So when i finally reached home, i was disappointed a see a small dent to the outer metal casing of the amp But I wasn't expecting anything worse.

So after a while I plugged it into my system. To my horror : there was no sound coming from my speakers!! I connected it to my other amplifier (Denon) and the system was working perfectly fine. So i connected it back to the Kenwood (this time to Speaker channel B). Still no sound.

Then I started turning the "Speaker select" knob between speaker A and B (just like that)..when I was switching between A and B, there was a loud BLIP sound coming from the speakers. Plus, right after i switched from A to B (assuming the speakers are connected to B), for the first second or so..I could hear the music coming in (very clearly)..and then it faded away! After that i kept on switching between the speakers, and everytime volume came in for a second and faded away!

What has happened to the amp? Can anyone please help? Here are a few pics (Kenwood KA-3500 Integrated Stereo Amplifier) :









p.s. Why aren't the pictures bigger? The original pics were of really good quality.

 

[peace_sells]

I have a feeling its the problem with the contacts (the pots). Any recommendations on good contact cleaners? I'd appreciate any help.

 

[greenhorn]

ABRO Electric Contact Cleaner EC-533 163 gm | eBay


check if sound is coming out of the headphone out. If the Power amp stage is working, you should get audio there

 

[peace_sells]

ABRO Electric Contact Cleaner EC-533 163 gm | eBay


check if sound is coming out of the headphone out. If the Power amp stage is working, you should get audio there

Thanks greenhorn. I haven't been able to check the headphone out..I seem to have lost the 3.5 mm to 6.35 mm converter..I'll buy/find it and find out asap!

 

[srisaikat]

Send pm to our forum member "reubensm". He is very helpful and knowledgeable with this kind of job.

 

[reubensm]

what a vintage beauty!! in my opinion, this should be an easy kill. however faulty amps are like human patients. they are better cured when they visit the doctor in person. this is as there are many possibilities, however simple they may be. another thing with such amps is that something may come off during transit and when they are subsequently switched on, the situation caused by transit may blow something else off. your amp would need a thorough check.

 

[peace_sells]

Reviving an old thread. I took it to the Kenwood service centre and they told me that the output transistors have been damaged. They said they don't have spare transistors.

I did some fact finding and apparently 4 pairs of 2SD588 and 2SB618 transistors are used in the output stage. So basically I want to know if I'm right.

Were these standard o/p transistors on most of integrated amps back in the day? If they are then should I try to replace them myself? Any one has any experience with Kenwood KA-3500 or 2SD588 and 2SB618 transistors?

 

[quad]

This thread may be useful -

2sd588 and 2sb618 replacements - AudioKarma.org Home Audio Stereo Discussion Forums

 

[Saket]

Reviving an old thread. I took it to the Kenwood service centre and they told me that the output transistors have been damaged. They said they don't have spare transistors.

I did some fact finding and apparently 4 pairs of 2SD588 and 2SB618 transistors are used in the output stage. So basically I want to know if I'm right.

Were these standard o/p transistors on most of integrated amps back in the day? If they are then should I try to replace them myself? Any one has any experience with Kenwood KA-3500 or 2SD588 and 2SB618 transistors?

Hello Saket!

You should take the amp to a good private service center rather than the Kenwood ASC. Your amp is a 1977 vintage. In fact, my 1973 Pioneer suffered a similar failure some time ago and I took it to a good repair shop. They replaced the transistors and one of the big capacitors and it works great now. So, my advice is to get it done by a good electronics repair shop.

Regards,
Saket

 

[peace_sells]

Just an update on this old thread. I got my KA 3500 repaired from AG Technologies in Bangalore. After replacing output transistors and some old capacitors, this amp is now working again. I just love the way this sounds! This might just become my primary amp!