transformer hum on my beloved HK 3270 receiver, help!

[gychang]

Like the clean layout and sound on 10year old 2 channel stereo receiver.

This receiver has a well known problem due to a transformer hum on some units and mine has that problem. When I turn on the volume more than 1/4 turn (only nice background sound level on my 90dB speaker), faint hum can be heard.

As u can see the it has a clean layout (well kept for 10yrs), is there a easy way to "isolate" the transformer to rid of the hum?, would appreciate any help on how to mod this thing for this newbie. I know how to cut and solder wires but a beginner in diy electronics.

if someone can point me to a web site for how to and perhaps parts that I may need.





gychang

[gychang]

repositioning the wires away from the transformer did not help to rid of the hum.



gychang

[ifrythings]

Your humm is probly not the transformer, on older units the electrolytic capacitors start to dry up and become useless for filtering. I would try taking some 1000uF caps and tack them in parellel on the big caps and the regulator caps and see if it goes away.

[Bigred]

Originally posted by ifrythings
Your humm is probly not the transformer, on older units the electrolytic capacitors start to dry up and become useless for filtering. I would try taking some 1000uF caps and tack them in parellel on the big caps and the regulator caps and see if it goes away.

Why would you discount the transformer hum and have him tack caps in when you haven't even asked to make clear that the hum is audible from the transformer itself or through the speakers? Theres a big difference.

So the question is gychang, is it an audible hum through the speakers and if so does the volume affect it or are we actually talking a hum from the transformer? This will lead us what to advise next.

[ifrythings]

Originally posted by gychang


When I turn on the volume more than 1/4 turn (only nice background sound level on my 90dB speaker), faint hum can be heard.

gychang

Originally posted by Bigred
Why would you discount the transformer hum and have him tack caps in when you haven't even asked if the hum is audible from the transformer itself or through the speakers?

I mentioned that because of what he said.

[Bigred]

It does "sound" like he is referring to the hum emitting from the speakers so yup I'd try the filter cap tacking but I just like to be sure before going guns o' blazing. Not a whole lot under the hood is there

[gychang]

Originally posted by Bigred
Why would you discount the transformer hum and have him tack caps in when you haven't even asked to make clear that the hum is audible from the transformer itself or through the speakers? Theres a big difference.

So the question is gychang, is it an audible hum through the speakers and if so does the volume affect it or are we actually talking a hum from the transformer? This will lead us what to advise next.

The hum is from the speakers, and it gets louder when I increase the volume, if it is the caps, could someone point out which one it is? (don't have a schematic though). Where can I get the part I need?.

thanks to all for the suggestions.

gychang

[ifrythings]

Originally posted by gychang

The hum is from the speakers, and it gets louder when I increase the volume, if it is the caps, could someone point out which one it is? (don't have a schematic though). Where can I get the part I need?.

thanks to all for the suggestions.

gychang

I would start by checking the caps circuled in red, the easiest way to do this is add one to it and see if it goes away, if it does, thats the one(s) you need to change.

[gychang]

Originally posted by ifrythings


I would start by checking the caps circuled in red, the easiest way to do this is add one to it and see if it goes away, if it does, thats the one(s) you need to change.

your earlier post suggested these were 1000uF caps.

1. how do I "add one to it" (parallel) can I hot wire from the bottom and solder the new cap?
2. will this work? http://www.mcmelectronics.com/produc...me=MCMProducts

thanks in advance.

gychang

[Bigred]

Well if your gonna be ordering the 1000µF cap just to tack in to try and check the filter caps and paying shipping etc. you might as well just buy the smaller sizes. You can use one of the new ones to tack and test. Afterwards just replace the smaller caps and be done with them. The 2 smaller side by side circled are 2200µF/35V and the single is a 1000µF/35V (they are cheap!) The 2 larger filter caps are 10000µF/63V and more costly.