Kenwood KT-5500 Mod

[kwape]

I've had this tuner hangin' around and put an order in to try out this mod. Here's a link to it http://www.fmtunerinfo.com/DIY.html#KT-5500

I have the caps ordered and will be giving the unit a complete recap. But I have a dumb question on the diodes.
"D 6 and D 7 diodes switched to Schottkys" I just took a guess at which schottkys diodes I need. I don't have a schematic and don't know what the original diodes are.

I ordered these:
http://www.mouser.com/Search/ProductDetail.aspx?R=SB160-Tvirtualkey62110000virtualkey621-SB160-T
&
http://www.mouser.com/Search/ProductDetail.aspx?R=1N5822virtualkey51120000virtualkey511-1N5822

If anyone has tried this mod or has a recommendation, I'd rather be safe then sorry.

 

[39cross]

From what I've read, 100V Schottkys are recommended. Perhaps something along the lines of MBR1100RLG or SB1H100-E3/73.
Hopefully someone can come along and confirm this, or suggest alternatives.

 

[kwape]

I grabbed the SB1H100-E3/73 diodes and it works fine. thank you for that. I recapped the unit with nichicon KZ, KL, elna silmic II, wima film. Following the recommended upgrades and replacing the rest. It is a noticeable improvement, about as good as a tuner of this class could sound. I would guess I spent 30-35$ on this.

 

[39cross]

That's great! Thanks for posting the photos.

 

[Spenser]

I am about to do similarly on my Kenwood KT-5500. Have you or others had experience with other routine modifications suggested on the 'fmtunerinfo' site? Raise the transformer from the chassis using rubber grommets? Snubber circuit? Do you recommend?

 

[Spenser]

In looking through what I could fine reference the aforementioned (Post #5 by yours truly), "fmtunerinfo" site "snubber circuit": it seemed judicious to post a reply to my own inquiry here due to what appear to me to be potential hazards. Sorry about this hijacking-sort-of revival of your nice thread. The Schottky diode choice advisory -- and the photos -- were very helpful to me as I went about putting together my own re-cap BOM!! Thanks again.

The description is not clear.

What is clear is that the capacitors need to be X or Y rated capacitors, depending on the actual circuit.

X capacitors are for use across the AC line. If they short-circuit, the risk is fire.

Y capacitors are from the AC line to the chassis. If they short, the risk is a shock to the user. (The often called "Death Capacitor).

Also it is not recommended to put anything is series with the neutral wire.

If it fails then there is no safety protection ground with 2 wire AC power cords.

There are commercially built line filters for this purpose if one deems them necessary.

And they will maintain the safety integrity on any unit into which they are installed.

If appears that his filter is concerned with differential mode noise.

A well designed power supply should take care of this issue.

If the noise is common mode noise, a simple ferrite filter with the AC line cord wrapped through it several times should take care on the noise.

If you look close at the picture, it looks like you can see the two resistors in series with the AC line, one for each leg and a capacitor across the AC line before the resistors and a capacitor across the AC line after the resistors.

The capacitors should be X rated if one wants to try this tweak.

 

[Kontrabaß]

Got one of these on my way as well. Can someone tip me off for a schematic? I’ve been searching hard and can’t find one anywhere!

 

[Spenser]

Welcome to 'Karma. Get yourself a paper copy from StereoManuals. It's worthwhile. On many levels. Here is an electron copy to hold you over.

 

[SLTHORP]

Going to have my KT-5500 restored as well, but have a question, there was mention of installing a snubber because of the non-polarized power cord. I am not into this stuff like most AKer's, what kind of snubber would be required and where to install it?
I can solder and de-solder pretty good, have replaced hundreds of capacitors on computer motherboards, just lack the knowledge and understanding of circuits and use of capacitors, diodes, rectifiers, etc. to achieve a desired result. If I have instructions I can do it, and would like to install a snubber as mentioned in the fmtunerinfo mod.