Sansui 3000a Receiver Updates/Mods

Hello,
I am relatively new to this forum. I recently purchased a Sansui 3000A reciever along with Sansui SP-3000 speakers off of craigslist. I love the sound I am getting from both the FM tuner and my Turntable. I read on this forum that many folks are recapping this receiver to preserve the wonderful sound that it produces. I am not sure if my receiver has the factory mod that Sansui issued to protect attached speakers from being fried. My question is, if recapping, which capacitors are recommended for replacement? Is this any other modifications I should do to improve the sound and longevity of the receiver? I am happy with the receiver now, but want to make sure that I replace anything that could cause a major failure in the future. The only thing I have noticed thus far is that sometimes when the FM tuner is playing, the sound will drop off, then come back intermittently. It doesn't happen very often. Not sure if this has something to do with the muting being on? Any advice on all these questions would be greatly appreciated.

Frank

All of the electrolytic caps need to be replaced, along with the diodes, resistors and additional capacitors specified in the service bulletin. Does the FM stereo circuit work properly? I had to rebuild the FM board on mine to get it to function at 100%.

Sam,
Thank you for the response. I will make a list of the electrolytics in the service manual for replacement as well as diodes, resistors, and service bulletin mod. I am also planning on using DeOxit D5 on all contacts, pots, connections, etc. Have you used this before? Thanks

You don't need to replace all of the diodes and resistors, just the ones mentioned in the bulletin. I had to replace several resistors and various ceramic and film caps on my FM board to get the multiplex circuitry working.

DeoxIT is the liquid of the gods.

Sam,
Thanks for the clarification. I am opening her up tonight for some DeOxit and to check if the service bulletin mod was done. Have a nice day.

I replaced the caps and 8 (?) diodes on the driver amp boards. Down sized the underneath power fuses to two amp for protection. I have two of these receivers, one modified, one as originally built. Can't tell much difference in sound quality except in the lowest bass range. Nothing dramatic. Pretty amazing unit for the mid 60s era. Still decent today.

Yes, I am very happy with this receiver. I just had a party at my house running some Sansui SP3000 speakers inside and some Polk bookshelf's outside off of this receiver and it performed like a champ. Do you have part numbers for the caps, resistors, diodes, and fuses that you ordered for the mod?

Based on the recommendation of one of the electronics gurus here, I used 1N4002 diodes. The caps and resistors were just standard parts from Mouser or DigiKey. I'm pretty sure I used Nichicon capacitors.

Sam,
I came across a bunch of 1N4005 diodes. Do you know if these would work as well? It looks like the major difference is that the reverse voltage is 600V on the 1N4005 and 100V on the 1N4002. I also read someone recommending the 1N4007, which has a reverse voltage of 1000V. It looks like the 1N4005 sits in the middle of these two. I am not sure what the original flaw was with the SM150 diodes originally installed on the 3000A.

It also seems very hard to find 1000 uF, 35V "non-polarized" electrolytic capacitors. Could you post a link to where you bought them. I have searched on Mouser and digikey without any luck. Thanks

http://www.mouser.com/ProductDetail...GAEpiMZZMtZ1n0r9vR22YT02h/38WmxEOhpZ4Us6%2bA=

http://www.mouser.com/ProductDetail...=sGAEpiMZZMtZ1n0r9vR22WEPlYsslMWCjFYYoXeUmHI=

The second one can handle a bit more ripple current. I don't remember which one I used in my 3000A, and I don't know if I'll feel like pulling it off of the shelf today.

Aren't these both Bi-Polar Capacitors? The service bulletin calls for non-polar. I just want to make sure I get this right.

Bi-polar, non-polar...same thing. They're not polarized.

Got it, thank you for the help.

Thanks Thread. Im taking mine to a shop for repair, gonna bring in these details.