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Sansui 3000 Repair/Factory Mod?'s

markuus3889

markuus3889

Diatom, what's that?
Hi,

I'm going to attempt to repair and do the factory modification on my Sansui 3000. This is the only receiver I own that doesn't work and I have the time to finally do the mod and repair.

I found this receiver along with a 3300 years ago in my dad's stuff. I tried it then not knowing anything about variacs or dimbulb testers. It worked briefly then smoked a small bookshelf speaker and I mean it smoked the thing. I tried new fuses and those blew in one channel immediately so I put it on a shelf and used the 3300.

Over the years I've read the 3000 or 3000a posts that come along to glean as much info as I can. I've got the parts to do the factory mod and am waiting for some trimmers and other stuff. While I was looking through the receiver I discovered someone has been into it before. Two of the four 2SC696 driver transistors have been replaced with ECG128(TR805,TR806) transistors and two output transistors are labeled SYL ECG87(TR004,TR005) and two are labeled ECG385(TR002,TR003) with the later having slightly different cases from each other(fakes maybe). As far as I can tell everything else is original.

So far output TR003(ECG385) has tested bad others are good and D807(SM-150?) is bad. I've tested the Driver transistors and they test fine albeit mismatched from channel to channel and this is as far as I've gotten.

I plan to change the drivers to 2N3439 and the outputs to MJ21196G. Predrivers 2SC292(TR802,804) test good and I haven't tested TR801,803 but I will.

I have started the factory mod and have the Capacitors mounted and wired and need to change the Diodes. I have 1N4002 that i will use but my confusion comes from the factory use of SW-05(D801-804) Diodes and SM-150(805-808) Diodes. SW-05 are used elsewhere in the receiver and I have seen that the recommended replacement is 1N5408. Would it be better to replace any SW-05 I encounter with 1N5408 or do as the mod suggests for the driver board diode replacement and use 1N4002, but then use the 1N5408 for the SW-05 on the Ripple filter board D001,D002 and D011(parts layout location G,3)?

Once I repair to working condition I intend to recap the unit, but am wondering if I should replace any electrolytics immediately or only as needed for the initial repair.

Thanks,

Mark K.

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Useful Links:

http://akdatabase.com/AKview/albums/userpics/10004/Sansui 3000 Service.pdf.

http://audiokarma.org/forums/index.php?threads/my-sansui-500a-restoration.567262/page-3#post-7539608.

http://audiokarma.org/forums/index.php?threads/dead-channel-in-sansui-3000.6552/.

http://audiokarma.org/forums/index.php?threads/sansui-3000a-transistors.223721/.

http://audiokarma.org/forums/index.php?threads/sansui-3000a-restoration.387857/

http://www.audiokarma.org/forums/index.php?threads/here-sui-sui-sui.478057/.

http://audiokarma.org/forums/index.php?threads/is-unmodded-sansui-3000a-safe-to-use.569595/.

http://www.audiokarma.org/forums/in...p-me-figure-out-if-this-is-a-misprint.214689/.

http://www.audiokarma.org/forums/index.php?threads/3000a-mod-question.509180/.

http://audiokarma.org/forums/index.php?threads/sansui-3000a-speaker-prot-mod.647005/.
 
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Factory Mod:
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New Trimmers:
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Rebuilt Driver Board:
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Outputs:
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It is alive! Everything works but on tuner it is loud and distorted in the right channel and tuning isn't great. Bias set and listened for a bit. Now deemed worthy; on to recap.

Ripple Filter:
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Pre-Driver Board:
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Thanks! Sounds pretty good but still listening critically. It's definitely got some power and it seems well balanced. I can't wait till my dad gets to hear it. Tuner is pretty good even without an alignment after recap. Without a doubt Recapping has made a difference in sound and performance. Virtually all caps tested twice their rated capacity, one was three times rated capacity, and one in the MPX board was bad. One of the large filter caps tested near 6000uf while the others tested near 4000uf. Hopefully all the Germanium used in this thing will last a while longer.

The only other thing to do is replace one dial bulb and I will put it back together. I'll update with a dressed photo.

Now I gotta dig out my 3300 and start the recap on that.

Thanks again,

Mark K.
 
So one more question. I have always had the intention to get this unit to function and do the modification. Before I actually opened this unit up to verify components, I was acquiring some parts based off the schematic and parts list in the manual. Mostly as a way to tack on parts to orders of few items with mousers fixed min shipping cost. I now realize this was somewhat perilous with Sansui's literature reputation. One of these tack on items was the large resistors on the driver amp board that according to the schematic and parts list were 800ohm 5Watt, but in practice 740ohm resistors were used. Luckily this is the only item I purchased that didn't match the paper and I'm not out too much if they are unusable.

So I have these nice heavier duty 800ohm 10Watt resistors, with the same dimensions, and while the originals aren't technically out of spec, does anyone think the 60ohm difference would cause any problems?

Has anyone that has been in their 3000 noted what resistors were used on the driver board?

The original resistors clearly get pretty warm and I otherwise don't have a use for the resistors I bought. Not really a big deal I'm just curious.

Thanks,

Mark K.
 
i would let them be and save the new ones for some other project. dont think the amp would benifit from those. looks like good quality resistors already factory mounted.
 
markuus3889 said:
Has anyone that has been in their 3000 noted what resistors were used on the driver board?
Click to expand...

isnt that board where the output transistors go? in that case they are most certainly the emitter resistors.

have you adjusted the idling current?

Edit: no it isnt. my bad. i didnt look close enough :)
 
The output transistors are on the back panel of the receiver. I have adjusted the bias as outlined by the Factory Modification service bulletin. It set just fine. Both channels are at 80mA and DC offset is 1.3mv for both.

In the picture below my finger is on one of the resistors(R821, R824, R827, R830) I'm referring to. They are located on the Driver Board (Pre-Power TRZ-2C) Pg. 26 in the SM.
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Notice the heat related residue on the board.

Thanks,

Mark K.
 
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yep i see now...try to place them as elevated from the board as possible. maybe not very easy since they are already on there:)
 
Nice job on this one....they aren't the most friendly amplifiers to work on.
I'd say the tuner would come alive even more after an alignment....due to the nature of the very discrete design, I would say there would be some adjusting to do....
 
kevzep said:
Nice job on this one....they aren't the most friendly amplifiers to work on.
Click to expand...

Thanks! Kevzep I have read your thread and know your dislikes for the unit but I couldn't just let it go any longer without a try and I won't part with it regardless. Will it last? Who knows with any of this stuff. There is a lot of Germanium. As it is, the tuner is picking up stations most other receivers I have won't, and I haven't played with the Local vs Dist switch. I live in a rural area of my state and the nearest city with a service tech is a hundred miles away and I'd rather do stuff myself anyway for a variety of reasons.

I am enjoying it! I am used to Harman Kardon products and it does sound a little different but I would say it sounds as good as my 730.

This is not going to be a daily driver and is not my main system. I am trying to get my older equipment refreshed. It seems like the parts for these things that were available in abundance and variety, at least since I've been paying attention, are becoming less and less so I feel it's time to do what I can, which is somewhat limited compared to most here.

Mark K.
 
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markuus3889 said:
Thanks! Kevzep I have read your thread and know your dislikes for the unit but I couldn't just let it go any longer without a try and I won't part with it regardless. Will it last? Who knows with any of this stuff. There is a lot of Germanium. As it is, the tuner is picking up stations most other receivers I have won't, and I haven't played with the Local vs Dist switch. I live in a rural area of my state and the nearest city with a service tech is a hundred miles away and I'd rather do stuff myself anyway for a variety of reasons.

I am enjoying it! I am used to Harman Kardon products and it does sound a little different but I would say it sounds as good as my 730.

This is not going to be a daily driver and is not my main system. I am trying to get my older equipment refreshed. It seems like the parts for these things that were available in abundance and variety, at least since I've been paying attention, are becoming less and less so I feel it's time to do what I can, which is somewhat limited compared to most here.

Mark K.
Click to expand...

Credit where credit is due!! :thumbsup:
I'd actually like to put the tuner section through its paces on one of these, they look like a really good design. Looks like quite a few IF stages, so I am guessing it has some very good selectivity.
Now crank it up and enjoy!!
 
I have to say thank you again to the knowledge base and helpful people here at AK that I was able to refer to. The mountain you all have built here gives me, the lesser sighted, a better vantage point with every new addition. I wouldn't have done it otherwise.

The 3000 is great! It has plenty of power and sound is really pretty nice! The tuner really is fantastic and I've only been using two pieces of wire for an antenna. I noticed the 3000 is the only one with the AFC switch in the 3000's line. I think this switch is magical or something. When you tune to a station near another and there is some interference, you can activate the AFC switch and then using the tuning knob fine tune the station you wanted to hear better. It doesn't always work but when it does it's pretty cool. Why wasn't this switch on all receivers?

One more repair was made to the unit before it was buttoned up and it came about in a kind of interesting way.

I don't normally listen to classical music on the radio but I was tuned into one of the very few classical stations in the area and would intermittently hear what I would describe as a motorboating sound. Seemingly random, but only while tuned to this station. A half a day went by and it happened a few times while I was doing stuff, moving around in the rooms I was in and I thought it might be me moving around and interfering with the FM signal somehow. Well it turns out my security motion detectors are giving off a signal the 3000 can pick up. This doesn't happen with any other receiver I have and I tested them. I'm not sure if the receiver is at fault or if it is the nature of its tuner. It's not really a big deal either way.

So while trying to trouble shoot the motorboating issue I was dripping cold spray on the MPX board and one transistor with 100% repeat ability would cut out the right channel when it got cold and come back when warm enough. This cutting out behavior under normal operating conditions was not presenting and no associated noisiness from a failing transistor could be heard. Below is the transistor; TR404 This was originally a 2SC693 replaced with KSC1845. I also replaced the left channel TR405 2SC693 with a matching KSC1845. No other problems could be found and the unit seems to work perfectly.

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Here it is dressed up.

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Thanks again,

Mark K.
 
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