Sansui Z-3000 Receiver

[genosmm]

Recently inherited a nonworking Z-3000 (120V) no owners manual...

Have done some searching and found that this model came out in 1982 and was the only model in the Z receiver line that did not use the "super feed forward" amplifier design.

Have only done basic testing so far. The output transistors and power diodes are blown.

Have been unable to find the repair manual or even the schematics for it.

Appreciate any suggestions or links.

Thanks

Gene

 

[willysan]

Have you checked www.agtannenbaum.com?
They have lots of schematics

Good luck

 

[Silver Fan]

I have had excellent luck dealing with http://www.stereomanuals.com/. See if they can help you out...

Ken

 

[BeatleFred]

1.) The Tannenbaum site has the Service Manual which contains the schematics & parts lists. The SM is actually a combination Z-5000/3000. Since Tannenbaum has the models listed in alphabetical order, you have to scroll all the way down to the bottom until you see the Z-5000/3000 listed. (Its in the Catalog of Manuals, S for Sansui section)

2.) I have a copy of the Z-3000 Owners/Operating Manual.

3.) Your quote about the Z-3000 not having the SFF design sounds like something I had already written about on this site.

B/F

 

[genosmm]

Willysan and SilverFan thanks for the links! both sites have the service manual that covers both the Z3k and 5k.

BeatleFred you are correct, I searched the forum to see if anyone else had posted a similar question for the Z3k.

I also checked ebay and there is currently a Z3k that no one has bid on (seems very low demand for Z3k).

Since it is the bottom of the Z line and does not have the unique circuit design of the others am thinking it is only worth salvage value.

Because a lot of components are blown, I do not have a lot of faith concerning Sansui's circuit design for the Z3k! I also checked, the original output transistors are not readily available so some circuit design may be necessary.

As a result of all these thing, I am thinking that would like to upgrade the circuit components (and possibly design) as much as practical.

Appreciate any suggestions, esp by someone who has done something similar.

Gene

 

[BeatleFred]

Hi Gene:

Well, I do have a Z-5000X that has SFF ckt. Non-working, blows main fuse when powering on, could have some blown transistors in there as well. If you're interested in it, feel free to make a $ offer. I also have a copy of the svce manual for it.

B/F

 

[genosmm]

B/F

Thanks for the offer! I am sure we can do something with these 2 blown units!

Sounds like all the Z models (that is if the more expensive Z models have the same circuit design as the Z5k) are lacking serious protection for the output transistors and power supplies.

This seems like a perfect opportunity to upgrade these models!

Have you taken the Z5k into a repair shop to find out what the repair cost will be? I received mine because it was not considered cost effective by the original owners to do any repairs.

It is my Gut Feeling that a number of mfr cost shortcuts were taken concerning these circuit designs. Therefore I propose that we try to find the most rugged similar design and copy it.

Am wondering if Sansui revised their Z models because of this problem?

Appreciate any feedback!!

Gene

 

[BeatleFred]

Hi Gene:

I had posted about my Z-5000X a while back on this site. I had bought it on Ebay very inexpensively (about $35). It was working when I got it but I noticed when I placed my hand on the top cover when it was On that it got quite hot. Then soon after, it just shut down on me. I noticed the main fuse was blown and everytime I replaced it, it would blow immediately as soon as I turned power On. I suspect some of the output transistors are blown and need to be replaced as well as some other components most likely. I havent gotten around to looking into fixing it, so its just been sitting around a while. I'd like to buy an O-scope (if I see a good deal on a Tektronix on Ebay, I just might go for it) and some more test equipment and get more into the testing/repair aspect of hi fi- its just a matter of finding enough time.

Since I have so many other Sansui receivers & amps, and I didnt pay alot of $$ for the Z-5000X to begin with, it doesnt really bother me that it went kaput. I knew beforehand that the Z models werent built as ruggedly in alot of areas as the previous models built in the 70's but nonetheless I was just curious to obtain an 80's-era Sansui receiver and check it out for myself.

Compared to nowadays- where all receivers are the generic A/V kind in black, it makes a model like the Z-5000X atleast somewhat unique looking. I dont think the Z models are horrible units or anything like that, in fact, I know someone from Online who owns a Z-9000 and he think its a very good unit- and he has done warranty repair work going back to the 70's, so if he says its good, then I do respect his opinion. Keep in mind though the Z-9000 is a Top of the Line unit so its built more substantially than the smaller models in the Line.

B/F

 

[genosmm]

B/F,

Totally agree with you that the Z3k does not come even close to the better Sansui's (do not know about the Z5k since have never seen one open)!

Since my original post have tried to do my homework and have read all the previous postings. Saw your preference for Super Feed Forward circuitry used on the AU-D9 and D11.

Am wondering if it is possible to use these more expensive models as the basis to upgrade the Z-3k and Z-5k?

From your experience with the Z-5k and mine with the Z-3k, I would say the amp section has design flaws! Also it is my gut feeling that they can be attributed to economic considerations rather than lack of EE design skills.

Have you compared the schematics of the Z-5k to the AU-D9 and D11?

Gene

 

[BeatleFred]

No Gene, havent been able to spend much time doing any in-depth study on the svce manuals to see how the SFF circuitry compares between the Z model receivers and AU-D integrated amps. If someone wants to try and modify/upgrade a Z receiver- thats certainly fine if one wants to tinker around and do some hands-on stuff and see how it goes, otherwise, if one wants to just get a better piece, the alternative is to just to get an AU-D9 or 11 amplifier which I feel is a much better model from a hi fi viewpoint than a Z receiver.

B/F

 

[genosmm]

B/F,

If you can recall what happened just before the damage occurred to your Z-5k it may help us understand where its vulnerabilities are?

Gene

PS agree with you concerning normally finding another model but am approaching this as a "learning experience" that hopefully we all can benefit from.

 

[BeatleFred]

Hi Gene:

The problem with the Z-5000X happened a while ago and since that time Ive been involved with alot of other Sansui models that I have acquired, so I dont recall much in the way of specific details about the time the amp stopped working.

I definitely know though, it was quite hot. And before I could get around to measuring & checking its bias current setting, the amp failed on me. Since the main fuse was blown, obviously the unit is not going to power On, and as long as the fuse keeps blowing - which is what happened immediately after I replaced it 2 or 3 times, then there's not much the unit can do anymore as all its functions are disabled. So, since then its been sitting here inactive.

The person I know who owns the Z-9000 (he posted about it on the www.sansui.us Message Board- its somewhere a-ways down below there in the old messages) offered to take a look at my Z-5000X and repair it for a very modest price (practically for free)- which I suppose I could still do if I made the effort to send the unit down to him (Georgia) but he has a somewhat busy schedule and I dont want to really impose on him. As I mentioned earlier, I might just get an O-scope and some other test equipment and try and fix it myself just for the practice of doing it. It would be nice to have it working again but its not the most important priority for me right now. Even if I did get it fixed, at best it would probably replace my small 30W Pioneer SX-3600 receiver which I currently use for lite-duty - to power my computer speakers (JBL HLS-410) so I can watch tv/vcr/dvd on my computer, which doesnt require much amplification power.

When the Z-5000X failure happened, I thought maybe the unit didnt like my 4 ohm speakers (Infinity Qb) but the Z models have 4 ohms listed on the back, so 4 ohms should be ok. Oddly enough, the 9900Z.....3900 Line that came out before in '80-'82 and look more ruggedly built, dont have 4 ohms listed in the back of the unit by the speaker terminals.

Regards, B/F

 

[genosmm]

Hope everything is OK family wise!!

Since this happened a while ago, I do not expect you to remember everything that happened immediately.

You may have already determined the prob. Too Hot!!

Next question: Why? As you mention, the bias may have been off (do not know how tempermental the Z models are)? Or maybe the Z models can Not really drive 4 ohm speakers (plus not all 4 ohm speakers are the same) What model were you using? Also it may have been both.

Are the amp sections the same for the Z5k and above?

Gene

PS am not trying to make the Zs into the best amp possible. Will most likely use it as a test amp for a while and then retire it to surround sound use.

 

[BeatleFred]

Gene- I was using my Infinity Qb speakers which are 4 ohms. I was not really using the system anywhere close to what could be considered as putting a strain on anything, so perhaps the bias current setting was way off, maybe the adjust pot and some other things went astray from vibration and so forth when the amp was shipped to me by the Seller, who knows. The amp blew on me before I could check the bias so I dont know if the amp wouldve worked ok had the bias needed adjustement and I had done that.

I believe the Z models do have two pairs of speaker terminals in the back, so in that case, connecting two pairs of 8 ohm speakers would be the equivalent of 4 ohms, so if the Z models would have any trouble with 4 ohms, I dont think Sansui wouldve put a 2nd pair of speaker terminals on there to begin with.

B/F

 

[genosmm]

I agree.

As previously mentioned from my own experiences and reading the postings of others not all 4 or 8 ohm speakers are the same. So if you run (2) 8 ohm speakers that are really 6 ohms each you may also have problems.

After accidently blowing up a favorite power amp I realized that you can never assume anything and it is best to be very conservative!!

After my power amp accident I found out that this happened frequently with this model which is why am a big fan of forums that allow you to post your experiences with a particular brand and model because this info will never be found in a review.

Gene