G-9000 resurrection

[txturbo]

I picked up a G-9000 that looked to be in nearly perfect cosmetic condition but was listed as non working from the the usual place. The unit was rust free and not a scratch that I could see, it even had the original hang tags on it. What's not to like?

I tried to get the seller to allow me to pick it up in person, however he insisted that he had packed it up perfect and would ship it. Of course it arrived with some damage, the back bumper was pushed in a little. I was able to knock off quite a bit from the price so I did not mind.

I took the heat sinks off the back to work on the sheet metal and noticed none of the outputs were original. After I got the sheet metal fixed up I took a look at the rest of the unit. That's when I knew it was going to be a long journey to get this one back to life.

Some one attempted to "Recap" this before I got to it. It looks like they used a hot butter knife to solder with. Nearly every board needs to be reworked.

So I decided to start at the power supply and work inward. The board was so hacked that I decided to remove it and rework it on the bench.

This is an example of the handy work..

At this point I am just kind of bummed.. I know it will be good again but I just did not expect that it would look so good cosmetically and be so hacked on.

 

[baeron]

I picked up a G-9000 that looked to be in nearly perfect cosmetic condition but was listed as non working from the the usual place. The unit was rust free and not a scratch that I could see, it even had the original hang tags on it. What's not to like?

I tried to get the seller to allow me to pick it up in person, however he insisted that he had packed it up perfect and would ship it. Of course it arrived with some damage, the back bumper was pushed in a little. I was able to knock off quite a bit from the price so I did not mind.

I took the heat sinks off the back to work on the sheet metal and noticed none of the outputs were original. After I got the sheet metal fixed up I took a look at the rest of the unit. That's when I knew it was going to be a long journey to get this one back to life.

Some one attempted to "Recap" this before I got to it. It looks like they used a hot butter knife to solder with. Nearly every board needs to be reworked.

So I decided to start at the power supply and work inward. The board was so hacked that I decided to remove it and rework it on the bench.

This is an example of the handy work..

At this point I am just kind of bummed.. I know it will be good again but I just did not expect that it would look so good cosmetically and be so hacked on.

Oh my goodness, hack job to no end
I can not believe that work.
Packing was not good at all.
You got lucky that it was not more.

Good luck with this Great Sansui.

 

[Sansuiman]

These tossers who fancy themselves to be techs and have no business poking around inside a Fisher Price toy turntable, much less a real piece of kit need to be....well, think of something approriately painful. Stuff like that really angers me, because it is just stupid. The packing job was piss-poor as well, though you came out fairly well on that I guess.

Anyway, it looks like it should be salvageable, but with far more work than should be needed because of all the damage done by some idiot with a soldering iron made for doing stained glass windows or copper roof flashings.

The only real good news is it is cosmetically decent. I have one here just the opposite: it works well enough, but has scratches, gouges, scuffs etc. It will never be a top-condition unit unless I find (and pay royally for) replacement knobs and a front panel. So, I keep it mostly as a back-up and parts unit for my really nice G-9000. It isn't outright terrible, but rough enough I'd give it a 4 or 5 out of 10. Not nice enough to be front and center in my loving room, I'll put it that way.

Anyway, you have the makings of a nice winter project there. If you keep your nose to the grindstone, you can have it done by the time the weather gets really nice again.

 

[Hyperion]

That's horrible, but if I remember rightly you are damn good at this, so although you are bummed right now, I'll bet you'll make a really good job of repairing the 'handiwork', and returning it to full working condition.

Please keep us updated on progress and of course pictures would be nice if you can.

 

[Watthour]

I just had to look it up in Webster's...

fug • lee - adj (Am slang) A state of disrepair beyond normal wear and use; Neglected or abused condition; State of haphazard or improper repair; (also see eBay as-is amplifier)

I suspected as much.

 

[kevzep]

Just the man to put this kludge back to better than factory......Another G9000 saved from certain death!!

 

[lbcgav]

That thing is going to be beautiful once you're done with it.

 

[txturbo]

So I started to clean up the mess a little bit and see what I was dealing with. The good news is that I just need to follow the mess of replaced capacitors. The bad news is that a lot of them were replaced.

First task was to clean off all of the old flux..

Now we can see what needs to be repaired..

Before.. It's not easy to see from this photo but lots of repair was needed.

After a couple of hours of restoration..

Most of the repairs were done using eyelets for strength.

Find the bad pad..

Clean it up and drill it out for the eyelet. Scrape off a little bit of the coating to expose the copper and then clean it with alcohol.

Install the eyelet and stake it in place.

It looks like every board except the tuner needs repair.

 

[txturbo]

Just the man to put this kludge back to better than factory......Another G9000 saved from certain death!!

Hopefully it will sing again!

I saw your post on the G-22000 Sanken TO3-P output replacements. Did you ever try the OnSemi's? I am not holding out much hope to find originals..

 

[Sansuiman]

Nice. Can you post where you got the eyelets and a part number? Looks great so far.

 

[txturbo]

Mouser has them..
I used two heights:

PCB EYELET 1/16 X.093
and
PCB EYELET 1/16 X.125

You also need a setting tool.
I rigged something up from a set of old watchmaking tools but you can buy them.
You need a handle, tool base and setting bit. This is the least expensive set I could find.

 

[Sansuiman]

Excellent, thank you.

 

[kevzep]

Hopefully it will sing again!

I saw your post on the G-22000 Sanken TO3-P output replacements. Did you ever try the OnSemi's? I am not holding out much hope to find originals..

I was running MJ15024/25 in it for a while, I found it had that "edgy" Pioneer type sound to it, and the distortion figures weren't as good either, so I tried the TO3P as an experiment and it ended up bringing it back to where it should have been.
I most definitely sounds better, more air, better imaging. The original devices are 10mhz, the ones I put in I think are 35mhz.
I also populated it will the extra pair of output transistors per side, and it made a huge difference in its ability to drive low impedance loads.

 

[Watthour]

...I also populated it will the extra pair of output transistors per side, and it made a huge difference in its ability to drive low impedance loads.

"Extra?" The one I had open had all its holes filled. However, it was a "DB" type. Is there a difference in the output section of the DB versus the less-crappy "regular" version?

 

[kevzep]

"Extra?" The one I had open had all its holes filled. However, it was a "DB" type. Is there a difference in the output section of the DB versus the less-crappy "regular" version?

View attachment 2083773

Oh sorry, I was talking about the G22000. They use the same assembly for both the 22 and 33K the 22 only uses 3 pairs, whereas the 33K uses 4 pairs.....

 

[Watthour]

That seems very sensible. Provided the drivers can do the extra few milliamps, it makes a lot of sense to distribute the load over the additional output devices. Given the cost of TO-3Ps being what they are, it seems almost silly not to do it.

 

[kevzep]

That seems very sensible. Provided the drivers can do the extra few milliamps, it makes a lot of sense to distribute the load over the additional output devices. Given the cost of TO-3Ps being what they are, it seems almost silly not to do it.

Exactly the same driver circuit in both the G22 and 33K. Same driver transistors.
Thats what I thought, would have been almost rude to not fully populate those output boards!!
Just a couple more emitter resistors, base resistors and so forth.....

 

[txturbo]

I was running MJ15024/25 in it for a while, I found it had that "edgy" Pioneer type sound to it, and the distortion figures weren't as good either, so I tried the TO3P as an experiment and it ended up bringing it back to where it should have been.
I most definitely sounds better, more air, better imaging. The original devices are 10mhz, the ones I put in I think are 35mhz.
I also populated it will the extra pair of output transistors per side, and it made a huge difference in its ability to drive low impedance loads.

Actually I was thinking about the TO-3P OnSemi NJW3281G and NJW1302G. They are 30 mHz parts.

 

[kevzep]

Actually I was thinking about the TO-3P OnSemi NJW3281G and NJW1302G. They are 30 mHz parts.

Ah yes they are 30mhz devices but I used the Sanken LAPT (Linear amplifier power transistor) devices as they do have superior performance to the Onsemi devices, you have a lot of options too.
Digikey are the Sanken distributor.
Check them out and see what you think.

 

[txturbo]

On the F-2796 head amp board their are 47 nF green film caps tacked on the backside across C33,C34,C35 and C36. I do not see them on the schematic. Should they be installed?