SX-1280 Restoration

[txturbo]

I got lucky and stumbled upon an SX-1280 this week. A contractor that was installing an air compressor at work noticed that we have several big receivers around the building. He said that he had one at home and was going to pitch it because it did not work. He was not even sure if he still had it. A couple days later he showed up with it and asked me to buy it. Done...

I wheeled it into the shop and connected it to the power analyzer for a quick evaluation. It lit up and made power on both sides, tuner wiggled and the stereo light flashed on as I tuned. That was enough.

Time to tear it down...

I have read many threads comparing the 1250 to the 1280. The consensus is that the parts in the 1280 are somehow not as nice and the 1280 is harder to work on. To me it's just different... The parts look to be of the same quality. Getting the boards out for service requires desoldering them, but that takes only a couple of min with a desoldering system.

In about 30 min it was stripped down to this:

The filter caps measured in the 13,000 to 14,000 range.

I can see previous repair work in the tuner. I noticed this gem installed, it should be a PA1001A:

According to the tuner info center this is a Toko KB4437, a known cross for the PA1000A.

Hopefully this week I can find some time to order parts..

 

[fernarias]

It's not about the quality of the parts but the quality of the build. The 1250 had shielding, the 1280 does not. The 1280 used more ICs therefore it required the use of less parts than the 1250 (cost cutting) and it's spells trouble now that those parts are not available. It's also unfortunate that the 1280 used outputs that are discontinued while the 1250 used to-03 that still are available (surprisingly). The faceplates on the 80 series also seem to damage easier than on the 50 series (probably due to the thickness of the clear coat after anodizing). Sound wise I think they are pretty close but I would have liked a 1280 built to the standards of the 1250 (same with 9800 vs. 9900, etc).

 

[redk9258]

Damn, you people are lucky! I never run across this kind of stuff! Good luck with the rebuild.

 

[txturbo]

It's not about the quality of the parts but the quality of the build. The 1250 had shielding, the 1280 does not. The 1280 used more ICs therefore it required the use of less parts than the 1250 (cost cutting) and it's spells trouble now that those parts are not available. It's also unfortunate that the 1280 used outputs that are discontinued while the 1250 used to-03 that still are available (surprisingly). The faceplates on the 80 series also seem to damage easier than on the 50 series (probably due to the thickness of the clear coat after anodizing). Sound wise I think they are pretty close but I would have liked a 1280 built to the standards of the 1250 (same with 9800 vs. 9900, etc).

I think the tuner is better in the 1250 (5 gang) and I do like the shielding, it is TOTL. It will be interesting to see how the 1280 sounds after restoration.

I do like them both and am glad to have stumbled on to the 1280.

 

[Idunno]

Lucky ain’t just the only word!
It took me two years to source a Pioneer SX-1980 here in the UK.
It would be nice if they were left in office buildings here!
On a serious note though, good luck with the restoration. I’ll be following this thread with interest as the SX-1280 is a lovely Receiver. One I’d like in my Ownership that’s for certain!

 

[tsd71]

Lucky bastard!! No need to build another power supply on this one. Not like the 1980, meaning fabricating a new PS board....good luck it's a challenging but not impossible build.

 

[onwardjames]

Damn, glad to see that kept out of the landfill. Watching with interest, as I always do, since I can't do this work.

 

[zebulon1]

The 1280 is one set I haven't messed with. I've always wanted one.
I'll live vicariously through you and your thread.
Keep it coming!

 

[kevzep]

Nice one, so jealous, I'd love a 1280......

 

[markthefixer]

The PA1002A is a remarked Toko KB4437. I have come across them before in 1980's and other units.
It was the clue to finding replacements.

It is interesting and impressive that the spacers holding the bent wire wrap pins survive.
I have GOT to get more hemostats!!

 

[txturbo]

The PA1002A is a remarked Toko KB4437. I have come across them before in 1980's and other units.
It was the clue to finding replacements.

It is interesting and impressive that the spacers holding the bent wire wrap pins survive.
I have GOT to get more hemostats!!

I bet Toko must have been the actual manufacture of the IC for Pioneer. I hope it still works. I picked up a set of Pioneer Integrated Circuit Technical data books. The back of the page for the PA1001 shows the PA1001-A as improved performance and one they describe as PA1001-AG with the part stamped as PA-1001A but with the Pioneer label in green. I did a quick search for the Toko data sheet and found nothing.

Yes... I was surprised that all of the plastic spacers did not crack. I tried to be gentle.

 

[rcs16]

I do not recall that Toko ever had a semi fab, so it could be any one of the Japanese semi fabs that were op at that time. There really was not that many making those sort of parts, Hitachi, Sanyo, NEC,Toshiba, Rohm, Matsushita(Panasonic),Mitsubishi, are the likely possibilities. Pioneer liked to use mostly Hitachi and Toshiba IC parts.
I also see a chip with label Pioneer PA4004 on it, another strange one that was not documented. I recall PA4004 being used in later tuner models? so it must have been pin compatible with the one that was in the 1280 documentation.
Since these are custom parts it is very unlikely that we would find datasheets and if we were to, they probably would be written in Japanese

 

[txturbo]

I thought I would follow up on the restoration of this SX-1280... I finished the electrical part a few weeks back but have been waiting on my brother to finish the cabinet.

The electrical part went well.. I ended up replacing every cap including the filters, the relays and a bunch of silicon. The lamps were replaced with LED's. I spent some time cleaning and alining the tuner. I must say the Pioneer tuners are very nice to work on, or maybe I should say align. The tuner is very quiet and sensitive now. The receiver is still breaking in but it sounds very nice.

I suspect that I won't see the 1280 again for a while, it ended up on my brothers work bench. He has taken quite a likening to it.

In order to re veneer the case he literally sands the old veneer off by hand with a block. He picked up some Claro walnut blocks for the ends of the face plate and veneer. I am handy with a soldering iron and volt meter but this is way beyond my skill set.

I am working on a Kenwood KR-9050. When I am done I will do a shoot out with the TOTL Pioneers and see how it stacks up.

 

[Oldsansui441]

That looks absolutely beautiful and l bet it sounds just as good , l haven't owned any of the 80 series yet but hope to one day.

 

[redk9258]

Man, that is one sharp rig!

 

[onwardjames]

Makes me miss my old 980. Txturbo, that's sexy as hell.