Technics SA-1000 repair/refurb started!

Well, it's been a heck of a while since I updated this. We have been doing a remodel for several months and I got more involved than I planned on but it is done at last and work on this has been going on.

First up is the reworking of the front panel LED displays. The custom modified LEDs are mounted from the back of the function callout pc board. I had to mark up the board and drill it out first. Some rewiring was required. The best solution I could find for the VU meter board was to use standard T1 parts. Each was hand formed to fit the front panel bezel. Both boards have been mounted and new resistors selected to decrease the brightness of the new ones. Typically the current has been decreased 3-10X.

Next up after the recapping and LED stuff was to replace two relays that have a pinout that nothing modern matched. My solution was to design a board set to adapt some new ones. One board goes on the bottom to match the old relay pins and the top board mounts the new relay. A set of inner pins carries the coil and contact connections. I needed several other boards for other projects so batched them up and ordered a stack from the supplier we use at work.

If anyone needs these boards I have plenty, PM me for arrangements.

The raw boards and relays, the Omron is the new one and the Matsushita the old one.



The inner connection carrying pins are mounted first.


Then the top board solders on next. The pin protrusion is kept minimal to allow clearance to the new relay.



The new relay soldered on and bottom pins are in. I used another bottom board to hold the pins in alignment while soldering.


Finished assembly soldered into board. Works like a champ!!

I have always wanted to see nudies of a 1000. That monster out monstered the rest of the industry. Your re-engineering is clean and smart. Those blue filter caps look like they have been replaced already. Nice stuff.

After that I got up the courage and brought it up on the variac/DBT combo. No smoke and I got sound but very soon remembered where I had left off. It had a fairly good hum which I had thought a recap may have solved. It didn't! After some poking around I found the blown parts pictured below in the -90Vdc regulated supply. The final pass transistor was shorted emitter to collector thus connecting the raw supply right through, all -107V of it.

There was still quite a bit of hum and further checking found a bad TO-220 pass transistor. Replacing that cured the remainder of the hum.
Here is what parts were blasted and the replacement:

SVDMZ306 6V zener -> 5V zener (can't recall which of several types on hand was used) + one 1N4448. The resulting 5.6V was close enough for the pot to adjust just off center.

2SA912 -> KSA1220A
2SA913 -> MJE15033G
2SC1912 -> MJE15032G


Bad guys from negative supply

KingBubba said:

I have always wanted to see nudies of a 1000. That monster out monstered the rest of the industry. Your re-engineering is clean and smart. Thoses blue filter caps look like they have been replaced already. Nice stuff.

Click to expand...

Thanks King! Yes the main filters had been done, they are Adcoms and I see no reason to replace them.

Absolutely fabulous job. The relay board mod is extremely well done.

Give Sarge a hug from another old dog owner. Hope he's continuing to do well.

Larry

Here's several sessions of work completed. Almost done!

I was up to recapping/rerelaying the rear board which is speaker switching/protection and power tap selection. This model automatically senses the incoming line voltages and uses power relays to switch windings. Scary! Mandatory to replace the relays with new ones for sure.

Back panel layed out for board access.




Here are the transformer tap switching relays, still the originals.


Board all recapped and new speaker relays installed.


Here are the two new transformer relays partially preassembled on the bench before going in. Yes, I did solder all the connections later! The Mouser part number for them is visible on the bag they are sitting on.


Top view with the back panel reinstalled. Everything worked fine! There is still a shield/cover to be reinstalled over the rear board.


Tuner reinstalled and up and running. I started out Saturday afternoon by aligning the AM and just as I had set up to do the FM the power went out due to a pretty good thunderstorm. We didn't get power back until very late in the afternoon but I did get the FM done, the amps and power meters so all adjustments are done.


All that's left is to figure out if I can install LED front panel lighting. I took some shots of it running last night and discovered that I had light bleed to the new LEDs for the function indicators due to installing them from the back of the board. I put on a coat of flat black paint from the back and will do at least one more coat this afternoon. This evening will be the test!

The camera just doesn't capture the beauty of the rich LED colors. The three function section colors are blue, orange and red for "safety", "FM" and "stereo".

Done!

It is all done now! Sounds great too. This guy is very good at staying out of the way and is very clean and accurate sounding.

The lighting was finished being converted to LED and is documented below.

I used good old generic .1" spaced perf board to hold the LEDs. I used two warm white T-1-3/4 parts in parallel, making sure they had very close turn-on voltages.


Here they are test fit into place. The boards use the same holes as the old incandecent lamp holders were screwed to.



On to the meter lighting, I used two more single warm whites but drilling a huge hole of about 3/16" diameter in a 1/4" wide acrylic casting was too scary so I turned down the lenses to just under 1/8" on a lathe. They are epoxied in place. The scriber tool is just there to weight the assembly down so it wouldn't tip over.



Epoxy has set, lit up now.


The initial main dial light test revealed the light was too concentrated around the LEDs so I tried using the material I use for vellum in Marantz dials to diffuse the light and it helped a lot. It is an art paper called "Opalux". The old caps were just the right size to hold them in place while the glue set. I just used a general purpose craft glue and only at the edges away from the LED ends.


I used the AC voltage for the dial lights to power the LEDs. I used some more perf board to build a DC supply. Just a bridge rectifier and a 330uF/25V cap. A hole was drilled into the inner chassis and a 4-40 by 3/8" long standoff used for mounting it. The screws/tooth washers were later "sealed" with some fingernail polish for added insurance. The blue wire isn't as close as it looks to shorting out! Still I added some insulation using a scrap bit of lexan laminate material.


The dial light diffuser all wired up. There's a 270 ohm resistor on the top side as a current limiter. Each LED pair runs at 16mA or about 8mA each, quite a ways from the 30mA limit.


The results! Sorry about the fuzzy middle picture. These were all taken with different ambient lighting making the brightnesses seem different.




Here's all the stuff that came out and was replaced, 190 pieces in all!


Ain't she purdy?

Pretty amazing tech work!! Great to see you've got it up 'n running!

WICKED!! Looks sweet Randy, lots of work and tlc into that unit.

Great job...

Always wanted to own one of those... another bucket list item...

Thanks all! Yes lotsa TLC and grunting, this sucker is north of 80 pounds! If the owner ever tells me he's selling it I'll give you a holler slow_jazz.

Beautiful work! Moving that thing around would keep a guy in pretty good shape I bet :scratch2:

Nice job! I particularly like the LED mods.

Last year I refurbished a SU-8099. It was in a terrible state and extremely filthy (tar, nicotine). The only way to remove the cigaret gunk was by spraying a foam designed for cleaning kitchenware, BBQ-gear and ovens. Works like a charm in a matter of minutes.

After cleansing using that foam and a soft paint brush, rinse thouroughly with luke warm water. Then blow the board with compressed air and let it "evaporate" on a warm (not hot) surface for a couple of hours. Looks brand new then.

roger2 said:

Beautiful work! Moving that thing around would keep a guy in pretty good shape I bet :scratch2:

Click to expand...

It tells you where your weak spots are! :yes:

The first Stereo Review I purchased was September 1978. In it was an advert for the Technics SA line, with the SA-1000 being the star of the advert. 330wpc was outrageous then. To this day, I have been in awe of the SA-1000. It is a wonderful trip back 36 years to see you work on this. Very nice work indeed, I hope the new owner appreciates not only your work but your skill and ability. Not many people can do this.

Wow, you have a great memory! Do you recall the list price back then?

According to Orion Blue Book the "New List" price of Technics SA-1000 was $1700

Ah, thanks Roger!! :thmbsp:

Wow!!!!!!!!!!!

You want to re-do my 5760?