Author Topic: Technics RS-1500  (Read 1124 times)

Offline HBAutomation

Re: Technics RS-1500
« Reply #15 on: July 30, 2018, 07:21:34 PM »
if nothing works she goes swimming...



Nooooo!
When You Come to a Fork in the Road, Take It!            [Yogi Berra]

Offline Agaton Sax

Re: Technics RS-1500
« Reply #16 on: August 01, 2018, 07:52:14 AM »
You have some lovely equipment.

The Technics RtR machines  had to play second fiddle to the Revox and Tandberg machines back in the day,yet the Technics transport  was probably one of the best ever made.

Technics took the 3M developed iso-loop system and perfected it.I'm told that the direct drive capstan motor is the same used in the SP10 turntable.Rumour has it that it was a 3M "Iso Loop" machine that destroyed large parts of Fleetwood Mack's Rumours multi track master.The machine was nicknamed "Jaws" by the (slightly irate?)  band. Technics overcame those problems and perfected the transport. These machines are popular with tape fans , so good is the transport that it is frequently used with external repro amps,often the $14 000 Doshi.

IIRC those fantastic Tandberg amps were Tandbergs final attempt to break into the very high end of audio before folding up their Hi Fi side to concentrate on their far bigger educational electronics arm.

SAE. Many years ago when the QUAD ESL63 was launched an unnamed shop got a pair. They tried everything they had but it just would not gel. Finally a salesman found a humungous SAE amp that really woke those stats up. It sounded stunning. As a poor student ,I used to hang around that demo room. One day I was left alone in there and turned the volume on the QUADs up slightly. Result-total silence.Probably the QUAD's notorious crowbar protection. I do not believe I ever disappeared so quickly-well except the day I scratched the mint vintage Rover on pole  outside the classic car dealer.

Sorry ,just stupid memories in a Blue Tooth world.

Offline HBAutomation

Re: Technics RS-1500
« Reply #17 on: August 01, 2018, 09:12:19 AM »
And here are some of SAEs latest creations.
http://hear-sae.com/
When You Come to a Fork in the Road, Take It!            [Yogi Berra]

Offline marcochezzi

Re: Technics RS-1500
« Reply #18 on: August 01, 2018, 09:59:04 AM »
You have some lovely equipment.

The Technics RtR machines  had to play second fiddle to the Revox and Tandberg machines back in the day,yet the Technics transport  was probably one of the best ever made.

Technics took the 3M developed iso-loop system and perfected it.I'm told that the direct drive capstan motor is the same used in the SP10 turntable.Rumour has it that it was a 3M "Iso Loop" machine that destroyed large parts of Fleetwood Mack's Rumours multi track master. The machine was nicknamed "Jaws" by the (slightly irate?)  band. Technics overcame those problems and perfected the transport. These machines are popular with tape fans , so good is the transport that it is frequently used with external repro amps,often the $14 000 Doshi.

IIRC those fantastic Tandberg amps were Tandbergs final attempt to break into the very high end of audio before folding up their Hi Fi side to concentrate on their far bigger educational electronics arm.

SAE. Many years ago when the QUAD ESL63 was launched an unnamed shop got a pair. They tried everything they had but it just would not gel. Finally a salesman found a humungous SAE amp that really woke those stats up. It sounded stunning. As a poor student ,I used to hang around that demo room. One day I was left alone in there and turned the volume on the QUADs up slightly. Result-total silence.Probably the QUAD's notorious crowbar protection. I do not believe I ever disappeared so quickly-well except the day I scratched the mint vintage Rover on pole  outside the classic car dealer.

Sorry ,just stupid memories in a Blue Tooth world.

Thank you Agaton, thats some great feedback, always nice to know the history, never a waste..!!

So some more history goes like this..

Way back in the day I was very close friends with the stepson of a gentleman called Brinn Rebstein, owner of the then Schuler Presses South Africa.

Brinn was an audiophile of note, magnificent equipment such as Audio Research, Steinhardt, Acustat, Tandbergs & Revox RtR's was the order of the day at his home back in the day, and I while we were absolutely not allowed to touch anything for fear of being quartered, we could watch and listen.

We are going back to mid 1970's to Mid 1980's, I was fortunate enough to be his very young neighbour, and we got on fairly well given he was a perfectionist of note, which made him inherently difficult..

That I can remember, he sported 2 x Revox 10.5" units and a smaller 7" Tandberg reel to reel unit in his system, and I loved those machines, don't know why, it' just the beauty of them working that appealed to me in a deeper level..

So something clearly planted itelf in my core way back then, and since I was just a mere student studying engineering at the time meant I could afford jack diddly, I decided that I would build my own, using parts salvaged from an Akai of sort that I had laid my hands on.. did not get very far, but functionally she worked believe it or not..!!..

Move on a few years and come 86' I get a bursary/job offer from the National Panasonic AKA Technics..

Somehow landed up in a specialised service division made up of 3 people including myself, where I met a professional broadcast video technician called Dennis Noble, very eccentric character who unfortunately quite literally drank himself to death, but prior to his leaving this planet I had got into a friendly chat about my homemade RTR, and on his request took it to the office  to show it off to him given his interest...

So help me, the very next day, without saying a word, he shows up at work with the Technics RS-1500 & 2 head blocks and a complete set of factory service manuals and hands it over to me as a gift, all 100% functional, the only thing missing were the reel NAB adaptors.. I quite literally had to pick myself up off the floor, I will never forget theat gesture of kindness!!

Teac/Tascam NAB adapters were quickly sourced from (I think) Spescom in Midrand sometime in 86'-87' cant really recall exact dates.

Brinn in the meantime had closed Schuler Presses down in JHB, purchased a farm called Jan Harmsgat in Swellendam, and turned it into one of the countries finest B&B's.

Time passes on for all of us I guess, Brinn moved on as well, and a number of years later, his daughter (with whom we remain close family friends) calls me and asks me to come over, there is something for me from Swellendam from Brinn. Turns out he had placed aside a few of his more popular RTR recordings and about 10 brand new sealed (Non-Ampex) 10'5" reels for me as he somehow remembered my dreams of his RTR's back in the day..

Quite remarkable really, I will keep those original recordings as long as I am on this planet, so help me...

Anyway, so I had a stint in the Audio Dept of Panasonic for a few years, only ever saw one 1500 come in faulty, and it was to do with the direct drive capstan motor feedback loop going open circuit so speed became unstable, easy repair, first and last time I ever saw another of those units..

Regarding the SL10 motor, you could be quite right, the capstan motor on the 1500 is literally enormous, when you open the back panel its mostly capstan motor in there, absolutely wonderful engineering, certainly from an era when true mechanical marvels were designed and built, properly..

Thank you for the feedback on the Tandbergs, also beautiful in my eyes, very stylish and unassuming.., having found those I was hoping to find the matching CD player, but they are difficult to find, however I will keep my eyes peeled open for those rare opportunities.

The SAE is a beast, its currently undergoing internal organ replacement, just ordered a whole pile of fresh components with the hope to ressurect her once again, they are tough old ladies, lets see if she survives open heart surgery at my hands once again..

Cheers & good day to all..
« Last Edit: August 01, 2018, 10:07:40 AM by marcochezzi »

Offline marcochezzi

Re: Technics RS-1500
« Reply #19 on: August 01, 2018, 10:02:51 AM »
Apologies - double post..

Offline marcochezzi

Re: Technics RS-1500
« Reply #20 on: August 01, 2018, 10:13:40 AM »
And here are some of SAEs latest creations.
http://hear-sae.com/

STU--NNING!!!

Offline marcochezzi

Re: Technics RS-1500
« Reply #21 on: August 13, 2018, 08:20:27 AM »
Right, so while it has nothing to do with the reel to reel, since I had already posted here regarding the SAE I might as well continue..

Ordered a ton af spares from RS Components and Mantech to try get the beast alive again, a handfull of the output transistors were in varying states of decay so I ordered those and thankfully the replacement units in the same style casing were available so those were a direct swop..


« Last Edit: August 13, 2018, 08:25:41 AM by marcochezzi »

Offline marcochezzi

Re: Technics RS-1500
« Reply #22 on: August 13, 2018, 08:30:37 AM »
Same cannot be said for the input board and the driver stage, again a pile of open and shorted transistors, unfortunatley I could not get same spec casing wise, probably would have through ebay but I just don't like working with ebay, so I went for equivalents and modified the collector connection accordingly...





For those of you that have repair experience on the amps and you look closely, you can see that I have done away with the use of the output attenuation switches as they tend to go faulty, frankly there is no real need for them anyway, so I just bypassed them..

Offline marcochezzi

Re: Technics RS-1500
« Reply #23 on: August 13, 2018, 08:40:46 AM »
All mylar caps were replaced, all electrolytics were replaced some time back but still technically new, another pile of burnt resistors were replaced, once again had to run replacements in parallel to get to the required resistance as I was unable to source the exact value locally..

Was using my small wharfedales as guinea pigs, which was a good thing because somewhere I managed to create a feeback loop so great that it immediately sent one of the speakers into orbit, and the speaker protection relay fused and literally melted in front of my eyes, looked like a welding arc...!! :walled: :walled:

Anyway, in too deep, pulled everything and replaced outputs, again... I did order extra for that "just in case moment", which proved itself correct, decision wise that is...

Offline marcochezzi

Re: Technics RS-1500
« Reply #24 on: August 13, 2018, 08:55:23 AM »
The original relays are made of unobtanium, so ordered 2 alternates from RS components, spec 2,5K ohm at 48 volts DC, and positioned them onto the relay board running stout cabling to the connectors..

This will do as a temporary fix, but what I will land up doing is redesign the protector board layout and manufacture a replacement board that fits the new relays properly, there is enough space in the cavity and will look better and cleaner..


Offline marcochezzi

Re: Technics RS-1500
« Reply #25 on: August 13, 2018, 09:16:35 AM »
Switched everything back on while wearing my welding helmet for that "just in case" moment again, was running one channel at a time only because 1. I only had one functional test speaker and 2. Output transistors are expensive a third time in...

Worked fine, so I thought, audio was good, but I noticed that the left channel outputs were getting very warm to the touch at very little load, which is a point of concern, so I started with all the adjustments, only to find that bias was running at 3.3V where the max should be 2.25V.. :fuse:

Anyone that has worked on these amps will tell you that they are not the easiest things to work on, they are heavy, cumbersome and certain components like on the output main board are just a pain in the ringer to get to..

So tried to adjust the bias pots with a very long screwdriver through the bottom of the casing as that is where the pots are, and no result from a voltage perspective, which means the bias regulation circuit components which is made up of three small transistors positioned exactly where you do not want them to be, has gone faulty..

So strip the entire guts out of her again, and yes, 2 of the 3 bias regulator trannies were toast, rushed off to GT electronics in the east rand and walked out with a handfull of fresh components early saturday morning....

Replaced everything bias regulation wise, for both channels..

Closed up the brick and powered up again, netting a positive result and was able to then set the bias according to spec..

Used my old Mission 770's as fresh guinea pigs and ran her at normal listening levels for the rest of Saturday and most of Sunday, absolutely perfect, in fact did not even get warm to the touch..

Fantastic, super happy with the result, long may she last this time around..

Always hated the Lamps in the SAE, again they are oridinary globes that burn out religiously, if they dont burn out then they become badly contaminated and the land up flickering so I decided to replace them with a more blue led light strip which looks more in keeping with the CD player display.. :roll:

While at it I attempted the same with the RTR with varying results, the photo's dont do the amp or RTR lighting any justice as the lounge lighting conditions are all wrong, so while it looks like the brightness of a old 1980's disco dancefloor, it really is not at all...

Now maybe I need to replace the RTR red counter display with blue... :dop:







Result...
« Last Edit: August 13, 2018, 09:19:18 AM by marcochezzi »

Offline Family_Dog

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Re: Technics RS-1500
« Reply #26 on: August 13, 2018, 03:46:35 PM »
Any of the Technics high-end product line is a bitch to work on! Well done, the hard work and hours spent on these units are finally now producing very good results.


-F_D



-Eric

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Offline HBAutomation

Re: Technics RS-1500
« Reply #27 on: August 13, 2018, 06:19:37 PM »
Fantastic. Labour of love.
Looks realy good. :thumbs:
When You Come to a Fork in the Road, Take It!            [Yogi Berra]

Offline Den123

Re: Technics RS-1500
« Reply #28 on: August 14, 2018, 09:59:56 PM »
Well done!!
Just for the perseverance.
Seriously, nice job. I know the feeling. Iím busy with a 460V AC (about 670V DC) 840A max current 3ph drive that let out a lot of expensive black smoke. Nice IGBTs. 1200A each. Takes a lot of patience and some balls I guess. Those IGBTs are old and scarce. They run just over GBP1000 each. !!!

Offline Den123

Re: Technics RS-1500
« Reply #29 on: August 17, 2018, 11:29:45 AM »
Hi Marcochezzi. Sorry to have bombed your thread. I thought you and others may be interested in large transistor repairs. Seriously, lovely R2R. If you ever want to sell .....