Amplifiers, Repair, Service

Lovely Technics SU-V8 Amplifier Repair & Service

18 Comments

The stunning Technics SU-V8 has to be one of the most beautiful amplifiers from the golden age. As part of my first #TechnicsMonth, let’s take a look at the classic SU-V8 integrated amplifier.

Yep, it’s #TechnicsMonth at Liquid Audio and what better way to start than with the Technics SU-V8. What that #TechnicsMonth is exactly, I don’t know, but I’m going to focus only on Technics for the next couple of articles.

Any way you look at it, this is a very nice looking amplifier. There were actually two versions of this model. One had lots of LED indicators for the top row of switching, this one does not.
One of my readers sent me this image of his gorgeous black SU-V8, with LED switch position indicators. This is a beautiful amplifier which unfortunately needs repair.

Before we go too much further, feel free to watch my accompanying video on this SU-V8 clean, repair and service:

Features

The Technics SU-V8 was the top integrated amplifier from Technics in the early ’80s. The 110 Watt per channel beauty featured some of the buzz-tech so typical of the time like ‘New Class A’ which isn’t class A, and ‘Super Bass’ which boosts the bass. As with most of these features, leave it turned off.

Everybody loves New Class A… don’t they..?!

This stunning silver amplifier has gorgeous machined aluminium knobs reminiscent of Accuphase gear and every switch and control feels solid, smooth and secure. It’s also a great sounding amp, solidly built and very serviceable. The SU-V8 is the kind of amplifier you might buy and keep for a really long time.

Anyhow, Technics was really in its stride during this era and consistently producing some of the sexiest looking and sounding hi-fi gear. Who could forget the futuristic SL-10 linear tracking turntable for example? The SU-V8 was the amp that matched the SL-10 and the other gear they sold, like the SB-8 honeycomb speakers.

You can read more about the SU-V8  at the Audio-Database entry for the amp and don’t forget to check out the awesome brochure @ HiFi Engine!

Specifications (adapted from Audio-Database)

FormIntegrated DC amplifier
Line Level Specifications
Effective output power110W/ch (8 ohms)
THD0.003% (-3dB, 20Hz – 20kHz)
Power bandwidth 5Hz – 100kHz
Frequency responseDC-20kHz+0 -0.1dB
DC-150kHz+0 -3dB
TIMToo low to measure 
SN ratio (IHF-A, DC)106dB
Noise (straight DC)550uV
Damping factor (8ohms)60
Load impedancemain or remote: 4 – 16 ohms
main + remote: 8 – 16 ohms
Other Specifications
Input sensitivityPhono MM: 2.5mV / 47 kohm
Phono MC: 170uV / 47 ohms
Line: 150mV / 47kohm
Phono SN ratioMM:88dB
MC: 71dB (250uV input)
Phono frequency response30Hz – 15kHz, +/- 0.3dB
FilterHigh: 7kHz – 6dB / oct
Subsonic: 20Hz – 12dB / oct
Loudness control+ 7dB (50Hz, Volume – 30dB)
General 
Year manufactured1980 – 1984
Power consumption260W
Dimensions430 W x 153 H x 351 D mm
Weight15.7kg

Problems

This poor old SU-V8 suffered so badly from dirt and previous poor service that it hardly worked at all. This is a perfect example of why getting the right service is critical. This thing ran on one channel, buzzed and popped when controls were actuated, protection kicked in all the time and was generally one very unhappy amplifier!

In fact, the grime level in this one was so great that it took me three hours of cleaning and servicing switches, controls and boards, just to remove the goop that had been sprayed into this thing over the years and get her working reliably again!

There are quite a few adjustments in these higher-end New Class A models, so all that had to be attended to as well, plus there was a broken board. For the rest of this article, we’ll get her back up and running and chat about why these are such a classic piece of gear.

The SU-V8 as she arrived. Looks OK from the front, except for the lid. All the case screws were missing, never a good sign.
What these images don’t show is the layer of grease covering literally everything.
You can see the general layout though. Dual mono design, two transformers, two diode bridges, two sets of filter caps.
This is ugly and should be fixed.

Cleaning

You can’t do anything much or even know what’s going on until you properly clean a very dirty piece of equipment like this. It’s always the starting point when servicing something like this, but it’s tedious. Unfortunately, there are no shortcuts.

This unit needed a deep clean and people ask me how I do this. It depends on the type of contamination and equipment I’m working on. There are risks of electric shock and damage if not done correctly and it’s helpful to have a drying oven, so it’s best to bring your gear in if it needs this level of attention.
The foaming cleanser really gets into the nooks and crannies and yet is gentle on the components themselves. Smaller boards like this go into the drying oven after rinsing and pressure drying.
After everything is washed and dried, I start the board rework. This is the driver board with the broken corner, now free of flux.
Top view of the driver board
Detail of the now much cleaner SU-V8
So much better

Repairs

Once I’ve cleaned and dried everything, reworked the boards as needed and thoroughly serviced the switches and controls, I generally start repairing things. In this case, the driver board needed fixing, as did the ‘New Class A’ logo lighting on the front panel.

Cyanoacrylate glue works quite well for these sorts of board repairs.
I soldered in an Edison-style incandescent lamp for the New Class A emblem.
Once the wiring is neatly heat-shrunk in place, it’s hard to tell it’s been repaired at all.
Much better!

Testing & Adjustment

Once the repairs are done, it’s time to allow the amp to warm up, carefully test everything and then make all the adjustments, as per the service manual.

There are many adjustments inside the SU-V8. Here, I’m adjusting the quiescent current (I think!).
Two bench DMMs are essential here, both for precision and to be able to see both readings at the same time and make symmetrical adjustments.
Finally, I get to test the owner’s SL-10 and SU-V8 together – lucky me!
What a beautiful system

The Finished Product

I try to include quotes from owners when they get the gear back, so so here’s what this lovely owner said when he plugged everything back in:

Wow, this sounds amazing!

This put a smile on my face and he’s right, it sounds fantastic, plus just look at the thing! My customer bought this amplifier for next to nothing because it barely worked. He spent some money having it properly cared for and now has a perfectly working example of a SU-V8, an iconic Japanese hi-fi amplifier. You’ve gotta be happy with that.

Naturally, I separately cleaned all the knobs and the fascia. I think it looks a million bucks.
Such a classy looking amplifier. Note I’ve added a new set of screws for the chassis cover as these were missing.

If you would like me to service, repair or restore your Technics SU-V8 or any other Technics amplifier, don’t hesitate to get in touch.

18 thoughts on “Lovely Technics SU-V8 Amplifier Repair & Service”

  1. Hi Mike,

    Currently doing some minor check ups on my black SU-V8. She’s a little quite in on channel and volume fixes this, either dirty contacts, or solder joint or relay. I purchased before stock ran out of discontined at Mouser, but Digikey has it. Panasonic Relay for the V9. Not sure it would suit the V8 though. Part is Panasonic HC2-HP-DC24V-F
    https://www.digikey.com.au/product-detail/en/panasonic-electric-works/HC2-HP-AC240V-F/255-3639-ND/3885784

    Thanks Cheers Sam
    p.s take care during the Corona19 that’s around the world atm

    Reply

    1. Hi Sam, thanks for commenting and for the relay part number. For those reading along at home, keep in mind that 9 times out of 10, relays can be very effectively serviced and do not need to be replaced. Very occasionally though, they will burn out or the contacts will fuse. In these cases, a new relay is a good way to proceed.

      Reply

  2. Dear Sir, thank you for your review. I stumbled over this amplifier by chance one year ago and was completely surprised by its sound and quality. Actually it took the place of my before Quad 33/ 303 combination with Spendor speakers… As I am not a real hifi nerd I have not an awfull experience of very many different amplifiers. I have now Broadmann VC 1 speakers. With these the SU- V8 ofcourse sounds even better. With these very good speakers- is it worth to upgrade the amplifier as well, like with a sudgen 21a, or is the SU- V8 in your opinion also capable to play in this league?

    By the way- thanks also for your review of the Technics SL- 10 turntable. That was a fantastic hint! I bought one and with the Ortofon OMP 30 it sounds even better then with the Technics MCP 310…. Thats really high class for little money.

    Reply

    1. Hi Erik, thank you for your very welcome comments and feedback. I agree with you, the SU-V8 really is a lovely amplifier. I think though that you will find a class-A or good MOSFET or VFET amplifier will sound even better, this is certainly my experience. I’m glad you found an SL-10 and thanks also for letting people know about the OMP-30. These have a very good quality diamond and are great sounding MM cartridge.

      Reply

  3. I own a black one for almost 40 years. Fantastic amp. it just died half a week ago. No more sound, after a few minutes there comes a loud short buzz.
    I’m sure it needs some TLC.
    Shame your workshop could’t be further from where I live (Netherlands, the other side of this world)
    Thanx for your vid, I definatly am going to have it repaired!

    Reply

    1. And don’t forget folks that there are potentially other remote switch assemblies that will also work. The trick is finding and trying some. If there is a local SU-V9 being parted out though, that could be very useful.

      Reply

  5. Hi Sam,
    thank you very much for your help.
    I write from Italy and it would be great if the cable was still available.
    I did a search on Ebay but couldn’t find the SU-V9 cable! 🙁

    Reply

  6. Hi Crina
    One of my V8s input selector cable broke also and i found one on ebay, but I was fortunate it was being parted out.

    There is a Technics SU-V9, i got a new inputboard from the seller for my V9, It should fit a V8, ask the seller he may have it. Shipping is pretty steep for a small cable. He still may have the cable for the input selector
    https://www.ebay.com.au/itm/264301163015

    Reply

    1. Hi, thanks and glad you found the article useful. I don’t have a switch like that in stock but this system was widely used. I am sometimes able to find parts like this given time and where equipment comes to me for service or repair. I’d need the unit here for physical matching in terms of length, number of detent positions etc. Do you live locally? I don’t generally sell or ship service parts for reasons relating to time, cost and the aforementioned need for matching in this case.

      Reply

    1. Hi Joe, it’s not necessary under normal usage conditions, ie adequate ventilation, amp sitting in free space, not in a cabinet, sensible speaker load etc. Generally, these things don’t run hot, if yours is, this indicates something else is not right.

      Reply

    1. Hi Jeremy, thanks for your question. I love helping my readers but I like keeping them alive as well! I don’t generally go into details about how I wash equipment for a number of reasons. There are technical considerations and the method varies according to the type of equipment, boards and dirt present. Most importantly though, it has the potential to kill you if you get it wrong. For these reasons, I strongly suggest not washing electronic equipment unless you have access to a temperature-controlled drying oven and really know what you are doing. I hope this makes some sense, let me know if you have any other questions.

      Reply

  10. They are a great amplifers i have 2 , a black and silver, and would never part with them. Great to see them getting revived and brought back to spec

    Reply

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