Lovely Technics SU-V8 Amplifier Repair & Service

I think the stunning Technics SU-V8 is one of the most beautiful amplifiers from the golden age. As part of my first Technics Month, let’s take a look at the classic SU-V8 integrated amplifier.

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

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.

Feel free to leave a comment and share your thoughts. Please keep it polite and respectful :)