Ever since the founding of the company in 1968,
Orange has been a pioneering force in the guitar
amplification industry. Today, with a team of theworld’s finest engineers, Orange continues topush back the boundaries of product design.

Our commitment to craftsmanship and quality
control has allowed our products to stand thetest of time, giving their owners as muchpleasure now as the day they were bought. To
maintain this level of excellence, all Orange
products are put through many rigorous test
procedures before leaving the factory.

THANK YOU FOR CHOOSING ORANGE2

WHAT’S IN THE BOX
1 x Valve Tester MKII
1 x Power Supply
1 x Mains lead
1 x Manual
1 x Pencil

3

IMPORTANT SAFETY

The exclamation point within anequilateral triangle and "WARNING" areintended to alert the user to thepresence of important operating orservicing instructions. Failure to heed
the instructions can result in severe
injury or death.

The lightning flash with arrowhead
symbol, within an equilateral triangle,
is intended to alert the user to thepresence of un-insulated ‘dangerous
voltage’ within the product’s
enclosure that may be of sufficientmagnitude to constitute a risk ofelectric shock to persons.

This equipment should be used under
the supervision of an adult at all times.

To reduce the risk of fire and electric
shock do not expose this apparatus torain or moisture. Do not use in damp
environments, e.g. bathrooms etc.

Do not place objects containing
liquids on, or near the product.
Do not operate this apparatus orconnect/disconnect a power plugwhilst hands are wet.

The “Caution, hot surface” symbol
indicates the marked item may be hot.
Ensure the apparatus is installed withplenty of space around the unit(> 6”/12.5cm) as this apparatus may
generate heat under normal use. Thisequipment is not intended to be used onsoft support (like beddings, blankets etc.).
This equipment should always be placedon a flat, stable surface.

Do not attempt to gain access tothe interior of the product. No user
serviceable parts inside. Refer allservicing to qualified servicing
personnel.

4The Orange Valve Tester MKII (VT MKII) supply input is19V DC 65W. The DC input socket is centre positive
polarity and the barrel plug is a ‘standard 2.5mm type.’To avoid the risk of product damage it is highly recommended to only use the power supply supplied with theproduct, or an exact equivalent.

Warning valves can get hot during testing, ensure they
are cool to handle before removing from the valve tester.
Valves are fragile, so always be gentle when handlingthem and attaching or detaching them from the VT MKII.

!

This device complies with the Canadian Interference Regulations CAN ICES-3(B)/NMB-3(B).
This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions:1) This device may not cause harmful interference.
2) This device must accept any interference received, that may cause undesired operation.
Note: This equipment has been tested and found to comply with the limits for Class B digital device, pursuant to Part 15 of the FCC Rules. These limits
are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiateradio frequency energy and if not installed and used in accordance with the instructions, may cause harmful interference to radio communications.

5WHY CHOOSE THE ORANGE VT MKII?
Commercial valve testers have been available, almost since valves were invented, incorporating many excellent
techniques and designs over the years. However, the vast majority have a number of common features, which we
considered to be a barrier to the modern valve user namely:•They require a certain level of user interaction in that parameters have to be set for individual valves being tested.

•They require a certain depth of knowledge about valve theory, which some users may not have.

•The results obtained on meters or digital readouts require a certain level of user interpretation.

•They are often quite large and bulky.

In a lot of cases, they are also not very portable andsince most are mains operated, require selection ofmains voltage if required to be used in other than theirnative country. When developing the VT MKII wedecided to ‘break the mould’ to produce a fully
automatic valve tester, which performs a wide range oftests quickly and accurately.

Requiring little or no knowledge of valve theory, it canbe operated by experienced users and those who justwant to know that the valves in their amplifier are ingood condition. It requires no user interaction otherthan inserting the valve to be tested into the correct
socket, selecting the type from a list using twoup/down buttons using an LED bar display, then finallypressing an ‘OK’ button to start the test.

6

The test then proceeds without any further user input
and elapsed time is shown on the LED display during thetest, then one of three LED’s is lit to indicate a ‘GOOD’,‘WORN’ or ‘FAIL’ condition.
In addition, the LED display indicates a ‘matchingnumber’ which is based on a summation of the many
results obtained during the test and has been specificallydesigned to reflect the operation of the valve, according
to its normal function in an audio amplifier.

For example, power valves are graded with theiremission and control grid performance as primaryfactors, whereas pre-amp valves are graded withdifferent parameters to reflect their role in signal
amplification and phase splitting applications. If thevalve is faulty or worn, then this will be indicated at theend of the test.
The simplicity of operation belies what is going on‘inside the box’, where a sophisticated microprocessor
controlled testing system (incorporating TubeSyncⓇTechnology) is in operation, allowing full control over all
inter-electrode switching and measurement operations.

In addition all voltages required by the tester areinternally derived, stabilised and controlled by themicrocontroller, allowing rapid static and transient
tests without generating unnecessary heat. The test
algorithms used have been developed using data fromtests on hundreds of new, used and faulty valves.
We are passionate about valve technology and our aim
throughout has been to make the Orange VT MKII asophisticated, modern, truly portable valve tester
which is primarily useful but also stylish, appealing toall valve users whether amateur, professional or in themusic retail trade.
7

BEFORE USING YOUR VALVE TESTER
With the VT MKII, Orange has designed a compact, safe and simple alternative to the large, dubious andcomplicated valve testers of the past. However, despite its small size the VT MKII is a highly accurate and sensitivepiece of test equipment, and should be treated as such.
When in use the VT MKII is taking thousands of micro measurements and performing a vast array of tests in orderto grade your valves. These tests measure very small voltage and current changes under high impedance
conditions, which means a number of external factors can affect the end results.

TO OBTAIN THE MOST CONSISTENT READINGS, WE ADVISE OBSERVING THE FOLLOWING:

With temperature being a factor we suggest that theVT MKII is used, wherever practically possible, in alocation where temperature and humidity will remain
constant. If inconsistent test results are beingobserved during the first couple of tests allow forfurther time for the effects of humidity, condensationand temperature to neutralise and re-test.

The grading/matching system is based on a decision
made after performing over 20 tests. For this reason
and the sensitive nature of valves (particularly 12AX7/ECC83s) some slight variance may be seen during
testing. If this is observed allow the valve to cool, move
the VT MKII into an area of constant conditions andre-test.

8Any condensation which may occur on the valve bases
or internally can influence initial results. Due to thethermal insulation properties of the packaging and thehigh thermal mass of the metal case, the VT MKII may
remain at a very low temperature for a considerable
time if left in the packaging. If it is brought into a warm
room and immediately used, condensation will
naturally occur and produce false test readings. We
recommend the VT MKII is allowed to stand for around30 minutes out of its packaging before initial use forthese effects to subside.

%!

Do not test hot or warm valves. The VT MKII uses highvoltages to ensure accurate readings from the valves
which are tested with the correct voltages as stated intheir manuals. Under testing, the valve will become
warm and this heat will alter impedances inside thevalve. If the same valve is then repeatedly tested
before being allowed to return to room temperature, orif a warm valve is tested having just been used (e.g. inan amplifier), false readings will be given. We advise
leaving valves to reach or return to room temperature
before testing.

!

9

CONTROLS AND FUNCTIONSADEBCFGAValve socket for octal power valves.

BValve socket for EL84 valves.

CValve socket for pre-amp valves.

D

Selected valve type text (both UK and US).

EValve matching value (range between 1 & 15).

F

Valve status result: GOOD, WORN, FAIL.

GControl buttons. Centre button selects valve
type and starts the test. The two outer buttons
move valve selection from right to left.

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VALVE SOCKETS & VALVE SELECTIONVALVE SOCKETS
EL34/6CA7; 6L6;
6V6/6V6GTA; KT66;
KT77; KT88; KT120
6550; 5881;
EXPANSION MODULE

EL84/6BQ5ECC81/12AT7;
ECC82/12AU7;
ECC83/12AX7; 12BH7PHYSICALLY DAMAGED VALVES!

No damage will occur to the VT MKII by testing faulty ordamaged valves.
Under no circumstances should any attempt be madeto insert into the test socket or to test a valve which is
physically damaged, as this could present a hazard tothe user or others.
If a glass valve envelope is accidentally damaged during
a test, the ‘OK’ button should be used to terminate thetest and the power connector removed.
The valve should then be allowed to cool after which it
should be removed using protective gloves and thensafely disposed of. DO NOT touch any exposed metalparts of the valve during the operation and ensure thatno fragments of glass remain around the tester before
using it again.
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USING YOUR VALVE TESTERSTEP 1

STEP 2

Decide which valve you would like to test and identify
what valve test socket is required for the test.

Carefully insert the valve into the correct valve socket andensure it is seated correctly.

Octal power valves (EL34s, KT66 etc.) use valve socket 1.

Only one valve must be inserted into the tester at a time.

EL84 valves use valve socket 2.

Valves must be tested at room temperature.

Preamp (ECC83, 12BH7) valves use valve socket 3.

Testing a hot valve may result in a failure as the tester iscalibrated to heat the valve up as part of the test sequence.

STEP 3

STEP 4

Ensure the supplied power lead is connected to thetester and is switched on. Press the ‘OK’ button to start,
then by moving the left and right selector buttons
select the valve type which you are about to test.

It takes approximately two minutes for the tester to testa valve, during this time a number of orange LEDs willilluminate and flash.

When the correct valve type has been selected press‘OK’ again and the test will commence.

As the test progresses the number of LEDs illuminatedwill gradually decrease until the test is completed. If thevalve fails at any point, the test is automaticallyterminated and the red ‘FAIL’ LED is illuminated.

12

STEP 5TEST STATUS

Once the test completes and the green, yellow or red
indicator lights, then the test is finished; however, asvalves may get hot during the test, we recommend thatyou make sure that the glass envelope is cool before
attempting to remove it.

GREEN - If the green LED is illuminated this indicatesthat the valve is GOOD.

In any case, we recommend the use of protective gloves
when handling valves.

RED - If a red LED is illuminated this indicates that thevalve has failed.

YELLOW - If the yellow LED is illuminated this indicatesthat the valve is worn and should be replaced
as soon as possible.

In the case of a RED FAIL light the tester will also display
a number ranging from 1-8, this reflects the valve failuremode. (See the fault log at the back of the handbook).
For example : if the FAIL LED and LED 7 are illuminatedsimultaneously after a test, the valve is a fail and thereason for the failure is due to control grid leakage.

Note: Some specific faults found by the VT MKII may be either transitory or not immediately obvious when used in normal
operation. However, they could manifest themselves when the valve comes under stress or heavy load during a performance.

13NEW FEATURES ON THE VT MKII
A more rugged mechanical design
with improved test sockets

New enhanced grid leakage
detection test

Improved algorithm with higher
current capability

New microphony function for ECC81, ECC82
and ECC83 and 12BH7 pre-amp valves

Valve failure mode identification

New thermal runaway test

Capability to function with external
expansion modules enabling the testing ofother valve types such as rectifiers and EF86s

Capability to test directly heated valvessuch as a 300B via the expansion module

14

VALVE MATCHING NUMBER
A ‘matching number’ indicated by the LED(s) at the endof the test, is based on a combination of measured
parameters to give an indication of how the valve will
perform, according to its typical function in an amplifier.

In general, the closer the LEDs are together the better,
if two matching valves are apart by more than 6 values
the VT MKII will fail the valve. See the examples below.
Both sections of the valve are fairly well matched.

After the valve has been tested, the tester will assign amatching number ranging from 1 to 15. Basically: the higher
the value, the higher the gain of the valve. If a number ofvalves are tested, the gain or ‘matching valve’ can then be
used to group together pairs or quads of valves.

VALVE MATCHING VALUE FOR DOUBLE TRIODE(PRE-AMP VALVES)
Double triode (pre-amp valves) have two valves inside one
envelope i.e. an A & B side. After the MK II has tested adouble triode (providing that the valve passes) two
matching value LEDs will illuminate.

Both sections of the valve are the same (one constant LED).

For section A the LED will flash and for section B the LED
will be constant. If only one constant LED is illuminated,
this means that both sides of the valve are the same.
15MICROPHONY MODE
To begin the microphony test insert the valve into
the PRE-AMP socket. (ECC81, ECC82, ECC83, 12BH7valves only).

When the valve is heated, the yellow light will go out andthe green will come on. The valve is now ready, tap thevalve gently with a pencil to test microphony. Note: If
there is any noise present in the valve some LEDs will
illuminate prior to tapping.

Toggle along to number 15 and hold the rightbutton down for 3 seconds. When the yellow lightcomes on the valve is heating up.

The higher the LEDs go in the moving LED bar, thegreater the microphonic disturbance. Note: this test isindicative only, however with experience the user caneasily detect a valve that exhibits a microphony issue.

16

EXPANSION MODULES
Insert the expansion module, then select number 15
using the right arrow button. The yellow and green lightwill illuminate for a second and then go out. This
indicates the tester has downloaded the test parameters
for the particular valve.

The number 15 LED should then remain solid, LEDs 1-14
will flash. to start the test press the OK button.
Expansion modules are available to purchase separately.
For further information please see orangeamps.com

17

FAULT LOG
FAULT NUMBER

REASON FOR FAULT

ALTERNATIVE REASON

1 - Immediate fail

Heater open circuit or value missing

1 - Fail during test

Heater current below minimum valve for valve type2

Heater current too highTotal or partial short circuit

3 - Pentode test

Anode current exceeds max valve for valve typeInternal leakage or short

3 - Triode test

Anode 1 current exceeds max valve for valve typeInternal leakage or short

4 - Pentode test

Anode current does not achieve min value for valve type

Very low emission

4 - Triode test

Anode 1 current does not achieve min value for valve type

Very low emission

5 - Pentode test

Screen grid current exceeds max value for valve typeInternal leakage or short

5 - Triode test

Anode 2 current exceeds max valve for valve typeInternal leakage or short

6 - Pentode test

Screen current does not achieve min value for valve type

Very low emission

6 - Triode test

Anode 2 current does not achieve min value for valve type

Very low emission

7Control grid leakage

8

Thermal runaway during test
18orangeamps.com