Classic Valve Amps - Valve Audio, Hifi & Guitar Amplifier Repairs

Valve Hi-fi Amplifier Repairs & Service

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TEST GEAR

Some the test gear that I use one a day to day basis for my business. I think it is important for the customer to know the equipment being used is of an industry standard.

Valve testing:
Where do I start, I am a bit of a collector of valve testers so have a couple of AVO CT160s (arguably the BEST valve tester ever made - IMHO), AVO MK II and MK IV an Orange DIVO VT1000 valve tester, Mercury 1100 emissions tester. With my range of testers I can basically test the following valve characteristics: 
  • Heater filament test: Short circuit
  • Heater filament test: Open circuit
  • Heater filament test: Tolerance check
  • Heater cathode insulation: Leakage
  • Heater cathode insulation: Short Circuit
  • Tests for heater current abnormalities
  • Amplification factor
  • Voltage gain
  • Power gain
  • Screen grid test
  • Mutual conductance test
  • Dual test for double triodes
  • Emission
  • Inter electrode leakage
  • Inter electrode short circuit
  • Flash-over (arc detection, high voltage breakdown)
  • Gas ionisation test (sometimes called cathode poisoning)

Bias Adjustment:
TAD Biasmaster MB2 uses either an octal or 9 pin Noval adapter placed in between the valve and the valve base and directly measures cathode current (actually it measures the voltage drop across a resistor in the cathode leg, if we are being picky!). Great piece of kit for quickly determining and setting the bias current to your desired value.

Soak Testing:
I use a combination of an FG-100DDS function / signal generator and Hantek digital storage scope for day to day testing as the equipment is compact and easy to set up. This in conjunction with my home made 120w dummy load (4,8 & 16 Ohm), gives me all the flexibility I need to test the vast majority of amps I have come across.  
  
 




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