‘Blog’ Category

FM1000 tube testing on BK 707-700

I was asked by a reader named Henry if I knew of B&K 700-707 test settings for FM1000 tube.

FM1000 is a unique Heptode detector oscillator, and as such really does not lend itself to “tube testing.”  It is best tested in-circuit.

That said, you can perform some basic checks on a FM1000 tube for shorts, leakage, and basic emission with your BK 700 or 707.  Using the bottom emission test panel, heater at 6.3v, Sensitivity at around 38, bottom switches set at 1, 8, 12, 2.

I asked Henry try testing an FM1000 tube to verify those settings, and his feedback is that they do work.

Q&A regarding different micromhos scores

Hey Tubesound,

Hoping you can answer a question for me. I have an Amplitrex and a TV-7D/U tube tester.  The Amplitrex tests a 12ax7 as new at 1600GM.  According to your TV7 GM calculator, I believe that should translate to 64 on the TV meter.  However, when I test the same 12ax7 on my TV-7 the meter only hits 42.  Does it sound like my TV7 needs some calibrating or am I missing something? Hope you can help and thanks for the great calculator.

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Q&A regarding HP Officejet R-series repair

Q&A regarding HP Officejet R-series repair:

Hi,

I have your article on “Repairing HP Officejet R-series”.  I used it several years ago; cleaning  the mirror fixed the problem.

I’ve lost flexible use of my hands so I wanted to get someone to do the service (suspect it needs cleaning and new bulb).  Local repair services refuse to work on ink jets.

Do you have a recommendation for help in the south NJ area?

Thanks, Jim

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repair broken TP-Link TD-8616 ADSL modem

If you are trying to fix a TP-Link TD-8616 modem, chances are good that this is your problem.

On May 21, 2012, I purchased from Newegg a new TP-Link ADSL TD-8616 DSL modem to replace a very old Westell modem that was supplied by Verizon. At that time, the reviews for this product were overwhelming positive. Less than two years later, this TP-Link modem is already broken, and I see that recent reviews are more up and down.

Simply put, this modem had garbage capacitors, which is a common quality-control manufacturing problem with modern electronics.

Symptoms: for the past several months, connection was erratic, sync erratic, speeds fluctuating. Unable to connect to modem admin via TCP-IP.

Repair was as follows: (more…)

Vintage Advertising page

On this page, you will find PDF’s that I create from my own collection of vintage advertising for tube amps, speakers, test equipment, microphones, etc.  The ads often provide production specs and other useful information.

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