‘Blog’ Category

FOR SALE rebuilt Heathkit IG-72 Audio Generator

beautiful and rebuilt HEATHKIT IG-72 Audio Generator$139 free ship inside continental USA

Here is a Heathkit IG-72 audio sine-wave generator, ideal for testing tube audiophile amps and guitar amps. This is a quality model that has an excellent low distortion sine wave for tube amp testing. And beautiful original cosmetics.

Rebuilt electronics, consisting of:

  • new capacitors (including correct orientation of caps regarding foil side of the caps)
  • upgraded the 5k-20W resistor to a 50W surface-mounted unit, for cool operation
  • meter smoothing capacitor
  • many resistors replaced to bring circuit into excellent overall accuracy
  • clean sine wave on all frequencies.
  • 3 wire grounded line cord installed to meet modern safety standards

I have attempted to photograph the sine wave below.  The sine wave looks better in-person than the photos show because my  camera has a tendency to bloom the scope trace.  (Photography is not my specialty!)

Paypal BUY-IT button here.

Heathkit IG72 audio generator $139 free ship USA


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.


Q&A regarding HP Officejet R-series repair

Q&A regarding HP Officejet R-series repair:


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


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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