GenRad Sound Level Calibrator 1562-A mercury bat, ger tr? - Page 1
Forum section: electronics / general

author: jonpaul
author_rank: Super Contributor
timestamp: January 13, 2022, 03:31:48 pm
content: Bonjour a tous, restoring a 1972 GenRad Sound Level Calibrator 1562-Ahttps://www.ietlabs.com/pdf/Datasheets/1562.pdfUsed to calibrate measurement precision mics like Sound level meters like Genrad 1982https://www.ietlabs.com/genrad-1982-precision-sound-level-meter.htmlThe original 9V mercury battery corroded a few partsTO-5 transistors, 2N1304, 2N1305, housing inside, battery snaps and case parts.As mercury salts are poisonous,1/ What is the best solvent to use? 99% iso alcohols seems ineffective.2/ How hazardous are the mercury compounds used in batteries?3/ Recommended cleaning procedure?Seeking a source on the severely corroded TO-5 metal can geranium transistors2N1305 GERMANIUM PNP 2N1304 GERMANIUM NPNMany thanksJon

author: bsw_m
author_rank: Frequent Contributor
timestamp: January 13, 2022, 06:20:33 pm
content: Potassium permanganate water solution may be it will help You.

author: jonpaul
author_rank: Super Contributor
timestamp: January 13, 2022, 07:15:16 pm
content: Update:Cleaned a bit, can use a standard 9V alkaline batt with snaps.Output is IN CAL for freq and 1V at jack.Needed an adapter, 1.125" to 0.500" reducer to fit my GR mics into the calibrated cavity, they were in the originlas kits but super rare.I kluged a PVC plastic pipe adapter and used felt gaskets...Voila! ......With the three 3 GenRad meters, ONE is in CAL at 114 db, the other read a bit low. As all are from 1970s, this is remarkable.All it needs is some careful corrosion cleaning, new battery snap and replacing the corroded transistors, 2N1304, 2N1305.For the $25 on ebay I am a happy guy!Bon journee,Jon

author: srb1954
author_rank: Super Contributor
timestamp: January 13, 2022, 10:32:36 pm
content: Quote from: jonpaul on January 13, 2022, 07:15:16 pmI found that the standard 9V alkaline batteries I tried were an extremely tight fit in the case. I was concerned that over time the pressure on the plastic cover of the snaps would cause a short to the metal case and consequently I don't leave the battery in the calibrator when it is not in use. However, it is a pain to reinstall the battery every time you need to use the calibrator.QuoteI believe that the dimensions of the cavity formed between the adapter and the microphone is relatively critical for obtaining proper calibration accuracy. The manual states:"So long as the volume enclosed by the coupler is kept constant, including the effective volume of the microphone to be calibra -ted, the sound-pressure level developed in the calibrator coupler is constant at 114 dB."If you have access to a lathe you could make the proper adapters relatively easily. If you want to go down that path I could measure up my 2 adapters ( 1/2" and 15/16") to provide the dimensions for you.

author: jonpaul
author_rank: Super Contributor
timestamp: January 14, 2022, 12:05:30 am
content: srb1954, many thanks for the kind notes!My adapter kluge was not accurate for the cavity volume but by chace a combination of a PVC pipe fitting and a few Heyco hole inserts could match the OD 1.125" and the 1/2" mic GR 1862 ., 0.500"This just a rough check and for sure I need the correct adapter.Please send a photo and sketch of the 1/2 " adapter , much appreciated!Please contact me with PM.Bon Journee,\Jon

author: 1audio
author_rank: Frequent Contributor
timestamp: January 15, 2022, 02:00:06 am
content: I have Solidworks drawings for the 1" and 1/2" and 1/4" adapters. Let me get those for you Monday. They were made from GR & B&K adapters and have the corrected volume adjustments. I'm looking for a machines who can make them from delrin at a reasonable price. The quotes are around $150 ea. which is crazy.I have 2 1562 calibrators (and 3 B&K pistonphones and a GR Omnical) and I need adapters for these to be useful.Both the 2N1304 and 2N1305 are available from eBay. However make sure they are bad. The circuit is pretty good about low stress.

author: jonpaul
author_rank: Super Contributor
timestamp: January 16, 2022, 08:05:24 am
content: Bonjour 1 audio, many thanksIndeed machine shops are very costly. Machine ship cost includes the setup, If we can find get a group buy, and get several made, the per unit will be less.I doubt if a 3D or Delrin part will behave acoustically like the original aluminum.Please send me by PM the solidworks in a format I can read like a PDF or BMP.Many thanks againJon