[Hallicrafters] Cleaning the inside of HT33A amplifier

[Glen Zook]

For the first 6-months, or so, of when I owned the Motorola reconditioned equipment center for the south-central United States (1970-1979) we did recondition tube type mobile equipment  for a few specific customers.  The equipment was cleaned by using a high pressure "steam" (actually hot water) with a detergent followed by plain water from the same system.  Of course there were not any dials, power transformers, etc.  After "steam" cleaning the equipment was baked for 72 hours in a specially constructed oven at around 140 degrees to 150 degrees in which baffles were installed to create a circular air flow.

After about 6-months Motorola came to the conclusion that, due to the age of the equipment, tube-type equipment would no longer be reconditioned.  The hybrid equipment (i.e. Motrac) was another matter and continued to be reconditioned until Motorola went out of the reconditioned equipment business in 1979.  In late 1970 we went to a glass bead process of cleaning the equipment.  Using this process resulted in a mat finish on shields, etc.  However, all units, regardless of the actual starting physical condition, looked exactly alike after going through the process.  The customers who purchased the equipment were very happy with the results.

One thing, due in a large part that "infant mortality" of solid-state devices was long gone in the equipment being reconditioned, was that the warranty rate for the reconditioned equipment was less than 0.1%.  The warranty period for reconditioned equipment was 1-year for both parts and labor whereas the warranty on new equipment was 90 days parts and labor and 1-year on parts.  Having a better warranty on the reconditioned equipment was a "selling point" that gave the customer more confidence in the equipment.  At the time, a warranty rate of 7% was considered optimum for new equipment as a "trade off" between production costs including inspections and actual costs of doing warranty work in the field.
 
Glen, K9STH


Website:  http://k9sth.com


________________________________
From: Richard Knoppow <1oldlens1 at ix.netcom.com>
To: WA1KBQ at aol.com; k5pgw at yahoo.com; hallicrafters at mailman.qth.net
Sent: Friday, November 11, 2011 8:51 AM
Subject: Re: [Hallicrafters] Cleaning the inside of HT33A amplifier


     FWIW, the complete routine we used at -hp- was as 
follows:
     Anything which could be damaged by water was removed. 
This included meters and on some equipment sealed 
transformers and chokes. All sealed compartments, like the 
RF compartment of a 608-C/D were opened up.
     The chassis was washed down with warm water from a 
garden hose. Then washed out with a paint spray gun loaded 
with water and dishwashing detergent and scrubbed where 
necessary with a dishwashing brush. Then it was rinsed with 
warm water from the hose again. Then blown out with 
compressed air to remove as much moisture as possible. Then 
it was baked in the oven at about 130F for at least 48 
hours. I preferred to bake longer but the oven was not 
always available. Some equipment required relubrication 
following washing.
     I don't think this technique is applicable to all 
equipment but certainly worked on the vacuum tube and early 
solid state stuff I was working on at the time.