|| PHILCO SERVICE HINTS & TIPS |
|PHILCO SERVICE HINTS & TIPS - NUMBER 41
Case Histories of Receivers
Radio Field Service Data by A. Ghirardi, 2nd. Ed., 1936
Excerpts re-printed from Radio Field Service Data, by Alfred A. Ghirardi, EE.
Published by Radio & Technical Publishing Co, New York City, 1936
Second Edition, pp. 2-1 and 2-111 to 2-134
(Companion Book to Modern Radio Servicing)
COMPILATIONS OF "CASE HISTORIES" (ACTUAL SYMPTOMS AND REMEDIES) FOR COMMON TROUBLES IN VARIOUS MAKES AND MODELS OF RADIO RECEIVERS
Value of Trouble "Symptoms" in Locating Troubles: In many lines of service work, an experienced technician can quickly tell a great deal about the location and nature of commonly occurring troubles by simply listening carefully to the operation of the device being serviced. For instance, an automobile service man listening intently to an automobile engine in operation knows instantly from his experience that a certain regular "metallic" clicking noise usually means that one or more valve tappets require adjustment; another peculiar characteristic "rattling" noise means that the fan belt is frayed or too loose and is striking something; a third low-pitched reverberating sound indicates that there is a leak somewhere in the muffler or exhaust manifold, etc. Knowing these "symptoms," he is able to get at the source of trouble immediately, and remedy it without making elaborate, time-consuming tests.
So, too, every wide-awake radio service man who has had some experience in servicing radio receivers, soon realizes that particular models of almost all makes of receivers develop certain definite troubles after being in use for some time, that is, almost the same troubles are usually found in the same model of receiver. These troubles are invariably accompanied by definite recognizable "symptoms" in the operation of the receiver -- symptoms which can easily be recognized by simply attempting to operate it. Experienced service men soon find themselves taking advantage of this fact almost unconsciously, for when called upon to service a familiar model and make of receiver with a trouble symptom which they have run across before in a similar receiver, they immediately proceed directly to test the particular part which caused the trouble in their last experience -- without taking the time required to analyze or test the various circuits of the entire receiver.
Value of a "Case History" Compilation : If a service man remembers, or has access to the "Case Histories" for most of the popular models of the various makes of receivers, he can often make more rapid diagnoses and repairs on numerous receivers which he is called upon to service, and can speed up his work considerably. A compilation of this kind, for over 1500 popular receivers has been made by the author from the actual service records of several large service organizations with which he is associated. It is authentic in every detail, and is presented with the hope that it will be a time-saver to practical radio service men in their daily work. In some instances, the troubles arising can be disclosed quickly by one of the regular test procedures which are described in Modern Radio Servicing, but very often they are of a nature which makes them particularly elusive and difficult to locate by ordinary test methods. It is for cases of this kind that the following "Case History" compilation is of particular value.
Common Sense in Using "Case History" Compilations: Before presenting the compilation of "Case Histories" the author wishes to discuss several points in connection with its use, that should always be kept in mind.
(1) When using a compilation of radio receiver "Case Histories," remember that the troubles listed are by no means the only ones which can occur in the respective sets. They are the ones which have been found to occur most frequently, and are those which a service man should suspect and test for first.
(2) No service man, or student of radio servicing, should entertain the idea that all he needs to do in order to become a successful service man is to "arm" himself with a voluminous list of receiver "Case Histories," throw all the rest of his analyzing and testing equipment and knowledge out of the window, and proceed to conduct his service work with little effort "by chart." Nothing could be further from the truth! As every experienced radio service man knows, hundreds of cases of everyday troubles in radio receivers are not the "conventional" ones, and they are often located only by the most persistent and careful testing and sometimes only by the merest chance or "luck."
(3) The list presented herewith will be useful as an accessory to the "conventional" routines of servicing and should be consulted as a "first try." If the correct "trouble symptom" and "remedy" are found with it, so much the better. The repair can then be made quickly without need for time-consuming analysis. If the "Case Histories" listed do not cover the particular case in hand, the service man should proceed immediately in accordance with the modern technique of analysis and testing explained in detail in the book Modern Radio Servicing by Ghirardi. In other words the list should be regarded as a possible time-saving accessory only -- not as a new kind of service man's "brain."
The Compilation of "Case Histories" for Receivers: It will be noticed that the receivers are listed alphabetically by manufacturers' names. The various models of each manufacturer follow each other in progressive alphabetical and/or numerical order. The various trouble "symptoms" which may be noticed when the receiver is turned on with the volume control set for "loud" operation are listed at the left, and the corresponding "causes" or "remedies" for each trouble are listed at the right. If the trouble occurs at a different setting of the volume control, this fact is stated. It is assumed that the service man has sufficient radio knowledge to enable him to proceed directly to remedy the trouble where only the "cause" is listed. (For a general "Trouble-shooting Chart" applicable to all general "types" of receivers see Section 6 of this book.)
Finally, the fact that a large number of "Case Histories" are presented here for many certain makes of receivers is not to be taken as an indication that these particular receivers (or the receivers of any manufacturer for that matter) are particularly subject to trouble, or that any reflection on the quality of the receivers of those particular manufacturers is intended. Such is not the case! No receiver is perfect! All receivers are subject to troubles eventually. It is natural that a larger number of those receivers which have proved to be most popular, and have therefore had the widest sale, should be in use. Consequently, it will be found that a large proportion of the service calls are for receivers of these types, mainly because of this preponderance of the number of them in use. It is on these receivers, therefore, that the largest amount of trouble information due to actual trouble-shooting experience has been obtained and recorded here.
The following chart lists the PDF files scanned from the PHILCO pages from
the "Case Histories," Section 2 of Radio Field Service Data, 1936.
Note: This publication only covered up to the 1936 model year.