Fender Laboratory

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There does not seem to be many photographs left to testify about what the inside of the Fender factory looked like. We get the ubiquitous ‘stock’ photos, including those of Leo at the punch press. But this is one of the painfully few examples we can see that shows what a typical electronic workbench looked like.

The above photograph was ‘borrowed’ from the book American Guitars (Tom Wheeler).  Here is what I see from the above photograph.  1 The service manual is opened to the schematic diagram of the amplifier being built. It does not appear to be the chassis layout, so this technician has to be electronics savvy. I have seen other factories where non-technicians were busy wiring up a chassis using a wiring diagram rather than a schematic. Why does this matter? I believe trained technical men also have used various pieces of test equipment, and develop a preference. Usually this preference leans toward the ‘good’ test equipment. But in this photograph, ‘good’ test equipment is shockingly rare.

Eico 460 oscilloscope is not the first choice of too many astute technicians, but it seemed ‘good enough’ at Fender.

2 The oscilloscope used is a lowly Eico 460. This is already a dozen years old by the time the photograph was taken. Sure, the 4.5Meg bandwidth is adequate for audio testing, but little else (read on). You might also notice a make-shift ‘visor’ taped to the CRT bezel. This would be done in an attempt to make the trace as visible as possible, without having the Intensity control so high as to damage to CRT. Once again, an oscilloscope that ‘features’ a higher accelerating voltage would have a brighter trace automatically. There would be no need for make shift visors. However, someone felt this oscilloscope was ‘good enough’ to use at Fender.

Eico 249 VTVM is a good, basic VTVM, but you can do ‘better’.

3 The VTVM being used is an Eico 249. It is a larger version of the popular 232. Neither is a terrible choice, and it even seems to keep with the Eico theme. This VTVM features a very large meter movement, making it easier to read. The reading wouldn’t have the accuracy of say a Hewlett-Packard VTVM (read on), but the reading would still be very usable. This actually isn’t a bad unit to have on your bench.

The Hewlett-Packard 200CD is a very popular, high-quality audio generator.

4 Now we see the audio generator; a Hewlett-Packard 200CD. This very high-quality unit, introduced in 1952, almost seems out of place here. However, it may offer insights into the philosophy over at Fender. The Hewlett-Packard signal generators usually had very accurate and clean sine-waves. It is not unreasonable to expect a THD level of less than 1% from this generator. Perhaps Leo wanted the amplifier designed, built, and tested without distortion? Thankfully, with an electric guitar (that Leo also designed to play cleanly?) the amplifier above would have a wonderful distortion when played at full volumes. The only downside to this wonderful generator is that it has no square-wave function. You cannot fully test all the parameters of your amplifier without a square-wave. Distortions, phase-shifting, and even frequency response is done either entirely or done ‘better’ with a square-wave. However, perhaps Leo decided since he wasn’t building a Hi-Fi he didn’t need a square-wave generator on any benches? This is still an out-of-place piece of test equipment on the same bench as the lesser units. Hewlett-Packard was also a company located in California, so to get a good deal on ‘decent’ test equipment shouldn’t have been a problem. Yet more Eico equipment (a kit that would have to be assembled by the owner), coming out of New York, is seen on this bench. There are other things you may see, if you have a keen eye. There are literally crates of preamp tubes on the bench, so this may be a production-line worker. That may be an isolation transformer under and to the left of the oscilloscope. There also appears to be two meter movements to the left of the oscilloscope. They do not appear to be any part of a VTVM-type unit, which makes me hypothesize that they may be hard-wired to show a certain parameter. One may be to show line voltage, or it may indicate the audio generator output. My final thought for today is the meter may be showing the output voltage, as measured across the dummy load. I do not see a dummy load, nor do I see a speaker. That small box at the extreme upper left may be a paging system, or it could be a radio. It looks much too small, and there seems to be controls on the panel, that this could be a test speaker. What do you get from all this? Not much. I still like to do all this investigative work, only to try and get a glimpse into the mindset of any vintage manufacturer. They must have had a business plan, and were as susceptible as you or I to the advertising of parts suppliers. If a part could do the same job, and save a nickel, you can be assured that Fender (or any other manufacturer) would be very interested in using that part. That technician above is probably electronics savvy, so he should know the difference between a ‘good’ oscilloscope and a ‘great’ oscilloscope, as an example. Yet a pair of lowly Eico ‘kits’ are seen being used. That should definitely be food for thought.