Ink-stamped letter on alternator housing

[Todd B.]

While at the national meet in Charlotte yesterday, I noticed a number of cars with restored alternators had a letter stamped in ink on the alternator adjacent to where the wiring harness plugs in.

When I got home, I wanted to see if my unrestored alternator still had visible markings. Here is what I found stamped on it:



To me, it looks like the letter "D", but I am not sure that's what it is.

Can anyone explain the significance of the letter? Does it correspond to the assembly date in any way, or is it just an inspection mark?

The car is a very early '64 (#347). Here is a photo of the numbers stamped into the body of the alternator:



Thanks,
Todd

By the way - to all who worked on putting together the national meet, I wanted to say Thank You - it was outstanding!

[Wayne M.]

Re: Ink-stamped letter on alternator housing

Todd -- I figure this one's an "H"; probably originally red ink, but now faded. This is on an unrestored 1100696 42 amp unit, later '65 MY, 5G7 date.

[John H.]

Re: Ink-stamped letter on alternator housing

Can anyone explain the significance of the letter? Does it correspond to the assembly date in any way, or is it just an inspection mark?

It's the broadcast code associated with that part number alternator; the guys on the line used it instead of the long part number to select the correct alternator for each car - the code for each car was on the build sheet.

[Todd B.]

Re: Ink-stamped letter on alternator housing

Thanks Wayne and John - I appreciate the explanation and the photo.

Regards,
Todd

[John P.]

Re: Ink-stamped letter on alternator housing

The letter stamped on these two alternators is an inspection mark. Broadcast codes were 2 letters and did'nt begin use until the 67 model year.Inspection marks were single letters.

[Gerard Q.]

Re: Ink-stamped letter on alternator housing

The alt on my 71....which John restored.

[John H.]

Re: Ink-stamped letter on alternator housing

The letter stamped on these two alternators is an inspection mark. Broadcast codes were 2 letters and did'nt begin use until the 67 model year.Inspection marks were single letters.

Yup - should have clarified my response - I'm mired in 1967.

[Ron N.]

Re: Ink-stamped letter on alternator-Related Question

Alternator diodes on a 67 SB

I understand 3 should be in Red ink marked 380 / YMDD / 466 and 3 in Black ink marked 423 / YMDD /466.

Can someone confirm and tell how the original ink applied (by stamp?) or send a photo if possible?

Thanks

Ron

[Wayne M.]

Re: Ink-stamped letter on alternator-Related Question

Alternator diodes on a 67 SB

I understand 3 should be in Red ink marked 380 / YMDD / 466 and 3 in Black ink marked 423 / YMDD /466. Can someone confirm and tell how the original ink applied (by stamp?) or send a photo if possible? .....

Ron -- here's an original +ve diode in red, of an early July 1965 alternator; 380/5F15/466. These go on the internal heat sink. I've also got another seven NOS D-1903 negative diodes (black ink) #1959830, with 1965-6 dates; these are pressed into the the rear case. Can't find the pic; will post another -- shows what the original fonts looked like.

[Wayne M.]

Re: Ink-stamped letter on alternator housing

Ron -- here's those other negative diodes with black ink.

[Joe R.]

Re: Ink-stamped letter on alternator housing

Wayne,

What do you mean by "negative diode?" I'm an EE, I have never heard that before today.

Joe

[Ron N.]

Re: Ink-stamped letter on alternator housing

Thanks Wayne. I found good photos from the archives. With these photos I was able to verify the correct markings that need to be on my alternator diodes.

Ron

[Jack H.]

Re: Ink-stamped letter on alternator housing

The diodes were packaged in 'positive' and 'negative' format with respect to the press-fit case vs. input stud. Think of the convention as being PN and NP junction orientation for the convenience of assy. It's different than ordinary axial lead diodes where you simply flip the component end to end to achieve proper circuit function.

[Jack H.]

Re: Ink-stamped letter on alternator housing

There were a NUMBER of qualified vendors and the labeling on some of the alternate suppliers (e.g. Motorola) is a touch different. The labeling was done by the supplier and the process is similar to that used to silk screen identifying marks on transistor cans and IC packages.

When Ford and GM began to produce alternators after Chrysler's debut in '60, the infant semi-conductor industry was SWAMPED to generate sufficient production quantity. Not only were Ford and Chrysler much larger than Chrysler in their consumption, the 'problem' was compounded by their use of a three phase (six diodes per alternator) alternator vs. Chrysler's use of a single phase unit with 4-diode, full wave bridge...

At that time just about 'anyone' who could produce silicon got into the act, including Dow Chemical's co-op venture with Corning Glass (Dow-Corning)!

[Wayne M.]

Re: Ink-stamped letter on alternator housing

....What do you mean by "negative diode?" I'm an EE, I have never heard that before today....

Joe --- was just repeating the terminology found in the P&A30 catalogs and the Chev training program booklets (fundamentals of operation -- diodes).

I understand that current can flow only one way through a rectifying diode, but there must be some difference between the three red-script "positive" diodes [mounted on the heat sink that is connected to the +ve terminal of the alternator] and the three black-script "negative" ones that mount in the grounded external alternator case. Otherwise, we wouldn't need two different diode part #'s .

I'm surprised that Jack H. hasn't jumped in here with a mini-doctoral thesis on three-phase full wave bridge rectification . Oops --- JH just beat me to it.