[soapfoot]

Hello,

I'm looking for info on four parts in particular:

43173
43174
43175
43176

The transistors have the Motorola logo, followed by "024," then the numbers I've listed above.

Any help or insight? I can't seem to find them on any cross-reference chart. The device in question is from around 1970.

Any leads?

Thanks!

[analogguru]

These markings are no standard markings, probably they are custom markings.  You won't find a datasheet in a standard - even old - databook.

Where are they from ? any pictures ?

[Whoops]

I also vouch for those transistors having custom markings produced for a specific company.

whats the gear that uses them?

[soapfoot]

Here's a collage of images.

It's from a Ludwig Phase II Guitar Synthesizer, circa 1970.

Lots of mysteries about this unit. I've really struggled with it.

These transistors only are color-coded--there are four NPN-PNP pairs that have green (NPN) and yellow (PNP) paint on top.

There's another pair PNP-NPN pair where one has red paint on top and the other has blue. I read somewhere that sometimes Motorola color-coded their transistors this way to specify various properties in this era, but I don't know more than that.

I've also noticed, looking at these pictures, that there are some colored stripes down the back. Presumably these signify something, but I'm not sure what.

[Whoops]

What do the people athe Diystompboxes or Freestompboxes forum say about it?

did you see the following link?
maybe it's useful in case you need to get replacements transistors

http://www.geofex.com/Article_Folders/Ludwig_P2/Ludwig%20Phase%20II%20Clone.pdf

[soapfoot]

I'm well-acquainted with that link, but thanks for sharing it!

I tried registering for DIYstomboxes weeks ago, but I never got the activation email (not in spam folder either). I tried multiple times, and ultimately gave up (and just assumed that they must not be interested in new members).

In the document you reference, RG Keen specified 2N5551 for all NPN transistors in the unit. I'm certainly open to that, however I'd love to understand what the original parts were, and understand the degree to which that's an ideal substitute in each individual case.

Ideally, I'd love to find something as close to original as possible, and also just to understand exactly why certain parts (presumably hFE grades) were selected for particular locations.

My goal is to get this performing as close to original as possible (even more so than "as close to optimal as possible," if that makes sense).

[Blue Jinn]

OT but I had trouble registering at DIYStompboxes  as well.

[soapfoot]

I gathered some data today and I thought I'd share it here in case anyone is doing a search with a similar issue in the future.

Turns out the transistors I was concerned about were okay, and in order to verify that, I removed them all and measured them with a simple transistor tester. In the process, I recorded my data so that I could share it here.

The one marked 43173 (painted green on top) is a simple NPN bipolar junction transistor, There were four examples of this, with hFE between 164-206 and Vf between 832-846.

The one marked 43174 (yellow paint) is the PNP partner to the above, with hFE between 141-263 and Vf between 770-839

The one marked 43175 (blue paint) is an NPN bipolar junction transistor with hFE of 421 and a Vf of 764

The one marked 43176 (red paint) is the PNP partner to the above with hFE of 268 and Vf of 783,

Fortunately, I won't be needing to chase these down at the moment, so I'll consider this one closed. Thanks for looking!

[Whoops]

I tried registering for DIYstomboxes weeks ago, but I never got the activation email (not in spam folder either). I tried multiple times, and ultimately gave up (and just assumed that they must not be interested in new members).

I registered there many years ago and had no problems.
But lately since the covid lockdowns I had problems in registering in a different number of forums, probably due to problems in maintenance at this point.

Anyway, that forum is useful but I much prefer the Freestompboxes forum

[PRR]

> tried registering for DIYstomboxes

Like ALLLLL "DIY" forums, they are suddenly rich with people who Joined in March or April 2020. Obviously many are getting in. Aron may be a little backed-up... but must be approving many members.

[JohnRoberts]

Those may be house numbers for a large manufacturer...

Peavey used a number of motorola TO3s, but our house numbers started with 704xxxxx as I recall from decades ago.  As I recall they were popular motorola parts just specified tighter for some useful parameters.

JR

[soapfoot]

Thanks, John--that definitely seems to be the case here.

There are also several National Semiconductor transistors in this unit that also have nonsense part numbers--and they're also all six digit numbers starting with "43."

[JohnRoberts]

Thanks, John--that definitely seems to be the case here.

There are also several National Semiconductor transistors in this unit that also have nonsense part numbers--and they're also all six digit numbers starting with "43."

Most mainframe MRPS (material resources planning system) inventory software used 8 digit part numbers. The first two or three digits defined the general type of component. Often production ICs have additional 4 digit markings that refer to year and week of manufacture.

JR

[mjrippe]

Thank you John, that is great info to have.  I see a lot of mfg part numbers and that helps to make some sense of them.

[soapfoot]

Although this unit was marketed by Ludwig, the circuit board art seems to have the old Electro-Voice logo. Perhaps they manufactured it, and the in-house part numbers are theirs?

[Audio1Man]

Hi soapfoot
As a mfg you can go to ON,RCA, TI  or other semi mfg and buy a selected  2N3055 or other standard part with special specs and they assign an internal HOUSE NUMBER for you. I did this @Acoustic Control, BGW, and several other places  just like John did @ Peavey.
Duke

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