Tektronix AM503: Noisy Q230 Dual JFET

The truth that (*2*)converting R220 additionally modified the noise must have pinpointed the noise supply, however such issues are all the time extra evident on reflection than in actual time working. This put up must assist me get started the following debugging spree a bit of additional up the educational curve.

The AM503 sign trail features a pair of … distinctive … differential amplifier ICs made via Tektronix again within the early days of built-in circuitry:


“In case you have removed all which is not possible, then no matter stays, on the other hand unbelievable, will have to be the reality.”


As a result of Q230 is socketed, I pulled it out and popped it into any other AM503, whereupon the noise adopted the transistor:

quite grisly as-is situation or as (*6*)New Previous Inventory collectibles.

In all probability a (*4*)center floor would suffice? A few the ones must arrive shortly, nevertheless it’s no longer transparent they’re a drop-in substitute.

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