|restoration of a wavetek 3000 signal generator|
|by ralph klimek 2014 |
|The wavetek 3000 is a late seventies advanced multi PLL signal generator with coverage from 10Mhz to 500Mhz and numerous options for coverage and modulation methods.|
|This unit had been recovered from a dumpster and was non functional. Recently a poor quality manual has been found on the internet. I have extracted the images from this source and cleaned them up using the GIMP.|
recovered manual was used to find the many faults that were present and
still present with this unit. My advice to people finding one
these units at a flea market or dumpster is to leave it there. There
are too many problems with this unit due to the serviceman un-friendly
construction methods, most notably needing to remove and open up
numerous tin cans to get at the circuits. Mine has been brought
back to life in as far as the unit produces a constant level frequency
stable output , that is, alas only loosely related to the thumbwheel
it also had numerous inherent implementation issues that were beyond tolerance or repair.
You will find that the +/- 18Volt supply rails are at zero volts. This is due to numerous tantalum capacitors inside the many tins having turned into short cicuits. Finding them was the motivation for my Kelvin Probe project. The dead bug construction method has not contributed to reliability either. Wavetek did not believe in using PCBs ! It has all been done with point to point wiring, nicely done, but it must have cost them a fortune in expensive american labour. I redid the PSU with three terminal regulators. Lets face it, the designers of three terminal regulators were better designers than me !
The power supplys did not use 3 terminal regulators, which were available when this unit was designed. Instead, they made their own regulators using the impossible to replace LM135 "indestructible" transistor. Guess what ?
This is the one that even after all my work, will consign this unit to landfill. Lack of consistency in the manual means I cannot really debug the electronics, the manual does not describe all the tin cans, only the basic default models units. My present fault condition renders the output frequency to be only loosely related to the machines settings, but very stable !
Some Praise is also due.
The circuit design is highly advanced and I believe, that when this unit worked, it displayed unprecedented low phase noise and lack of spurious output. I have also read that this unit provided a Gold standard in phase stability and low noise for its time. The circuit design is worthy of something that HP would have done but implemented correctly.
The tin cans are not sealed, can be easily removed just by unscrewing the lockdown screw. It is not require to unsolder all the connectors....I was laboring ,incorrectly, under this illusion. The teflon terminal posts are actually a plug and socket ! The maintenance method was to indentify the failing tin can and return to manufacturer. Some tins were utterly and completely beyond inspection and repair due to internal progressive assembly.
Utter and complete condemation.
see my epilogue below. IC sockets in a place that is totally and utterly beyond reach and repair.
IC sockets should never ever be used for production equipment, only for test and development and eproms.
clicky here ! is the complete manual image archive ! I have
downloaded the manual that has recently appeared (I have lost the
reference but many many thanks to the kind person that scanned it and
make it available. I have doctored the scanned images to
remove crud and make them legible and printable using the tools provided by the GIMP.|
|all these capacitors must be replaced. They will all become shorts or are shorts||the front panel pcb has been liberated||the businesslike front panel|
|millions of tin cans. label the coaxs before removing them ! Not all the tins are described in the manual. Ouch.||thumbwheel connectors. One of my thumbwheels has jammed||output attenuator module|
well worth saving from landfill
|the backplane provides many usefull test points||these are not just terminal posts, they are sockets ! Dont unsolder them !||most of the tin cans contain this style of construction. It is very amatuer dead bug style, good for one off construction but it must have cost a fortune in labor. Maybe I got the "missing prototype" unit ?|
|blank||on the left, IC sockets inside all the tin cans. Intermittants anyone ? Why were they not soldered in, why no PCB ? adjustments not reachable from outside the tin. Was my instrument the prototype ? This is a relatively clean and good example.Some ic sockets were inside fully soldered up tins. Many Adjustments could not be reached from outside the tins.|