Products > Test Equipment
Marconi 2022E RF signal generator repair and refurb
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bd139:
Thought I should probably write this up in a dedicated thread rather than let it be lost in the noise of the TEA thread.

Bought a Marconi 2022E from scotttrade12 on eBay for £100 delivered. This was advertised as dead, which it indeed was. Well packaged, accurately described. Good job.



Has NO STD on some masking tape on the top. More to follow...
bd139:
After some dissasembling and testing, the root cause was found. Someone nicked the OCXO / TCXO module out of it  :palm:

That's what NO STD means clearly.

According to the service manual this drives the synthesizer and CPU.

bd139:
Some reverse engineering later, the missing OCXO pins were identified and a 10MHz TTL level signal was injected into the synthesizer board 



Temporary bench set up  :palm:



It boots and everything appears to work panel-wise. No idea about the RF situation yet.



Next steps are to build a replacement OCXO module. There is a pot on the rear of the unit which gives an adjustment range on the ADJ pin noted on the board and there are +5V and +12V rail supplies on the OCXO footprint. I will ID which of these is supposed to supply the oven power and go from there. I've measured the footprint out and ordered 5x CTI OCXO modules from Aliexpress. I will produce an adapter PCB for it in Kicad and order from JLCPCB.

Aliexpress link: https://www.aliexpress.com/item/1005003277492150.html

Stay tuned... in about a month and a half  :-DD
Zenith:
STD, an unfortunate abbreviation which has another meaning.

I thought you were being unduly pessimistic about the possible state of this. It has a nice sharp display.

If this uses the standard Macaroni OCXO of that era, they are a dodgy number, especially at 30 years old. If it had come with one, it wouldn't have been as cheap and you would probably have had to change it anyway.

A right result so far. I shall follow the thread with interest.
bd139:
STD may be appropriate for some hardware I’ve used (Telequipment I’m looking at you).

Better to have disappointment elevated than happiness destroyed :)

Designing PCB now. I have a Kicad footprint for the OCXO module after building another one for an HP unit a couple of years back.

Oh investigating the images suggests that the unit is 1989 vintage but the synthesiser board is 1994 vintage which is weird. Possibly factory replacement. The old synth board has a very naff crystal oscillator installed usually apparently. There aren’t even footprints for this on the board.

For the money I’m very happy. I prefer to buy broken stuff cheap and fix it.
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