Re: [Amateur-repairs] Old test eqpt? Chuck it? Refurbish it?

Hi all,

The real Achilles heel of those analyzers is the flyback transformer. Long ago I had spare kits for them and, trust me, they sold like hot cakes!. Now it is just unobtanium. Another failure points are the OM-345, OM-350 and OM-360/370 amplifiers. But for those there are still some replacement assemblies sold online. I sold also the original ones for a long time and still have some of the models. When they fail, the error codes come in groups, sometimes all and every one.

All in all, I still have a 2955B and is a great instrument, even if the ones I use daily are the the R&S CMTs

73 Jose EB5AGV

El 01/07/2025 a las 9:18, jahman via groups.io escribió:

Well, you're in luck!

Marconi 2955 Communication Service Monitor

$1,990 - https://www.ebay.com/itm/284689545136

$1,950 - https://www.ebay.com/itm/356941529543

$1,750 - https://www.ebay.com/itm/356583617089

$1,523 - https://www.ebay.com/itm/286439999912

$1,340 - https://www.ebay.com/itm/386832700583

73 de Andrew/N5ASE

-0-

On Tue, Jul 1, 2025 at 2:56 AM maxwelloau via groups.io <maxwelloau=gmail.com@groups.io> wrote:

At an Amateur convention recently I picked up two Marconi 2955 units that had been stored in farmer brown's shed for years. 

1) All self test failed. Required 4x 4k7 resistors + 2x 220uf 25V capacitors. Unit is in calibration when compared to a 2024 NATA calibrated 2955R and Agilent E4421B signal generator. 

2) Full of millipede carcases. No corrosion except small section on rear panel, was fully operational (some scope waveform trigger problems). Old FW was updated but had to include the CAL chip all from another unit. Scope problem was edge connector cleaning. So some calibration was required and manually its a painful process but as my time is retired and worth Zero, its a labour of love. 

 

A testament to the good design Marconi, their designers and the reliability of normal components like R, C, IC and relays.  I marvel at the green CRT quality and both 100% usable after 30+ years.

End result is two units destined for the metal scrap bin are now usable and in fact more than very good.  Sought after for anyone testing RF and radio equipment. 

With the good info from groups.io and using the technician brain you cant beat repairable in my books. 

maxwelloau

 

--   73 EB5AGV - JOSE V. GAVILA - La Canyada - Valencia (SPAIN)     http://agvradio.com  AGVradio     http://jvgavila.com  Personal WEB