Excellent!!! Nice repair, Scott. Changing those bulgy caps seems to me to be a good idea even if the unit was totally working. I've used several different models - the Marconi 2945A, the HP 8920A and even the dreader Singer CSM-1 - and they are all very versatile. I guess that's why they are all so darned expensive (except the Singer).
That's a blast from the past. Memories of using that on mountaintops when working for NZPO Telecoms. It was a wonderful beast compared to needing 3 times the volume of instruments stacked in the back of the 4wd to do the same job (yes, volume - I'd need 3-4 45 litre fishboxes worth, vs just this unit occupying one) I'm surprised this unit needed recapping - mid 1980s electrolytics predate the taiwanese electrolyte theft issues but they had high inductance due to the winding method in use (offset layering didn't come into widespread use until 1992 - this greatly reduced ESR) FWIW: acceptable spec on electrolytics is +150-20% - and as long as those caps have a 0.1uF bypass nearby I wouldn't have replaced them (This was normal on older designs for PSU rail noise bypassing) WRT using silver solder: Don't. The boards are built for and tinned with 64/40 solder. Using lead free solder WILL result in cracking issues in a few years
Funny that I had to tweak the one I have last week for the same thing. Well now you swapped out those capacitors should be good for another 20 years. I still think they are the best analyser I have used. Although I have just bought Stabilock 4040. I don’t know why Stabilocks are all a pain in the arse.
@@TheDefpom once Macaronis disappeared from the market due to the GEC-Plessey takeover in 1988(*), there was a dearth of decent combined instruments We wanted to buy another 20 2955 units after being deliriously happy with the original and found that nothing on the market came close to duplicating its functionality whilst all being more expensive (*) it's not quite true, there were replacement models but the 2955 doubled in price during the takeover and became unobtainium after 1989 whilst the GEC-Plessey/Ferranti "military spec" model which came as an "upgraded" device was even more expensive, substantially inferior in almost every respect, not portable (HEAVY!!!) and didn't take kindly to being chucked in the back of a 4wd then taken up a mountain goat track I'm sure that 'mil spec' was shorthand for "A casing heavy enough that oiks in combat boots can't kick it to death" but the temperature stability and long term accuracy were shirty, to put it nicely - and dropping it really upset the internals in ways that the 2955 would just shrug off
Hello dude! Mine is a 2955b, i noticed that when in tx-mon (option 1 fitter), receiver sensitivity is shit, however im not sure where to look for as i no have any schematic or service manual. I suppose maybe receiver front end has some amp failing....
Interesting video Scott> I've got no idea what it 's for but I enjoyed watching you repair it. Do I win a lollipop for noticing you subliminal messages? Even the upside down one. Proves I was paying attention.
Those through partition links he calls penetrators are not meant to be soldered. They are prone to poor connections which is probably why someone has soldered them.
rosin flux (which is what these boards will have given their age) comes off trivially with alcohol and a toothbrush (meths or isopropyl doesn't matter much, even vodka will work) NB: i don't recommend using the toothbrush for its intended purpose after cleaning boards. It may taste funny...
Thanks that will be very good i do see others on youtube but they have all the gear but no idea. i am shure you know now but the component that looks like a relay is a mixer, Good luck from the uk, Dave 2E0DMB@@TheDefpom
That thing that looked like a relay was a double balanced diode mixer, on the subject of om 345 s, they all eventually died in my 2022 Sig gen, I replaced them with mmic s made by mini circuits or avantek can't remember which, they were certainly a lot cheaper than the guy on eBay offering replacements, it's now been working fine for over over 10 years
The MCL SBL-1 DBM was likely one of the most popular, low cost medium injection level RF mixers ever made. I've built at least half dozen transmit/receive converters with it. I wonder if it is still available in the steel hermetic package.....doubt it, or maybe at a premium price.
Hello Good evenings. very interesting her videos! I congratulate you for so much dedication. I wanted to consult him, a few weeks ago I bought a Radio test Set Marconi 2955B and he only had error 23 but then errors 33-35 and 39 were added. From what I could read is that my instrument would be out of adjustment? because I have not been able to determine if it will be an OM-345 problem or just a calibration. Could you tell me how it would be? since you had an error 38 and corrected it with a setting. I do not have the Service manual in good condition it is only digital but it looks very bad. Thank you very much and a big greeting! Sebastian
Without researching this myself I cannot tell you exactly what is wrong, but it at least sounds like they are all from the same board, I suggest pulling boards, cleaning the edge connector GENTLY, and checking for bad tantalum or electrolytic caps, if that didn’t solve it then get a physical service manual (I saw the 2955b on eBay not long ago) and go through the alignment process until you find bits that don’t work correctly.
Those penetrators are not normally soldered. they are spring loaded and press against the boards. someone must have done that to try to solve a problem.
One of them did have a fair bit of tarnishing under it, probably what was wrong originally, they are all soldered now so at least that is never going to be an issue in future.
@@TheDefpom they shouldn't have had tarnishing. All those contacts were gold plated. what kind of atmospheric environment has it been in over the years?
@@miscbits6399 I have seen tarnishing on the gold plated board edge connectors dozens of times on different equipment, it does tarnish and cause problems, it just takes a LOT longer to happen.
Excellent!!! Nice repair, Scott. Changing those bulgy caps seems to me to be a good idea even if the unit was totally working. I've used several different models - the Marconi 2945A, the HP 8920A and even the dreader Singer CSM-1 - and they are all very versatile. I guess that's why they are all so darned expensive (except the Singer).
That was a cracking video Scott. Very well done mate.
Great video. Thanks! Would love a video showing the full alignment process...
Nice repair Scott.
I've got a ? Back 20yrs ago, you could test your cb output with a 12v bulb will it work for the ts440
That's a blast from the past. Memories of using that on mountaintops when working for NZPO Telecoms. It was a wonderful beast compared to needing 3 times the volume of instruments stacked in the back of the 4wd to do the same job (yes, volume - I'd need 3-4 45 litre fishboxes worth, vs just this unit occupying one)
I'm surprised this unit needed recapping - mid 1980s electrolytics predate the taiwanese electrolyte theft issues but they had high inductance due to the winding method in use (offset layering didn't come into widespread use until 1992 - this greatly reduced ESR)
FWIW: acceptable spec on electrolytics is +150-20% - and as long as those caps have a 0.1uF bypass nearby I wouldn't have replaced them (This was normal on older designs for PSU rail noise bypassing)
WRT using silver solder: Don't. The boards are built for and tinned with 64/40 solder. Using lead free solder WILL result in cracking issues in a few years
Funny that I had to tweak the one I have last week for the same thing. Well now you swapped out those capacitors should be good for another 20 years. I still think they are the best analyser I have used. Although I have just bought Stabilock 4040. I don’t know why Stabilocks are all a pain in the arse.
AllTheGearNoIdea - what made you get the 4040 when you already have a 2955? They seem to be very similar functionality wise.
@@TheDefpom once Macaronis disappeared from the market due to the GEC-Plessey takeover in 1988(*), there was a dearth of decent combined instruments
We wanted to buy another 20 2955 units after being deliriously happy with the original and found that nothing on the market came close to duplicating its functionality whilst all being more expensive
(*) it's not quite true, there were replacement models but the 2955 doubled in price during the takeover and became unobtainium after 1989 whilst the GEC-Plessey/Ferranti "military spec" model which came as an "upgraded" device was even more expensive, substantially inferior in almost every respect, not portable (HEAVY!!!) and didn't take kindly to being chucked in the back of a 4wd then taken up a mountain goat track
I'm sure that 'mil spec' was shorthand for "A casing heavy enough that oiks in combat boots can't kick it to death" but the temperature stability and long term accuracy were shirty, to put it nicely - and dropping it really upset the internals in ways that the 2955 would just shrug off
Hello dude!
Mine is a 2955b, i noticed that when in tx-mon (option 1 fitter), receiver sensitivity is shit, however im not sure where to look for as i no have any schematic or service manual. I suppose maybe receiver front end has some amp failing....
is that Loctite 362 silver solder? thanks
yes
Interesting video Scott> I've got no idea what it 's for but I enjoyed watching you repair it. Do I win a lollipop for noticing you subliminal messages? Even the upside down one. Proves I was paying attention.
It is a communications tester, for testing transmitters and receivers. How many messages did you spot ? There were 4, maybe 5 I forget now.
I only saw 3. I obviousely wasn't paying as much attention as I thought I was.
Didnt see any. Was too busy watching out for the penetrators.!!! 😲
I would like to know which connector you forgot to reconnect. As my Marconi is showing all failures with the same fault codes. Dave M1FIF.
David Cubitt - it was the ribbon cable that runs to the main pcb from the rf section, which pops out from under the crt.
Thanks I will check it out.
Hello , My Marconi self test fail 3.0 Failed 31 and 3.2 Failed 37
Kindly advise from your point of view. Thanks a lot.
Those through partition links he calls penetrators are not meant to be soldered. They are prone to poor connections which is probably why someone has soldered them.
Yes I came to the same conclusion.
Hi, where do you find a list of what the error codes mean?
Kevin Rea
Lancaster California USA
They are in the service manual, you can find it online.
Hi,
could you show us a sample of how you clean off the flux from the board ?
kevin rea
rosin flux (which is what these boards will have given their age) comes off trivially with alcohol and a toothbrush (meths or isopropyl doesn't matter much, even vodka will work)
NB: i don't recommend using the toothbrush for its intended purpose after cleaning boards. It may taste funny...
Hi
Can you make some more videos of the unit being used,
Thanks Dave
David Browne - once I get onto doing some of these cb repairs I’ve got sitting here you will see it getting used.
Thanks that will be very good
i do see others on youtube but they have all the gear but no idea.
i am shure you know now but the component that looks like a relay is a mixer,
Good luck from the uk,
Dave 2E0DMB@@TheDefpom
@@TheDefpom the phase noise wobble on SSB sounds awful, but doesn’t seem to cause an issue with the SINAD on RX, odd.
That thing that looked like a relay was a double balanced diode mixer, on the subject of om 345 s, they all eventually died in my 2022 Sig gen, I replaced them with mmic s made by mini circuits or avantek can't remember which, they were certainly a lot cheaper than the guy on eBay offering replacements, it's now been working fine for over over 10 years
The MCL SBL-1 DBM was likely one of the most popular, low cost medium injection level RF mixers ever made. I've built at least half dozen transmit/receive converters with it. I wonder if it is still available in the steel hermetic package.....doubt it, or maybe at a premium price.
Hello Good evenings. very interesting her videos! I congratulate you for so much dedication. I wanted to consult him, a few weeks ago I bought a Radio test Set Marconi 2955B and he only had error 23 but then errors 33-35 and 39 were added.
From what I could read is that my instrument would be out of adjustment? because I have not been able to determine if it will be an OM-345 problem or just a calibration. Could you tell me how it would be? since you had an error 38 and corrected it with a setting. I do not have the Service manual in good condition it is only digital but it looks very bad. Thank you very much and a big greeting!
Sebastian
Without researching this myself I cannot tell you exactly what is wrong, but it at least sounds like they are all from the same board, I suggest pulling boards, cleaning the edge connector GENTLY, and checking for bad tantalum or electrolytic caps, if that didn’t solve it then get a physical service manual (I saw the 2955b on eBay not long ago) and go through the alignment process until you find bits that don’t work correctly.
@@TheDefpom Thank you so much! i will purchase the fisical manual and them i will check all PCB´s.
The MF10 is a switched capacitance filter
Those penetrators are not normally soldered. they are spring loaded and press against the boards. someone must have done that to try to solve a problem.
One of them did have a fair bit of tarnishing under it, probably what was wrong originally, they are all soldered now so at least that is never going to be an issue in future.
@@TheDefpom they shouldn't have had tarnishing. All those contacts were gold plated.
what kind of atmospheric environment has it been in over the years?
@@miscbits6399 I have seen tarnishing on the gold plated board edge connectors dozens of times on different equipment, it does tarnish and cause problems, it just takes a LOT longer to happen.
So your blaming Dave for the failure / unplugged ;)