TNP #40 - Stanford Research FS735 Dual Distribution Amplifier Teardown, Repair & Experiments

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8 ай бұрын

In this episode Shahriar repairs a fault SRS FS735 dual distribution amplifier. These instruments provide two independent 7-channel 10MHz distribution modules with exceptional signal purity and isolation. The instrument does not properly powers on which points to a potential problem with the internal power supply.
The unit has two identical power supplies; one for each module. Both power supplies have a failed startup capacitor which can be easily replaced. After the repair, the power supplies are verified for functionality and power delivery. The schematic of the entire unit is described as well as a view of the module PCB. The performance of the unit across frequency, harmonic distortion as well as isolation behavior is also measured and verified.
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Пікірлер: 67

@jhonbus

Ahh, the classic "ovenized bootstrap capacitor" PSU design...

@bioazard50

Had the same failure in our lab. I ended up replacing both power supplies and it's been running perfectly for a few years!

@trevorvanbremen4718

Thank you VERY much Shariar! While I do love your typical video where you play at the 'daylight' end of the spectrum (GHz / THz), I truly appreciate that you still throw out videos down at my DC end of the spectrum (MHz in this case)

@garci66

Loved the Chernobyl reference ;).

@IanScottJohnston

Those 4mm banana adaptors on your BK Electronic Load are worth their weight in gold.....nice one!

@purerhodium

I love Pooch.

@gwyllymsuter4551

Always informative

@ChrisSmith-tc4df

I have a pair of the half-sized FS735 10MHz distribution amps. I found the limiting/reshaping functionality quite novel and unexpected, but that does ensure a consistent output amplitude over a wide range of inputs without relying upon AGC as well as transforming anything in to sine wave output.

@R2AUK

👍 The schematic doesn't look complicated and doesn't seem to contain rare parts. Looks like something that can be easily replicated if necessary.

@aqib2000

Hi and welcome the noise path

@WAEviltechie

Distribution amplifiers are very frequently used in the broadcast industry for SDI, but also for analog reference signals like black burst or tri-level sync. Could be fun to take a look at one of those and see how it compares.

@Richardincancale

This video reminded me of a video that I now see is ten years ago(!) by Gerry Sweeney on YT on how to take an old Rubidium clock from eBay and turn it into a 10 MHz lab standard. IIRC he used a cable TV multi-port amplifier to provide the functionality of the SR unit here. It would be fascinating to compare the results!! In practice it worked fine for his home lab, maybe not to Shariah’s standard though :-)

@ChrisSmith-tc4df

I would have used the BNC T at the scope input such that it is the shortest stub on the 50ohm transmission line.

@blays.7178

Just went on google to see if i could afford that lcr meter and hoooooooly meter, this thing is way up to 15k.. I guess i will use my f generator and scope for a little more time.... But maan this thing can measure leakage and everything... Could not imagine what else could do in L mode... you are a lucky guy to play with tools like that and you also posses knowledge that is very very rare... i watch your channel from very beginning and i love it every single minute... You are super professional and know your stuff... Thank you soo much, to share that knowledge like that, you truly are awesome person :] also say hi to pooch :D

@raymiller5738

Thanks, Shahriar, seems to be a theme going with SMPS, looks like some component specification issues throughout the industry. It is possible to get to the bottom of some of the common failure modes?

@vincei4252

The ex-girlfriend joke made me laugh more than I should have 😂

@AndrewZonenberg

Is this essentially the output stage of a FS752, but without the GPSDO driving them (requiring the 10 MHz to come from somewhere external)? I've been dreaming of getting a FS752 for my lab for a while now.