Repair: R&S FS300

[Bicurico]

Hello,

I have been asked to help on a possible R&S FS300 repair.

The device shows these errors:
---
Device error "7FFF"
Confirm Message with ENTER
---
SYS-Menu

Self-Test Error

Voltage AB Error 0x0800
Voltage DB Error 0x00004000
VCO Error
---
Message

Message: FS ERROR 0x8E00
Parameter 0x00007000 and 0x0000
---

Any ideas what these errors mean? I understand some voltages might be out of spec, but what, where, how?

How feasable is a repair? Could this be just a couple of capacitors one has to replace or is this some complex laboratory only repair?

Is there a service manual?

I am reluctant to accept the challenge and would know about your opinions.

Regards,
Vitor

[Qw3rtzuiop]

Hello,
there is a service manual available on Gloris for FW version 2.8 and newer. But it is not very useful in regard to your error codes.

It sounds like a voltage error. But the PSU checks its output values itself. If the LEDs are blinking during boot up it should be an PSU issue. Otherwise it looks like an issue on the front end. The front end also contains an analog board (AB) and a digital board (DB).

Fun fact:
The modules of the instrument (Controller, PSU, Frontend) are using USB for the communication between the modules.

[Bicurico]

Thank you for the information.

Can you give me an opinion on how repairable the AB and DB are?

Regards,
Vitor

[Qw3rtzuiop]

Thank you for the information.

Can you give me an opinion on how repairable the AB and DB are?

Regards,
Vitor

Im sorry. I dont know. There arent even pics of the board available. The most useful thing from the service manual is the block diagram. But even that contains not much information.

[Dino KL0S]

My FS300 suddenly died recently and I'm guessing it's a power supply failure and need to dig into it...R&S told me it's too far out of life cycle to even look at. If anyone has had a similar experience please chime in! 73 - Dino KLØS   

[DC1MC]

Kind of side question, has anybody seen a tracking generator board for FS300, in the chassis there is a socket for it, also in the front panel an opening, but I've never encountered such a board, if anybody has any information, it will be appreciated
If it has a tracking generator board, please contact me, I'm interested in buying it.

 Cheers,
 DC1MC

[Qw3rtzuiop]

The FS315 has a tracking generator board.

[Bicurico]

Update: I declined and suggested to the owner to sell the unit "as is". While it has these faults going against it, it has the fact that no repair attempt has been carried out in favour.

I believe the the value of this is unit can be assumed as: repaired OK > broken, but untouched > broken with unsuccessful repair attempt

Since chances are low that I would be able to repair it, due to no documentation and little response from this forum, I did not risk "helping" a friend, as the most probable outcome would be money spent in shipping plus loss of value.

Thanks for your help!

Regards,
Vitor

[Manolo Mos]

Hello. This is my very first post in this forum.
Well, I've seen another RS FS300 with the same symptoms.
The problem was the tiny fan at the back side stucked. Just replace.

[Bicurico]

Thanks!

I will ask the owner to check the fan. Would be amazing if that is the only problem!

Regards,
Vitor

[CaTeR]

Hi @Bicurico - did you had any luck by checking the tiny fan?


best regards

[Bicurico]

No. The device was sold as is before the hint regarding the fan was posted.

Regards,
Vitor

[Steverook1]

Mine too !! did replace line fuses and these expired on switch on. Now taking apart the unit to explore the power supply (All screws removed so far have been loctited in) Hoping I can repair.

Regards
Steve

[Steverook1]

Hello,
 I wonder if you can identify the large transistor/diode and the value of the resistor which seems to have let all of the magic smoke out. The transistor/diode appear to be short circuit. There is also another transistor on the other side of the pcb 11N30C3 which appears to be short circuit. The resistor would appear to be connected to the bridge rectifier.
Determined to get this unit working again

Regards
Steve

[Steverook1]

An update having replaced resistor, diode & transistor (which were short circuit & open circuit for the resistor) at least the unit now powers on without blowing fuses and the fan is running but the bad news is all the error messages similar to what Bicurico posted on 4 Jan Voltage AB ,Voltage DB so its looks as though back to the drawing board. At least some voltages are marked on the other pcb to where the blown up components were. Not sure how one is expected to measure these though ?
I wonder if it is possible to run the power supply out of the unit not attached to the backplane (seems unlikely but worth asking?)

Many thanks

[vertsyeux]

In case anyone finds this post and has some info, my PSU board expired spectacularly. With fried components on both sides of the board and no schematics available for the power supply, I'd say this board is deceased. I see from the block diagram that the main supply is 17.5V @ 6A and wonder if wonder if anyone has had any joy feeding the DC-DC converter board from an external supply - this would ascertain whether the unit is at least salvageable..

[dl6lr]

I see from the block diagram that the main supply is 17.5V @ 6A and wonder if wonder if anyone has had any joy feeding the DC-DC converter board from an external supply - this would ascertain whether the unit is at least salvageable..

My FS-300 runs with a laptop power supply inside after the original SMPS released the magic smoke.

[vertsyeux]

Thanks dl6lr, I ran a couple of wires out and it works fine of my bench supply. I'll get a Lambda or XP 18V/5A module off RS or Farnell and built it into the original enclosure..