WAVETEK SCHLUMBERGER STABILOCK 4031 Repair and Fix

WAVETEK SCHLUMBERGER STABILOCK 4031 Repair and Fix
Thanks to Paul Kelly G3SDH
for the Repair documents and web information.
Download service manuals.
Do these repairs at your own risk, this video is for information only.

The 4031 RF Attenuator fix can be found on the following link.

This is a comprehensive repair, you will need the service manual, for card and component identification. If the Power supply rails , 5v, 15 and -15v are correct check the rear Card 1 10Mhz output is not drifting, if all OK move onto the removable cards, change all the 10uF, 2.2uF, 22uF, 47uF and 100uF SMD capacitors, around 50-70 caps, take your time and check all the tracks after replacing the capacitors. I would suggest trying a few different removal techniques.
I also checked all the SMD RF coils/chokes on every Panel. Two were found to be open circuit.
UHF SYNTH 213-041
BOARD 461-436 03, REPLACE L3 560nH

FM Modulator 217 031
BOARD 461 455 05, REPLACE L3 10uH.

To do in circuit tests, you will need Riser/extender cards.
Not all the cards have capacitors that need changing but i would recommend a visual inspection for damaged tracks, dry joints etc.

[funktechnikdirk]

Very nice video!
I ❤Schlumberger 4031 Stabilock!!!
LIKED & SUB

[nameone]

I refurbed 2 of STABILOCK 4015 units. I replaced all the caps. Using 2 soldering irons. First put flux on the joints, then both the irons. When the cap is off, clean the solder with wick then clean the pads with IPA. Took about 20 hours to do 160 caps. Then I still had to fix the faults.

[uki]

Nice repair run through! You should consider changing the large caps on the PSU. A failing -15V (dropping low or having very big ripple) will also produce the same error behavior that your unit had shown. Some factory placed caps were used very close to their limits, like -15V supply is generated by a inverting regulator and uses 16V capacitors. You can get modern capacitors with the same height, diameter and pin distance but 25V and 40V. Use only 105°C at 5000h or better. 73 de DC3AX
And I am pretty sure you forgot to recap the counter unit. It is mounted under the attenuator outside on the wall of the RF cage.

[boxingday]

Great job, I was wandering if you take on commissions?