Secutest repair

Because I get more and more secutest for repair, I experimented with several fixtures. Secutests are a pain to work on because there is no room and there are dangerous voltages inside.

There is a PCB with big relais:

Relais pcb

This is one of the many versions. The PCB hangs upside down in the cabinet. The view is blocked by most models, by a transformer and many wires. Many problems come from this PCB. I remove the relais, check and service or replace them and clean the pcb. Often there is a lot of dirt under the relais. Do not ask how it gets there, I do not want to know the owners do with these instruments. Most have a hard life but can get quite old with some TLC. G&M does not provide service information, so I reverse engineered it and made my own schematics. 

After cleaning

The pcb that piggybacks to the display pcb’s

Also a lot of relais that connect test signals to the banana jacks and analog signal handeling.

The display pcb

The rotary switch contacts, LCD display and digital signal handeling.

The powersupply and some signal handeling stuff

There are several versions of this board also. The one above is temporary without the 5 relais. I removed them to repair some inner PCB damage. But how to measure in this beast under power without electrocuting your self, it is very dangerous for a service tech inside there. 

This was no succes

This setup was no succes, because the short cables and high voltages I do not like it if all pcb’s are loose on the table (and half over each other because the cables are to short.

so I mounted them on a perfoboard. Better as nothing. Then a customer gave me a box with junked secutest parts. I made a fixture from an old cabinet and some extension cables. This was a big improvement. It is flexible and safe. If you want to work on your own secutest be very careful, nothing is labeled. Cable colors are random. No silkscreen. The pcb’s are multi-layer and you need a very good and powerful (de)soldering gear (and desolder skills). 

The latest fixture

Another view

I use a small “thing” to simulate the DUT (device under test). It holds a resistive load, on/off switch, indicator light and some resistors (f.i. a 110M for Riso, a 7 ohm for Rsl, etc) to check all functions. 
The problem is there are many versions. Not only with different hardware but also regarding the menu’s and functions. 

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