Triller element versterker Tira BAA120

De binnenkant

Een versterker om triller elementen aan te drijven. Je sluit er een functie generator op aan als bron dus eigenlijk een soort audioversterker.

Ik had geen triller elementen maar de versterker had voldoende aan een 4 ohm load. Deze zit in dat blik tussen scoop en amp. Een berg weerstanden parallel in olie gehangen. Werd aardig warm toen hij vol open ging.

Fixed

Julabo oilbath

Julabo after repair

This is an oil bath with a compressor to cool and a heating spiral to heat the oil. There also is a pump in the bath. That was stuck. Besides that the two mains switches where burned and a lot of other small problems. It was not used for a long time. They are not very handy to work on. It needs to stay right-up because the compressor does not likes it to lay on its side.

The controller

 

Magnetometer

 

Yep, that’s all folks

Here is an instrument you do not see every day. A magnetometer, the voodoo is in the fluxgate sensor. But that is nothing more as a boring grey piece of potted tubing. The principle is not so difficult but building a good sensor is. (so I’m told) The 3rd part is software to analyse the data.

The real magic comes from the man who uses this instrument to measure magnetic fields in X,Y,Z directions on places where they have, or want to install, a scanning electron microscope. Those magnetic fields can influence the beam of electrons in the SEM. Interpreting of the data is complex and not many people do this.

The owner was in Norway when it died and he contacted me. He brought it to me the next day and collected it the next day on his way to Germany. It was not a very complex repair. I also placed a new battery the owner already had. The old one bulged and was almost penetrated by the pins from the components because it is mounted under the pcb.  It had a low battery beeper but the owner did not hear that  so I mounted a bright blue led that lights up when the beeper goes on.

 

A real Phluke PM-3335

Very nice scope

This scope is a bit confused. Is it a Fluke or a Philips, or both. Philips on the front, Fluke on the top of the cabinet.

Not much wrong with it. It had starting problems, the PSU wined and there was a broken knob- shaft-potmeter. I made a new shaft for the potmeter, serviced the powersupply and checked the rest. 

It is made very service friendly. The cabinet is made to hold PCB’s in a service-position

build-in PCB extenders

The underside

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. 

More PCB repair

These burned things began their lives as resistors. The problem is the pcb is fried too.

Not good !

First step, make pictures and a sketch and then I mill away the burned section.

After milling the burned section

Then I make an insert and glue that in.

Ready to rebuild

I connect the new pads to the rest and cover it with pcb coating

After coating

And this is how it looks like finished

I took bigger resistors and lifted them from the PCB