Retrofitting a 1986 Maho MH400E

the 29Volt is a bit to high, but not the cause of the problem.
The Machine was built for 380/220V.

I believe Brad measured them without e-stop switched on, so this is the Voltage without any load.

I remind that the big transformer in the back has other windings for higher main voltages, so they can switch them.

[strike]Did you press CE button after stromunterbrechung?[/strike]
sorry, type too quick, read too slow (:
If you need some parts for tnc I could probably find some... I am from middle EU.

Hi All,

I have already had the TNC to my electronics serviceman, He has replaced capacitors and found the 5V Rail was down to 4.75V, he has fitted an external 5V supply to the internal 5V Rail.
The TNC would not complete the startup sequence while it was being bench tested without the Maho Connected to it.

Brad

Hi Brad,

this sounds like bad eproms to me, but chris wrote that the eproms are already exchanged....

Did you have an look on the service manual from the tnc.
In this you will find test routines for the single boards, and description of the leds.

Brad
I was wondering if the external 5 volt supply is a switching or a linear type power supply?
While the TNC is on the bench , could someone check

---

-- the sweep frequency --- video signal levels that go to the video monitor ? Would be useful if the monitor is up graded to a LCD type.
-- the voltage going to the LS 403 scales from the TNC X-Y Z connectors. Think pin 4 =Com an pin 3 =+ 5 volt DC , Please ask Mark or db1981 to check which pins as I may not remember correctly.
Any thought of while at the bench to emulate some of the MAHO signals to see if the TNC will progress further thru the boot up sequence ? db1981 has provided a digram of the signals .

During the MAHO down time, any thoughts on replacing the old DC caps ___ in the Indromat 3 TRM 2 _ the MAHO 24 volt DC supply? _ the monitor?

Remember that back in the 1970s or 1980s IC chip manufactures tried using aluminium bonding wire vers gold , what a disaster that became. Could the replacement eproms be New Old Stock with that bonding wire mess up?

The tnc has to startup with a Text Message , only with power connected .

There are 2 x 5V rails, arme they both checked ?