Burnt MST3 and SL3 on Wersi DX500

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Fonsspons
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Burnt MST3 and SL3 on Wersi DX500

Beitrag von Fonsspons »

Hi,
my name is Jo, I'm new to the forum.
Purchased a fully functional Wersi DX500. While unplugging and replugging the MST3 and SL3 cards I made a terrible and stupid mistake... Switched the MST3 with an SL3. with smoking results. Both cards are broken now. I'm trying to figure out what has possibly burnt. looking at the pins and the schematics, I am under the impression that the SL3 should have less damage than the MST3 (although that was the smoky one). I put the pinlist next to each other and notice that an SL3 in the MST3 slot will result in the same 5V on the same pins (5V on P29 and DGND on P32), but otherwise when an MST3 being put in the SL3 slot, that will result in much worse, namely 15V on SCS4 and Res-in(?), 15V on SCS2, and -10V on SCS2,3,0(or8) and SCS1, while sharing the same AGND. I'm trying to figure out the possible damage to both cards via the schematics in the assembly manual, but that is taking me a while.
Somebody here that can help me?
Much appreciated!
Greetings from Belgium
Jo
(Oh, and a big thanks to Happy Freddy for all the pdf files!!!)
happyfreddy
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Registriert: 19. Jul 2012, 09:32
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Re: Burnt MST3 and SL3 on Wersi DX500

Beitrag von happyfreddy »

Hi,

I think that´s the worst case will happen.
The simply best to do is using a new MST 3 .
First even is to check if there is any copper line on both sides of MST 3 " burned up " = no connection
between the routed pins any more...
I think only the ICs will be damaged and not the board itself.

Second to find out the burned up ICs
You are right that there are some connector pins possible to make here the worst scenario

Pins SC 0 , SC 1 , SC 2 , SC 3 of MST 3 have on slot SL 3 a connection to - 10 V / - 15 V.
The corresponded IC is IC 24 ( 74 LS 138 ) at his output pins. I think that IC is now defect

Pins SC 4 and Pin RESIN are connected on wrong place SL 3 with + 15 V

SC 4 runs to same IC 24 with same result

The pin RESIN is named as line " 15 " and this runs to IC 11, 12, 16 ( TIMER ) and Master IC 1 68B09

I think You can forgot those ICs and declare them as DEFECT.

To check the SL 3 its very easy to find out damaged ICs.
First try to run this SL 3 alone, If it doesn´t run find out what IC is damaged :
Just change one IC after another with a runing SL 3

If any problems contact me via PN
I can test the boards and repair them
Fonsspons
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Re: Burnt MST3 and SL3 on Wersi DX500

Beitrag von Fonsspons »

For the moment I can not do any test on the DX, since I have no MST3 to boot. I am awaiting a box with 5 slaves and an MST in 2 next weeks... That should give me plenty of room to test things out. Let's hope I can fix this! I already cleaned the 2 boards and see no signs of interrupted lines. I might unplug the ic's and see what might be interupted.
Thanks for the input, will keep u updated on the progress!
Thanks
jo
happyfreddy
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Re: Burnt MST3 and SL3 on Wersi DX500

Beitrag von happyfreddy »

Ground and plus 5 Volts is on both boards at same pins

Analog Ground ( AGND ) and digital Ground ( DGND ) are connected together at Power Supply

So a voltage of + 15 V and - 15 V resp - 10 V works

I don´t think that the SL 3 has any damage but still the MST 3 on place at SL 3 in the rack.

The output pins of the decoder 74 LS 138 ( SC 0 , 1 , 2 , 3 , 4 ) connected at wrong place with - 15 / - 10 V and + 15 V
will still damage this IC.
For + 5 V works the output pins at PD 3, PD 6 , PD 7 and Q 3 are connected at wrong place with AGND which means then
DGND , so this latch IC will perhaps also be damaged bacause output pins shortened at wrong place
Surely damaged will be the ICs connected to RESIN which has on wrong place a connection to
+ 15 V.
Ths means the processor and the TIMER as same both RAMs

So You also have to control the power supply PS 12 with the 3 LEDs for + 5V , + 15 V and - 15 V

When the voltage of + 15 V is missed th voltage of + 5 V will not work correctly because therefore
this voltage of + 15 V is needed.
Also on the power supply is the RESET Logic IC 7705 . His output signal is the RESIN Signal at backplane MB 40.

If You get a new MST 3 and Slaves don´t try the old MST 3 any longer. just use the new one

At the Slaves You have to look what type of Slave You got.
There is a differnce between old SL 3 and newer SL 30.
You can see it quickly when regard the orange Tantal Elko´s at IC TL 084

SL 3 has a value for this Elkos of 2,2uF
SL 30 has a value of 0,33 uF

Don´t mix the Slave types, only use same as in Your organ located.
Fonsspons
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Re: Burnt MST3 and SL3 on Wersi DX500

Beitrag von Fonsspons »

I will put your explanation next to the schematics tomorrow and see if I can work things out!
Thanks!!!
Fonsspons
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Re: Burnt MST3 and SL3 on Wersi DX500

Beitrag von Fonsspons »

Hi,
sadly I am still waiting for my cards from the UK.
Meanwhile I see a Combo and a DX10 for free. Any spare parts in there for my dx500???
Thx!
Jo
happyfreddy
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Re: Burnt MST3 and SL3 on Wersi DX500

Beitrag von happyfreddy »

hi,
The COMBO Organ is from age of Helios generation 1976 and a special model
( transportabel with 140W Amp integrataed in lower case part ) of the ORION.

In this organ You don´t find any component usable for Xour DX 500

The DX 10 is the OMEGA organ and same as the Expander EX 10
It os based on the Synthesizer MK 1
Some chips will be same as used in DX 500 but there is no reason to buy this organ only for getting some
spare parts for repair of the DX 500.
I hope You get ordered parts from GB soon
Fonsspons
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Registriert: 14. Jan 2021, 01:20
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Re: Burnt MST3 and SL3 on Wersi DX500

Beitrag von Fonsspons »

Ok, thx! I leave it then. It is crowded enough here! :D
IMG_20210305_170056.jpg
(2.15 MiB) 688-mal heruntergeladen
DX500 cards were send back to the seller by customs. He payed my money back. He now wil try to smuggle them to Brussels. Only have to pay him when received. Crazy story! :D
Fonsspons
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Registriert: 14. Jan 2021, 01:20
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Re: Burnt MST3 and SL3 on Wersi DX500

Beitrag von Fonsspons »

Hi,
due to summer, have been working a lot outside. Hence the log absence here.
But, the MST4 cards did arrive well and are properly installed in the DX500. It's working great!!
Thanks for the advice. Much appreciated!
IMG_20210830_140946.jpg
(2.51 MiB) 140-mal heruntergeladen
Klausph
Beiträge: 40
Registriert: 14. Aug 2021, 21:22
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Re: Burnt MST3 and SL3 on Wersi DX500

Beitrag von Klausph »

Wow this looks like a Wersi with 4 or 5 manuals :shock: :D
Btw. did I see a Saturn there on the other picture?
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