NSM Triomint - Bitte um Hilfe

[DerKito]

Hi again!

In the meantime, I've done some research on my own unit, which is similar but not the same. My unit is a "triomint gold" while yours is a "triomint".

First off, we need to compare and verify a few things about the control board, or "CPU board". It's the board within the silver box that's plugged into the lower section of the power supply board inside the door.

Please open the silver box and carefully slide the board out. You don't need to remove the screw. Just pry out the three plastic parts holding the lid on either side of the box in place. After sliding the board out, you should be able to see the following (see picture): On the right portion of the PCB, just below three EPROM chips in "upright" position, white letters should say "Ersatzteil-Nr. XXXXXX" (Sparepart-No.) and "Sach-Nr. XXXXXX" (Equipment-No.) both followed by a six digit number. Please either write down the numbers or take a closeup picture of the text. We need to compare our PCB versions so I can give you the proper instructions on where to measure which signal. We'll try to perform our mesaurements on the power supply board later, so you don't need to operate the CPU board outside of the silver box.

[burrerdj]

The spare part number (107190) and equipment number? (028000) are located on the silver box (see picture I send earlier). There are no numbers on the circuit board. Not sure if you need this, but the EPROMs are numbered 107061, 107062, and 107063.

[DerKito]

Alright. That's a bit strange. However, can you post a high resolution picture of the top side of your circuit boards? The one inside the door (the power supply board) and the CPU board?

[burrerdj]

Here are the requested pictures. If all the new capacitors catch your eye, one of the first things I was asked to do was replace all the power capacitors

[DerKito]

Hi there!

Okay. The pictures do help! Interesting that there's no silkscreen on your CPU board. Usually these have silkscreen on them.

I attached a picture. Please measure the voltage in DC at this resistor. It should be around 5VDC. If it's not, then check bridge rectifier "GL3". You can also trace back the connection of this resistor on the power supply board. There should be resistors soldered not directly to the board, but at contacts which makes it easy to replace these resistors. It should be either one or two of them. I can't give you the exact reference, because the picture of your power supply board is a bit blurry.

[hab_noch_dm]

Vermutlich wurde die Platine mal mit einem lösungsmittelhaltigem Reiniger abgewaschen. Daher die fehlenden Bezeichnungen. Solltet ihr vielleicht bei der Fehlersuche berücksichtigen.
Noch etwas anderes: stimmen die Ausgangsspannungen auf dem Netzteil denn überhaupt?

[DerKito]

Hi Uli!

In diesem Thread wurden die Spannungen schon mal thematisiert.

https://goldserie.de/phpBB3/viewtopic.p ... 4&start=15" onclick="window.open(this.href);return false;

Ich gehe davon aus, dass die 50 Volt zum antreiben der 7 Segment-VFD noch fehlt. Aber zumindest die CPU sollte anlaufen und dann entsprechend die Münzsperren anziehen. Ich will vorher sichergehen, dass wir die CPU nicht für defekt erklären, wenn vielleicht wo anders noch ein Problem besteht.

[burrerdj]

The voltage at the indicated resistor on the CPU board is +3.4v

Using the test points on the power supply board the +5Va provided +5V as did the +5Vb test point.

I found 2 resistors (r141 and r159) mounted on posts. I believe these are the other resistors you mentioned. The voltages at these resistors are 13.4v in and 3.4v out for both resistor.

[burrerdj]

Forgot to include the following:

r141 is 4.3K ohms (silver, red, orange, yellow)
r159 is 22K ohms (silver, orange, red, red)

[DerKito]

Hi again!

Alright, 3.4VDC is too low. Behind R241 (the resistor marked in the picture I uploaded where you measured 3.4VDC on one end) we need at least 5VDC.

There's two options for now:
First: Decrease the resistance of R159 until the voltage at R241 (on the CPU, the one I marked) goes up to around 8VDC to 10VDC. Since this circuit is a voltage divider, you should be good to go with 1k Ohm instead of 4.3k

Second: Take +5Va from the CPU (it's basically at each of the 74LS03 NAND ICs at Pin 14) and pull a wire to R241 - not to the side where you measured 3.4VDC but "behind" R241.

I would go with the first option since R141 and R159 are serve the purpose of adjusting the voltage for brownout detection.

[hab_noch_dm]

Hi Uli!

In diesem Thread wurden die Spannungen schon mal thematisiert.

https://goldserie.de/phpBB3/viewtopic.p ... 4&start=15" onclick="window.open(this.href);return false;

Da hab´ ich ja sogar was geschrieben!
Ach du schande - ist das lange her...

[burrerdj]

I had to order resistors. They will be here Thursday.

While I wait I want to try bringing 5v over to the backside of r241, but I have a couple of questions:

1. should I disconnect r141 and r159?
2. does it matter where I source the 5v? Much easier to use the 5va test point on the power supply board.

Lastly, I checked the existing voltage on the backside of r241, it was 4.6v. Does that seem right given the 3.4v input?

[DerKito]

Hi!

Let me answer your questions:

1. No, this is not necessary as long as you're not sending

2. The easiest and safest is to source +5V directly from the CPU board. You can find the rail not far from R241 on a capacitor. I marked it in the attached picture.

3. What you're measuring is to be expected due to the circuit behind R241. I attached a schematic I threw together for the brownout detection circuit on the older CPU boards.

[burrerdj]

I located a 1.13K resistor and installed it at r159. The input voltage at r241 increased to 7.79v. There were no other noticeable changes.

[DerKito]

Did you verify the voltage on both sides of R241 on the CPU board? Did the voltage increase to at least 5V behind R241?