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General NLG Chat => General Chat, Slot Shop **Tech Talk** Welcome wagon and other stuff. (Off-Topic Post Welcome) => Topic started by: Chris-socal on June 15, 2019, 10:55:25 AM

Title: Need advice with rectifier circuit
Post by: Chris-socal on June 15, 2019, 10:55:25 AM

I am troubleshooting a problem on an older game that has an onboard rectifier and regulator. The circuit has an onboard reed relay. Does anyone know what they would be mechanically switching? There is a dead short somewhere between the rectifier and the regulators and I am trying to understand their circuit.
Thanks if anyone can help.


Chris

Title: Re: Need advice with rectifier circuit
Post by: foster on June 15, 2019, 03:51:23 PM

If there is a short from the positive rail to the ground rail then I would first suspect any diodes and filter capacitors
Diodes and capacitors can fail open or shorted

Title: Re: Need advice with rectifier circuit
Post by: Chris-socal on June 16, 2019, 09:20:02 AM

My thoughts exactly. I checked every diode and the electrolytic capacitors. The only ones I didn’t pull were the  epoxy dipped caps. More on those in a minute. After checking traces and trying the board in the game a few more times I ran out if low amperage fuses. I was also at the point where I figured one component must be faulting under load that I couldn’t detect... so I did exactly what you are not supposed to do, I put a bigger fuse in. That is when one of the epoxy dipped capacitors blew its top. Now the question is, was that cap the cause of the short or was that a symptom of too many amps traveling through to the real problem?
Also, can you help me identify the correct type of cap? You can see the good ones below the blown one in the attached photo.

Title: Re: Need advice with rectifier circuit
Post by: foster on June 16, 2019, 11:45:35 AM

I am wiling to bet its the same value as the other ones still intact.
especially if it was same physical size


smart engineers try to keep the Bill of Materials as simple as possible

Title: Re: Need advice with rectifier circuit
Post by: Chris-socal on June 16, 2019, 03:33:30 PM

Thanks. I replaced it with a electrolytic and the game plays blind now. Thanks!
Unfortunately the CRT has a cracked neck. Does anyone recognize this monitor?

Title: Re: Need advice with rectifier circuit
Post by: Paul on June 16, 2019, 09:05:35 PM

The monitor brand is - R.G.B. Color Monitor

Title: Re: Need advice with rectifier circuit
Post by: slcjeeper on June 16, 2019, 11:24:57 PM

Give VDC a call. They may be able to help you. https://cathoderaytubes.com/ (https://cathoderaytubes.com/)

Title: Re: Need advice with rectifier circuit
Post by: Badbaud on June 20, 2019, 03:53:23 PM

Quote from: Paul on June 16, 2019, 09:05:35 PM

The monitor brand is - R.G.B. Color Monitor

That is the monitor that Sigma used for their poker games.
Easy to fix, just do a cap job.

Title: Re: Need advice with rectifier circuit
Post by: Amechanic on June 20, 2019, 04:47:20 PM

I believe he said that the neck of the CRT is cracked..

Title: Re: Need advice with rectifier circuit
Post by: Badbaud on June 20, 2019, 06:38:37 PM

Yes, I am checking tomorrow for a replacement tube, I have six 10 foot long shelves of tubes and monitors.

Title: Re: Need advice with rectifier circuit
Post by: Stayouttadabunker on June 20, 2019, 07:21:56 PM

Quote from: Amechanic on June 20, 2019, 04:47:20 PM

I believe he said that the neck of the CRT is cracked..

Badbaud missed that boat leaving the dock...but threw himself a life preserver...lol