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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: soop on April 11, 2018, 05:32:43 AM

Title: Quick help measuring potentiometer frequencies
Post by: soop on April 11, 2018, 05:32:43 AM

can someone give me a quick heads up on how to measure the frequency of VR105 on a white CD unit?

Looking at this http://www.pcenginefx.com/forums/index.php?topic=8926.msg396086#msg396086 guide, it says "Connect the counter lead (typically the red lead in a red/black pair) to Pin 1 of Connecter P6
Connect the ground lead (black) to Pin 5 of Connector P5"

But I can't see any markings for P6 or P5 on the board.  Where am I supposed to connect the probes?  I would have thought it was just on the pins of the potentiometer itself.

I also can't find many things with 5+ pins

Title: Re: Quick help measuring potentiometer frequencies
Post by: NightWolve on April 11, 2018, 05:35:28 AM

I'd PM thesteve to get this noticed, I don't see him wander around as much as years past.

Title: Re: Quick help measuring potentiometer frequencies
Post by: Punch on April 11, 2018, 05:42:35 AM

I'd help you but I think you mean the original CD unit, right? The Turbo Duo has the jumper connectors clearly labeled on the board's silk screen.

Title: Re: Quick help measuring potentiometer frequencies
Post by: soop on April 11, 2018, 05:48:12 AM

Quote from: Punch on April 11, 2018, 05:42:35 AM

I'd help you but I think you mean the original CD unit, right? The Turbo Duo has the jumper connectors clearly labeled on the board's silk screen.

Yeah, the OG unit.  It's all marked - like every single resistor - but the only Ps on here are two "test points" of 5 and 6 pins

Title: Re: Quick help measuring potentiometer frequencies
Post by: soop on April 11, 2018, 05:55:09 AM

https://i.imgur.com/ojc1HaB.jpg (http://i.imgur.com/ojc1HaB.jpg)

Here's the bottom of the unit.  The potentiometers are at the bottom left, and the two test points are on the middle left and bottom right

Title: Re: Quick help measuring potentiometer frequencies
Post by: NightWolve on April 11, 2018, 06:20:51 AM

Couldn't see your image at first, it gave an "imgur is over-capacity" error message. Interesting, but it worked on a refresh.

Title: Re: Quick help measuring potentiometer frequencies
Post by: Punch on April 11, 2018, 06:40:38 AM

Soop, aren't the connectors on the other side of the board alongside the laser assembly? Doesn't make sense to place it underneath the board since you'll usually need a disc spinning to test the cd reader.

Title: Re: Quick help measuring potentiometer frequencies
Post by: soop on April 11, 2018, 06:53:21 AM

Quote from: Punch on April 11, 2018, 06:40:38 AM

Soop, aren't the connectors on the other side of the board alongside the laser assembly? Doesn't make sense to place it underneath the board since you'll usually need a disc spinning to test the cd reader.

Ah, I'll check.  I'd planned to temp solder some wire and clips to the pot and connect it to the multimeter that way. 

Ok, I've just checked. The two test points, p103 and p104 are present on the other side, along with some connectors labeled p106 and 107 thaI can see, but no P5 or P6