Modchip and read quality

General information to do with the PlayStation 1 Hardware. Including modchips, pinouts, rare or obscure development equipment, etc.
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damiank94
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Modchip and read quality

Post by damiank94 » February 9th, 2019, 10:01 pm

Hello all,

I have PSX 5502 with OldCrow modchip. My question is:

Does 4-pin install modchips in PU-18 could affect reading discs? If yes, then switching to let's say Mayumi with stealth would "fix" this?

Also, I have a PSone with PM-41(2) board. I've tried to install a modchip but something went wrong. Right now console's behaviour is like it didn't "noticed" disc. Laser try to focus, CD spins for two-three times and stops. There's no "Please insert PlayStation disc". Just menu. For now modchip is desoldered, and every solder point was cleaned.

Cheers.

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TriMesh
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Re: Modchip and read quality

Post by TriMesh » February 11th, 2019, 12:41 am

The short answer is that on a PU-18 the modchip shouldn't interfere with reading the disc.

On the older boards (PU-7, PU-8, PU-18, PU-20) the output data from the modchip is connected directly to the mechacon MCU as a digital signal and no connection is made to the analog side of the circuit. The only thing you need to watch (especially with the stealth modchips with more wires) is to keep the wires away from the low-level signal processing parts of the circuit (OPU connector, RF amp chip, etc).

With the later boards (PU-22, PU-23, PM-41), the pin carrying the wobble signal was deleted and the signal was carried as part of the subcode from the integrated CD/Audio IC - as a result, the modchips were modified to inject the wobble into the analog part of the tracking servo - this does have the potential to interfere with CD operation, and is most likely to do so when using the old three-wire + link install.

The PM-41 uses the same approach, but the PM-41(2) has a reputation for being especially sensitive.

damiank94
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Re: Modchip and read quality

Post by damiank94 » February 12th, 2019, 12:31 am

Hey TriMesh,

Thanks for answer and clarify.

Based on this diagram, where's best place to put modchip?

Image

damiank94
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Re: Modchip and read quality

Post by damiank94 » February 14th, 2019, 9:33 am

Okay, I have installed Mayumi. Modchip works as intended, booting everything. But there's still problem regarding playing games. After ten minutes or so, fmv and music starts to stutter. Problem is, that this happens only on burned cds. Also load times are longer. Original games works ok. I moved laser unit (entire drive to be precise) to other console with same motherboard. And on other motherboard everything works as it should. What's going on?

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