Major 588 - adding UK40 & -40

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Phuture
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Major 588 - adding UK40 & -40

Post by Phuture »

Hi,

Installing a Spectrum Communications UK40 & -40 EPROM SC02B board and as part of the "-40" band connections the instructions say to cut round pins 7, 8 and 9. On the track to which the pins 8 and 9 are both connected there is a 47uF electrolytic, a zener (MZ205) and a 0.047 cermaic cap. Do these components need to remain connected to pins 8 and 9 (and even pin 7) after cutting or are they serving another part of the circuit or do they become redundant if I am to simply cut around pins 8 and 9?

Major 588 PLL02A.jpg

Link to Major 588 schematic: http://www.cbtricks.com/radios/major/m5 ... 8-5_11.pdf

Thanks!
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Re: Major 588 - adding UK40 & -40

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Phuture
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Re: Major 588 - adding UK40 & -40

Post by Phuture »

Hi Claude,

Thanks for the links. It's the PTBM059COX board (as provided in the schematic link in my OP). I would think the cuts go directly round 7,8 and 9 but just trying to understand the function of the other components on that line.

Thanks!
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Re: Major 588 - adding UK40 & -40

Post by Phuture »

Anyone?
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Re: Major 588 - adding UK40 & -40

Post by Mitch »

Those 'other components' are the voltage regulator circuit for the PLL, so are very necessary. You need to isolate pins 7, 8 & 9 because they're channel switching inputs not normally used but are needed to drop frequency/band to the -40 channels, the output from the eprom board connects to them but they need to be seperated from previous connections else it won't work properly. Just make sure the pins are isolated and the other connections are maintained using links if you need to, you wouldn't want to break the PLL chip.
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Phuture
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Re: Major 588 - adding UK40 & -40

Post by Phuture »

Mitch wrote: 16 Oct 2022, 13:46 Those 'other components' are the voltage regulator circuit for the PLL, so are very necessary. You need to isolate pins 7, 8 & 9 because they're channel switching inputs not normally used but are needed to drop frequency/band to the -40 channels, the output from the eprom board connects to them but they need to be seperated from previous connections else it won't work properly. Just make sure the pins are isolated and the other connections are maintained using links if you need to, you wouldn't want to break the PLL chip.
Got it. Thanks Mitch - much obliged. :thumbup:
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