BCD436HP: Electric diagram

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Valeriy

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Well , I would like to know if the electric diagram of the BC436HP and/or a service manual are available, in order to try to fix the hardware.
Thanks for any explanation.
 

fxdscon

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Well , I would like to know if the electric diagram of the BC436HP and/or a service manual are available, in order to try to fix the hardware.
Thanks for any explanation.
Unlikely you will find anything for schematics or service manuals for that scanner.

Back in the late 90's - after talks with the FCC - scanner manufacturers discontinued release of service manuals and/or schematics to customers and the general public for all radios that could receive above 800Mhz. This was done to appease the FCC's concern over the growing ability to monitor the cellular bands by using illegal modifications to consumer equipment.

Read these 3 posts...... 59, 60, and 61 at this link:



EDIT ---> Just noticed your location. Regulations where you are may be different.
 
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Valeriy

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Thank you for the reply, I understand the issue.
I don't need to try any unlawful modifications... :)
Anyway receivers with unlocked analogue mobile phones band have never been illegal in Europe.

I would like to try to restore the original sensitivity of my 436, and just thought that a chip directly linked
to the SMA-F antenna connector might be slightly damaged.
 

Ubbe

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The antenna connector should go to the pre-filters, under that screening lid, and that IC might be an expander to forward bias the different switch diodes that selects the different band filters. It shouldn't be any active components besides those switching diodes and perhaps a couple of protection diods, two in a three pin smd, and then the pre-flters and after that comes the amplifier.

Are all frequency bands affected? Try to remove the protection diods if they have gone bad, or measure them that they only conduct one way and not the other.

/Ubbe
 

Valeriy

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Are all frequency bands affected? Try to remove the protection diods if they have gone bad, or measure them that they only conduct one way and not the other.
/Ubbe
I still monitor some DMR VHF agencies, but analogue VHF sensitivity is reduced, as well as civil air band sensitivity.
Analogue UHF is gone (previously my 436 was less sensitive in UHF than in VHF, but now I hear just nothing in UHF).
Also the range 70 - 75 Mhz (italian mountain rescue service and firefighters) is gone.

Thank you for the explanation, sooner or later I'll take the time to open my 436 and check those components.
 
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