Date : Sun, 21 Sep 2003 21:46:48 +0100
From : Andrew Hancock <Andrew.Hancock@...>
Subject: Re: Two BBC Micros need some help!
Ah, -5v supply is very low, it's about -1.5v.
Maybe this is the reason for non-starting Beeb and psu.
Any ideas, as the BBC Service Manual states
"However it is not recommended that attempts should be made to repair this
power supply, instead it should be treated as a module to be exchanged."
It does supply a circuit diagram, no where do I start for missing -5 volts?
Regards
Andrew
-----Original Message-----
From: Andrew Hancock [mailto:Andrew.Hancock@...]
Sent: 20 September 2003 18:47
To: 'bbc-micro@...'
Subject: [BBC-Micro] Two BBC Micros need some help!
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Hi Beeb Fans
I've eventually got around to unpacking some BBC Micro stuff from store. In
went into store in 1986! Unfortunately, the first items unpacked haven't
survived the misuse to much!
1. BBC Micro B No. 1 at power up, Usually Startup Beep stays on.....Cassette
motor relay clicks, and cassette motor LED stays lit.
Issue 4 Board, Model A, expanded by me to Full Model B later as years went
by. Fitted with Acorn 1770 DFS.
2. BBC Micro No.2 Model B at power up does nothing. No lights, no beep, no
cassette motor click.
Issue 7 Board. Fitted with Acorn 0.9 DFS 8271. No other roms, expansion
boards.
Both models were purchased from new and used every day until they went into
storage.
Q1. Any quick tips, guidelines before I download the BBC Service Manauls?
Q2. Which should I concentrate on? No.1 on No.2?
I've done the usually things, ensure all socketed chips are inserted fully,
and I've tested the voltages.....
Beeb No.1 Voltage 5.53v
Beeb No.2 Voltage 4.74v
Beeb No.2 voltage looks a little low, is this within tolerance?
I could swap motherboards over very quickly and check the second
motherboard?
Regards
Andrew
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