Need a Service Manual for an AMSTRAD PC5086 - UK Vintage Radio Repair and Restoration Discussion Forum

paul.brett · 22nd Dec 2012, 9:40 pm

Does anybody know where I can get one from?

There are several 'dodgy looking' website offering to sell me one, but I'm not interested in those.

Thank-you.

mike_newcomb · 24th Dec 2012, 11:36 pm

Hi Paul, you might try asking same on old-computers.com

As this is not something the average user would have, it may help (you) if you advise why it is required, as if the pc has a problem, someone may be able to help with it.

Good Luck - Mike

paul.brett · 25th Dec 2012, 10:20 am

Mike,

I have an intermittent problem, where the computer refuses to boot. It powers on OK, and the correct voltages are being supplied to all the various components. It does not issue a normal POST beep sequence, video is not initialised, and the floppy drives do not spin/seek.

Sometimes it does boot OK. Normally after being warmed on a radiator.

Any ideas people?

mike_newcomb · 25th Dec 2012, 10:59 am

Is this a purely floppy disc PC? If so, try disconnecting/reconnecting floppy power and interface cables.
Then if still have problem, try swapping the cables such that the floppies are reversed, thus it will be 'looking' at a different drive first.

However the fact nothing appears on the monitor is suspicious.

Regards,
Mike

cmjones01 · 25th Dec 2012, 4:24 pm

A service manual may not even exist for this model. However, if it's only at XT-class PC as the model number suggests, it might not be too hard to check the basics. Apart from the obvious reseating chips and checking power supplies, find the CPU (it might be a V20 or similar rather than an 8088/8086) and look up its data sheet. Check for a reset pulse and clock signal. If they're ok, check for activity on the address and data buses. It sounds like something's stopping the CPU running: in my experience it's often lack of reset or clock, or stuck interrupts or wait states that make things grind to a halt.

Chris

SnowyDog · 29th Dec 2012, 11:11 pm

I used to repair these, working as a service engineer for GEC Avery (UK) in the early to mid 1990s.

The 2086/5086 machines suffered from a clock generator problem which caused the described symptom. IIRC we had to change caps in the timebase circuit. I'm unable to recall the old / new values or the references. I did have an annotated schematic for the motherboard at the time, so I do know one existed.

I also remember some PSU issues. I think it was the 8086 models that had a "power fail" / "power good" signal, this also gave similar symptoms but I think the machine appeared completely dead in these cases.

Also a batch of machines I encountered where the BIOS EPROM(s) went dodgy. Could be a contender, might be worth dumping the EPROM(s) a number of times, look for unexpected bit-changes.

SnowyDog · 29th Dec 2012, 11:36 pm

Quote:

Originally Posted by paul.brett

There are several 'dodgy looking' website offering to sell me one, but I'm not interested in those.

Thank-you.

Forgot to mention that I can vouch for these guys:-

http://www.manuals-in-pdf.com/downlo...-p-445996.html

I have obtained a couple of hi-fi schematics from them in the recent past; one was available for download the next day, the other took a few weeks. Manuals were good quality scans. I'd use PayPal rather than credit card though, but then I am always somewhat over-cautious!

Robin

22nd Dec 2012, 9:40 pm	#1
paul.brett Tetrode Join Date: Dec 2005 Location: Wisbech, Cambridgeshire, UK. Posts: 97	Need a Service Manual for an AMSTRAD PC5086 Does anybody know where I can get one from? There are several 'dodgy looking' website offering to sell me one, but I'm not interested in those. Thank-you. __________________ My vintage Computer Museum. Please visit soon!

24th Dec 2012, 11:36 pm	#2
mike_newcomb Rest in Peace Join Date: Apr 2012 Location: West London, UK. Posts: 665	Re: Need a Service Manual for an AMSTRAD PC5086 Hi Paul, you might try asking same on old-computers.com As this is not something the average user would have, it may help (you) if you advise why it is required, as if the pc has a problem, someone may be able to help with it. Good Luck - Mike

25th Dec 2012, 10:20 am	#3
paul.brett Tetrode Join Date: Dec 2005 Location: Wisbech, Cambridgeshire, UK. Posts: 97	Re: Need a Service Manual for an AMSTRAD PC5086 Mike, I have an intermittent problem, where the computer refuses to boot. It powers on OK, and the correct voltages are being supplied to all the various components. It does not issue a normal POST beep sequence, video is not initialised, and the floppy drives do not spin/seek. Sometimes it does boot OK. Normally after being warmed on a radiator. Any ideas people? __________________ My vintage Computer Museum. Please visit soon!

25th Dec 2012, 10:59 am	#4
mike_newcomb Rest in Peace Join Date: Apr 2012 Location: West London, UK. Posts: 665	Re: Need a Service Manual for an AMSTRAD PC5086 Is this a purely floppy disc PC? If so, try disconnecting/reconnecting floppy power and interface cables. Then if still have problem, try swapping the cables such that the floppies are reversed, thus it will be 'looking' at a different drive first. However the fact nothing appears on the monitor is suspicious. Regards, Mike

25th Dec 2012, 4:24 pm	#5
cmjones01 Nonode Join Date: Oct 2008 Location: Warsaw, Poland and Cambridge, UK Posts: 2,677	Re: Need a Service Manual for an AMSTRAD PC5086 A service manual may not even exist for this model. However, if it's only at XT-class PC as the model number suggests, it might not be too hard to check the basics. Apart from the obvious reseating chips and checking power supplies, find the CPU (it might be a V20 or similar rather than an 8088/8086) and look up its data sheet. Check for a reset pulse and clock signal. If they're ok, check for activity on the address and data buses. It sounds like something's stopping the CPU running: in my experience it's often lack of reset or clock, or stuck interrupts or wait states that make things grind to a halt. Chris

29th Dec 2012, 11:11 pm	#6
SnowyDog Triode Join Date: Apr 2009 Location: Bicester, Oxfordshire, UK Posts: 37	Re: Need a Service Manual for an AMSTRAD PC5086 I used to repair these, working as a service engineer for GEC Avery (UK) in the early to mid 1990s. The 2086/5086 machines suffered from a clock generator problem which caused the described symptom. IIRC we had to change caps in the timebase circuit. I'm unable to recall the old / new values or the references. I did have an annotated schematic for the motherboard at the time, so I do know one existed. I also remember some PSU issues. I think it was the 8086 models that had a "power fail" / "power good" signal, this also gave similar symptoms but I think the machine appeared completely dead in these cases. Also a batch of machines I encountered where the BIOS EPROM(s) went dodgy. Could be a contender, might be worth dumping the EPROM(s) a number of times, look for unexpected bit-changes.