Hello all,
Working on my first C64 / Breadbin / 250407. Purchased as non-working. Getting black screen.
More detail below, but for those that want to get right to the question.... Here are a few waveforms comparing the Pin15 output on the VIC chip (luma/sync) to the pin 4 on the AV socket (composite signal).
[url]https://imgur.com/gallery/PpqcqPY[/url]
My question is: Is the composite waveform range of 0.1v-1v too low for a c64?
More detail:
Symptoms are that...
Scruit
Member
Last Activity: 08-18-2022, 05:07 AM
Joined: 04-05-2022
Location: Central Ohio
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What is a normal composite signal range for a C64?
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Does the Oak OTI067 have a splash screen / initialization message at bootup?
tl;dr ... Question: Does the Oak OTI067 have a splash screen / initialization message at bootup?
More detail:
Working on "Uncle Sherman", my Mitsubishi MP-3200 386 from 1988. Before I start up old computers I have a process where I disassemble, test for shorts, visually inspect, capture EPROM images etc.
My T866II+ give me a "pins not detected" error on the EPROM from the Oak-based (OTI067 GPU but apparently a no-name card??) I assumed the EPROM was bad, ordered a replacement and figured I'd program a downloaded ROM image to it.... -
Diode mode testing of motherboards question
(I am self-taught in electronics over 20 years as a hobbyist, but I lack some of the fundamentals that folks who went to school for this would know... so please bear with me as I get deeper into this new hobby of retro computing...)
I'm familiar with diode mode in that it produces a small voltage between the leads and displays the the amount of voltage drop when the leads are connected... however....
Why do the board repair folks always put the positive lead to board ground and use the negative lead to probe the board itself? My intuition would be to put the negative... -
Re: MOSFET testing question
Thank you for your response.
At this point the mosfet is on my bench, disconnected from anything. I still measure 1.7v from drain to source, even after shorting the legs.
Another observation: If I short all the legs and then measure drain(+) and source(-) then it will count DOWN from 1.9v to 1.7v then stop. If I touch the gate with the positive probe for half a second then move it to the drain then it counts UP from 0.5v to 1.7v.... -
MOSFET testing question
I am testing an NPD603AL (N-Channel Logic Level Enhancement Mode Field Effect Transformer) from an old Comapq Proliant 1500 CPU daughterboard. Symptoms are no post / no video, with only the psu / blackplane / cpu daughterboard and CPU in place.
[B]First question:[/B] This is not explicitly listed in the datasheet [U]title [/U]as a MOSFET, however in the [U]description [/U]it states it uses D-MOS technology. I assume this means it's just a MOSFET, and the "logic level" means it only needs 5v gate-source charge instead of 10v. Is that correct?
I am... -
Compaq Proliant 1500 PSU - unknown pins?
Compaq Proliant 1500 from the mid 90's. The PSU fires up and a green light appears on the backplane, but no POST / no video / nothing on POST card.
The first thing I did was test the pins from the PSU and I see most pins are labelled quite clearly and I have verified all those voltages.
There are 4 pins on the PSU that I don't recognize from their silkscreen labels. I was hoping someone here would know?
Pin labels that I know and check out ok:
"5" = 5.1v
"N5" = -5.0v
"12" = 12.0v
"N12" = -12.0v... -
Data pins on ISA bus looks weird
Any thoughts on what sorts of things could cause these oscilloscope readings in the ISA data pins if a Compaq Proliant 1500 (P166)
[url]https://imgur.com/gallery/643LVkh[/url]https://Any thoughts on what sorts o.../643LVkh[/url] -
Re: Anyone have a datasheet for Mitsubishi M60073-1702FP (Compaq 149473-002)?
I have sent an inquiry to Mitsubishi directly. If I get the datasheet I'll link it here.Leave a comment:
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Re: Anyone have a datasheet for Mitsubishi M60073-1702FP (Compaq 149473-002)?
I appreciate your response.
Registering there replaces the datasheet URL with: [url]https://www.mitsubishichips.com/?filetype=datasheet&kw=M60073-1702FP[/url]
This resolves to a page that looks like an un-configured webserver. "Free Static HTML5 Website Templates | 2022 Update"
[url]www.mitsubishichips.com[/url] does not appear to be owned by Mitsubishi.Re: Anyone have a datasheet for Mits... I appreciateLeave a comment:
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Anyone have a datasheet for Mitsubishi M60073-1702FP (Compaq 149473-002)?
It's a QFP-160 that is connected to the CLK line on the bios rom on mny Compaq Proliant 1500.
I am trying to figure out why I have no clock signal at the bios rom, but without a datasheet I'm kinda stuck on what this IP does.
Thanks! -
Schematic Request for Compaq Proliant 1500
An actual schematic showing pin-by-pin wiring would be awesome, but a block diagram showing how the major modules relate would be very helpful (PCI bridge, EISA controller, SCSI, onboard Cirrus Logic) etc.
System does not post and I'm trying to understand why the BIOS and SYS MGT ROMs have no clock signal coming in, whereas the scsi, pci slots and pci-eisa bridge chips do.
Compaq Proliant 1500 (Socket 5 P166)
Backplane: "Assembly number 004341-001" and "Replace with compaq spare 169048-001"
Processor daughterboard: "Assembly... -
Re: New Members - please post your introductions here
Hello all.
My name is Grae and I am an IT guy by trade. Separately I do some electronics and arduino stuff as a hobby. Generally working more at digital level rather than analog, but continuing to learn.
What brings me here is I found my old Compaq Proliant 1500 P166 in the attic where it has languished for 20 years. I want to get it set up again but it won't post.
After a couple of weeks trying high level stuff I finally decided to get medieval on it and have been going to town with...Leave a comment:
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