View Profile: Hugo Holden - Vintage Computer Forum

December 14th, 2018, 02:40 PM

Hugo Holden replied to a thread Toshiba T1200XE - capacitor problem maybe? in Vintage Computer Hardware

Well at least the computer is powering for a while. I'm not sure if it is then powering down due to a remaining hardware fault or because the...

21 replies | 1949 view(s)

December 6th, 2018, 03:11 PM

Hugo Holden replied to a thread Processor Technology 16KRA board repairs and Delay Lines. in S-100

Here is their website with the contact details. All you will have to provide is their part number for their device, in the case of the 16KRA card it...

4 replies | 264 view(s)

December 6th, 2018, 03:57 AM

Hugo Holden replied to a thread Processor Technology 16KRA board repairs and Delay Lines. in S-100

Corey, I simply requested 5 pcs and they made them for $20.68 each and posted them by air mail. I know that quite a few of the PT cards have...

4 replies | 264 view(s)

December 6th, 2018, 12:50 AM

Hugo Holden started a thread Processor Technology 16KRA board repairs and Delay Lines. in S-100

I have been repairing 16KRA memory boards for my SOL-20. In one case the digital delay line had failed. I have written an article about this and my...

4 replies | 264 view(s)

December 1st, 2018, 11:23 PM

Hugo Holden replied to a thread DIP Switch Story. in S-100

I replaced the DIP switches on three 16KRA memory cards and the DIP switches on the SOL-20 main board with the high quality Omron switches in...

17 replies | 1184 view(s)

November 25th, 2018, 09:06 PM

Hugo Holden replied to a thread DIP Switch Story. in S-100

That is very interesting. The material left behind on these switches might well be that filler. If it is , it is very hard and it takes more than...

17 replies | 1184 view(s)

November 25th, 2018, 03:21 PM

Hugo Holden replied to a thread DIP Switch Story. in S-100

Though in situations where the Gold plating was always dry and clean from the beginning (like in Tek Scope attenuators) it still happens. Of course...

17 replies | 1184 view(s)

November 24th, 2018, 04:14 PM

Hugo Holden replied to a thread DIP Switch Story. in S-100

After a bit of research I have found that a lot of DIP switch manufacturers do not publish the details of the insides of their switches. However,...

17 replies | 1184 view(s)

November 24th, 2018, 01:29 PM

Hugo Holden replied to a thread DIP Switch Story. in S-100

Yes, I'm not sure what this material is either. The interesting thing in some cases it is nearly optically transparent. The Gold looks perfectly...

17 replies | 1184 view(s)

November 24th, 2018, 01:21 PM

Hugo Holden replied to a thread 74LS30 Testing Failures in S-100

As mentioned in post 2 and Chuck mentioned in post 8, the TTL output stage is good at sinking current, not sourcing it. So if you are using an LED...

10 replies | 650 view(s)

November 24th, 2018, 04:26 AM

Hugo Holden replied to a thread 74LS30 Testing Failures in S-100

Just thinking about this for a while I wonder if the new IC's you have been sold are not in fact genuine 74LS30's That sort of intermediate state at...

10 replies | 650 view(s)

November 24th, 2018, 03:58 AM

Hugo Holden started a thread DIP Switch Story. in S-100

I have been working through a number of faults on some Processor Technology memory cards and I came across a familiar problem. Familiar in that I...

17 replies | 1184 view(s)

November 24th, 2018, 02:33 AM

Hugo Holden replied to a thread 74LS30 Testing Failures in S-100

I was wondering about this too, but Phillip said the signals he was using to drive the IC under test were coming from another TTL IC (7493), which...

10 replies | 650 view(s)

November 23rd, 2018, 10:05 PM

Hugo Holden replied to a thread 74LS30 Testing Failures in S-100

Phillip, This is very interesting. I have worked on many pcb's with large numbers of 74 series and 74LS IC's, I have never yet found one sort more...

10 replies | 650 view(s)

November 19th, 2018, 07:44 PM

Hugo Holden replied to a thread For you monochrome lovers out there, which phosper do you prefer? in General Vintage Computer Discussions

Part of this relates to the early CRT's for both television and general electronic work. In the industrial setting green was common for monitors and...

43 replies | 2706 view(s)

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