TRS-80 Model 4P Test and Teardown

#septandy #trs-80 #model4p
In this video, we have a first for my channel, a TRS-80 Model 4P! It's a donation from a viewer and it's my first time ever even using one of these machines. It seems to have some faults, so let's figure out how to bench test this machine to help isolate the issues.
Part 1: This part!
Part 2: • TRS-80 Model 4P 80-col...
Part 3: Coming soon
0:00 Intro
1:15 Unboxing
3:16 Tour and test of the 4P
17:54 Model 4P Teardown
28:42 Bench testing the 4P
--- Video Links
When good caps go bad: (t-shirt donated by Jesse)
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Adrian's Digital Basement Merch store:
my-store-c82bd2-2.creator-spr...
Adrian's Digital Basement ][ (Second Channel)
/ @adriansdigitalbasement2
Support the channel on Patreon:
/ adriansdigitalbasement
-- Tools
Deoxit D5:
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O-Ring Pick Set: (I use these to lift chips off boards)
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Elenco Electronics LP-560 Logic Probe:
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Hakko FR301 Desoldering Iron:
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Rigol DS1054Z Four Channel Oscilloscope:
www.rigolna.com/products/digi...
Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:
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TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)
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TS100 Soldering Iron:
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EEVBlog 121GW Multimeter:
www.eevblog.com/product/121gw/
DSLogic Basic Logic Analyzer:
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Magnetic Screw Holder:
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Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
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RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)
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Plato (Clone) Side Cutters: (order five)
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Heat Sinks:
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Little squeezy bottles: (available elsewhere too)
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--- Links
My GitHub repository:
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Commodore Computer Club / Vancouver, WA - Portland, OR - PDX Commodore Users Group
www.commodorecomputerclub.com/
--- Instructional videos
My video on damage-free chip removal:
• How to remove chips wi...
--- Music
Intro music and other tracks by:
Nathan Divino
@itsnathandivino

[@TurboCharged_RubberDuck]

The more Adrian Black we get the better! Long videos are definitely NOT a problem!

[@fishx0ff]

The long videos with all the dirty details are great. Don't worry about the length. I really appreciate learning about the depths of the whole system which you only get from the false starts and dead ends, and all that extra time gives me a chance to actually absorb and remember some of it. Not to mention it's a much better reflection of reality--at least *my* reality when troubleshooting something!

[@Dragonborn_1992]

I completely agree with you.

[@ceebee23]

absolutely.....

[@SonicBoone56]

Agreed

[@essas.coisas]

I feel the same way

[@sq1rlsqu4d]

Exactly this :) I'm not sure that folks with short attention spans are the target audience of Adrians' videos anyway ;)

[@CapnKetchup]

For these kinds of technical videos, lonnnnnggggggg format is just fine with me!!! Do what you need to do in order to show us how you fix things. Thanks for all you do!!!

[@jwhite5008]

We totally can skip ahead if we want to - not that I ever was bored on Adrian's video. Even if you make mistakes - everyone does - we will gladly learn from those and be thankful. You can cut probing all 16 lanes if they look the same, and repeated disassembly-reassembly too, but other than that - leave everything in.

[@LKonstantina915]

its weird how I never skip, I usually grab a snack and watch. Its weirdly entertaining.

[@acidhelm]

I like long videos!

[@geordish]

I don’t like long videos. I love them!

[@petefish9401]

I don't love them, I adore them ;-)

[@kittyztigerz]

i agree longer is better i enjoyed it

[@TheGunnarRoxen]

Long videos are better. I love the details!

[@8bitwiz_]

One warning for when you put the whole thing back together: the 80-column horizontal sync depends on a little varcap in the middle of the motherboard, and the CRT will not sync to 80 columns if it is incorrect. I'm pretty sure it drifts over the years too, making the chance that it needs adjustment approach 100%.. This might also be why your HDMI converter is having problems. The difference is that a CRT will show something if the sync is wrong, but digital converters might blank the video.

[@jwhite5008]

Yes! (Had no idea about the variable capacitor, or model 4, but this makes a lot of sense in this situation) Leaving the comment here so that youtube may give it more priority.

[@stevesstuff1450]

@@jwhite5008 :Ditto...!! 🙂

[@TechnicolorMammoth]

I don’t mind the length. I understand that these tear downs, repairs, etc can never be set in stone time wise. It’s illogical to think otherwise. Sometimes a video does have to wait a few days till I get a chance to watch the whole thing, or it’s broken up and watched on breaks or the like. I love these videos. Especially the repair ones, and the longer they are the more I know it’s gonna be a good one! Keep up the amazing work, Adrian. I admire your work ethic and passion. I try to personally emulate that in my personal and work life.

[@LynxCarpathica]

Indeed, the more technical, and in-depth a part is, the longer the better. More info, more to learn, and more to explore. love the lenghty videos, where you try your best to find the fault.

[@InfiniteLoop]

Adrian, we don't mind the longer videos, we just like the tech and the repair stuff. you're doing a great job.

[@user-yr1uq1qe6y]

I went to the barber today and the young lady asked me if I was going to be going out for a date or something. I didn’t have the heart to tell her that nope, I was going home to watch several men fix some old computers. We certainly are living life to the beat of a different drum and I love it!

[@Unfinished80]

I'm going through a really hard time in my life right now but your videos are always bright spots on my week. I really look forward to them. Thank you Adrian!

[@sirtanon1]

I feel for you. Keep your head up. Focus on the good things and you'll get through it.

[@Unfinished80]

@@sirtanon1 Thanks!

[@Unfinished80]

@@martinr1834 Thanks!

[@tiemenfiat1321]

Your production rate of video's is astonishing for a non fulltime KZbinr. 40 minutes is great and the detailed repairs too. Ga zo door! (Keep on going like this)

[@pastedtomato]

"This could be a somewhat quick video" Famous last words. Jokes aside, I love long videos, I really enjoy the troubleshooting and explanations

[@HERRH1]

Really like the technical details and the way you try to make sense of it all looking into those old manuals/designs. 45~60 minute videos are fine as we still want to know all details 🙂. Keep up the good work!

[@roadsiderebels3039]

You sir, are an entertainer. The longer the better!

[@SimonZerafa]

Am I the only one that prefers longer videos? The longer the better in fact 😁

[@Nimmbin]

Length of your videos is just fine. I enjoy the everything you create so keep em coming my friend 😁

[@julieileneowen]

I like the long videos. People can always skip ahead if it's something they're not interested in specifically. But for example, I have a model 4p, which basically works, and I've been wanting to open it up, but knew it was going to be a real hassle, seeing that teardown on what to do, and not do was very helpful to me.

[@danfm1]

This machine looks awesome, this is totally something I'd imagine a hero of early 80s movie would use in like an abandoned lab

[@PatrickFinnegan]

These longer videos are great!

[@Colin_Ames]

I have no problem with long videos, I can always watch part of them and then return later. Your content is excellent and deserves to be presented in long format.

[@SC-CAJUN]

The length is fine! Longer the better for me 🙂

[@Astragali]

Adrian, the long-form videos are absolutely fine - I find all your videos very absorbing, so it's always a pleasure to get the longer-duration vids.

[@phillipowen1395]

Keep them 50 minutes. Your videos are excellent and deserve the time. As a long time electronics guy, I appreciate everithing you do. I Can't imagine how much time you spend editing and I enjoy them. And ad free to boot! Thank you Adrian!

[@erlkiing]

i do love your longer videos, its something i enjoy listening and watching while i work on my paintings, the more the better!

[@ThePhoenixAscendant]

Love the letter that Seth sent, the text being big and bold and very readable gives a feeling of inclusion to the viewer, very nice.

[@HamJamming]

I really like your TRS-80 videos because back when I was a young guy I owned both a Model 1 and a Model 4 and used them both heavily for over 10 years, under both TRSDOS and CP/M, before I had to switch over to Windoze.

[@DIYDaveOK]

These videos are such a nostalgia trip for me. I started with a Model I before it was called a Model I, wrestling with the cassette interface, then had a Model III, got disk drives for it, then later moved to a Model IV. This like a throwback to when I was a teenager and wrote genealogy software and financial management stuff but never knew how to sell it. Wonderful throwback to that bygone era when discovery was magic, Creative Computing was THE magazine of choice, and the IBM PC was yet to arrive. So many fun memories of that golden age.

[@melkiorwiseman5234]

The cassette interface in the original Model I had a bug which meant that it was possible for it to read a 1 as a 0 off the tape, especially if either the tape or the player were even slightly sub-prime. The ROM BASIC code was later adjusted to compensate for the error so that tape storage became more reliable.

[@Mil_UwU]

Just came to say I'm a big fan of the long videos!! Cheers!

[@DeepThought007]

Take the time you need to do the videos! That's what makes them fun to watch. You're thoroughness.

[@georgedyson9754]

I love long videos - especially those over an hour! These short ones are most unfulfilling! More please!!!!

[@ultrametric9317]

WE all love these videos!!! It doesn't matter how long they are. Most of us have spent hour upon hour trying to diagnose computer problems, hardware and software, and we know how time can get away from you. It's fine! You skip over the obvious parts and we get that too.

[@emilykoch5382]

The length of your videos are why you are one of my favorite channels. Love the detail.

[@richshealer3755]

45 minutes on a subject likes this is great. Leaving us wanting more is a good thing. Long videos that repeat themselves several times through are a waste for everyone. You don't do that so I know it's worth the time.

[@SudaNIm103]

I like the longer videos. I’m usually feeling up to speed with the topics you cover; Often the most enjoyable aspects of your videos are brief off-hand comments: you reasoning aloud about a particular symptom, or rhetorically offering a brief bit of insight into why a troubleshooting approach I’d have waited to pursue is in the forefront of your mind. It’s often those moments that leaving me feeling like I really learned something scarce and valuable. As much as I enjoy the rare cases where I’m maybe one step ahead of you and I’m yelling at the screen; it’s the times I’m left a bit shellshocked by your experience and insightfulness that are my favorite. ❤

[@falksweden]

The longer videos, the better. The impatient ones can always fast forward but we who enjoy detailed and long videos can't add content that's been edited out :)

[@TheRattlebunny]

I completely agree. Longer videos are great. I’m dealing with a diabetes related infection in my leg which is keeping me from my own channel, but worse it’s keeping me out of my own lab. So, I live vicariously through your videos and those of your fellow recent panel members. So, thanks and keep doing such a great job. 👍👍👍

[@4k3n4t3b]

wonderful work Adrian, congrats.

[@mikes3872]

Keep’em looooong!!! Love the detail and info you provide 👍

[@wintermute740]

I like your videos. Long or short, I don't care which, because they're always both entertaining and educational. I could have never restored a 5150 to add to my collection without your videos.

[@briangleeson1528]

Dude, the long videos are great! The short videos are good too. However, you are the creator, but I think we will be here no matter what. My vote is for long videos whenever possible.

[@fyreantz2555]

Keep the info coming, dude! This is good stuff.

[@insanelydigitalvids]

I enjoy every minute of your videos, Adrian. None are too long or too short. It's also fun to see you going down a rabbit hole -- that's when you really get into troubleshooting, and I learn so much -- and see the joy on your face when you fix the machine!

[@Gloworm17]

I like a mixture of both. Long videos give me the length and depth of a TV show proper. The short (5-10) videos giving me something to pass the time while doing something else. I can watch the short ones in a restaurant vs having to plan to watch longer ones.

[@quakesin1982]

I love the longer videos, I like to see all the details, keep it up!

[@astererratum6546]

Long format is definitely best! I love all the details even if I can't understand everything, I still love all the bits and bobs! Love the videos as usual!! Keep it up!!

[@edittext]

Your genuine enthusiasm is infectious and I can't help but get invested in each of your projects. Keep doing exactly what you are doing!

[@Dirty_Bits]

Long format videos, at least from you, are thoroughly appreciated. Keep putting in the fine detail oriented work!

[@s.lancaster2830]

I like long in-depth videos. Once or twice a week I have the need for some long form computer-related content. And your channel is perfect for that

[@JohnJones-oy3md]

5:36 - The Model 4P all buttoned up always reminded me of a sewing machine case.

[@AceStrife]

The videos I enjoy the most on KZbin are ones I can just sit back and relax with some food without worrying about having to find another video or two before I finish eating. KZbin saves the position of the video you were at if you pause and come back later, so I don't see any real reason to make short videos unless it's for ad revenue or viewer demographics (ie; short attention span kids). They do attract more random clicks if someone gets the video pushed to them.. but at the same time I personally believe that they detract from the established viewerbase of the channel who are more into long form videos, as evident by the comments on this one. Either way, it's always up to the content creator to decide how they want their content out there. But if making longer videos cuts down on the editing work required, I'm all for it!

[@philh9421]

Love the long videos. Have them in the background while I work on software in my day job.

[@sonnymoorehouse1941]

I for one Really Enjoy your in-depth Videos. The long videos end up being your best, They Freaking Work !!!!!!! Thank You for doing what you do !!!!!!

[@four20team]

I love the short videos as much as the long ones. It's great when you get into detail on how something works. And when something fails you explain how it failed and what to look for. You have helped me so much in my career working with electronics (slot machines mostly). How to logically approach "misbehaving" power supplies and whatnot. Please keep up the awesome job 🙂

[@LordChariot]

I love the long deep dives with detailed explanations. Make them as long as you want. We can always fast forward.

[@MD4564]

Loving the long videos, the details you go into are great :)

[@sfperalta]

Ah, a stroll down memory lane. I bought a TRS-80 Model I in 1980 (because Apple II was "too expensive"). After various upgrades (expansion, memory, dual floppies), I probably spent as much as the Apple II would have cost out of the box. Oh well. Sold my Model I and bought this computer (the Model 4P) because it was "portable" (wink) and because it ran CP/M and that seemed to be all the rage at the time. But a lot of CP/M software seemed to need a lot of work to get running (kind of like Linux LOL!). Finally sold the 4P and got myself a Macintosh Plus, beginning a lifelong devotion to all things Mac. Which led to a job at Apple a couple years later, and from which I retired in 2015. What fun! Adrian, keep up the detail. These videos are fascinating!!

[@LiteralTester]

Team Long Format, Love watching/listening while working!

[@umby9]

Keep those long videos coming! It's always awesome to watch you work on these machines, all of which are older (sometimes several years, sometimes decades) than me.

[@ericmallory3050]

Love longer videos, thanks for the content!!!

[@crouchinghamster6407]

I *love* the long videos. I have your videos running on my 27" iMac in the garage while I'm working on my own set of vintage computer projects. What a lovely way to spend an evening. Thank you for making all your videos!

[@dodgydarryl]

I love the honesty of all the false starts and the struggles you have to find these faults. I think if you edit them down too much we would lose the sense of challenge in these repairs.

[@sbleed]

I prefer to binge watch for hours. Longer videos get my views. If I see a 15 minute video, I usually skip cause I don't want to spend half an hour again looking for a 15 minute video. Keep 'em long 'n strong.

[@Nabraska49]

The video lengths are just fine and you do a really good job of story telling .. keeping it interesting and pleasant to listen too . And the search for the gremlins are my favourite part.

[@parrottm76262]

Another vote for the long(er) vids. Love the deep dives. Those are the most likely to teach us something we never knew. You can always come back later if needed (modern problems).

[@trmazi]

I love the long content! keep em' coming!

[@TheRetrospective]

lovely video 💕 warms my retro heart

[@thomaswright6776]

The long videos are great! The best thing is you always explain what you are doing and that makes then really interesting as well as entertaining!

[@Doug_in_NC]

I love the long format videos, they let you get down into the weeds, and I’m here for that!

[@michaels.niquette3879]

I like the longer videos. You do great work! Thank you.

[@BobPlank_KK4DIV]

I really enjoy the long videos. Keep them coming. Since finding your channel, I have really learned lots about repairing old electronics and I enjoy seeing all the details. Someone gave me an old TNC used in ham radio packet communications with some leaky battery damage that I am going to attempt repair after being inspired by your videos. I opened it up, saw a Z80 processor and some other components that looked familiar and thought to myself, I may be able to do this. Again, thanks for the videos and I appreciate the long ones.

[@pupaepedorra]

Lengthy, detailed videos are the reason why i subscribed.

[@mattsword41]

love that your videos are long form. Watch them both for entertainment but also to learn. They never seem overly verbose to me (and I have a pretty short attention span!) and hold my interest. Love them :)

[@mindbender50]

Its the content that matters...if i see a long video and throughout the video I see trials and tribulations that can help me in my troubleshooting I will love it... time is relative.. even failures are helpful! That being said I have yet to follow you down some deep rabbit holes that I did not view them through to the end I love your channel..:)

[@levmonster5156]

Love the long videos. The deeper the mystery the better.

[@thomasferguson3687]

Keep the loooong!! Love the projects.

[@andrewb9830]

Picked one of these up this week. So after watching this I won't be diving in blind. Thanks.

[@stupidystu]

You always bring a smile and make this oldish fella feel young again so long videos are good for me.

[@ccarson4075]

Longer videos mean more knowledge, they don't bother me at all keep em coming!

[@blackcoffeedevelopment3522]

Just came over here from the Dave's Garage Channel and the first thing I see if the "Just here for the King Cake". As someone who lives in NOLA, just had to smile and click subscribe :)

[@tony359]

Very cool video! those machines are so primitive and so fascinating at the same time! :) Looking forward to part two.

[@lucydraws1237]

I really like the long videos because I find them very interesting and I’m a big retro technology fan and sometimes when I take a nap I like to have your videos in the background and I like to listen to them when I fall asleep since I get so zoned into your videos :)

[@AltimaNEO]

I enjoy the long videos. I tend to watch your content while Im relaxing, during dinner, or cooking.

[@solzarcat555]

About your question at the start of the video I will give you an answer, Adrian I enjoy your long videos for sure keep making them. they make me able to fall asleep at night and something about your voice makes me not feel a constant fear like something is hunting me. anxiety is a really bad problem I have and your voice makes me not feel it anymore, your voice works better then my medication does. it's really weird I know, but I really like your voice.(I'd watch you even if your videos were 5 hours long you make really good content and have a golden voice)

[@brucewoods9377]

Mate, I love these videos, the longer the better. I was a Tandy/Radio Shack technician in Adelaide South Australia when the model 1 first came on to the Australian Market. Serviced model 1’s through Model 4’s before leaving to re-enlisting in the RAN. Your videos bring back old memories for me

[@tarzankom]

I like the longer running videos. 40-50 minutes (or even longer) seem to be a good amount of content.

[@AnotherMaker]

Thanks for the awesome content as always. Thanks for the tip on using the RGB2HDMI. I'm definitely going to make up a cable and us that moving forward. Every model 4 I have, had PSU issues, so I finally just made an ATX test harness and it's so helpful on these machines.

[@JamesPotts]

I love the shirt!! Oh, that brings back memories.

[@zepo82]

Thank you Adrian for all this, sometimes I listen to you audio only at work cos it's calming and I kinda know whats going on from your descriptions. Work at the post office at the moment, lots of boring moving post and sorting...so it's a boon :D

[@8BitRetroJournal]

Adrian, you are killing it for #SepTandy2022. Love all of your TRS80 content! Seth is starting to rival Stuart from NH in what he sends in to you.

[@Arivia1]

I love long videos! I'm not big on CRT repairs but otherwise I watch every minute you put out.

[@cjhickspe1399]

Long format works for me. I tend to the hardware side so I like the detail. Keep up the good work.

[@patrickbateman3490]

Oh, wow... Kudos to you!

[@mikeschumacher]

Your video lengths are fine. I appreciate that you don't push them into the 90-minute and up range so that I can squeeze them in one sitting.

[@BurleyBoar]

Like many others, I love the longer videos. More important for me is meaningful content! You bring us along for your exploration and journey on these computers. As long as it is that, make these as short or long as needed.

[@DaveVW]

I generally like the long videos. Keep up the great repairs (and attempts)

[@tambarskelfir]

long format is just fine, keep it up

[@madzen112]

Boot disks, that's a long time ago! Love your enthusiasm, keep it up!

[@gazza8234]

I own a couple of 4Pees. Modified one with internal 360k, 720k and external floppies, XLR8er 512K ram, Hirez graphics and battery backed RTC. Also modified the boot rom so it sets the XLR8er speed at boot, loads the MODELA/III Rom image from the hard drive and can also boot from an IDE hard drive. Luv my 4Pee, best comp Tandy made. BTW check the soldering on the Power Supply output connector. It WILL need repairing also replace the yellow time bombs on the P/S. Good luck.

[@einsteinx2]

Love the long videos!

[@aa-au]

Your videos are of good content and length. You clearly have a good way of explaining the items you're working on, and this shows with the amount of subscribers and patrons you have - you actually have a good subs/patrons ratio! You're one of my sample channels I am analysing, amongst some others. Also, you're voice is clear and concise, not like my mumbling voice on my videos.