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In the previous video, it looked like the brown pinch roller built into the tape was gummy, and had gunk on the tape itself. It could have just a reflection, but it looked gunky like how an old 8-tracks pinch roller goes gummy also.

Dave gave us double the goodnes today :D A Teardown and a Repair video is just awesome

wow a "review" a teardown and now a repair of this computer :P nice

I remember seeing a few of those at my university back in the mid-80's. They were always part of rack full of HP (natch) equipment, all connected together with thick HPIB cables.

The tape drive itself looks good. The tape though, looks like the internal rubber roller has turned to goo. This is a problem with 8-track tapes that also use an internal pinch roller. I bet there is still data on it.

Really enjoyed these three videos, Dave. Thanks for putting all three up - perfect Friday evening material. Makes me want to go out and fix things!

The drive wheel (red rubber) breaks down, also the old tape media flakes off. I did replace the rubber drive wheel with another type but had to gently sand it down with a fine grit to get the size right. Replacement tapes were available at the time (15yrs ago). Was an awesome HPIB controller. Now I use EZGPIB and a LAN adapter. I donated the HP85 to the college along with truck loads of other gear and parts. Keep up the great work!

Well done Dave! Even though I haven't seen the new videos yet (will watch soon), I am glad we have a return to good old electronics on this channel!

I like how you smelled it. Everyone always pokes fun at me at work when I smell dead computers and phones etc... gotta love that old smell!

Also we need more retro computer content. Would also be interested in seeing your full vintage calculator collection.

Every time i see you do a rapair video i feel very happy Dave. I really like how you do a step by step troubleshouting.One learns a lot from these kind of videos.

The tape doesn't move because capstan melted away, ya dingus :)

Sounds like the motor is probably belt drive and the elastic belt has long since rotted...I bet a new rubber band gets you up and running. If it is moving it can't rewind forever so that should have gotten to the end of the tape.

I like this repair videos. Teach-me how troubleshoot some old school staff i have to fix. Thanks a lot.

nice and safe .... famous last words

Love your videos Dave! You make me want to find old broken electronics and fix them!

In repairing a lot of tape based machines Belts and Capstan replacement is a must for anything over a few years old. Should do it anyway for peace of mind! Awesome series of vids Dave! Thanks Mate - a Fellow Sydney sider

Took me a while but I was looking forward to watching this and wasn't disappointed!

You, Mister, are my new hero.

We're in like Flynn and Bob's your uncle, that's Bobby Dazzler till the cows come home! Winner winner chicken dinner!

Dave, the tape capstans tend to get goopy over the years, might be the cause of your tape drive issues!

My father worked on a survey of the sewer systems in San Antonio Texas and then as a draftsman/assistant cable system engineer and I remember him bringing home the marketing shwag for these along with test plots of x-wing fighters, darth vader and other cool stuff. I remember wishing I could get my hands on one, I'm not really sure what I would have done with one but they looked so cool. Eventually I wound up with a TI 99 which was a much more capable computer and had pretty advanced graphics and sound for the time all accessible via a basic interpreter after the computer was stolen I got an ATARI 800 which lagged behind the TI 99 in a lot of ways but had the largest color pallet of any personal computer available for years, had a very hackable graphics processor and an almost cult like user community.

Always great to watch you troubleshoot :) and a lovely piece of tech!

I'm so glad to see I'm not the only one who forgets to plug things back in, before booting up... LOL! I was going to say, those ribbon cables used to be so stupid easy to mess up. You really had to be careful of the positioning.

Three videos within 2 hours

awesome, just awesome. I love these teardowns of stuff that is so beautiful inside. Wish they made stuff like that these days - except everything would probably cost about 20x what it does now

I had a similar problem with my first computer - 64K memory running at a blistering 4 MHz. (Z-80A) My very first repair was when I plugged the memory card of my first computer in one position off. (was just pin headers) Blew a 5V regulator apart. My first parts change, and my first PCB component replacement. Looks like a dog's breakfast, but it works. I still have it - 32 years later. (can't get hard sector disks for it.)

Awesome! Reminds me of my 1st computer when I was 6 - the commodore PET with tape drive ( audio tape !)

It's a nice combination. A guy that rips products relentlessly and mercilessly, but is not sensitive about people seeing how he screwed live either. I wonder if that fuse might have been added after the engineering crew offset the connector just like that and produced a fireball. It probably saved a lot of fiery factory repairs for HP.

8:30 so that's where apple got it from!

This reminds me of my old english made Wordplex/Compaq portable I had in 1983. I went mad one day and installed a 10mb hardisk that costs about a weeks pay.

Thank you

Darn, I had one of these things when I worked at Telstra, I think it was used to run an automated test setup (very slowly), because it had HPIB support to talk to out test equipment. In the end it got stipped (Ultimate tear down) - I think I still have the CRT in my junk box. I kind of now regret not putting it asside for keeps, but hey, you cannot keep everything.

You could see, on-camera, that the pins in the connector were mis-aligned again when you put it back together.

fantastic, i loved this three videos of the HP 85 thing, thank you.

Dave, it would be fun to do a 'then and now' of old tech vs new stuff, things like that ribbon cable and today everything is made so you can't plug it in wrong, etc. My suggestion is to tear them down side by side.

It was that little loose washer you discarded in the teardown. The tape deck can't run without its emotional support!

Well, we now know what an error 23 is. :-)

The tape in your tear down had gunk from the rubber on the rollers degrading in it. I would suspect it would be one of the main issues with the tape drive. Tape drive electronics are generally very robust.

CuriousMarc has some excellent restoration videos of the capstan and belts

I was hoping it would be the magnetic washer :P

Check for belts, bands and silicone-type gears. Band and belts you can get from ebay. And in case it a gear you can 3D print one. Pinch roller like an 8track seem to live on the cartridge. Itis rare that the computer dont time out the tape drive at some point because is waits forever. That could mean that this failure mode wont show on a self test or service mode test. What if you PUT the tape after it boots. READ and WRITE (PLAY and REC) are probably working and the path to FF and RW is giving trouble. On power up probably want to RW the tape, just skip this step by putting the tape after.

You can see that the rubber rollers have melted so it's off the Wagner Electronics to see if they have square cross section O-rings to glue back on.

Nice videos. Just a suggestion, if you like old calculators then perhaps a fundamentals Tuesday or something on LC circuits overclocking a voyager series calculator by adjusting the LC circuit values.. could even get the uCurrent in there showing the increased current draw and battery life predictions maybe. I have an HP-15C I could send over if you are interested.

The problem with the tape drive is that the rubber on the drive wheel has turned into goo. The drive wheel can't turn the wheel inside the cassette anymore. This is a standard problem that happened to all units after a certain number of years. The goo ruins any tape cassette that is inserted, which is possible to see in the teardown video. Don't try other tapes until the problem is fixed. People have come up with different solutions to replace the missing rubber with something else. Do a Google search.

I got one of these at a garage sale as a kid, loaded with carts/app tapes/manuals. Need to dig it out again seeing lots of sudden interest in it. Maybe sell it at VCF West.

Now you can try connecting it to some of your equipment via the HPIB :)

This was great. Makes me feel a little better about forgetting to plug cables back in, haha!

Hey Dave Jones and everyone else if you leave the ground strap disconnected all of the electrons that will flow through that ground strap we're falling through screw hole that was used to attach the brown strap to the board.

When HP made good quality stuff!!

the tape drive wheel is melted and half of it is in the tape. goo yech

Love that hp. And I would really enjoy a video on an attempt to repair the tape drive.

"WE forgot to plug the cables back in." - No.. You did.. "WE fixed it" - Ok. WE can take credit for that. ;)

I would realy enjoy more repair videos.

Nice job, Dave.

+EEVblog, you've been very lucky of not having caused major damages, apart a blown fuse! If you broke one of that custom ICs, that would have been really a pity!

Definitely do another video of the attempted tape drive repair

Definitely need to go for the "quadrella" and get the tape drive working.

"Bingo! 12 volts.. Winna winna, Chickeen Dinna." rofl classic.

That loose magnetically-attached-washer from the teardown video was clearly there to prevent the fuse from blowing...

Dave, you got a big ol' hole where the fuse should be!

I always watch your videos at 2x speed, so that HP computer looked like it was running at 1.2MHz!

I really enjoyed this video , I look forward to the tape deck being looked at :)

Nice one Dave, good machine that.

I'd blame the tape, looked pretty nasty in the teardown video where the capstan is meant to mate with the tape's built in transport mechanism...

HEY!!! i may have seen something! that will be a problem! that light blue cap near the fuse the long one. Had strange lumps underneath it's blue packaging. The metal maybe rotting! and therefor the cap itself maybe in trouble.

I think your tape drive isn't working because both the pinch roller next to the head and the roller in the cassette have perished and are covered in slime with some of it having been splattered onto the tape itself.

I would check all the voltage lines before ever turning it on

At 13:44 the blue Sangamo cap looks definitely leaking.

I think you missed the fact that the roller in the tape was rubber that has since completely melted into goo.

Awesome, love repair videos!

When it didn't power on, I thought clearly it's that stray washer.

crt's are just awesome

respect the ribbon cables

You're close to having enough fuse repair vids for their own channel.

Hi. The link at the end of this video sends me to video #903, not the one that is shown in the preview. And when I watched your #903 teardown of this computer and the somehow unlisted video #904 I noticed some kind of goo on the tape and in the cassette around where the capstan would make contact. Maybe there is a rubber pinch roller that has turned to goo in the cassette .

You should tear down some old Commodore computer, since i'm pretty engaged with that stuff. One question to you: how can we get one of you EEVBlog-custom Multimeter? Are there on sale?

You must have cheated, since you showed us the unit in action already, you TURNED IT ON BEFORE YOU TOOK IT APART! (No worries, I would have done the same thing!).

Hi this resistance element has been replaced because ??? that tube welded ??? I do not see it well??? I find it strange, greetings and thanks for your videos.

In the teardown video, when you showed the tape cartridge, there appeared to be an orange-ish liquid around the drive wheel in the cart. There is a good chance that the cart is bad. Try using your thumb to manually advance the tape within the cart without any notable resistance. There is a possibility that the tape media itself has gone crusty, or decomposed enough to the point that either the oxide coating has fused the tape together on the reels, the tape has snapped somewhere, or the drive loop within the tape cart is broken (see: upload.wikimedia.org/wikipedia/commons/9/96/Computer_Tape_Cartridge.jpg)

love your repair videos dave :)

The orange capstan in the tape looks super crusty and I suspect the orange stuff on the one in the drive itself isn't supposed to be there.

Don't tear it apart, turn it on!

You will fix the tape for sure

Good enjoyable video to watch, Good Work! keep it up

Hi Dave, at about 6:50 when you probed the Cap, I noticed a white sticker on the back of the power supply board with "-2016" on the bottom line. Just out of curiosity, is that a date or something else? Great video btw!

Maybe the earth strip was that wide, so it was'nt overlooked?

you should've called HP tech support about the error.

As I noticed, there is no communication equipment in it? It's a pity.

Acum stiu de unde ICE Felix s-au inspirat cu HC-85. Tastatura la fel, comenzile BASIC la fel... dar, combinat cu un rip de la ZX Spectrum.

this is like whenever i try to do maintenance or 'repair' :D

"Don't tun it on, take it apart!" (put it back together) "Let's look at what we did wrong" - Every curious tinkerer

The transformer/inductor at 6:07 is called an autotransformer. See: en.wikipedia.org/wiki/Autotransformer

I remember that computer as a kid. Great video!

That mech keyboard tho.

Have you checked the drive belt for the tape deck?

Yay vintage computers!!!!!!

It looks better without the cover

nice work dave! turned a mistake into yet another ripper video. keep it up mate.

So you USED it "quite some time" before take it apart! Bad Dave!