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Before plugging an HP 85
- Thread starter fargo
- Start date
daver2
10k Member
That it is configured for the correct mains voltage in your location.
I would also check for electrical safety (insulation resistance and a good earth - if your machine has an earth).
The RIFA capacitors may 'let go' - and fill the room with acrid smoke.
Also, internal capacitors may need replacing/reforming.
Dave
I would also check for electrical safety (insulation resistance and a good earth - if your machine has an earth).
The RIFA capacitors may 'let go' - and fill the room with acrid smoke.
Also, internal capacitors may need replacing/reforming.
Dave
daver2
10k Member
Sorry, that was the short answer - my wife was calling to say that my tea was out on the table!
It depends upon how important the machine is to you.
For example, is it an important machine (e.g. a prototype computer). In this case probably not. An HP-85 was a consumer product...
Was it owned by (for example) a family member. I suspect not from your initial post.
Did it cost you much money, or was it given to you free?
If it goes 'bang' when you do power it up - is that of any consequence to you?
Only you can answer the above.
Most importantly is your safety. As this will be plugged into the mains power two things could happen: (1) electrocution and (2) fire.
I would test the machine for electrical safety first using a PAT tester (sic). This ensures that the mains electrical insulation is in good order and that the protective earth (if fitted) is in good order.
I would then take the machine apart and look at the condition of the RIFA capacitors, electrolytic capacitors and tantalum bead capacitors. of course, clean it out with a vacuum cleaner and get rid of the dead bugs and dust as well at the same time! I would then check for signs of damage or burning / heat.
However, other people (myself included) just power the things up and hope!
I had a load of equipment to dispose of a while ago. I just took the equipment outside (on a nice sunny day), plugged it into a disconnected extension lead and turned the equipment on. I then went inside and plugged the extension lead into the mains - being a suitable distance away! If the thing went BANG or burst into flames - it got skipped. If it did nothing - it was given away as none working. If it seemed to work, it was given away as may work...
For important machines (however) I don NOT recommend this course of action!
The main culprits are capacitors.
RIFA capacitors are on the mains side and crack. They let out horrid-smelling smoke, can go BANG and can also burst into flames.
Electrolytic capacitors can leak and dry up. If they start to break down and start to 'gas' they can also go BANG.
There is very little easy way of testing tantalum bead capacitors. They are known as "smurf grenades" and can also go BANG as well.
If you fancy just powering it up, make sure the mains voltage is correct for the machine and your mains supply and ensure it is in a well ventilated area and you are not in the immediate vicinity...
Dave
It depends upon how important the machine is to you.
For example, is it an important machine (e.g. a prototype computer). In this case probably not. An HP-85 was a consumer product...
Was it owned by (for example) a family member. I suspect not from your initial post.
Did it cost you much money, or was it given to you free?
If it goes 'bang' when you do power it up - is that of any consequence to you?
Only you can answer the above.
Most importantly is your safety. As this will be plugged into the mains power two things could happen: (1) electrocution and (2) fire.
I would test the machine for electrical safety first using a PAT tester (sic). This ensures that the mains electrical insulation is in good order and that the protective earth (if fitted) is in good order.
I would then take the machine apart and look at the condition of the RIFA capacitors, electrolytic capacitors and tantalum bead capacitors. of course, clean it out with a vacuum cleaner and get rid of the dead bugs and dust as well at the same time! I would then check for signs of damage or burning / heat.
However, other people (myself included) just power the things up and hope!
I had a load of equipment to dispose of a while ago. I just took the equipment outside (on a nice sunny day), plugged it into a disconnected extension lead and turned the equipment on. I then went inside and plugged the extension lead into the mains - being a suitable distance away! If the thing went BANG or burst into flames - it got skipped. If it did nothing - it was given away as none working. If it seemed to work, it was given away as may work...
For important machines (however) I don NOT recommend this course of action!
The main culprits are capacitors.
RIFA capacitors are on the mains side and crack. They let out horrid-smelling smoke, can go BANG and can also burst into flames.
Electrolytic capacitors can leak and dry up. If they start to break down and start to 'gas' they can also go BANG.
There is very little easy way of testing tantalum bead capacitors. They are known as "smurf grenades" and can also go BANG as well.
If you fancy just powering it up, make sure the mains voltage is correct for the machine and your mains supply and ensure it is in a well ventilated area and you are not in the immediate vicinity...
Dave
Thank you Dave. Your answer sets a general guideline to deal with any vintage electronic device and it’s appreciated.
I hope someone experienced with HP 85 specifically can tell us which parts are more prone to failure, e.g. psu, memory, crt, etc.
I hope someone experienced with HP 85 specifically can tell us which parts are more prone to failure, e.g. psu, memory, crt, etc.
daver2
10k Member
The PSU and CRT are the more electrically-stressed items - and have the bulk of the components I have identified.
Tantalum bead capacitors are used everywhere.
Dave
Tantalum bead capacitors are used everywhere.
Dave
syzygy
Experienced Member
Case in point, which I experienced last night.
Nice clean looking, healthy, tantalum capacitor - 40+ years old but never smoked or drank or did other drugs.
Last night, upon application of power, it released its "magic smoke".
As I understand it, all electronics work by virtue of internal magic smoke. Upon the release of said magic smoke, they no longer work.
The HP 85 is a computer I would like to have one day. CuriousMarc has a whole page and videos about it: https://www.curiousmarc.com/computing/hp-85-scientific-computer
jplr
Experienced Member
I have a slightly related question. I learned programming in high school in France in 1973.
What puzzles me is that in my memory the device used looked similar to the HP-85 (except I don't remember a CRT), yet this is impossible as HP-85 appeared in the 1980'.
It had a kind of assembler language, I guess it was also used on calculators. We printed on a (thermal?) printer and there were (magnetic?) cards.
Maybe it was an HP 9810A?
Is this possible?
What puzzles me is that in my memory the device used looked similar to the HP-85 (except I don't remember a CRT), yet this is impossible as HP-85 appeared in the 1980'.
It had a kind of assembler language, I guess it was also used on calculators. We printed on a (thermal?) printer and there were (magnetic?) cards.
Maybe it was an HP 9810A?
Is this possible?
I read through the page and watched some videos. That gave me a general idea about the computer's internal. I opened the computer and visually inspected its electronic components. I found no leakage, short or overheating marks. I gave the internals some cleaning and plugged the AC cable in. I left the computer pegged in for few minutes before switching it on. Once I flipped the switch on, the computer came into life without any problem
All I have to do now is to fix the tape drive or upgrade it to accept DC200 cartridges (instead of the native DC100 ones)If the computer had a full keyboard, then it could be HP 9830A, which was introduced into markets in 1972.
daver2
10k Member
Nice going.
No RIFA smell...
Dave
No RIFA smell...
Dave
Thankfully none! BTW, the reason I plugin the AC and leave it for sometime before switching any old computer on is a RIFA from another HP computer! The RIFA in that computer's psu exploded while the computer was plugged in and switched off!
daver2
10k Member
Yes, they can do that if they are on the mains side of the power switch.
Dave
Dave
Sometimes they can fail days later, when you least suspect it. I once got caught off-guard because I didn't know this type of capacitors can hide inside the AC inlet filters.
daver2
10k Member
Tick, tock, tick, tock, tick, tock, poof!
Dave
Dave
seaken
Veteran Member
Hi @fargo , I read this thread with interest as I recently undertook a similar adventure. In my case it was my Father-in-Law's first business computer which he gave to me after he bought his IBM PC. This is the NorthStar Advantage I mentioned in this other thread:
What Dave said is true. This computer has sentimental value to me so I was extremely hesitant about powering it up after thirty years of storage. I followed all the tips from Dave and others and got ready to "go for it". In this case I powered it on by accident! I plugged in the computer to a power strip that was off, then when I was ready I turned on the power strip, thinking i would then switch on the power switch on the computer itself. But much to my surprise the computer beeped and displayed a message on screen. Whew! That was nerve racking! But it worked! And no explosions! There was no indicator on the switch which was off or on. I marked it now on the case with a sharpie.
Glad to hear your HP85 powered up with no incident.
Seaken
What Dave said is true. This computer has sentimental value to me so I was extremely hesitant about powering it up after thirty years of storage. I followed all the tips from Dave and others and got ready to "go for it". In this case I powered it on by accident! I plugged in the computer to a power strip that was off, then when I was ready I turned on the power strip, thinking i would then switch on the power switch on the computer itself. But much to my surprise the computer beeped and displayed a message on screen. Whew! That was nerve racking! But it worked! And no explosions! There was no indicator on the switch which was off or on. I marked it now on the case with a sharpie.
Glad to hear your HP85 powered up with no incident.
Seaken