Desktop calcs - residual noise levels?



#13

Something you rarely see mentioned - how much noise the desktops generate when running (excluding printer or tape noise).

Do all of the 9xxx machines have cooling fans? Are any especially noisy or especially quiet?

How about the bigger desktop printers like the 46 and 81? I have a 46 and when the printer is switched on (even if not actually printing), it is very noisy - obstrusively noisy to be honest. Is this typical?

On some of the 9xxx models, are the fans actually needed, especially if the tape drives aren't being used? Obviously, I wouldn't want to risk overheating one but if the fan is only present for a tape mechanism, presumably it can be switched off safely?

I'm just thinking ahead here, hoping that I will build up a good collection of the large desktops and ideally, at least one of them can be used on a permanent basis and left running without noise getting to be a problem.

Any experiences to add here please?

Mark


#14

Hello!

Quote:
How about the bigger desktop printers like the 46 and 81? I have a 46 and when the printer is switched on (even if not actually printing), it is very noisy - obstrusively noisy to be honest. Is this typical?

I have two 46es and both are noisy, so it seems to be typical. Since I wouldn't know what to do with the printouts anyway, I just keep the printer switched off and the noise goes away!

Greetings, Max


#15

Quote:
Hello!

I have two 46es and both are noisy, so it seems to be typical. Since I wouldn't know what to do with the printouts anyway, I just keep the printer switched off and the noise goes away!

Greetings, Max


With the machine on and the printer on, when you switch off the printer, does it wind down really slowly? I haven't looked inside but it sounds to me like there is a heavy flywheel or something inside. The 46 makes me think of my earliest computing experiences with teletypes clunking and rattling away. I was shocked by the noise when I first switched the 46 on as I had never read anything mentioned about noise levels before.

Mark


#16

The 46 and 81 use a printer mechanism made by Seiko (IIRC). It's also used on other calculators from the same time period and yes, it's really noisy and takes a long time to stop. On the other hand it make really cool sounds when you print numbers that cause the hammers to print in series like: 123456789, or a really loud sounds when you print the same number in each position: 5555555555.

The 9100A/B calculator doesn't have a cooling fan but has no printer built in. The 9815 has a fairly quiet cooling fan, but the printer is incredibly loud. The 9810 is just the opposite -- noisy fan but very quiet printer.

Edited: 23 Oct 2008, 9:20 a.m.

#17

The 'flywheel' is actually the metal character drum that the hammers bang onto (through the ribbon and paper, of course). It's a solid lump of metal, and quite heavy when removed from the printer.

Yes, it's a Seiko/Epson mechanism.

It should 'run down' slowly. If it doesn't then the bearings _certainly_ need looking at.

#18

When technology was 'new', people wanted it noticed! If you spent the amount of money these things cost (using 2008 adjusted dollars), you'd like people to know you were special when they walked by your office.


#19

Quote:
When technology was 'new', people wanted it noticed! If you spent the amount of money these things cost (using 2008 adjusted dollars), you'd like people to know you were special when they walked by your office.

To be honest, I am not sure whether you are joking or not! But I can imagine some people using the noise to their advantage! However, I always thought the early desktops were usually shared machines and not personal.

Mark


#20

Isn't the 9100A/B completely silent?

Andreas

#21

The 9805 may well not have a fan, since it's built like a 46/81. But I think all other 98xx machines have cooling fans. Certainly the following do (I have all of them) : 9810, 9820, 9830, 9815, 9825, 9831, 9845B, 9826, 9836, 9816, 9817

The 9100 doesn't have a fan. Apart from the magnetic card reader,
it's silent

The fan shouldn't be _that_ noisy. I have found it helps -- a lot -- to take the fan out of the machine (I can talk you through this for most models), take it apart (again, I can help you), clean and relubricate the bearings. I do this as a matter of course.

Yes, you can still hear the fan, but I don't find it annoying. I would also not disconnect the fan, I suspect it's there mostly to cool the logic (rather than, say, a card reader), and I'd rather put up with the noise than have to replace chips.

Somebody else mentioned a noisy HP9815 printer. There's a little bit of foam in this unit (same mechanism as a 9825) which tends to decay with age. It's not hard to replace it.

The printer unit in the 46/81 is actually an Epson mechanism I believe. I have a 'lubrication chart' for that, actually in the manual for a Fluke data logger. It's basically a drop of machine oil on all the sintered bush bearings. I do that to every 46/81 that crosses my bench.


#22

Hi Tony!
I have a 9825 with a loud fan, but the most annoying fan I got is in an HP programmable power supply. It's really getting on my nerves, and I think I'll give it a try and lubricate the bearings.
I did replace the foam on my 9825 printer with some insulation rubber band, but I am still looking for the perfect replacement. What kind of foam do you use for the 9815/25 printer?

Andreas

#23

Thanks for all the replies. Looks like the dream-machine, aka 9100 is the best one to get for normal use too although I still dream at night of getting more from the other desktop series - these are some of the most fascinating machine HP ever produced IMO.

Tony - I have a 9815 with a quiet fan but the printer foam pad has been removed completely (by myself as the residual goo was clogging the mechanism). Presumably, there is no structural reason for the foam other than noise reduction? Thanks...

Mark


#24

As far as I know, the foam is simply there to quiten it down a bit. The printer should work fine without it, and I don't think it'll wear out much faster.

I can't remember what I used to replace it. Probably just a piece of soft foam, carefully glued in place.

As regards which machine to 'go for' : The 9100 series is interesting, it was HP's first calculator series, but my favourite is the 98x0 series. It's conceptually simpler than the 9100, which makes it a lot easier to understand in detail, there are quite a few interfaces which are not _too_ hard to find. There are no custom ICs other than the ROMs, so they should be possible to repair.

I think if I had to pick just one HP desktop, it would be the 9830.


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