Test Equipment Anonymous (TEA) group therapy thread

[wkb]

Corporate balderdash...

Some companies here peel the stickers off before selling to the salvage guys because 'muh corporate security reasons OMG!"' or some similar inane misguided crap.

[RikV]

A few weeks ago I acquired a HP8640B with -working- option 02. It has serial 1523Uxxxxx. Previously did some cleaning (was used in a heavy smokers environment) and tests and all seems basically working.
Of vourse it has the usual "mechanical" problems. But mine does not have the "slide contact rotating" swithes on the range control but ordinary cam switches.
I found different versions of the manual on the net, but none that covers this serial. Artek does not have anything either tha cover the "U" serials of tha year. Would there be significant differences between the "A" and "U" builds? I do have the "military" manual that also covers the 1523A.
Anyone has a more representative manual and is willing to share?

[W6EL]

Well, I just won an auction on a HP 8648C 100kHz-3200MHz Signal Generator. It is shown powered on in the auction, but who knows if it works.
The idiots who previously owned it removed the serial number/option stickers too, so hopefully I can figure out those details (maybe written inside, maybe via GPIB) too.

I wonder how hard it would be to add option 1EA to get the higher power output if not already installled?

VFD display or LCD? I think these are great generators, I have the 8647A myself.

[W6EL]

A few weeks ago I acquired a HP8640B with -working- option 02. It has serial 1523Uxxxxx. Previously did some cleaning (was used in a heavy smokers environment) and tests and all seems basically working.
Of vourse it has the usual "mechanical" problems. But mine does not have the "slide contact rotating" swithes on the range control but ordinary cam switches.
I found different versions of the manual on the net, but none that covers this serial. Artek does not have anything either tha cover the "U" serials of tha year. Would there be significant differences between the "A" and "U" builds? I do have the "military" manual that also covers the 1523A.
Anyone has a more representative manual and is willing to share?

I have one of these and I hate it. It's far too complex in every wrong way inside it. Despite it's "work of art" appearance, it is truly a mess. Anyway, my service manuals are:

"8640B-Signal-Generator-Operating-and-Service-Manual-08640-90017.pdf" MD5: 91bdd8fe1688def7666f49d5eeed3003

and

"8640B-Signal-Generator-Service-Manual-08640-90215.pdf" MD5: f44d771a91e59a2b5f4e365c85ec0811

Let me know if you need either. I just found them using google, so you probably have these already.

I went through a few months working on this and then purchased an 8647A for $300 and never looked back. Wish I could get back the time I spent gluing little wafer switch fingers, making new switch levers, and aligning gears. Even when an 8640B is perfectly working, it will never really do as well as a modern signal generator. You will always be at the mercy of the time trimmer pot which will move 100 hz if you simply look at it much less attempt to turn it. Even with an external reference signal, which it needs at 5 MHz (and converting from 10 MHz adds threshold-switching PPMs!), you are still looking at a generator which cannot lock below 100 Hz resolution.

Jumanji: A young people's jungle adventure game. Fun for some, not for all. PS: Read directions carefully

[W6EL]

Another TRW Swap Meet, another great deal.

I came across these two Fluke 8505A multimeters. The guy wanted $50 for the pair. I asked for less, he wasn't so sure, so then I said we could do $50 if he would open it and verify they were not empty of modules.

"Earl, get the man the screwdriver"

And then, yes, both were filled with sweet modules. The units were marked "repairable" and I was told the prior owner just never got around to finishing it up.

At home, both units powered on just fine. The only issue I found is that one ohms module is "always on" and will fowl up voltage readings if the 4-wire button isn't pressed. This same ohms module also doesn't work sometimes. I swapped the module and the problem moved with it. So I made one "nice" 8505A with the working ohms meter and the RMS module.

The second 8505a has the averaging AC module and the busted ohms one. I'm guessing I can fix the ohms one up, and then have a nice unit to sell (minus two button covers for those side buttons -- anyone have some extra square-shaft button covers? Mine are too fat even though they fit the shaft they do not fit the slim rectangular holes).

As for calibration, AC and DC look very close. Ohms (the working one) appears about 1% high. Not too bad! The "last cal date" in memory on the unit is "0000000" so presumably this was reset. I will have to look and make sure there's not some dead battery for the memory inside it -- I have not reviewed all the schematics yet.

Compared to the HP 3490A, these Fluke meters really are quite ugly. They have more sophistication for sure, such as filtering and offsets, but they are just so ugly. The HP unit is a much more pleasing appearance, IMO. And the HP design is also much more straight forward. The Fluke is modular but at the expense of making things more difficult to follow (or so it seams at first glance anyway). I guess I'll just have to keep one of each...

[factory]

A few weeks ago I acquired a HP8640B with -working- option 02. It has serial 1523Uxxxxx. Previously did some cleaning (was used in a heavy smokers environment) and tests and all seems basically working.
Of vourse it has the usual "mechanical" problems. But mine does not have the "slide contact rotating" swithes on the range control but ordinary cam switches.
I found different versions of the manual on the net, but none that covers this serial. Artek does not have anything either tha cover the "U" serials of tha year. Would there be significant differences between the "A" and "U" builds? I do have the "military" manual that also covers the 1523A.
Anyone has a more representative manual and is willing to share?

The letter is the country code, your 8640B was built in the South Queensferry site in Scotland, the numbers are still the year +60 & week, of the last design revision.

The list of known HP serial number prefix country codes, there may be others, but I lose interest in the modern stuff.
A = America
E = England (Bedford)
G = West Germany (Böblingen)
J = Japan (made by Yokogawa)
U= United Kingdom (South Queensferry)
No letter = America

They used normal rotary wafer switches in the earlier ones, along with dotty LED displays.

David

[RikV]

W6EL,
Thanks for your reaction. I am a bit surprised you dislike the device, but indeed: it is complex. Mine does not have those wiper-plexi disks, so maybe less trouble. Anyhow, I already have the manuals you quote.

factory,
I am aware of the serial# coding but is there an essential difference between a 1523A and a 1523U? Or are they exactly the same?

[TERRA Operative]

Well, I just won an auction on a HP 8648C 100kHz-3200MHz Signal Generator. It is shown powered on in the auction, but who knows if it works.
The idiots who previously owned it removed the serial number/option stickers too, so hopefully I can figure out those details (maybe written inside, maybe via GPIB) too.

I wonder how hard it would be to add option 1EA to get the higher power output if not already installled?

VFD display or LCD? I think these are great generators, I have the 8647A myself.

Mine is a HP branded LCD display version. I'm not sure if that's better than the VFD type?

[W6EL]

Well, I just won an auction on a HP 8648C 100kHz-3200MHz Signal Generator. It is shown powered on in the auction, but who knows if it works.
The idiots who previously owned it removed the serial number/option stickers too, so hopefully I can figure out those details (maybe written inside, maybe via GPIB) too.

I wonder how hard it would be to add option 1EA to get the higher power output if not already installled?

VFD display or LCD? I think these are great generators, I have the 8647A myself.

Mine is a HP branded LCD display version. I'm not sure if that's better than the VFD type?

I always like the VFD, but at the same time, I'm paranoid that it'll crack and be all over... VFD is so pretty.

[W6EL]

W6EL,
Thanks for your reaction. I am a bit surprised you dislike the device, but indeed: it is complex. Mine does not have those wiper-plexi disks, so maybe less trouble. Anyhow, I already have the manuals you quote.

Can you show us a photo of the non-wiper--plexi version? This sounds interesting.

[Ice-Tea]

Well, I just won an auction on a HP 8648C 100kHz-3200MHz Signal Generator. It is shown powered on in the auction, but who knows if it works.

I might have some spare parts if needed. Hit me up if you need to.

[m k]

As for calibration, AC and DC look very close. Ohms (the working one) appears about 1% high. Not too bad! The "last cal date" in memory on the unit is "0000000" so presumably this was reset. I will have to look and make sure there's not some dead battery for the memory inside it -- I have not reviewed all the schematics yet.

No batteries, EEPROM instead.

There are also relays.

[TERRA Operative]

Well, I just won an auction on a HP 8648C 100kHz-3200MHz Signal Generator. It is shown powered on in the auction, but who knows if it works.

I might have some spare parts if needed. Hit me up if you need to.

I know I need a rear foot and the front panel moulding to start, but I will know the rest next week. I'll be in contact.
Thanks! 

[tggzzz]

My newest fleabay toy has been delivered: a Tek THS720A scope. Isolated inputs, 2 channel, 100MHz 500MS/s, with an almost complete selection of accessories. It works nicely except that the NiCd battery is dead. Not really surprising given the age.

Condition was "used" without mentioning the battery. Price was very decent but not very low.

Replacement batteries (NiMH not NiCd) available for £34.

I have some old (i.e. unused expired) sub-c NiCds, and could probably disassemble the existing battery for its strange "collar" connector.

Options:

• do nothing, mains only operation. (Don't actually need the scope, let alone battery operation) - but that's par for the course here!
• buy near replacement
• hack my own
• complain to vendor

[TERRA Operative]

Standard sized C-cells are used in the battery packs in these scopes. With a bit of extra wire and a contact bent out of nickel, you can make the scope work on 4x individual cells.

Also, if you are up for a few SMD resistors, you can convert to a THS720P for free. (No recalibration/adjustment needed), also if you are good with soldering SMD chips
Also you can remove the Flash chip and upgrade the firmware to the latest v1.16 with a chip programmer (If not already there). I used my TL866+ programmer, and then solder the chip back in place, but a recal/adjustment is needed.

And I have made a design (Which I'm planning a second revision) to convert the backlight to LED. Double the brightness for half the power use. (I can send you gerbers, but best to wait for the new version I think)

[W6EL]

As for calibration, AC and DC look very close. Ohms (the working one) appears about 1% high. Not too bad! The "last cal date" in memory on the unit is "0000000" so presumably this was reset. I will have to look and make sure there's not some dead battery for the memory inside it -- I have not reviewed all the schematics yet.

No batteries, EEPROM instead.

There are also relays.

Speaking of relays,

I am thinking K1 on the Ohm board is probably the problem with the ohms source terminals being always active. I'll pull it out today and test it. I suppose it could also be the drive circuit and also even the logic. The relays seem to be plentiful on ebay.

[factory]

W6EL,
Thanks for your reaction. I am a bit surprised you dislike the device, but indeed: it is complex. Mine does not have those wiper-plexi disks, so maybe less trouble. Anyhow, I already have the manuals you quote.

factory,
I am aware of the serial# coding but is there an essential difference between a 1523A and a 1523U? Or are they exactly the same?

The 8640B 1523A & 1523U prefix are the same revision, seems the US army manual covers the early versions, 1523U must have a serial below 00700.  Pictures of the wafer switch from 1536U prefix in the first post here; https://www.vintage-radio.net/forum/showthread.php?t=112364

The later manual shows all the revisions for the US & Scottish made 8640Bs from 16xx upwards, see picture below.

David

[W6EL]

W6EL,
Thanks for your reaction. I am a bit surprised you dislike the device, but indeed: it is complex. Mine does not have those wiper-plexi disks, so maybe less trouble. Anyhow, I already have the manuals you quote.

factory,
I am aware of the serial# coding but is there an essential difference between a 1523A and a 1523U? Or are they exactly the same?

The 8640B 1523A & 1523U prefix are the same revision, seems the US army manual covers the early versions, 1523U must have a serial below 00700.  Pictures of the wafer switch from 1536U prefix in the first post here; https://www.vintage-radio.net/forum/showthread.php?t=112364

The later manual shows all the revisions for the US & Scottish made 8640Bs from 16xx upwards, see picture below.

David

Ahh, so is it the very early ones that were made with conventional wafer switches?

What about the black-face military ones?

This thread is so useful.

[factory]

Ahh, so is it the very early ones that were made with conventional wafer switches?

What about the black-face military ones?

This thread is so useful.

No idea about the military version, don't think I've seen any over here, they do have some differences, for example the counter part has one less digit in the display.

My newest fleabay toy has been delivered: a Tek THS720A scope. Isolated inputs, 2 channel, 100MHz 500MS/s, with an almost complete selection of accessories. It works nicely except that the NiCd battery is dead. Not really surprising given the age.

Condition was "used" without mentioning the battery. Price was very decent but not very low.

Replacement batteries (NiMH not NiCd) available for £34.

I have some old (i.e. unused expired) sub-c NiCds, and could probably disassemble the existing battery for its strange "collar" connector.

Options:

• do nothing, mains only operation. (Don't actually need the scope, let alone battery operation) - but that's par for the course here!
• buy near replacement
• hack my own
• complain to vendor

I'd go for make my own, batteries in something 20+ years old are a consumable.
As for complaining to the seller, how likely are you to consider buying from them again? As they could potentially add you to the blocked buyer/bidder list.

Standard sized C-cells are used in the battery packs in these scopes. With a bit of extra wire and a contact bent out of nickel, you can make the scope work on 4x individual cells.

Also, if you are up for a few SMD resistors, you can convert to a THS720P for free. (No recalibration/adjustment needed), also if you are good with soldering SMD chips
Also you can remove the Flash chip and upgrade the firmware to the latest v1.16 with a chip programmer (If not already there). I used my TL866+ programmer, and then solder the chip back in place, but a recal/adjustment is needed.

And I have made a design (Which I'm planning a second revision) to convert the backlight to LED. Double the brightness for half the power use. (I can send you gerbers, but best to wait for the new version I think)

Only a few resistors labelled on the board, do the others downgrade it to a THS710A?

David

[tggzzz]

Standard sized C-cells are used in the battery packs in these scopes. With a bit of extra wire and a contact bent out of nickel, you can make the scope work on 4x individual cells.

Also, if you are up for a few SMD resistors, you can convert to a THS720P for free. (No recalibration/adjustment needed), also if you are good with soldering SMD chips
Also you can remove the Flash chip and upgrade the firmware to the latest v1.16 with a chip programmer (If not already there). I used my TL866+ programmer, and then solder the chip back in place, but a recal/adjustment is needed.

And I have made a design (Which I'm planning a second revision) to convert the backlight to LED. Double the brightness for half the power use. (I can send you gerbers, but best to wait for the new version I think)

Oh dear, that thread looks like another interesting time sink

But thanks

The different battery clip is an interesting concept; I'll consider that. The NiCds I have are tabbed an in an 8-cell battery, so some "adjustment" would be required in any case. The advantage of having one contact on the side of the battery pack is that if the pack is inserted the wrong way round no damage is done. When I first looked glanced at the battery I wondered about inserting it backwards.

I'm prepared to consider adding a few SMD resistors, not desoldering a flash chip.

[m k]

I am thinking K1 on the Ohm board is probably the problem with the ohms source terminals being always active. I'll pull it out today and test it. I suppose it could also be the drive circuit and also even the logic. The relays seem to be plentiful on ebay.

K1 has a national stock number, so should be available through a reliable source also.
(5945-01-243-4048)

Mostly every middle point of a signal path is available through backplane.

RT6 and later the signal path is sort of a single route.
There is a selection between DC and AC.

Before that is a selection what comes in.
Inputs directly or RT1/2/3 through some option to DC or AC.

So practically everything can be messing with everything.

[RikV]

factory,
This was VERY interesting information. Thanks a lot!
Now is the time for a brave man to start disassembling this machine... Hope I don't end up with some expensive scrap metal...

[electronomicon]

I just replaced the vfd of my 34401A and I have to say this was way easier than expected!
I don’t have a desoldering gun, so I expected this to be quite a difficult job, but simply retinning the pins and using a mechanical desoldering pump worked like a charm! Probably the easiest desoldering job I’ve encounterd so far .

And the Chinese replacement vfd looks great! It’s certainly on par now with my 33120A’s vfd. Just ever so slightly more blueish. And a huge improvement over the previous state.
The panel in front of the display was also quite dirty from the inside, cleaning that probably also helped.

[W6EL]

I just replaced the vfd of my 34401A and I have to say this was way easier than expected!
I don’t have a desoldering gun, so I expected this to be quite a difficult job, but simply retinning the pins and using a mechanical desoldering pump worked like a charm! Probably the easiest desoldering job I’ve encounterd so far .

And the Chinese replacement vfd looks great! It’s certainly on par now with my 33120A’s vfd. Just ever so slightly more blueish. And a huge improvement over the previous state.
The panel in front of the display was also quite dirty from the inside, cleaning that probably also helped.

BEAUTIFUL! Wow! I'd be looking at that thing all day if I had one.

[RikV]

Concerning the 8640B: would anyone have an idea where I could find 3D drawings of those gears? My son could produce them in some resin.
stl., gif.... ipj..