Date   

Re: Tek 7K flex extenders available again

 

It is great that we have members who are able to provide so many things that make maintaining our collections easier.

Hi Etienne, and anyone else who may want one of John's flexible extenders,
Please conduct these transactions directly with John.

Hi John,
If you can remember in the future, please contact interested parties off line even when you are contacted through TekScopes like Etienne did.

Thanks, Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of John Griessen
Sent: Saturday, May 23, 2020 8:00 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek 7K flex extenders available again

On 5/23/20 6:50 AM, evdsp39 wrote:
HI John,

I am very interesting to buy the 7k flex extender so plese tell me the cost included the shipping at this address :

COLISEXPAT - ref.276174
10, rue Eugène Hénaff
93000 - BOBIGNY
FRANCE
tel: 01.84.74.03.75 Mob : 06.76.40.32.22

I will pay by PAYPAL or AMEX card

Thank you for answer.

Etienne.
I sent you a paypal invoice.

--
John Griessen






--
Dennis Tillman W7pF
TekScopes Moderator


Re: 475 questions

Albert Otten
 

On Sat, May 23, 2020 at 10:39 PM, <ciclista41@yahoo.com> wrote:


Are "low-homic" current sensing resistors different from any other resistor of
the same rating?
Oh no, not at all. Since you are a beginner with 'scopes I thought too quickly that you might also not have small value resistors handy.
BTW I don't have a 475 myself and I sold my 465 long ago. For fun I measured the +12V and -12V in my 454 (an earlier analog 'scope than the 465) and found 10-11 ohms at both supply lines. A near zero value is really strange.
BTW in case you don't have one yet, a stabilized variable DC power supply with variable current limiting is very useful. Not just as power source but also in fault seeking. For instance, you can feed one of the big filter caps with a few volts DC and measure (or read) the (leakage?) current drawn.

Albert


Re: 475 questions

ciclista41@...
 

Hi Albert,

Are "low-homic" current sensing resistors different from any other resistor of the same rating?

I checked my vast supply of components and found four 47K ohm resistors. By the way, that is my entire collection of components, unless you count various non-working or old devices on boards taken out of service before they quit working. I still have quite a few even though I took a load of that sort of thing to the city's special collection day for all sorts of recyclables when we moved from Tempe to Mesa about three years ago. Rather than buying new computers when better ones became available, I would hand the older motherboards down to my son, who would get an upgrade from his previous hand-me-down, and I would get the best I could of approximately 2-year-old technology at sale prices. That way, I could afford to "keep up." So, I have several motherboards from computers that my son no longer used, as well as the occasional computer power supply that no longer had the proper connectors for the new boards I got. Then, of course there are various obsolete routers, low baud dial-up modems, and some non-computer boards from appliances that quit or were replaced with improved ones. One of the reasons I ordered a powered solder sucker was to make cannibalizing these old boards for devices with which to build or repair new stuff. I'll see if I can find some low-homic resistors unless you tell me what you prescribe is something different.

Bruce


Re: Tek power cables, older equipment

Sean Turner
 

Thanks for the suggestions everyone! I think either the air conditioner cord or one of the adapters will be perfect for what I want.

Sean


Re: Tek power cables, older equipment

Eric
 

I make my own. The Leviton No. 5269 fit the frames with no modification. They fit, barely but it is not a force fit

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of sdturne@q.com
Sent: Saturday, May 23, 2020 1:08 PM
To: TekScopes@groups.io
Subject: [TekScopes] Tek power cables, older equipment

For instruments like the 114 pulse generator, 184 time mark generator, and more. Does anyone know of a good place to either get these power cables? I have one, that came with my Type 114. With a 184 on the way, I'd like to find another.

Thanks!

Sean


OT Deoxit performance on extremely low level switches? OFF-list only

Ed Breya
 

First, please respond directly to me only OFF-list, and only with relevant info. I don't want to get off on another huge Deoxit good/bad/whatever discussion, which has been covered many times. I would just like any feedback or experience info on whether Deoxit would help to improve mechanical switch contact performance used in very low level circuits.

One of my projects involves boxing up some special transformers and a switching system, for isolating and dividing down AC signals by large factors (E-3 to E-6), down as far as the 1 nV RMS region. A fair number of switching elements are needed to route and select various transformer output taps to send to the single output connection. There are two transformers to cover two frequency bands 10 Hz-1 kHz, and 1 kHz-100 kHz, and each has four outputs for the decade dividing. The switching elements need to have as low an on resistance (<< 1 ohm) as possible, and function well at extremely low levels. Since this is an AC system, I'm not worried about Seebeck effects, just the low level contacting ability. The primary sides of the transformers are at more normal levels, so the switches there are not critical.


I have all sorts of nice low level regular and Hg reed relays that would do the job, but since the output side is to be isolated, to minimize interference, it would be much better to do all the switching passively with mechanical switches. This would avoid needing electricity, and the proximity problems of having relay coils and capacitance in the low level environment, and power supply and line noise and ground loops (no power cord), or messing with battery power. Especially, there would be no power transformer emissions to worry about.

I have lots of mechanical switches of all sorts. I'd like to go with a rotary wafer type to select the transformer taps and frequency ranges. I have mostly standard Ag plated type contact ones and some Au ones. I can usually build a switch from pieces for almost any arrangement.

Another, but quite complicated option is to use low level reeds actuated by a mechanically driven magnet, but doing that would be a big project in itself, so scratch that, unless a simple way pops up. Another way is to make heavy analog switches with big MOSFETs, but that's a lot of parts, a battery, and issues with capacitance and crosstalk. So, good old mechanical switching seems the best way to go - if only it can actually be done.

The big question then, is how to get a regular, environmentally exposed contact to be usable in the nV region. Wetting the contacts with Deoxit is the only practical thing I can picture so far. There is another class of contact "protectors" based on synthetic oils, but I think I need chemical action too, so these may not work - I'll have to investigate that too.

So anyway, does anyone have experience or knowledge of how Deoxit would behave for low level contacts? It may boil down to a "try it and see" scenario, but it would be nice to have some info in advance. OFF-list only, please.

Ed


Re: Tek power cables, older equipment

Tom Gardner
 

On 23/05/20 18:07, sdturne@q.com wrote:
For instruments like the 114 pulse generator, 184 time mark generator, and more. Does anyone know of a good place to either get these power cables? I have one, that came with my Type 114. With a 184 on the way, I'd like to find another.


Re: Tek power cables, older equipment

David Holland
 

https://www.lowes.com/pd/PRIME-6-ft-3-Prong-Gray-Air-Conditioner-Appliance-Power-Cord/1002462146


Something like that works on my 184 & 106....

May have to trim off the little nubbin on the female end, but it works well
enough...

David

On Sat, May 23, 2020 at 1:07 PM <sdturne@q.com> wrote:

For instruments like the 114 pulse generator, 184 time mark generator, and
more. Does anyone know of a good place to either get these power cables? I
have one, that came with my Type 114. With a 184 on the way, I'd like to
find another.

Thanks!

Sean




Tek power cables, older equipment

Sean Turner
 

For instruments like the 114 pulse generator, 184 time mark generator, and more. Does anyone know of a good place to either get these power cables? I have one, that came with my Type 114. With a 184 on the way, I'd like to find another.

Thanks!

Sean


Re: Tek 222/224 Battery Replacement - Project Update

Michael W. Lynch
 

Jeff,

Excellent Project! I do not have one of these little scopes, but if I did, I would be buying this kit!

Thanks for all your efforts.

--
Michael Lynch
Dardanelle, Arkansas


Tek 222/224 Battery Replacement - Project Update

Jeff Davis
 

Hi all,

I'm happy to announce that the Tek 222/224 Battery Replacement project is complete. I'm in the process of testing and shipping the first 25 orders from deposits received from folks here on TekScopes; after that, I've got another 14 boards available before I would have to go back and get some more built.

For those of you unfamiliar with the project, the Tektronix 222 and variants such as the 224 were sold originally with a sealed lead-acid (SLA) battery. Replacements for these SLA batteries stopped being manufactured a long time ago and, due to the form factor of the original battery, there are very few available SLA batteries that can be made to fit in the scope.

This kit allows the use of up to three readily available 18650 rechargeable lithium batteries to replace the now unavailable SLA battery. No modifications to the scope are required other than removal of the original SLA battery. Charging and protection circuitry is provided, allowing the use of unprotected 18650 cells. The kit consists of one assembled and tested battery charger circuit board, one 3D printed case, and some miscellaneous parts such as light pipes to bring the LED indicators to the front of the case and a jumper cable to attach to the scope’s battery connector. The kit does not include rechargeable 18650 lithium batteries (required for operation).

Here's a link to the order page: https://www.n0dy.com/product/tekcharger/.

For those of you interested in the history of the project, I maintained a status page with updates on progress at https://www.n0dy.com/2020/03/29/tek-222-224-charger-order-status/,

Some technical details from the original circuit designer can be found at http://kitsune-denshi.net/projects:tek222bat.

Best regards,
Jeff / N0DY
www.n0dy.com


________________________________
From: Jeff Davis
Sent: Thursday, March 26, 2020 10:02 AM
To: TekScopes <TekScopes@groups.io>
Subject: Tek 222/224 Battery Replacement

Hi all,

One of my customers approached me a few weeks ago about a project to replace the sealed lead acid battery (now unobtainium) in Tek 222/224 scopes with lithium ion cells that presumably will continue to be available for the foreseeable future. He pointed me to a really well done project with a public domain license. There's a YouTube video on it - https://youtu.be/LJ2VS3aohV0.

After a couple of weeks of capturing schematics, sourcing parts, etc. I'm about ready to hit Send on an order for the PCBs. Before I do that, however, I wanted to check with the community to see if there's sufficient interest to order more than the minimum quantity of boards.

How about it, Tek 222/224 collectors? Any interest in a battery pack replacement based on the design in the YouTube video above?

Regards,
Jeff / N0DY


Re: 7B80 sweeping off the screen

ik1zyw@...
 

Thank you Roger and Albert for the excellent advice.
I have the rackable 7603 and side-probing on the live system is not possible. But if the middle bay is left empty then signals can be brought outside easily, it just needs some planning since you connect test leads when the unit is on the desk and then carefully plug it in.

It turns out Q424 was bad. Socketed transistors are suddenly cool! The original part is 2N4122 which I replaced with a BC557 which has lower f_max but the same pinout. Other transistors mentioned by Roger are OK.

Now I will move to the calibration part of the 7B80 manual because the sweep is compressed: who knows what has been done to that 7B80 between 1974 and 2007 before I got it.

Thank you!
Paolo


Re: 475 questions

Leanna L Erickson <lle@...>
 

You may need to bend replacement FW Bridges to more horizontal after replacement.

On May 23, 2020, at 9:57 AM, Harvey White <madyn@dragonworks.info> wrote:

I'll give this a try, so my replies are in line

On 5/23/2020 12:48 AM, ciclista41 via groups.io wrote:
Hi Harvey,

So frustrating! I had a reply nearly as long as your post above, but accidentally hit some button and the entire thing evaporated. Oh well, maybe I will be less wordy and more to the point this time.
I used to have that problem, and then I took the entire "old" message, copied it to a word processor (notepad is fine), then did my editing, then pasted it back. Useful if you anticipate a long reply. As for emails, I use Thunderbird, and haven't had that problem.


Thanks for such a thorough set of suggestions and explanations! This sort of advice is so valuable to me. I understood the part about the rectifiers right away. The part about the linear voltage regulators will take some research on my part to get up to speed on that.
Ok, think of it in plumbing terms. You have a bucket from which you syphon water, that's the load. You have a water supply with a valve, that's the series/pass transistor. You've got a mechanism for measuring the water height in the bucket, and you set it for a certain level.

The bucket gets water removed, which we know. Think of that as the power going to the load (rest of circuit) and doing its job. So we have to adjust the valve to keep the amount of water going in equal to the amount going out. That's all the complicated circuitry. Measure height of water in bucket and adjust valve. Suppose we take less water? Then the bucket starts to get too full, and the mechanism closes the valve. Take more water? Bucket gets too low and we open the valve a bit more. Turn over the bucket, and we "ought" to go valve full on. However, if we don't want that, the little extra resistor and transistor act like a flow limiter so that you only get so much water going out.



I think I almost understand the part about NPN emitter followers, though. I'll be using all of that as well as everyone else's advice as I figure this thing out. Glad the advice has not been conflicting! Gives me confidence that I'm headed in the right direction.
You are. There's likely some good books on transistors out there, but one of the absolute best sources is the service manual itself. Tektronix (and HP) are noted for the quality of their service manuals.

Some on this list have been involved with electronics for years, and this kind of thing is familiar territory for them.

So, tacking a question on to this reply that's meant for anyone following the thread, since you've spent so much time already:

How do I know what generic components are best to replace the original parts? For instance, the tantalum caps come up a lot, but I assume when folks replace them, they don't use the same as the originals. What DO they use? There are so many types of capacitor, even in this one scope, and it's more than 37 years old. The large power supply caps are replaced with newer, smaller electrolytics, but I've heard that some brands are more reliable and last longer than others. What are some good choices?
Many tantalum capacitors can be replaced by aluminum ones. (standard aluminum electrolytics). Depending on the power supply, there are some parameters you want to follow. Others will want to amend these thoughts.

Capacitance, I'd personally use as much or a little more, but not double.

Voltage, going a bit higher is good, depending on where the part is. Early capacitors were thought to be capable of withstanding more of the voltage rating than not, so a 12 volt circuit might have a 15 volt rated capacitor. Time and evidence proved this wrong. Now, I'd use a 25 or 35 volt capacitor on the 12 volts. 25 being somewhat preferable to the 35 volt part. Get too high, and the capacitor doesn't work as well.

Temperature rating, most capacitors are rated at x thousand hours of operation at y degrees. You may not get to that temperature limit, but the typical temperatures are 85 degrees C and 105 degrees C. I'd use the 105 degrees C part.

Nichicon is a good brand, Panasonic is a good brand. Most people steer clear of clearly Chinese made parts which may not be made to appropriate standards.

I looked up one of the original rectifiers, an MDA960-3. I found a NOS of it on Ebay for almost $9 plus shipping. At that rate, this is going to get expensive very quickly. So what can I use instead? I assume that by looking up the specs on each original component that I end up replacing and finding something that meets or exceeds those specs, I'll probably be okay, but I could really use the voice of experience here.
Ask on the list. I think that a 960-3 is a bridge, 600 volts, and 3 amps. Any decent equivalent will work. A 5 amp bridge would work, but more than that and you may find that it's too big to fit properly. You could make an equivalent with (IIRC) 1n5400 series diodes, but that's awkward in a physical sense. The advantage of the bridges is that it's all one unit, and the case provides a heat sink. Any part with current (AC or DC) flowing through it will get hot. It may not be a measurable amount of heat, but there will be some. Generally, the higher power parts (semiconductors and resistors) have some method of dumping that heat, frequently into a chassis.



I'm aware of Digikey and Mouser. I ordered some diodes from Digikey several years ago to build a rectifier that I used to convert the power from a hub generator on my touring bike to charge my phone as I rode. It even worked, although my buddy said the one I built for him killed his phone. Mine had some issues that I never resolved. I'm hoping to soon have the ability to design my own circuit, rather than copying someone else's, and have it be rock-solid! But, I digress...
There are some places you can also buy parts. All Electronics, Electronics Goldmine are two of them. They operate as "dump surplus/excess inventory" and as such, if you see it, buy it and enough for future needs. No guarantees that they will have it again once sold out. James Electronics operates more as a hobby distributor, and has a more consistent inventory. You may find older parts there as well.

Mouser and Digikey are, of course, industrial distributors. If I buy resistors from them (I use surface mounted parts), I would consider buying in lots of 100 for the best price, perhaps even 1000, depending on my history of using the part. You'll see the economies of scale if you go to building things. Replacement parts are another matter, though, since you are not likely to need 100 each of 47 uf/200 volt capacitors. (certainly not at what I think they go for).

You may also find in your area, depending on where it is, some surplus electronics stores that have stocks of parts. Florida has at least two that I know of. Those stores are hard to find, though.

Harvey



Thanks again, Harvey!

Bruce




Re: 475 questions

Albert Otten
 

On Fri, May 22, 2020 at 04:02 AM, <ciclista41@yahoo.com> wrote:


Yes, I re-read them just after turning the scope off, before my last reply,
and I re-read them just now. All three are shorted regardless of the polarity
with which I measured them. So it's surprising to me that the board doesn't
pop, get hot, or release magic smoke when I run it.
Hi Bruce,
Strange indeed that you measure 0 ohms at some LV lines while they come up to several volts when the 'scope is powered up. Is there any chance that something is wrong with your analog meters? As a test you might measure the resistance of those low-ohmic current sensing resistors R1478 (3 ohms) and R1468 (0.6 ohms) if these are easy to access.
Albert


Re: Update on my 7854 diagnostics project

Holger Lübben
 

Hi!

The trick is: In this case the front panel is also a pcb ;-)

This board is 0.8mm thick, white soldermask and black silk screen.
Here is a closeup of one of my red & white ones:

http://w140.com/tekwiki/images/7/77/P7001_program_overlay_card.jpg

If you look closely you can see the copper borders under the silkscreen

There a two downsides:
1) You can't get inner holes with sharp corners - usually you have to deal with 3mm corners. Thats the reason why my 7854 keyboard overlay card has a big hole per keyboard row - compared to individual holes for each key on the original card
2) I've tried a local pcb manufacturer and one of those cheap chinese ones and both reuqire at least one pad on the pcb. Thats the reason for the two pads on my panels.

But beside from that: They are great and look even better in real world.

If you want to have professional front panels you can also use services like www.schaeffer-ag.de. That's one of the local german ones, but I think you'll find such a company in every country.

Holger


Re: Tek 7K flex extenders available again

John Griessen
 

On 5/23/20 6:50 AM, evdsp39 wrote:
HI John,
I am very interesting to buy the 7k flex extender so plese tell me the cost included the shipping at this address :
COLISEXPAT - ref.276174
10, rue Eugène Hénaff
93000 - BOBIGNY
FRANCE
tel: 01.84.74.03.75 Mob : 06.76.40.32.22
I will pay by PAYPAL or AMEX card
Thank you for answer.
Etienne.
I sent you a paypal invoice.

--
John Griessen


Re: 475 questions

Harvey White
 

I'll give this a try, so my replies are in line

On 5/23/2020 12:48 AM, ciclista41 via groups.io wrote:
Hi Harvey,

So frustrating! I had a reply nearly as long as your post above, but accidentally hit some button and the entire thing evaporated. Oh well, maybe I will be less wordy and more to the point this time.
I used to have that problem, and then I took the entire "old" message, copied it to a word processor (notepad is fine), then did my editing, then pasted it back.  Useful if you anticipate a long reply.  As for emails, I use Thunderbird, and haven't had that problem.


Thanks for such a thorough set of suggestions and explanations! This sort of advice is so valuable to me. I understood the part about the rectifiers right away. The part about the linear voltage regulators will take some research on my part to get up to speed on that.
Ok, think of it in plumbing terms.  You have a bucket from which you syphon water, that's the load.  You have a water supply with a valve, that's the series/pass transistor.  You've got a mechanism for measuring the water height in the bucket, and you set it for a certain level.

The bucket gets water removed, which we know.  Think of that as the power going to the load (rest of circuit) and doing its job. So we have to adjust the valve to keep the amount of water going in equal to the amount going out.  That's all the complicated circuitry.  Measure height of water in bucket and adjust valve. Suppose we take less water?  Then the bucket starts to get too full, and the mechanism closes the valve.  Take more water? Bucket gets too low and we open the valve a bit more.  Turn over the bucket, and we "ought" to go valve full  on.  However, if we don't want that, the little extra resistor and transistor act like a flow limiter so that you only get so much water going out.



I think I almost understand the part about NPN emitter followers, though. I'll be using all of that as well as everyone else's advice as I figure this thing out. Glad the advice has not been conflicting! Gives me confidence that I'm headed in the right direction.
You are.  There's likely some good books on transistors out there, but one of the absolute best sources is the service manual itself.  Tektronix (and HP) are noted for the quality of their service manuals.

Some on this list have been involved with electronics for years, and this kind of thing is familiar territory for them.

So, tacking a question on to this reply that's meant for anyone following the thread, since you've spent so much time already:

How do I know what generic components are best to replace the original parts? For instance, the tantalum caps come up a lot, but I assume when folks replace them, they don't use the same as the originals. What DO they use? There are so many types of capacitor, even in this one scope, and it's more than 37 years old. The large power supply caps are replaced with newer, smaller electrolytics, but I've heard that some brands are more reliable and last longer than others. What are some good choices?
Many tantalum capacitors can be replaced by aluminum ones. (standard aluminum electrolytics).  Depending on the power supply, there are some parameters you want to follow.  Others will want to amend these thoughts.

Capacitance, I'd personally use as much or a little more, but not double.

Voltage, going a bit higher is good, depending on where the part is.  Early capacitors were thought to be capable of withstanding more of the voltage rating than not, so a 12 volt circuit might have a 15 volt rated capacitor.  Time and evidence proved this wrong.  Now, I'd use a 25 or 35 volt capacitor on the 12 volts. 25 being somewhat preferable to the 35 volt part.  Get too high, and the capacitor doesn't work as well.

Temperature rating, most capacitors are rated at x thousand hours of operation at y degrees.  You may not get to that temperature limit, but the typical temperatures are 85 degrees C and 105 degrees C.  I'd use the 105 degrees C part.

Nichicon is a good brand, Panasonic is a good brand.  Most people steer clear of clearly Chinese made parts which may not be made to appropriate standards.

I looked up one of the original rectifiers, an MDA960-3. I found a NOS of it on Ebay for almost $9 plus shipping. At that rate, this is going to get expensive very quickly. So what can I use instead? I assume that by looking up the specs on each original component that I end up replacing and finding something that meets or exceeds those specs, I'll probably be okay, but I could really use the voice of experience here.
Ask on the list.  I think that a 960-3 is a bridge, 600 volts, and 3 amps.  Any decent equivalent will work.  A 5 amp bridge would work, but more than that and you may find that it's too big to fit properly.  You could make an equivalent with (IIRC) 1n5400 series diodes, but that's awkward in a physical sense.  The advantage of the bridges is that it's all one unit, and the case provides a heat sink.  Any part with current (AC or DC) flowing through it will get hot.  It may not be a measurable amount of heat, but there will be some.  Generally, the higher power parts (semiconductors and resistors) have some method of dumping that heat, frequently into a chassis.



I'm aware of Digikey and Mouser. I ordered some diodes from Digikey several years ago to build a rectifier that I used to convert the power from a hub generator on my touring bike to charge my phone as I rode. It even worked, although my buddy said the one I built for him killed his phone. Mine had some issues that I never resolved. I'm hoping to soon have the ability to design my own circuit, rather than copying someone else's, and have it be rock-solid! But, I digress...
There are some places you can also buy parts.  All Electronics, Electronics Goldmine are two of them.  They operate as "dump surplus/excess inventory" and as such, if you see it, buy it and enough for future needs.  No guarantees that they will have it again once sold out.  James Electronics operates more as a hobby distributor, and has a more consistent inventory.  You may find older parts there as well.

Mouser and Digikey are, of course, industrial distributors.  If I buy resistors from them (I use surface mounted parts), I would consider buying in lots of 100 for the best price, perhaps even 1000, depending on my history of using the part.  You'll see the economies of scale if you go to building things.  Replacement parts are another matter, though, since you are not likely to need 100 each of 47 uf/200 volt capacitors.  (certainly not at what I think they go for).

You may also find in your area, depending on where it is, some surplus electronics stores that have stocks of parts.  Florida has at least two that I know of.  Those stores are hard to find, though.

Harvey



Thanks again, Harvey!

Bruce



Re: Update on my 7854 diagnostics project

Ke-Fong Lin
 

Hi Holger,

If that's not a secret, where did you have your keyboard overlay card manufactured?
There's multiple sources of PCB fabs that are very good quality, and cheap.
But I've trouble finding a suitable front panel manufacturer.
Thank you.

Best regards,


Re: 7B80 sweeping off the screen

Roger Evans
 

Albert,

Thank you for that particular insight, my suggestion was just to have a single plugin (the 7B80) in the 7603 and move it to whichever slot gave best access for probing. Your suggestion is much better since you are using the working parts of the 7603 to diagnose the part which is not working. I have previously suggested that if you have one channel not working on a normal double channel (not mainframe plus plugins) scope you can use the working channel to probe the non working channel from the input connectors as far as the channel switch.

Roger


Re: Looking for P7001 / GPIB ROM images

Holger Lübben
 

Hi Raymond,

Thanks for your help.

My board and ROM layout matches your description.
Here is a picture of my board:
http://w140.com/tekwiki/images/f/f0/P7001_GPIB_adaper_right_dismounted.jpg
As you can see someone changed some of the ROMs in the past - maybe thats the source of my problems.

It would be nice to get the files in "plain binary format" (*.bin), but I can reformat nearly every format.

Holger

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