Date   

RM545B Looking for a good home (Austin, TX)

Steve Raasch <sraasch@...>
 

I've moved to a new home in Austin and don't have room to keep this beauty. I violently object to putting it into a landfill, and thought someone here might be interested.
This unit has the 1A1 plugin and is very clean. BONUS: it has *history* that I'll share with the person who chooses to rescue it :)

PM me if you are interested.


TDS540B switches during boot VGA output from color to monochrome

HK
 

Hello! Any idea what to change to make my new TDS540B don't switch after booting to monochrome only at the VGA output? For a short time before the splash screen it outputs colored.
The internal screen is damaged: After 40 minutes there is a thermal problem, the internal monochrome display fades away..., but VGA is still alive.

Thank you!
- Henry


Re: Graded display on CSA803 / 11800 series

Perdad
 

Good work ! Just what I was looking for. Small and simple.

Per


Re: TM506

Stephen
 

On Tue, Jul 21, 2020 at 02:13 AM, Colin Herbert wrote:


I actually have one TM504 and two TM503 mainframes in my possession. One of
the TM503s has the serial #200778 and was made by Tektronix London, England,
so maybe yours was, too. The pass transistors are all Motorola by the look of
it and are three 037300 and three 034900.
I’m not in front of it at the moment, but as far as U can remember, the ones in mine are also Motorola’s.


Re: Cleaning the screen of a TDS744A ?

Harvey White
 

Do you want blue on a scope with a color display?

Harvey

On 7/21/2020 10:04 AM, toby@telegraphics.com.au wrote:
On 2020-07-21 9:33 a.m., DaveC via groups.io wrote:
I would try 70% IPA and cloth wipe.

I've also had good results replacing faceplates with 1.5mm acrylic.

--Toby
Did you find it in Tek blue?
No, the ones I was replacing were clear. Check with Walter at Sphere for
genuine ones.

--Toby

Dave C.




Re: Cleaning the screen of a TDS744A ?

toby@...
 

On 2020-07-21 9:33 a.m., DaveC via groups.io wrote:
I would try 70% IPA and cloth wipe.

I've also had good results replacing faceplates with 1.5mm acrylic.

--Toby
Did you find it in Tek blue?
No, the ones I was replacing were clear. Check with Walter at Sphere for
genuine ones.

--Toby


Dave C.



Re: TM506

Stephen
 

On Tue, Jul 21, 2020 at 02:13 AM, Colin Herbert wrote:


I actually have one TM504 and two TM503 mainframes in my possession. One of
the TM503s has the serial #200778 and was made by Tektronix London, England,
so maybe yours was, too. The pass transistors are all Motorola by the look of
it and are three 037300 and three 034900. Bear in mind that this TM503 has
just three standard bays and no high-power bay.
To the best of my knowledge, there were no manuals printed specifically for
Tek stuff made in England, The Netherlands (Heerenveen) or the Channel
Islands, but I _have_ seen "Change Information" that at least mentioned
equipment made other than in Portland or Beaverton.
Colin.
Yes, most of the TEKTRONIX equipment I get over here in mainland Europe was usually Manufactured in the Netherlands or the UK. Very few are from Beaverton. That makes things a bit trickier to troubleshoot because the manuals are non existent, and those available may have slightly different values...


Re: Cleaning the screen of a TDS744A ?

DaveC <davec2468@...>
 

I would try 70% IPA and cloth wipe.

I've also had good results replacing faceplates with 1.5mm acrylic.

--Toby
Did you find it in Tek blue?

Dave C.


Re: Cleaning the screen of a TDS744A ?

toby@...
 

On 2020-07-21 4:34 a.m., David Slipper wrote:

What is the best way to get greasy finger prints off the plastic sheet
that is in front of the CRT ???
Dave,

I would try 70% IPA and cloth wipe.

I've also had good results replacing faceplates with 1.5mm acrylic.

--Toby


Thanks in advance

Dave





Re: TM506

Colin Herbert
 

I actually have one TM504 and two TM503 mainframes in my possession. One of the TM503s has the serial #200778 and was made by Tektronix London, England, so maybe yours was, too. The pass transistors are all Motorola by the look of it and are three 037300 and three 034900. Bear in mind that this TM503 has just three standard bays and no high-power bay.
To the best of my knowledge, there were no manuals printed specifically for Tek stuff made in England, The Netherlands (Heerenveen) or the Channel Islands, but I _have_ seen "Change Information" that at least mentioned equipment made other than in Portland or Beaverton.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Stephen
Sent: 21 July 2020 13:25
To: TekScopes@groups.io
Subject: Re: [TekScopes] TM506

On Tue, Jul 21, 2020 at 01:03 AM, Doug Bercich wrote:


The photos - to me, if I'm interpreting them correctly - show diodes on the
first one and a thermal switch on the second. I'm not sure which manual you're
working from but that might be part of the problem. The manual on BAMA is from
the '60s but the one on TekWiki is from 1974 and looks very similar to your
unit.
Yes, I can see the 2 diodes. They are connected together on the other side.
The other one, I don’t know what it is...
So where are the High Power slot pass transistors???

The manual I have is from TekWiki. And my board read 1973. But the serial number does not start with a B. It’s 200324

Remember to be VERY careful while probing around. We've all done it - let a
meter lead slip and bridge some transistor legs or worse... Also, if you're
using a mains powered oscilloscope during troubleshooting you can't just clip
the ground wire anywhere or you can end up with worse problems than you
started with.
I am not probing anything anything at this point. Let alone with the unit ON. Just checkIng values and fuses.


Re: TM506

Stephen
 

On Tue, Jul 21, 2020 at 12:11 AM, Colin Herbert wrote:


If it is of any significance at all, I also have a TM504 and a Service Manual
for it. Apart from the Tektronix-made transistors that I have already
mentioned (they are all NPN), there are also some Motorola-made ones, SJE925
which are PNP, in the standard bays. In the high-power bay the Motorola MJ2955
was the earlier PNP type, but later NPN types were sourced from RCA and were
2N6258 (superseded at B011750 by RCA 36568).
Thank you Colin.


Re: TM506

Stephen
 

On Tue, Jul 21, 2020 at 12:33 AM, <scm@menasians.com> wrote:


Generally, the center pin on a TO-247 transistor is the collector. A good
guess for the emitter and base can be gleaned from a datasheet for a
documented power transistor. Everything can be verified by making the
continuity measurements I described earlier. A second level of verification
can be made by unsoldering the leads to the emitter and base of a good (not
shorted!!) transistor. The base-emitter measurement should look like a diode
in with the same polarity as the base-collector diode.
I will do that as someone else also suggested earlier.


Re: TM506

Stephen
 

On Tue, Jul 21, 2020 at 01:03 AM, Doug Bercich wrote:


The photos - to me, if I'm interpreting them correctly - show diodes on the
first one and a thermal switch on the second. I'm not sure which manual you're
working from but that might be part of the problem. The manual on BAMA is from
the '60s but the one on TekWiki is from 1974 and looks very similar to your
unit.
Yes, I can see the 2 diodes. They are connected together on the other side.
The other one, I don’t know what it is...
So where are the High Power slot pass transistors???

The manual I have is from TekWiki. And my board read 1973. But the serial number does not start with a B. It’s 200324

Remember to be VERY careful while probing around. We've all done it - let a
meter lead slip and bridge some transistor legs or worse... Also, if you're
using a mains powered oscilloscope during troubleshooting you can't just clip
the ground wire anywhere or you can end up with worse problems than you
started with.
I am not probing anything anything at this point. Let alone with the unit ON. Just checkIng values and fuses.


Re: TM506

Stephen
 

On Tue, Jul 21, 2020 at 12:47 AM, Roger Evans wrote:


U340 is a 7447 BCD to 7 segment decoder, £1.50 plus postage on eBay.
One of my local stores should have them.
Are you sure that U340 is the culprit?
Nope. Just a guess.

U 340 drives the individual segments of all the
7 segment displays in parallel. A fault with U340 will give the same missing
segment or wrong segment on each of the eight display positions.
There are 2 (or maybe 3) positions I could see that actually light up (not all do) with one missing segment. Every time the same one.

Your pictures show only one position on at any one time which looks like U335 is
not switching its outputs in sequence (scanning the eight display positions).
I suggested where to test the scanning circuitry in an earlier post.
Did you? There are so many replies that I must’ve missed something. My apologies.

Anyways, now that the TM itself isn’t working properly, I can’t test anything anymore until it’s fixed.


There is a _lot_ of information in the archives here about the pass
transistors, I would take time to read it before ripping everything out of
your TM506.
I’m just going to replace all of them just to be on the safe side. And one less variable to worry about (hopefully)
Don't despair, I bought a TM503 with three failed plugins and no UK/US mains
voltage selection and ended up with everything working and had a lot of fun in
the process.

Roger
Excellent. But I’m neither as skilled nor as patient as you obviously are.
I’m not an EE by any stretch. I’m a computer engineer. But I do work quite a lot on old tube guitar amps, and built a few too. Very basic and simple compared to these things. And that’s where the extent of my knowledge stops. I’m learning though...


Re: TM506

Doug Bercich
 

The photos - to me, if I'm interpreting them correctly - show diodes on the first one and a thermal switch on the second. I'm not sure which manual you're working from but that might be part of the problem. The manual on BAMA is from the '60s but the one on TekWiki is from 1974 and looks very similar to your unit.

Remember to be VERY careful while probing around. We've all done it - let a meter lead slip and bridge some transistor legs or worse... Also, if you're using a mains powered oscilloscope during troubleshooting you can't just clip the ground wire anywhere or you can end up with worse problems than you started with.


Re: TM506

Roger Evans
 

U340 is a 7447 BCD to 7 segment decoder, £1.50 plus postage on eBay. Are you sure that U340 is the culprit? U 340 drives the individual segments of all the 7 segment displays in parallel. A fault with U340 will give the same missing segment or wrong segment on each of the eight display positions. Your pictures show only one position on at any one time which looks like U335 is not switching its outputs in sequence (scanning the eight display positions). I suggested where to test the scanning circuitry in an earlier post.

There is a _lot_ of information in the archives here about the pass transistors, I would take time to read it before ripping everything out of your TM506.

Don't despair, I bought a TM503 with three failed plugins and no UK/US mains voltage selection and ended up with everything working and had a lot of fun in the process.

Roger


Re: TM506

SCMenasian
 

Generally, the center pin on a TO-247 transistor is the collector. A good guess for the emitter and base can be gleaned from a datasheet for a documented power transistor. Everything can be verified by making the continuity measurements I described earlier. A second level of verification can be made by unsoldering the leads to the emitter and base of a good (not shorted!!) transistor. The base-emitter measurement should look like a diode in with the same polarity as the base-collector diode.


Re: TM506

Colin Herbert
 

If it is of any significance at all, I also have a TM504 and a Service Manual for it. Apart from the Tektronix-made transistors that I have already mentioned (they are all NPN), there are also some Motorola-made ones, SJE925 which are PNP, in the standard bays. In the high-power bay the Motorola MJ2955 was the earlier PNP type, but later NPN types were sourced from RCA and were 2N6258 (superseded at B011750 by RCA 36568).

It gets more and more tricky to understand.

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Stephen
Sent: 21 July 2020 11:34
To: TekScopes@groups.io
Subject: Re: [TekScopes] TM506

On Mon, Jul 20, 2020 at 10:54 PM, <scm@menasians.com> wrote:


You should be able to figure out what the pinouts are with an ohmmeter.
According to my diagram, the collectors go to pins 7B (NPN) and pins 11B
(PNP); the emitters go to pins 7A (NPN) and pins 10A(PNP) and the bases go to
pins 6A(NPN) and 11A(PNP) on the backplane connectors. Also the collectors are
the metal cases if the package is T03 or other metal case from that vintage.
Interesting... thanks.
Mine are not in à TO-3 case. They are in à TO-247 case.

The High-Power ones are not TO-3 either.
One is a pair of diodes connected together, and the other one I haven’t removed it yet. Can’t see what it is....
Here are some pictures:

https://groups.io/g/TekScopes/photo/250733/1?p=Created,,,100,2,0,0

https://groups.io/g/TekScopes/photo/250733/0?p=Created,,,100,2,0,0

The diodes are labeled: 0274-00-8236 and 0274-00-8336
Maybe I’m wrong, but they look like diodes to me.


Re: TM506

Stephen
 

On Mon, Jul 20, 2020 at 10:54 PM, <scm@menasians.com> wrote:


You should be able to figure out what the pinouts are with an ohmmeter.
According to my diagram, the collectors go to pins 7B (NPN) and pins 11B
(PNP); the emitters go to pins 7A (NPN) and pins 10A(PNP) and the bases go to
pins 6A(NPN) and 11A(PNP) on the backplane connectors. Also the collectors are
the metal cases if the package is T03 or other metal case from that vintage.
Interesting... thanks.
Mine are not in à TO-3 case. They are in à TO-247 case.

The High-Power ones are not TO-3 either.
One is a pair of diodes connected together, and the other one I haven’t removed it yet. Can’t see what it is....
Here are some pictures:

https://groups.io/g/TekScopes/photo/250733/1?p=Created,,,100,2,0,0

https://groups.io/g/TekScopes/photo/250733/0?p=Created,,,100,2,0,0

The diodes are labeled: 0274-00-8236 and 0274-00-8336
Maybe I’m wrong, but they look like diodes to me.


Re: TM506

SCMenasian
 

You should be able to figure out what the pinouts are with an ohmmeter. According to my diagram, the collectors go to pins 7B (NPN) and pins 11B (PNP); the emitters go to pins 7A (NPN) and pins 10A(PNP) and the bases go to pins 6A(NPN) and 11A(PNP) on the backplane connectors. Also the collectors are the metal cases if the package is T03 or other metal case from that vintage.

17701 - 17720 of 187058