Date   
Re: Looking for a TU-75B $400

Adrian
 

Better than me - I was thinking 400 bucks for an old Russian military airplane was a bit optimistic!

On 1/29/2019 9:35 PM, Jim Potter wrote:
For a few minutes I thought you were looking for a WW2 Tuning Unit. Then I realized this was on the TekScopes forum.

Re: Wanted 7B15

ArtekManuals
 

Let us all know  how that turns out
that one for $55 looked very clean at first glance

Dave

On 1/30/2019 1:07 AM, fred@... wrote:
On Tue, Jan 29, 2019 at 05:56 PM, Artekmedia wrote:
There are TWO on that infamous auction site "EVIL-BAY" at the moment


Hi Dave,
thanks for the info, I took my chances and bought one.

--
Dave
Manuals@...
www.ArtekManuals.com

Type 310 HV Transformer.

penguin2004au
 

Greetings to the group:

Does anybody have winding specs for the Type 310 HV transformer, early version (although there may be no difference between early and late production)?

Regards:

Re: No start 7854 Power supply

 

SOLVED !!!

OK, The voltage at the emitter of Q45 was about 110V, which was less than the voltage at the base (118V) which is set by the Zener diode VR45, so the over-voltage circuit wasn't causing the shutdown.

Not long afterwards the supply changed its behaviour, settling down in to what I can best describe as "normal" tick-mode.

I then spent a few happy hours chasing my tail, looking at the I-Sense (pin 13) and E-Sense (pin 15) signals on the controller IC to see if they were causing the oscillator stop signal on pin 8 to be asserted.

I should say at this point that I was using a dummy load connected to P82 on the LV regulator board.

I checked the schematic just before probing the Fault-Sense signal at pin 2 and realised that without the thermal switch connected to the LV board that a supplies out of balance condition would shut the inverter down.

Once I put a jumper on P72 on the LV regulator, the supply sprang to life!

In summary there were multiple faults on this supply and one pilot error :)

1. Both inverter transistors were dead short.

2. R44 in the over-voltage stop circuit had literally broken in two.

3. Both CR36 and CR37 in the inverter control circuit had leads corroded through.

4. Lots of under board corrosion, solder in some holes corroded away.

5. The 22 ohm inverter base drive resistors (R32 and R40) were both open circuit (even though they looked OK).

6. The collector lead of Q46 (over-voltage stop) was corroded away where it connected to the can.

7. Pilot error - PUT A JUMPER ON P72 ON LV BOARD WHEN USING A DUMMY LOAD

The supply was ticking when it was installed in the MF, so on a hunch I checked the thermal cut-out switch by probing the connector that went on P72. That was open circuit, but that turned out to be simple as one of the wires had come off the thermal switch.

The mainframe now powers on but there are other issues - but that's for another thread.

Dave

Re: No start 7854 Power supply

 

Oh yes, I forgot to add the tank capacitor C37 that failed short very soon after I replaced the inverter transistors.

So a total of 7 faults!

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David C. Partridge
Sent: 30 January 2019 12:26
To: TekScopes@groups.io
Subject: Re: [TekScopes] No start 7854 Power supply

SOLVED !!!

OK, The voltage at the emitter of Q45 was about 110V, which was less than the voltage at the base (118V) which is set by the Zener diode VR45, so the over-voltage circuit wasn't causing the shutdown.

Not long afterwards the supply changed its behaviour, settling down in to what I can best describe as "normal" tick-mode.

I then spent a few happy hours chasing my tail, looking at the I-Sense (pin 13) and E-Sense (pin 15) signals on the controller IC to see if they were causing the oscillator stop signal on pin 8 to be asserted.

I should say at this point that I was using a dummy load connected to P82 on the LV regulator board.

I checked the schematic just before probing the Fault-Sense signal at pin 2 and realised that without the thermal switch connected to the LV board that a supplies out of balance condition would shut the inverter down.

Once I put a jumper on P72 on the LV regulator, the supply sprang to life!

In summary there were multiple faults on this supply and one pilot error :)

1. Both inverter transistors were dead short.

2. R44 in the over-voltage stop circuit had literally broken in two.

3. Both CR36 and CR37 in the inverter control circuit had leads corroded through.

4. Lots of under board corrosion, solder in some holes corroded away.

5. The 22 ohm inverter base drive resistors (R32 and R40) were both open circuit (even though they looked OK).

6. The collector lead of Q46 (over-voltage stop) was corroded away where it connected to the can.

7. Pilot error - PUT A JUMPER ON P72 ON LV BOARD WHEN USING A DUMMY LOAD

The supply was ticking when it was installed in the MF, so on a hunch I checked the thermal cut-out switch by probing the connector that went on P72. That was open circuit, but that turned out to be simple as one of the wires had come off the thermal switch.

The mainframe now powers on but there are other issues - but that's for another thread.

Dave

Re: No start 7854 Power supply

John Griessen
 

On 1/30/19 6:26 AM, David C. Partridge wrote:
Once I put a jumper on P72 on the LV regulator, the supply sprang to life!
In summary there were multiple faults on this supply and one pilot error

Thanks for the story telling, Dave. It will help when I debug one of my 7104's.

7854 display problem

 

OK when I powered this 7854 on fixing the PSU, if failed POST with a ROM
failure (dratted Mostek mask ROMs).

So as to be able to continue testing, I "borrowed" the ROM board
(670-5047-02) from my personal 7854 and put it in the patient.

It passed POST, but this is what the screen looks like: <
https://groups.io/g/TekScopes/files/7854/7854%20Initial%20Display%20Problem.
MOV>

It sort of looks like it may be trying to display the normal Self Test
Complete screen, but it sure isn't right!

Any suggestions for likely culprits?

Thanks
David

Re: 7854 display problem

 

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David C.
Partridge
Sent: 30 January 2019 15:43
To: TekScopes
Subject: [TekScopes] 7854 display problem

OK when I powered this 7854 on fixing the PSU, if failed POST with a ROM
failure (dratted Mostek mask ROMs).

So as to be able to continue testing, I "borrowed" the ROM board
(670-5047-02) from my personal 7854 and put it in the patient.

It passed POST, but this is what the screen looks like: <
https://groups.io/g/TekScopes/files/7854/7854%20Initial%20Display%20Problem.
MOV>

It sort of looks like it may be trying to display the normal Self Test
Complete screen, but it sure isn't right!

Any suggestions for likely culprits?

Thanks
David

Re: 7854 display problem

 

Looks like it won't let me put the link on a single line - grrrr

D.

Re: 7854 display problem

Dave Daniel
 

tinyurl.com

Sent from a small flat thingy

On Jan 30, 2019, at 12:09, David C. Partridge <@perdrix> wrote:

Looks like it won't let me put the link on a single line - grrrr

D.


Re: 7854 display problem

Chuck Harris
 

Or even easier, if you put down a "<" and ">" on a line,
and paste the link between them, you will be signaling
that it is a link, and it will not be broken when it wraps.

-Chuck Harris

Dave Daniel wrote:

tinyurl.com

Sent from a small flat thingy

On Jan 30, 2019, at 12:09, David C. Partridge <@perdrix> wrote:

Looks like it won't let me put the link on a single line - grrrr

D.




Re: 7854 display problem

bobh@joba.com
 

This usually works,

https://groups.io/g/TekScopes/files/7854/7854%20Initial%20Display%20Problem,.MOV

Nice job on documenting your process and trials.  I'll definitely save your summary since I have a copy of the beast myself.

Bob.

On 1/30/2019 10:09 AM, David C. Partridge wrote:
Looks like it won't let me put the link on a single line - grrrr

D.


Re: 7854 display problem

 

I did that, but it still broke it across lines

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Chuck Harris
Sent: 30 January 2019 17:24
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7854 display problem

Or even easier, if you put down a "<" and ">" on a line,
and paste the link between them, you will be signaling
that it is a link, and it will not be broken when it wraps.

-Chuck Harris

Dave Daniel wrote:
tinyurl.com

Sent from a small flat thingy

On Jan 30, 2019, at 12:09, David C. Partridge <@perdrix> wrote:

Looks like it won't let me put the link on a single line - grrrr

D.




Re: 7854 display problem

 

Drat it - it still split the link!

<https://tinyurl.com/ycarxp3k>

David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David C.
Partridge
Sent: 30 January 2019 16:15
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7854 display problem

link got split

<https://groups.io/g/TekScopes/files/7854/7854%20Initial%20Display%20Problem
.MOV>

Sorry

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David C.
Partridge
Sent: 30 January 2019 15:43
To: TekScopes
Subject: [TekScopes] 7854 display problem

OK when I powered this 7854 on fixing the PSU, if failed POST with a ROM
failure (dratted Mostek mask ROMs).

So as to be able to continue testing, I "borrowed" the ROM board
(670-5047-02) from my personal 7854 and put it in the patient.

It passed POST, but this is what the screen looks like: <
https://groups.io/g/TekScopes/files/7854/7854%20Initial%20Display%20Problem.
MOV>

It sort of looks like it may be trying to display the normal Self Test
Complete screen, but it sure isn't right!

Any suggestions for likely culprits?

Thanks
David

Re: No start 7854 Power supply

johnhstrauch
 

What does your dummy load consist of. I need to fab one to work on this 7000 series PSU that I have.
JH

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David C. Partridge
Sent: Wednesday, January 30, 2019 6:26 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] No start 7854 Power supply

SOLVED !!!

OK, The voltage at the emitter of Q45 was about 110V, which was less than the voltage at the base (118V) which is set by the Zener diode VR45, so the over-voltage circuit wasn't causing the shutdown.

Not long afterwards the supply changed its behaviour, settling down in to what I can best describe as "normal" tick-mode.

I then spent a few happy hours chasing my tail, looking at the I-Sense (pin 13) and E-Sense (pin 15) signals on the controller IC to see if they were causing the oscillator stop signal on pin 8 to be asserted.

I should say at this point that I was using a dummy load connected to P82 on the LV regulator board.

I checked the schematic just before probing the Fault-Sense signal at pin 2 and realised that without the thermal switch connected to the LV board that a supplies out of balance condition would shut the inverter down.

Once I put a jumper on P72 on the LV regulator, the supply sprang to life!

In summary there were multiple faults on this supply and one pilot error :)

1. Both inverter transistors were dead short.

2. R44 in the over-voltage stop circuit had literally broken in two.

3. Both CR36 and CR37 in the inverter control circuit had leads corroded through.

4. Lots of under board corrosion, solder in some holes corroded away.

5. The 22 ohm inverter base drive resistors (R32 and R40) were both open circuit (even though they looked OK).

6. The collector lead of Q46 (over-voltage stop) was corroded away where it connected to the can.

7. Pilot error - PUT A JUMPER ON P72 ON LV BOARD WHEN USING A DUMMY LOAD

The supply was ticking when it was installed in the MF, so on a hunch I checked the thermal cut-out switch by probing the connector that went on P72. That was open circuit, but that turned out to be simple as one of the wires had come off the thermal switch.

The mainframe now powers on but there are other issues - but that's for another thread.

Dave

TDS-540 trips GFI

ham789@...
 

TDS-540 Trips GFI.

USA, 120VAC single phase.

I replaced the transistor and transorbs in the standby power supply.
Plugged the PS into AC without installing into the scope and it trips the Ground Fault Interrupter.

I can't find anything amiss in the input line filter or rectifier circuitry.

I don't normally use a GFI. I just use a GFI protected socket while I'm testing line powered stuff.
I pulled a working TDS-540 out of the attic and it has the same symptom.
As soon as I flip the power switch on the rear, it trips the GFI.
Tried a second GFI. Same problem.

The socket tester claims the line power is connected to the socket correctly.

I'm inclined to just ignore it, but thought If ask if anybody else is seeing this.

If not, anybody have thoughts on diagnosing the problem?

Re: TDS-540 trips GFI

Ken Winterling
 

I'm not familiar with the TDS-540 but I have had this problem with other old gear that used ceramic caps as filters across the mains and from mains to chassis.  I replace them with line/mains-rated X and Y or X/Y caps.  

Ken WA2LBI LG G6

------ Original message------From: ham789@...: Wed, Jan 30, 2019 14:43To: TekScopes@groups.io;Cc: Subject:[TekScopes] TDS-540 trips GFI
TDS-540 Trips GFI.

USA, 120VAC single phase.

I replaced the transistor and transorbs in the standby power supply.
Plugged the PS into AC without installing into the scope and it trips the Ground Fault Interrupter.

I can't find anything amiss in the input line filter or rectifier circuitry.

I don't normally use a GFI. I just use a GFI protected socket while I'm testing line powered stuff.
I pulled a working TDS-540 out of the attic and it has the same symptom.
As soon as I flip the power switch on the rear, it trips the GFI.
Tried a second GFI. Same problem.

The socket tester claims the line power is connected to the socket correctly.

I'm inclined to just ignore it, but thought If ask if anybody else is seeing this.

If not, anybody have thoughts on diagnosing the problem?

Re: TDS-540 trips GFI

Glenn Little
 

If there is an EMI filter at the mains input, that is probably the problem. The capacitors to ground can leak enough to trip the GFI. If the filter is not a sealed assembly, replace the capacitors with properly rated capacitors. If the filter is sealed, replace the filter with a new one. A used one may leak as bad as the one that you have.

Glenn

On 1/30/2019 2:43 PM, ham789@... wrote:
TDS-540 Trips GFI.

USA, 120VAC single phase.

I replaced the transistor and transorbs in the standby power supply.
Plugged the PS into AC without installing into the scope and it trips the Ground Fault Interrupter.

I can't find anything amiss in the input line filter or rectifier circuitry.

I don't normally use a GFI. I just use a GFI protected socket while I'm testing line powered stuff.
I pulled a working TDS-540 out of the attic and it has the same symptom.
As soon as I flip the power switch on the rear, it trips the GFI.
Tried a second GFI. Same problem.

The socket tester claims the line power is connected to the socket correctly.

I'm inclined to just ignore it, but thought If ask if anybody else is seeing this.

If not, anybody have thoughts on diagnosing the problem?


--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Substituting a 466 CRT in a 7633 ?

Jose Luu
 

Dear list,

A few years ago I had 7633 pretty much destroyed in shipping (CRT broken, chassis and one plugin crushed), got a refund, but not willing to let go such good electronics to the trash, I managed to get 2 CRTs for a good price: 154-0721-00 (fitting the 7633) 154-0749-00 (fitting a 466), the later being new (NOS).
Poring over the schematics, I figured the NOS one would do and would be better, being new.
One difference: mechanically the deflection plates pins where on the other side, so I ran wires around the neck.
It did not work with this tube, then I mounted the right one (154-071-00) and it worked.
Has anyone done this ? Is this doable ? did I miss some voltage differences on the schematics ?
Now the current tube is showing its age, I am quite inclined at trying it again, but would do it only with some reassurance that it has a chance of success.

Thanks
Jose

Re: No start 7854 Power supply

johnhstrauch
 

Never mind. I did a bit of searching and found a dummy load docx which has all the info. With pictures !
Just placed an order with Mouser.

Thanks for posting your troubleshooting process. Always helps others with there own troubleshooting procedure.

JH

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of johnhstrauch via Groups.Io
Sent: Wednesday, January 30, 2019 1:40 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] No start 7854 Power supply

What does your dummy load consist of. I need to fab one to work on this 7000 series PSU that I have.
JH

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David C. Partridge
Sent: Wednesday, January 30, 2019 6:26 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] No start 7854 Power supply

SOLVED !!!

OK, The voltage at the emitter of Q45 was about 110V, which was less than the voltage at the base (118V) which is set by the Zener diode VR45, so the over-voltage circuit wasn't causing the shutdown.

Not long afterwards the supply changed its behaviour, settling down in to what I can best describe as "normal" tick-mode.

I then spent a few happy hours chasing my tail, looking at the I-Sense (pin 13) and E-Sense (pin 15) signals on the controller IC to see if they were causing the oscillator stop signal on pin 8 to be asserted.

I should say at this point that I was using a dummy load connected to P82 on the LV regulator board.

I checked the schematic just before probing the Fault-Sense signal at pin 2 and realised that without the thermal switch connected to the LV board that a supplies out of balance condition would shut the inverter down.

Once I put a jumper on P72 on the LV regulator, the supply sprang to life!

In summary there were multiple faults on this supply and one pilot error :)

1. Both inverter transistors were dead short.

2. R44 in the over-voltage stop circuit had literally broken in two.

3. Both CR36 and CR37 in the inverter control circuit had leads corroded through.

4. Lots of under board corrosion, solder in some holes corroded away.

5. The 22 ohm inverter base drive resistors (R32 and R40) were both open circuit (even though they looked OK).

6. The collector lead of Q46 (over-voltage stop) was corroded away where it connected to the can.

7. Pilot error - PUT A JUMPER ON P72 ON LV BOARD WHEN USING A DUMMY LOAD

The supply was ticking when it was installed in the MF, so on a hunch I checked the thermal cut-out switch by probing the connector that went on P72. That was open circuit, but that turned out to be simple as one of the wires had come off the thermal switch.

The mainframe now powers on but there are other issues - but that's for another thread.

Dave