Date   

Re: Repairing my Tektronix 454 oscilloscope need some advice

Chuck Harris
 

Use a 9V battery, or two, in series with a 10K resistor, and
a low current meter.. then test in the usual way.

-Chuck Harris

Victor via Groups.Io wrote:

Albert,
This afternoon, I was reviewing the measurement done yesterday and found a problem (intermittent connection) with the cable connecting the wave generator to the Q1430 collector. After repair it I test again my 454 and now with a 1Vpp on the collector of the Q1430, I get 52V at the HV test point.So, with this result I believe my HV transformer is Ok. I have a doubt about the HV diodes... what do you think ? By the way how do you test HV diode,I understand you cannot do it with a regular tester.Tomorrow before made the test that you recommend today. I would like to review the HV CRT circuit to see if any resistor or capacitor are out of specs (transistors have been test and look good).
Thank you,Victor


-----Original Message-----
From: Albert Otten <aodiversen@...>
To: TekScopes <TekScopes@groups.io>
Sent: Thu, Feb 20, 2020 3:19 pm
Subject: Re: [TekScopes] Repairing my Tektronix 454 oscilloscope need some advice

Victor,

Today I did more waveform measurements.  I always viewed the primary voltage and primary current ( A6302 current probe) waveform and each time I tuned for resonance. Last time I made a frequency reading mistake (when you turn the FG504 knob cw the the frequency deceases...). Without other probes attached it was 27 MHz.  Probes at the secondary side lower the resonance frequency somewhat.
From the visible transformer right side 3 very short blank wires go to ceramic supports. From front to rear these are connected to winding terminals 7 (tripler circuit), 9 (cathode, D1452) and 10 (grid, D1440 visible). Resistances to GND: 547R, 243R and about 20k respectively.
Findings:
Always nice resonance with simultaneously primary voltage maximal, current minimal and no phase shift between these two.  In hindsight this could be expected when the primary side acts as a nice parallel RCL circuit with not too low Q factor. R was about 10 Ohm. Also each time the secondary voltage was in phase with the primary.
Amplifications, crude values:
from primary to 7: 375, to 9: 185, to 10: 195.
I did a more precise simultaneous measurement of negative peak at 9 and the DC voltage at HV TP (with DMM). The "loss" was about 10 V (of value about 80 V), looks realistically.
Anyway, it could be very informative to view those secondary waveforms.

Albert

On Wed, Feb 19, 2020 at 09:36 PM, Albert Otten wrote:


Victor,

Obviously there is not enough secondary HV, or a diode is bad. If you remove
the plastic cover of the HV box you can access at least one diode which is
connected to a hot winding end (I don't remember which one, I think it has
been mentioned in another recent 454 thread). With 1 V pp over the primary you
could view the wave form at that secondary winding, using a 10 M (and 10X)
probe. Then a bad (open) diode plays no role.
I estimated the primary impedance (about 10 R) by comparison of amplitude (1 V
pp) with the  open-circuit output amplitude of the 50 R generator. Did you
also do such? Maybe tomorrow I will (just for fun with my 7854) view both
voltage across and current into the primary. With the 7854 keyboard calculator
it's easy to determine reactive and real input power to primary. I guess it
will mostly be real power because of the (cold!) CRT filament load. (Of course
the phase shift between voltage and current can be viewed on an arbitrary
scope, without storage or calculator).
You might also view the collector waveform during normal operation. The 0.22 A
current seems to be small and probably indicates that Q1430 can not deliver
enough power to increase the oscillation to normal level; either because a
fault in the feedback circuit (resistor string to Q1414 etc.) or a too heavy
secondary load (shorted HV cap?) or ...(?)

Albert





Re: Tektronix 1L5 Crystal Discriminator

Jason A.
 

Thanks Tom! I'll open it up and take a look. My fear is that it would be potted inside. It's definitely worth a shot!


Re: Tektronix 1L5 Crystal Discriminator

fiftythreebuick
 

Jason, be sure to include the same part for a 3L5 in your searches. I believe they both have the same board in them, and I'm almost sure the discriminator is the same.

And before you give up, I'd open that thing up and see what's going on inside. I fixed a Collins crystal filter that was not too different from what's probably inside that one. You just never know!

Tom

On Thu, Feb 20, 2020 at 10:03 AM, Jason A. wrote:


Question #2 - does anyone have a 1L5 that is working you don't need anymore or
one you are parting out?

Thanks and best regards,

Jason


Re: Repairing my Tektronix 454 oscilloscope need some advice

Victor
 

Albert,
This afternoon, I was reviewing the measurement done yesterday and found a problem (intermittent connection) with the cable connecting the wave generator to the Q1430 collector. After repair it I test again my 454 and now with a 1Vpp on the collector of the Q1430, I get 52V at the HV test point.So, with this result I believe my HV transformer is Ok. I have a doubt about the HV diodes... what do you think ? By the way how do you test HV diode,I understand you cannot do it with a regular tester.Tomorrow before made the test that you recommend today. I would like to review the HV CRT circuit to see if any resistor or capacitor are out of specs (transistors have been test and look good).
Thank you,Victor

-----Original Message-----
From: Albert Otten <aodiversen@...>
To: TekScopes <TekScopes@groups.io>
Sent: Thu, Feb 20, 2020 3:19 pm
Subject: Re: [TekScopes] Repairing my Tektronix 454 oscilloscope need some advice

Victor,

Today I did more waveform measurements.  I always viewed the primary voltage and primary current ( A6302 current probe) waveform and each time I tuned for resonance. Last time I made a frequency reading mistake (when you turn the FG504 knob cw the the frequency deceases...). Without other probes attached it was 27 MHz.  Probes at the secondary side lower the resonance frequency somewhat.
From the visible transformer right side 3 very short blank wires go to ceramic supports. From front to rear these are connected to winding terminals 7 (tripler circuit), 9 (cathode, D1452) and 10 (grid, D1440 visible). Resistances to GND: 547R, 243R and about 20k respectively.
Findings:
Always nice resonance with simultaneously primary voltage maximal, current minimal and no phase shift between these two.  In hindsight this could be expected when the primary side acts as a nice parallel RCL circuit with not too low Q factor. R was about 10 Ohm. Also each time the secondary voltage was in phase with the primary.
Amplifications, crude values:
from primary to 7: 375, to 9: 185, to 10: 195.
I did a more precise simultaneous measurement of negative peak at 9 and the DC voltage at HV TP (with DMM). The "loss" was about 10 V (of value about 80 V), looks realistically.
Anyway, it could be very informative to view those secondary waveforms.

Albert

On Wed, Feb 19, 2020 at 09:36 PM, Albert Otten wrote:


Victor,

Obviously there is not enough secondary HV, or a diode is bad. If you remove
the plastic cover of the HV box you can access at least one diode which is
connected to a hot winding end (I don't remember which one, I think it has
been mentioned in another recent 454 thread). With 1 V pp over the primary you
could view the wave form at that secondary winding, using a 10 M (and 10X)
probe. Then a bad (open) diode plays no role.
I estimated the primary impedance (about 10 R) by comparison of amplitude (1 V
pp) with the  open-circuit output amplitude of the 50 R generator. Did you
also do such? Maybe tomorrow I will (just for fun with my 7854) view both
voltage across and current into the primary. With the 7854 keyboard calculator
it's easy to determine reactive and real input power to primary. I guess it
will mostly be real power because of the (cold!) CRT filament load. (Of course
the phase shift between voltage and current can be viewed on an arbitrary
scope, without storage or calculator).
You might also view the collector waveform during normal operation. The 0.22 A
current seems to be small and probably indicates that Q1430 can not deliver
enough power to increase the oscillation to normal level; either because a
fault in the feedback circuit (resistor string to Q1414 etc.) or a too heavy
secondary load (shorted HV cap?) or ...(?)

Albert


Re: DS1742W-120 replacement adapter?

Ken Eckert
 

The boards are extremely cheap from JLCPCB, online quote.

On Thu, Feb 20, 2020 at 10:54 AM victor.silva via Groups.Io <daejon1=
yahoo.com@groups.io> wrote:

Has anyone had a build of these made up and ten or so that they wish to
sell?

If not, is anyone interested in going in on a group buy (of unpopulated
boards)?

Thanks,
Victor




Re: DS1742W-120 replacement adapter?

victor.silva
 

Has anyone had a build of these made up and ten or so that they wish to sell?

If not, is anyone interested in going in on a group buy (of unpopulated boards)?

Thanks,
Victor


Re: Tektronix 1L5 Crystal Discriminator

Jason A.
 

Question #2 - does anyone have a 1L5 that is working you don't need anymore or one you are parting out?

Thanks and best regards,

Jason


Re: 547 scope HV transformer problem. One practical solution.

Chuck Harris
 

Just to add some other flies for the ointment:

When I first started my 547 HV repair project, my scope,
which had sat idle for several years before I got it,
would only run for 15 minutes before the HV crashed.

After I experimented for several days, the run time kept
increasing, until after a week, it ran continuously.

I thought it had cured itself, and I was done!

Well, then I got busy with something else, and the scope
sat idle for a couple of months, and the process had reset
to the original 15 minutes before crash.

The issue is heat induced epoxy loss, and seems to be
related to moisture absorption by the epoxy. It seems
also to be related to a chemical change in the epoxy.

There is a temporary improvement when the internal
heating of the transformer winding dries out the winding...
but it is only temporary.

The oscillator stops because the ferrite core is operating
at a bad point in the ferrite's curves. Its frequency is
just below the frequency where core losses start to go
exponential. And, to add insult to injury, when the core
heats, it approaches the Curie temperature (about 150F),
which is where the ferrite ceases to be a magnetic material.
This causes the frequency to rise... which you guessed it,
makes the losses rise even more.

Back in the old days, when the EHT ran at 60KHz, and beeswax
was used to impregnate the winding, the HV section was right
in front of the scope's fan... out in the open. It stayed
cool and breezy.

Tektronix wrecked all that when they decided to make an
extended temperature range scope (647) and switched over to
an epoxy varnish potting material. They also decided to
unify the HV section to fit in a plastic box... to keep
it clean, and allow reuse on all of their future scopes.

The epoxy varnish, even when new, was much more lossy than
the original beeswax, so the engineers lowered the frequency,
and added a provision for heatsinking the transformer core.

They also started to think about using solid state rectifiers
to replace the old power hungry 5642 tubes.

You can achieve an improvement by cooling the transformer,
through most any means: fan, heat sink, solid state rectifiers,
lowering the operating frequency, lowering the drive voltage...

Lowering the drive voltage will make it hard to see fast, low
repetition rate waveforms... kind of like hobbling a race horse...

Lowering the EHT's operating frequency can be done by parallel
addition of a capacitor to the 1000pf resonance capacitor
C808.

Ultimately, I found that rewinding the transformer was the
only sure long term solution.

We probably wouldn't have ever noticed this problem if Tek
had chosen an MOPA (Master Oscillator Power Amplifier) design
to drive the transformer, instead of using a modified Hartley
oscillator. It only takes a slight lowering of the feedback
efficiency to reduce the oscillator's gain below unity, and
make the oscillator stop.

-Chuck Harris

Ernesto wrote:

Hi Morris,

Yes, the deflection factors, which I called the "gain of the CRT" is an inverse function of the high voltage, and I have taken this into account. It requires simple readjustments of the gain of the vertical and horizontal amplifiers. When all this is over I will care about finding good standards to calibrate the scope with. In the meantime I have made some more observations:

After being relieved with the good results of lowering the HV to 1500 V I decided to try out a "thermal enhancement".
After removing the plastic cover of the HV section, I placed over it an old PC supply whose little fan did blow mostly over the transformer. And here is what I got:

- With HV = 1500 V, the supply current raised slightly in the first minutes, then it stabilized. One and a half hours later it was still the same, and the supply was still running fine.
- With HV raised to 1655 V, the same happened and I ended the test after one hour.
- With HV returned to the nominal 1850 V, exactly the same happened. The HV supply DID NOT FAIL.

So the COOLING OF THE TRANSFORMER will solve the problem of my 547, which originally failed after running for about 10 minutes.

The easiest implementation of the cooling can be to drill holes in the cover right above the HV transformer and place on top a little fan (with a filter), blowing on the transformer with the plastic cover off.
But I don't like the aesthetics of the fan sticking out on top of the instrument, so I will do the cooling internally. A change from electrical engineering to industrial engineering, haha.

Cheers,

Ernesto




Re: 547 scope HV transformer problem. One practical solution.

 

Hi John, thank you for pointing me to the world of oscilloscope washing, cleaning.

I read about the experiences of others and the industry washing oscilloscopes with water. The hairs on my head used to stand up at the idea, but now I recognize that it is relatively safe, although it requires WORK.
I compare it with my long experience of "don't fix what is not broken", and the good luck I have with my old scope that had a 40 years leave of absence.

I perfectly cleaned the exterior of my 547, and it is shiny. The inside is different, with plenty of dust deposited on the tubes and surfaces. I like to preserve it like that for its dramatic effect. The instrument will be perfect for my grandchildren to play with it when they are a little bigger, and it may awaken their interest in electronics. I plan to show them the inside of the scope to be impressed with its age, but after that the inside will be off limits to them.

But... if I experience any failures, I feel competent enough to trace them to the failed component, or particles of dust, and I will remove just those offending particles.

NOTE: I have a different standard for washing myself, staying clean inside and changing my underwear, ha ha ha.

Cheers,
Ernesto


Re: Repairing my Tektronix 454 oscilloscope need some advice

Albert Otten
 

Victor,

Previously I wrote "I did an easier and less risky test. F1437 tied to GND,...". Actually, with the signal between GND and collector, this doesn't help at all because of the high inductance of L1437. It works since C1437 and R1149 provide a low impedance AC path to GND. I noted this later on. The right way is to tie C1437 "+" to GND. Luckily in practice I hardly noted any differences in amplitudes between tied to GND or not. C1437 is located in a clamp at the rear panel, next to Q1430.

Albert


Re: 547 scope HV transformer problem. One practical solution.

 

Hi Morris,

Yes, the deflection factors, which I called the "gain of the CRT" is an inverse function of the high voltage, and I have taken this into account. It requires simple readjustments of the gain of the vertical and horizontal amplifiers. When all this is over I will care about finding good standards to calibrate the scope with. In the meantime I have made some more observations:

After being relieved with the good results of lowering the HV to 1500 V I decided to try out a "thermal enhancement".
After removing the plastic cover of the HV section, I placed over it an old PC supply whose little fan did blow mostly over the transformer. And here is what I got:

- With HV = 1500 V, the supply current raised slightly in the first minutes, then it stabilized. One and a half hours later it was still the same, and the supply was still running fine.
- With HV raised to 1655 V, the same happened and I ended the test after one hour.
- With HV returned to the nominal 1850 V, exactly the same happened. The HV supply DID NOT FAIL.

So the COOLING OF THE TRANSFORMER will solve the problem of my 547, which originally failed after running for about 10 minutes.

The easiest implementation of the cooling can be to drill holes in the cover right above the HV transformer and place on top a little fan (with a filter), blowing on the transformer with the plastic cover off.
But I don't like the aesthetics of the fan sticking out on top of the instrument, so I will do the cooling internally. A change from electrical engineering to industrial engineering, haha.

Cheers,

Ernesto


Re: help tek 475 power supply

Roberto
 

hi Rogers thank for indications I will control the transistor
Roberto


Re: Repairing my Tektronix 454 oscilloscope need some advice

Albert Otten
 

Victor,

Today I did more waveform measurements. I always viewed the primary voltage and primary current ( A6302 current probe) waveform and each time I tuned for resonance. Last time I made a frequency reading mistake (when you turn the FG504 knob cw the the frequency deceases...). Without other probes attached it was 27 MHz. Probes at the secondary side lower the resonance frequency somewhat.
From the visible transformer right side 3 very short blank wires go to ceramic supports. From front to rear these are connected to winding terminals 7 (tripler circuit), 9 (cathode, D1452) and 10 (grid, D1440 visible). Resistances to GND: 547R, 243R and about 20k respectively.
Findings:
Always nice resonance with simultaneously primary voltage maximal, current minimal and no phase shift between these two. In hindsight this could be expected when the primary side acts as a nice parallel RCL circuit with not too low Q factor. R was about 10 Ohm. Also each time the secondary voltage was in phase with the primary.
Amplifications, crude values:
from primary to 7: 375, to 9: 185, to 10: 195.
I did a more precise simultaneous measurement of negative peak at 9 and the DC voltage at HV TP (with DMM). The "loss" was about 10 V (of value about 80 V), looks realistically.
Anyway, it could be very informative to view those secondary waveforms.

Albert

On Wed, Feb 19, 2020 at 09:36 PM, Albert Otten wrote:


Victor,

Obviously there is not enough secondary HV, or a diode is bad. If you remove
the plastic cover of the HV box you can access at least one diode which is
connected to a hot winding end (I don't remember which one, I think it has
been mentioned in another recent 454 thread). With 1 V pp over the primary you
could view the wave form at that secondary winding, using a 10 M (and 10X)
probe. Then a bad (open) diode plays no role.
I estimated the primary impedance (about 10 R) by comparison of amplitude (1 V
pp) with the open-circuit output amplitude of the 50 R generator. Did you
also do such? Maybe tomorrow I will (just for fun with my 7854) view both
voltage across and current into the primary. With the 7854 keyboard calculator
it's easy to determine reactive and real input power to primary. I guess it
will mostly be real power because of the (cold!) CRT filament load. (Of course
the phase shift between voltage and current can be viewed on an arbitrary
scope, without storage or calculator).
You might also view the collector waveform during normal operation. The 0.22 A
current seems to be small and probably indicates that Q1430 can not deliver
enough power to increase the oscillation to normal level; either because a
fault in the feedback circuit (resistor string to Q1414 etc.) or a too heavy
secondary load (shorted HV cap?) or ...(?)

Albert


Re: DC508A Frequency Range

Gary Robert Bosworth
 

Thanx Dan. Your response is exactly what I wanted to see. I very much
appreciate your time in answering my question.

Gary

On Thu, Feb 20, 2020 at 5:17 AM Gary Robert Bosworth <@grbosworth>
wrote:



On Wed, Feb 19, 2020 at 7:48 PM Dan G <dgajanovic@...> wrote:

Hi Gary,

The Prescale Input contains a high-pass filter (R2368/R2466/L2362/C2362)
designed to engage Input-Out-Of-Range at low frequencies that could cause
false triggering of the U2350 prescaler IC. The exact frequency response
of
the input depends on this filter, R2422 Threshold Adjust and the 4-stage
UHF amplifier. I suspect that the combined tolerances provide a safety
zone
around the 100 MHz - 1.3 GHz range large enough to ensure that an
instrument will meet spec, but 50 MHz is far enough from spec that it
might
depend on the particular unit and calibration.

On one of my DC508 units (post-B020000 s/n, whose prescaler board
is fairly similar to the DC508A), the lower cut-off frequency for a
10 mV RMS (28.3 mV p-p) sine wave is 51.3 MHz. At 20 mV RMS,
the cut-off frequency decreases to 37.9 MHz.

On another early, recently restored and calibrated DC508 unit
(pre-B020000 s/n, slightly different prescaler board design), the lower
cut-off frequency for a 20 mV RMS sine wave is 54.6 MHz. It can count
a 1.75V RMS signal down to 39.3 MHz.

These data points are for DC508, but I would expect the DC508A to
behave in a similar fashion. In short, while the Prescale Input of your
unit might be able to count a 50 MHz signal of sufficiently high
amplitude,
I would not consider its inability to do so an indication of malfunction.

Just to be clear, all this applies to the Prescaler (Left) Input only.
The Direct (Right) Input has no such high-pass filter, of course,
and can count very low frequencies.

dan



--
Gary Robert Bosworth
@grbosworth
Tel: 310-317-2247

--
Gary Robert Bosworth
@grbosworth
Tel: 310-317-2247


Re: DC508A Frequency Range

Gary Robert Bosworth
 

On Wed, Feb 19, 2020 at 7:48 PM Dan G <dgajanovic@...> wrote:

Hi Gary,

The Prescale Input contains a high-pass filter (R2368/R2466/L2362/C2362)
designed to engage Input-Out-Of-Range at low frequencies that could cause
false triggering of the U2350 prescaler IC. The exact frequency response of
the input depends on this filter, R2422 Threshold Adjust and the 4-stage
UHF amplifier. I suspect that the combined tolerances provide a safety zone
around the 100 MHz - 1.3 GHz range large enough to ensure that an
instrument will meet spec, but 50 MHz is far enough from spec that it might
depend on the particular unit and calibration.

On one of my DC508 units (post-B020000 s/n, whose prescaler board
is fairly similar to the DC508A), the lower cut-off frequency for a
10 mV RMS (28.3 mV p-p) sine wave is 51.3 MHz. At 20 mV RMS,
the cut-off frequency decreases to 37.9 MHz.

On another early, recently restored and calibrated DC508 unit
(pre-B020000 s/n, slightly different prescaler board design), the lower
cut-off frequency for a 20 mV RMS sine wave is 54.6 MHz. It can count
a 1.75V RMS signal down to 39.3 MHz.

These data points are for DC508, but I would expect the DC508A to
behave in a similar fashion. In short, while the Prescale Input of your
unit might be able to count a 50 MHz signal of sufficiently high amplitude,
I would not consider its inability to do so an indication of malfunction.

Just to be clear, all this applies to the Prescaler (Left) Input only.
The Direct (Right) Input has no such high-pass filter, of course,
and can count very low frequencies.

dan



--
Gary Robert Bosworth
@grbosworth
Tel: 310-317-2247


Re: 547 scope HV transformer problem. One practical solution.

Morris Odell
 

Hi Ernesto,

I'm not surprised that the focus and astigmatism are still OK with reduced HV but don't forget that the CRT deflection factors will be affected by the HV which means the calibration will be all wrong in both the X and Y directions. Not a problem if you are just doing qualitative observations but of you want to set up the scope to do proper measurments you will need to have the correct HV and calibrate it according to the manual..

Cheers,

Morris


Re: DC508A Frequency Range

Dan G
 

Hi Gary,

The Prescale Input contains a high-pass filter (R2368/R2466/L2362/C2362)
designed to engage Input-Out-Of-Range at low frequencies that could cause
false triggering of the U2350 prescaler IC. The exact frequency response of
the input depends on this filter, R2422 Threshold Adjust and the 4-stage
UHF amplifier. I suspect that the combined tolerances provide a safety zone
around the 100 MHz - 1.3 GHz range large enough to ensure that an
instrument will meet spec, but 50 MHz is far enough from spec that it might
depend on the particular unit and calibration.

On one of my DC508 units (post-B020000 s/n, whose prescaler board
is fairly similar to the DC508A), the lower cut-off frequency for a
10 mV RMS (28.3 mV p-p) sine wave is 51.3 MHz. At 20 mV RMS,
the cut-off frequency decreases to 37.9 MHz.

On another early, recently restored and calibrated DC508 unit
(pre-B020000 s/n, slightly different prescaler board design), the lower
cut-off frequency for a 20 mV RMS sine wave is 54.6 MHz. It can count
a 1.75V RMS signal down to 39.3 MHz.

These data points are for DC508, but I would expect the DC508A to
behave in a similar fashion. In short, while the Prescale Input of your
unit might be able to count a 50 MHz signal of sufficiently high amplitude,
I would not consider its inability to do so an indication of malfunction.

Just to be clear, all this applies to the Prescaler (Left) Input only.
The Direct (Right) Input has no such high-pass filter, of course,
and can count very low frequencies.

dan


Re: DS1742W-120 replacement adapter?

Tom B
 

I found this to look at Gerber files online .  I have not tried it.

https://www.gerber-viewer.com/

Tom Bryan

On 2/19/2020 7:13 PM, joeschm@... wrote:
I would also be interested in a couple of these adapters. I looked over the files at the link but don't have the appropriate apps to open them.


Re: DS1742W-120 replacement adapter?

joeschm@...
 

I would also be interested in a couple of these adapters. I looked over the files at the link but don't have the appropriate apps to open them.


Tektronix 1L5 Crystal Discriminator

Jason A.
 

I recently purchased a 1L5 off of eBay and popped it on the bench and attempted to start calibrating it. 10KHz up seems fine, but it is completely deaf in the 50Hz-9990Hz range. On the oscilloscope screen, setting it for say 20KHz center frequency, it rises just below 10KHz and plateaus as noise all the way to the zero line. Calibration points for the sub-10KHz frequencies seem to have no effect. Checking through the circuit description and schematics, it seems to be a single part responsible for the <10KHz discriminator duty. From everything I am seeing, it is part number 119-0103-01 labeled as a Crystal Discriminator, called out in the schematic as just a rectangle with two terminals (in, out) and an arrow looping back into it on top. It is also is listed as being responsible for the same frequency band 50Hz-9990Hz that is non-functional. I have not disassembled the unit. I am guessing that part is non-existent on the spares market. Checking all the waveforms on the board per the schematic from TekWiki, it looks like everything is pretty close to the waveforms shown, save the one called out between the junction of C180, D200 and the collector of Q200.

I have emailed the person who sold it to me on eBay and will request to send it back unless someone here knows something I don't.

Any ideas?

Thanks in advance!

Jason