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Tektronix 7633 Scope, Can anyone please help Old64goat!!!
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Electro Detective:
If it's Game Over, time to put it all back together,
double check all connections,
turn the sucker on,
get verified signals going into it,
play with ALL the controls, tweaking the trigger dial and switches whilst doing so,

then if no life, officially declare it DUT DOA   :-BROKE

If you don't need a cool looker retro doorstop or bookend, then it's Ebay time,

or flog it off here at EEVblog   :-+
finom1:
New update from The Old64goat:
"Anyway here are the measurements of the HV board without the metal case that has the 2N3055 on it:
6" long, 2" wide and 2" thick.
NOW I found an open transistor on the Z-AXIS board using my SENCORE Cricket but it is too hard for me to see let alone replacing it.
So if one of those guys would be willing to replace that bad transistor on the Z-AXIS booard as well as checking out the HV board I will give the dementions of the Z=AXIS board:
6" long, 2" wide and 3/4" thick.
I only tested two transistors on the Z-AXIS board so there may be more bad transistors.
As I understand that board is part of the CRT circuit.
Bill"
David Hess:
I am not convinced the high voltage transformer is bad but I can understand not wanting to mess with it anymore.  There are other tests I would do for confirmation and it is not clear to me exactly how Old64goat tested it.

To me this seems like an ideal 7633 to repair for someone who is familiar with them.  Whatever is going wrong with the high voltage board is probably the only problem.
David Hess:
I did a little research on replacement parts.

There *is* a history of 7633 transformer failures although probably no more than any other 7600 series oscilloscope.  My guess is that most diagnosis never get that far because of difficult access to the high voltage board.  The 7623A used the same transformers.

Replacement transformers are non-existent.  Replacement high voltage boards are expensive.  However you can probably get a 7623A (1) or 7633 with a known working high voltage board which has the transformer for $40 or less on Ebay; unfortunately shipping will be like $60.  Maybe a cheap 7623A or 7633 can be found on Craigslist to save on shipping charges.

Q1184   151-0126-00   2N2484   NPN High Gain Amplifier
Ideal replacements: 2N5088/9 BC546/48/50
Would probably work: 2N3904
Q1187   151-0188-00   2N3906   PNP General Purpose Amplifier
Ideal Replacements: 2N3906
Would probably work: 2N4403 2N2907
Q1190   151-0136-00   2N3053   Medium Power Amplifier
Ideal Replacements: MJE180/1/2
Would probably work: 2N4401 2N2222 (2)
Q1195   151-0140-00   2N3055   Power Transistor 0.3MHz
Ideal Replacements: 2N3055 (0.3MHz) 2N3771G 2N3772G
Would probably work: 2N3055AG MJ15015

(1) I found suitable 7632As which went for $10 and $25 recently on Ebay and they also included some plug-ins.  The shipping cost for each was about $60 though.

(2) For extra derating, I might use a pair of Vbe matched 2N4401s in parallel if I did not have a suitable TO-126 or TO-225 packaged transistor.  There are higher power TO-92 transistors but they are more expensive than the recommended MJE180 series.
oldway:
I am also not sure that the transformer is defective, it would be necessary to make additional tests.

The current with a 600R function generator is very low, perhaps insufficient.

50R was already much better.

Ideally, the primary of the transformer should be supplied from a LF amp with a 4.7R series resistor.

Magnetizing current and transformer ratio would be compared with values of a known good working transformer of the same type....but this is not available....

Repairing without spare parts is something very difficult.... |O
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