Author Topic: Restoration / Repair of Tektronix 545 - Finished.  (Read 15897 times)

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Offline Fireball XL5

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Re: Restoration / Repair of Tektronix 545
« Reply #25 on: September 11, 2016, 01:02:56 am »


Did you wash the tubes?! That means you washed off the silkscreen on them! :palm:

EDIT: it looks like some of it survived, just be careful cleaning tubes.

Only some tubes have water soluble markings, usually it's etched into the glass. Unfortunately, it's the nice looking ornate logos that wash off.


Is there a cleaning method to prevent lose of silkscreen or label? If so, could it be added to the Restoration sticky at the top of this section?
(Unless it's already there and I missed it)

Also, I'm in awe of the folks who take on a project to bring back these devices I took for granted (shame on me). Amazing work!
 

Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #26 on: September 11, 2016, 08:01:00 am »
GE tubes often have a water soluble label but the tube number is etched in.
I was aware of this issue and as  most of the dirt is on the top of the tubes -  that was the area that got most attention,  so  most of the print (that was left)   stayed on.
Some of the labels didn't like even handling,  but a lot of tubes were not seated well,  some corrosion and dirt in the socket.
Edit : window cleaner and IPA was only used on the chassis,  tubes were cleaned with distilled water for tops,  IPA for the pins.
@martin.m  thanks re the part number clue,    all the tubes went back in to their own sockets,  except my 1 dud 6080, replaced with a tested NOS.
« Last Edit: September 11, 2016, 08:09:16 am by VK5RC »
Whoah! Watch where that landed we might need it later.
 

Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #27 on: September 11, 2016, 08:32:06 am »
I tested (traced the output of every tube)  rather interestingly the 'matched pairs'  of the distributed amp weren't v close,  but no changes made.
Whoah! Watch where that landed we might need it later.
 

Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #28 on: September 16, 2016, 12:10:52 pm »
The centre frame support was chromed and it was peeling badly, some bits had disappeared into the bowels of the unit, hard to find and remove!
Below is a photo of the centre frame removed and the handles taken off, just before it went to the sand blasting (well glass bead actually) cabinet.
I went for a Chrome Paint which is looking alright so far.
Whoah! Watch where that landed we might need it later.
 

Offline Cubdriver

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Re: Restoration / Repair of Tektronix 545
« Reply #29 on: September 17, 2016, 12:17:51 am »
It looks like your restoration is progressing nicely, Rob.   :-+

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 
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Offline richnormand

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Re: Restoration / Repair of Tektronix 545
« Reply #30 on: September 17, 2016, 04:09:56 pm »
I tested (traced the output of every tube)  rather interestingly the 'matched pairs'  of the distributed amp weren't v close,  but no changes made.

I remember matching tube on a curve tracer years ago.
At the beginning of life they drift a lot and then settle down. Unfortunately after a year or two of use they would age differently and redoing the matching was of benefit. Then, as emission dropped near the go/no go, the mu would be effectively out of specs and the only solution was either buying a set of matched tubes or about 25% more regular tubes than needed and do the exercise. I used to keep all of them and got some success matching end-of-life tubes also. That would usually last about an extra year.

Its not as critical in many circuits, just weeding out the outliers at each end of the distribution was usually OK.Look at (for same plate voltage) grid bias and gain.

« Last Edit: September 17, 2016, 10:36:57 pm by richnormand »
 

Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #31 on: September 17, 2016, 09:41:26 pm »
Thanks for the comments, I don't have much experience with tubes but am learning ,   I am still some time away from 'switch on'.
Currently in the process of 'stuffing a can capacitor' ,  the main 150, 300 and 225 v rail filter,  it tested bad in circuit,  was supposed to be 10uF, out of circuit was 100nF, 7k ohm dc resistance,  cutting the can open and can get 3 new Nichicons inside. Getting the paper and foil out was a real pain.
Whoah! Watch where that landed we might need it later.
 

Offline FlyingHacker

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Re: Restoration / Repair of Tektronix 545
« Reply #32 on: September 18, 2016, 03:57:37 am »
While re-stuffing is the ultimate, it is also a pain. A lot of guys just clip the old ones out of circuit and put the new caps on the underside.

Either way don't forget to hook up the ground on ground can capacitors.
--73
 

Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #33 on: September 18, 2016, 12:04:51 pm »
Capacitor ReStuffing, I used a drill and a sharp wood chisel (~6mm wide)
3 New 10uF Nichicons (500v) with good heat shrink around it all, tested ok before stuffing (and after!) earth is connected to the can !
Can cut open with cutting disk on Dremel
Can sealed with "JB weld" epoxy - i like it because it is quite viscous and doesn't set in 5 mins.
Whoah! Watch where that landed we might need it later.
 
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Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #34 on: September 18, 2016, 12:06:06 pm »
Final Photos
Whoah! Watch where that landed we might need it later.
 

Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #35 on: September 19, 2016, 06:17:16 am »
C 751 Back in place , with notice to others
Whoah! Watch where that landed we might need it later.
 

Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #36 on: September 19, 2016, 06:26:39 am »
Brave Pill time (apologies to Jeremy Clarkson)
Rechecked filter caps for ESR - OK, Fuse  -holder broken so replaced, No earth leakage of note from mains active and neutral,
Powered up via AC lab power supply , initially at 180v for 30 secs x2, then 210 v ,
Note No Fan so only on for a minute or 2, BUT
A trace !

Much rejoicing. Until today wasn't sure of the status of the tube,
I am sure there will be a few faults to trace etc.
Whoah! Watch where that landed we might need it later.
 

Offline dave_k

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Re: Restoration / Repair of Tektronix 545
« Reply #37 on: September 19, 2016, 10:51:50 am »
Still, aren't you glad you had the fire extinguisher handy?  :-DD

Great work .. can't wait to see how the rest of the restoration goes.
 

Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #38 on: September 19, 2016, 10:58:47 am »
Actually I have 2 fire  extinguishers -  a CO2 for a small fires that I want to keep things tidy - and a dry chemical if things e.g. solvents plastics etc really get going. :wtf:
When I first fired it up I didn't touch the CRO, except for the tip of a DVM probe - just to make sure, I don't have a lot of faith in 60yo transformer insulation.

I have had it going for a bit longer as I put the fan and ducting back in , enough to have a look at the minus 150V rail and some minor adjustments the 225v rail is quite a bit out (180v) but the 500 and other rail were spot on.
Whoah! Watch where that landed we might need it later.
 

Offline Cubdriver

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Re: Restoration / Repair of Tektronix 545
« Reply #39 on: September 19, 2016, 04:46:43 pm »
Beauteous!   :-+ :-+

-Pat
If it jams, force it.  If it breaks, you needed a new one anyway...
 
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Offline SeanB

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Re: Restoration / Repair of Tektronix 545
« Reply #40 on: September 19, 2016, 08:09:32 pm »
Nice touch with the label there with tape holding it down.
 
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Offline steve_w

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Re: Restoration / Repair of Tektronix 545
« Reply #41 on: September 22, 2016, 05:47:27 am »
Excellent restoration.  Pleas keep up the good work.

regards

SW
So long and thanks for all the fish
 
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Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #42 on: September 22, 2016, 10:52:29 am »
A bit of an update.
She is starting regularly, going properly through the 40sec or so delay before HV, and works well for about 5-10mins, the rail voltages are a bit off and drifting a bit - not unexpected given what I think has been a long time switched off (possibly 25yrs) . the 225v rail is low (about 190v - so a problem there) All the rails should be governed by the 150v rail , the 225 is still off when all the others are spot on

 I have rechecked the main rails filter caps and they are still OK by ESR.
She is drawing a little more power than I think she should, about 650W - should be 550W acc to manual.
Below is a rough screen shot of a 2V P-P  1kHz sine wave; vertical scale OK, time base a bit fast.
After bout 10mins or so, the triggering becomes intermittent then stops - so a bit of hunting required.
I am looking at the current draw through the power rails, bit tricky as the schematic is a bit wrong (or later mods) and the components can be quite widely scattered on the chassis, for example the rectifying diodes are nearly 30cm away from the filter caps!
Below is also a quick shot of a "warm" bit of test gear as Martin.M would say.
Whoah! Watch where that landed we might need it later.
 

Offline tautech

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Re: Restoration / Repair of Tektronix 545
« Reply #43 on: September 22, 2016, 07:52:53 pm »
She's looking very tidy Rob.  :-+

Unlike transistor based equipment it is not safe to let the fingers do the walking over componentry to find any hot ones that shouldn't be.  :scared:
Is the 225V rail showing excessive ripple? Usually that might suggest the rails is overloaded and operating outside its design parameters.
Is the 225V rail low immediately after power on or sags later?
Is it related to loss of triggering?

Avid Rabid Hobbyist
 
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Online Martin.M

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Re: Restoration / Repair of Tektronix 545
« Reply #44 on: September 23, 2016, 02:50:18 pm »
Martin is actually in restoration of a monster radio, very busy   :)
 

Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #45 on: September 25, 2016, 11:02:09 am »
martin ; we await with interest, a great pity I can't read German and Google translate does a lousy job of your tek blog
I should have followed tautech's  suggestions (which I only read this afternoon) re the 225v rail, but earlier  today started followed the collapse of triggering at about 8mins after cold start up, quite a bit of tracing later I discover it was the multivibrator, which has a voltage divider and a trim pot in the middle which I can adjust and get it to trigger hot, guess what rail it uses for the top voltage rail ? Thats right the 225v. Oh well I have learnt a lot about multivibrators!  :palm:

I ASSUMED the 225v rail was constant-low but that is not the case I believe. I think it is dropping from about 205 cold to 185 warm and this shift is enough to destabilise the multivibrator. I have done one tube swap in the 225v regulator circuit (the 6080) the main regulator tube but no great change. The trigger stuff is all on the top shelf - so access is easy, the power stuff is mainly underneath - so a bit more tricky - still pretty careful re the "low voltage circuits" as these 100-500v rails can belt off about 200mA!
All the voltage rails have minimal ripple (within 5mV) and the current draw (measured by voltage drop across the current limiting resistors) is also in specification.

Checked the HV circuit and it is good at about 10,200V (should be 10k).

Pictures below are a screen shot ( a sacrilege using an Agilent scope to repair a Tek I know) from the top to the bottom of the input then progressing "shaped' waves for the trigger waveform.
Below is also a "warm fuzzy" shot of all those thermions! :-+
Whoah! Watch where that landed we might need it later.
 

Offline dave_k

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Re: Restoration / Repair of Tektronix 545
« Reply #46 on: September 25, 2016, 11:49:26 am »
Nice progress! One question, is this unit old enough to have been fitted with selenium rectifiers? You may want to consider replacing them with silicon diodes, though it is not a straight-forward swap.
 

Offline VK5RC

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Re: Restoration / Repair of Tektronix 545
« Reply #47 on: September 25, 2016, 09:05:05 pm »
@dave k,  I think this unit has had the conversion,  the selenium rectifiers were (i think)  bolted to the central vertical chassis member,  there are a few holes there,  and a mini chassis with a series of diodes (forward drop 0.6v) with some additional power resistors,  I will post a photo and a diagram of which diodes are for which power rail a bit later today.
Whoah! Watch where that landed we might need it later.
 

Offline Cyberdragon

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Re: Restoration / Repair of Tektronix 545
« Reply #48 on: September 26, 2016, 03:12:21 am »
Are they old diodes? They came out with "solid state rectifier" kits in the 60's so that you could replace selenium diodes. The cool thing about them is that the silicon diodes are in big sockets like fuses.
*BZZZZZZAAAAAP*
Voltamort strikes again!
Explodingus - someone who frequently causes accidental explosions
 

Offline jh15

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Re: Restoration / Repair of Tektronix 545
« Reply #49 on: September 26, 2016, 06:38:35 am »
I have a 535, and a 6080 had a bad crimp and the filament was not hot enough, or maybe it was another pin, drove me crazy.

Need to power it up again and impress maker spaces.
tek 575 curve tracer top shape, 535 top shape, 465. 545 hickok clone, Telsa Model S,  Ohio Scientific c24P single board computer, many c-64 from my club days, Giant electric bicycle, Rigol stuff, Heathkit AR-15 receivers 2, Heathkit et 3400a trainer and interface,
 


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