Author Topic: Tektronix 475 repair assistance  (Read 20276 times)

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Online tggzzz

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Re: Tektronix 475 repair assistance
« Reply #50 on: October 19, 2017, 12:49:37 pm »
What makes you think its been damp then?

Looking at the pictures, what else?
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Offline bd139Topic starter

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Re: Tektronix 475 repair assistance
« Reply #51 on: October 19, 2017, 12:54:55 pm »
You can tell because of how the dirt is stuck to the front. If it's dry, the colouring is uniform with shadowing where there is protection from dust. If it's damp, the dirt clumps.

A little bit of moisture won't do much harm to these. It's "been in the shed and the mains cable has disintegrated" levels of decay you need to worry about.
 

Online tggzzz

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Re: Tektronix 475 repair assistance
« Reply #52 on: October 19, 2017, 01:01:46 pm »
You can tell because of how the dirt is stuck to the front. If it's dry, the colouring is uniform with shadowing where there is protection from dust. If it's damp, the dirt clumps.

A little bit of moisture won't do much harm to these. It's "been in the shed and the mains cable has disintegrated" levels of decay you need to worry about.

The more difficult case (both to diagnose from such a photo, and to cure) is if mould has been growing. Knowing the provenance would help a lot.
« Last Edit: October 19, 2017, 01:04:33 pm by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline bd139Topic starter

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Re: Tektronix 475 repair assistance
« Reply #53 on: October 19, 2017, 01:16:04 pm »
I've bought stuff from them before and all dirt was superficial ;)
 

Offline Specmaster

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Re: Tektronix 475 repair assistance
« Reply #54 on: October 19, 2017, 01:31:29 pm »
Well they claim it was found in a cupboard.

I never tweaked twigged about the damp would make dirt stick to certain spots, see it's true, you do learn something new each day  :popcorn:
« Last Edit: October 19, 2017, 02:35:30 pm by Specmaster »
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Online tggzzz

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Re: Tektronix 475 repair assistance
« Reply #55 on: October 19, 2017, 02:30:09 pm »
Well they claim it was found in a cupboard.

I've seen dank and musty cupboards before :)
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Online tggzzz

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Re: Tektronix 475 repair assistance
« Reply #56 on: October 21, 2017, 02:20:57 pm »
Edit: oooooh tempting https://www.ebay.co.uk/i/282694103060

You may have a delicious dilemma: whether to buy that or to save your pennies (and brownie points) for the Kempton Park hamfest. I've decided to do the latter.

At Kempton Park I've seen a non-functional HP1740a go for £5 (or was it £10), a claimed working 465 for £40, and I've bought a working 5.5 7.5 digit DMM for £40. At another hamfest I got a Dekapot 4 decade switched resistor for £10; the clicks as you rotate the contacts is almost pornographically tactile :)

[Edit: 5.5 -> 7.5]
« Last Edit: October 21, 2017, 07:59:29 pm by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline bd139Topic starter

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Re: Tektronix 475 repair assistance
« Reply #57 on: October 21, 2017, 06:05:50 pm »
There’s only one answer and that is both :)

I could do with a substitution box actually.

I’m going to be honest: I want a 465B without DM44 for the bench. Trace is much sharper than the 475 is and the delay sweep is nicer. The DM44 is a compromise but not terrible. Also need a decent counter. I had a 5315A with OCXO and channel C but flogged it when I got my rigol DG1022Z with the intent of building a GPSDO but the 1022 is stupidly unsensitive.

How early do you have to turn up to get the interesting stuff at Kempton?

Spent some time with my head in the 475 and the trade moving right is related to timebase rather than z-axis. Managed to inject signals right into the amps from my DG1022Z and it works fine.
« Last Edit: October 21, 2017, 06:09:13 pm by bd139 »
 

Online tggzzz

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Re: Tektronix 475 repair assistance
« Reply #58 on: October 21, 2017, 06:26:34 pm »
There’s only one answer and that is both :)

I could do with a substitution box actually.

I’m going to be honest: I want a 465B without DM44 for the bench.

How early do you have to turn up to get the interesting stuff at Kempton?

Clearly you are a really hoopy frood :)

Timing depends on whether you want best choice or best price. Overall you should expect prices to be lower than fleabay, but you can also twiddle knobs.
 
I would expect to see a 465 class machine, but a 465B is rarer. Resistor/capacitor boxes depend on what people are throwing out, but they are expensive on fleabag.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline bd139Topic starter

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Re: Tektronix 475 repair assistance
« Reply #59 on: October 21, 2017, 06:31:15 pm »
Towel in hand :)

Thanks for the tips. I’m going to take £100 cash with me and my wife hopes I will come back with some. I don’t want to look like a crazy person loading tens of dead scopes into the car though so being quite objective.
 

Online tggzzz

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Re: Tektronix 475 repair assistance
« Reply #60 on: October 21, 2017, 06:43:55 pm »
Take more than £100; demonstrate your iron will.

More seriously, £35 for a 465 was very cheap.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline bd139Topic starter

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Re: Tektronix 475 repair assistance
« Reply #61 on: October 21, 2017, 07:13:43 pm »
Never paid more than £40 for a 465. Granted they’ve all been dead. Only one was completely shot and that was repairable (caps/rectifiers out) and only got sacrificed for parts as it was more broken than the other two! :)

Sold both working ones for £150 each.
 

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Re: Tektronix 475 repair assistance
« Reply #62 on: October 21, 2017, 07:58:10 pm »
How'd you sell the 465s? Fleabay?

One reason for taking more than £100 is that you may well find a lot more than you expect. There is usually some interesting test equipment, quite apart from affordable good SMA/BNC cables.

BTW, I've just seen (and will correct) my previous statement: it was a working 7.5 digit DMM for £40.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline bd139Topic starter

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Re: Tektronix 475 repair assistance
« Reply #63 on: October 21, 2017, 08:06:53 pm »
Fleabay. But it now £150. Chuck some wittig probes in. Take some nice photos. Ignore offers from idiots. Wait about 2-3 weeks and done.

7.5 digits for 40 is pretty amazing!

Going to be honest: I’m very limited with space which limits purchases more than the cash. This is what I have to work with currently which isn’t ideal. All the vintage stuff lives on the table opposite this pile :)


 

Offline Specmaster

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Re: Tektronix 475 repair assistance
« Reply #64 on: October 21, 2017, 08:11:51 pm »
Fleabay. But it now £150. Chuck some wittig probes in. Take some nice photos. Ignore offers from idiots. Wait about 2-3 weeks and done.

7.5 digits for 40 is pretty amazing!

Going to be honest: I’m very limited with space which limits purchases more than the cash. This is what I have to work with currently which isn’t ideal. All the vintage stuff lives on the table opposite this pile :)


Wow, you need some shelving badley
Who let Murphy in?

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Offline Specmaster

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Re: Tektronix 475 repair assistance
« Reply #65 on: October 21, 2017, 08:13:53 pm »
How'd you sell the 465s? Fleabay?

One reason for taking more than £100 is that you may well find a lot more than you expect. There is usually some interesting test equipment, quite apart from affordable good SMA/BNC cables.

BTW, I've just seen (and will correct) my previous statement: it was a working 7.5 digit DMM for £40.
Hmm you really a TEA when you can walk away from a working 7.5 digit DMM for £40  :wtf:
Who let Murphy in?

Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi
 

Offline bd139Topic starter

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Re: Tektronix 475 repair assistance
« Reply #66 on: October 21, 2017, 08:14:36 pm »
Yeah tell me about it. The whole corner is being ripped out and replaced with an ikea (office grade) desk with shelving in the next few months. Keep spending my budget on toys though :)
 

Online tggzzz

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Re: Tektronix 475 repair assistance
« Reply #67 on: October 21, 2017, 08:32:46 pm »
How'd you sell the 465s? Fleabay?

One reason for taking more than £100 is that you may well find a lot more than you expect. There is usually some interesting test equipment, quite apart from affordable good SMA/BNC cables.

BTW, I've just seen (and will correct) my previous statement: it was a working 7.5 digit DMM for £40.
Hmm you really a TEA when you can walk away from a working 7.5 digit DMM for £40  :wtf:

Erm, I only walked away when it was £50 :) Sometimes later is better, at Kempton and other car boot sales.

But then I got an 8.5 digit for £75 :) but had to spend £25 on a new Fischer mains switch/selector/filter :( and make my own cable :( But that was offset by the battery powered transportable 10V sources and Guildline resistors for £14 each (not at Kempton)

Took the reference to Hannover maker faire,  and it is 9.999571V, and the 8.5 digit DMM is (now,eventually) ~25ppm different.
« Last Edit: October 21, 2017, 08:38:59 pm by tggzzz »
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline bd139Topic starter

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Re: Tektronix 475 repair assistance
« Reply #68 on: October 21, 2017, 08:35:37 pm »
Ok I walked away from that other Tek 475 when it went past £36.

Final price for a dead, untested scope with suspect status .... £55

Mental  :scared:
 

Offline Specmaster

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Re: Tektronix 475 repair assistance
« Reply #69 on: October 21, 2017, 09:53:22 pm »
Well it was worth a shot anyway.
Who let Murphy in?

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Offline Specmaster

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Re: Tektronix 475 repair assistance
« Reply #70 on: October 21, 2017, 09:56:04 pm »
Erm, thats £25 extra for a single digit, but still fair play, you ended up with something better so your membership is still valid :phew:
Who let Murphy in?

Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi
 

Online tggzzz

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Re: Tektronix 475 repair assistance
« Reply #71 on: October 21, 2017, 10:07:04 pm »
Erm, thats £25 extra for a single digit, but still fair play, you ended up with something better so your membership is still valid :phew:

I ought to work out whether the price follows the square or cube of the number of digits :) Other 8.5 digit meters have gone for 20* that at a recent auction!
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline Specmaster

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Re: Tektronix 475 repair assistance
« Reply #72 on: October 21, 2017, 10:13:43 pm »
Well you certainly got a bargain thats for sure, just wish they had similar sales around the Essex area so I can see if I could nab a bargain or two  :popcorn:
Who let Murphy in?

Brymen-Fluke-HP-Thurlby-Thander-Tek-Extech-Black Star-GW-Avo-Kyoritsu-Amprobe-ITT-Robin-TTi
 

Offline bd139Topic starter

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Re: Tektronix 475 repair assistance
« Reply #73 on: October 21, 2017, 11:44:32 pm »
There used to be a ham fest out that way in the Harlow area. No idea if it’s still on now. Still got the large bag of resistors I got there for 50p. All Philips 1% metal films mixed values with leads formed. A whole kg!  Would be about 25 quid on eBay now.
 

Online tggzzz

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Re: Tektronix 475 repair assistance
« Reply #74 on: October 22, 2017, 07:29:15 am »
There used to be a ham fest out that way in the Harlow area. No idea if it’s still on now

As the dates get announced, they are noted here: http://rsgb.org/main/news/rallies/ Expect more to appear in the new year.
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 


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