Test Equipment Anonymous (TEA) group therapy thread

[bitseeker]

But just for fun I took the DC504 over to the second TM500 I got for parts (but is basically functioning although it's in the process of getting cleaned up). The DC504 did come on when I tried it in that TM500, in any slot. Also, the other plug-ins I have all work OK in both TM500s in any slot.

 

I'm going to stop for a while and think about this one, any ideas are gratefully accepted at any time as always ... 

Heh, make the second TM500 the primary and the problematic one the parts unit.

[bitseeker]

I've been thinking of building an improvised resistor-in-a-probe for measuring DC voltages (with some division ratio) without loading sensitive circuits with the cable capacitance.  (Similar to the probe built-in to the HP 410B in DC mode.)

You could have the ratio selectable as well, and have the impedance go from LoZ to G or T. That'd be quite a flexible instrument.

[xrunner]

Heh, make the second TM500 the primary and the problematic one the parts unit.

LOL - functionally that's what could be done, but -

A. It isn't as pretty as the other one (yea I know swap all the pretty parts ...  )

B. I need to figure out what's wrong anyway so might as well fix it. 

I think it has something to do with the various power being supplied to each compartment (duh). I may have assumed too much, in that having two plug-ins powering up and working means that everything is A-OK. I think Tektronix has more to teach me. 

[tautech]

Heh, make the second TM500 the primary and the problematic one the parts unit.

LOL - functionally that's what could be done, but -

A. It isn't as pretty as the other one (yea I know swap all the pretty parts ...  )

B. I need to figure out what's wrong anyway so might as well fix it. 

I think it has something to do with the various power being supplied to each compartment (duh). I may have assumed too much, in that having two plug-ins powering up and working means that everything is A-OK. I think Tektronix has more to teach me. 

Maybe, maybe not.
As with any old equipment that may have had some twit twiddle with it you need to approach it with both eyes wide open. (was gunna add a wink but that's not right....well you know what I mean.  )

[AF6LJ]

Heh, make the second TM500 the primary and the problematic one the parts unit.

LOL - functionally that's what could be done, but -

A. It isn't as pretty as the other one (yea I know swap all the pretty parts ...  )

B. I need to figure out what's wrong anyway so might as well fix it. 

I think it has something to do with the various power being supplied to each compartment (duh). I may have assumed too much, in that having two plug-ins powering up and working means that everything is A-OK. I think Tektronix has more to teach me. 

Maybe, maybe not.
As with any old equipment that may have had some twit twiddle with it you need to approach it with both eyes wide open. (was gunna add a wink but that's not right....well you know what I mean.  )

I troubleshoot all my high voltage circuits by the Braille Method.

[frozenfrogz]

I got my Solder Peak SP-1010DR desoldering station today and was able to fix a Fluke 8060A I got last week in no time! The DIP40 socket needed to be taken off, as well as a resistor network. The board needed some thorough cleaning in the upper part and one trace needed rebuilding. After bringing it back to life, it seems to be spot on!
So basically I got a fully working 8060A for 10€ and 30 minutes time.

[MarkL]

I think it has something to do with the various power being supplied to each compartment (duh). I may have assumed too much, in that having two plug-ins powering up and working means that everything is A-OK. I think Tektronix has more to teach me. 

Modules use one or more of the many different supplies provided by the TM503.  Some supplies are isolated per slot and some not and are common to all slots.  See attached PDF snippet.  I would guess the DC504 is using something that the PS503A and DM501A don't need.

A quick look at the service manuals shows:

  PS503A uses 25VAC isolated winding, +11.5V non-isolated.
  DM501A uses 25VAC isolated winding.
  DC504 uses: +33.5VDC and -33.5VDC non-isolated supply.

Seems like the +/-33.5VDC would be the first suspect.  I would check all the supplies.

There's SOOO many modules available.  SOOO much temptation...

[bitseeker]

LOL - functionally that's what could be done, but -

A. It isn't as pretty as the other one (yea I know swap all the pretty parts ...  )

B. I need to figure out what's wrong anyway so might as well fix it. 

No worries. I was being facetious and would be compelled to track down the issue as well.

Seems like the +/-33.5VDC would be the first suspect.  I would check all the supplies.

Yes, thou shalt check voltages.

There's SOOO many modules available.  SOOO much temptation...

Are you attempting to resist? In the TEA thread? 

[xrunner]

Maybe, maybe not.
As with any old equipment that may have had some twit twiddle with it you need to approach it with both eyes wide open. (was gunna add a wink but that's not right....well you know what I mean.  )

Oh I know mate, I always make sure when poking around in these things that the unit unplugged and the end of the cord is visible to my eye on the floor. I have a very good habit of looking for the end of the cord on the floor before sticking my hand inside. 

A quick look at the service manuals shows:

  PS503A uses 25VAC isolated winding, +11.5V non-isolated.
  DM501A uses 25VAC isolated winding.
  DC504 uses: +33.5VDC and -33.5VDC non-isolated supply.

Seems like the +/-33.5VDC would be the first suspect.  I would check all the supplies.

There's SOOO many modules available.  SOOO much temptation...

Turns out you are correct Mark, there were two power supply systems inoperative - the +/- 33.5 and the +11.5 that goes to 3 of the 4 compartments (the high power has it's own +11.5 PS). All the fuses for them were blown (two 1.6A and one 5A). I replaced them with spares and now the DC504 is working.

Why did I not initially think any fuses were blown? Because as I said both plug-ins I got (DM501A & PS503A) were working perfectly in all the compartments. But, I was fooled into believing that meant ALL the modules made for it would work, but I was mistaken. The DC504 uses the +/- 33.5V supplies and the other units do not! So there you go. No harm done but I learned a good lesson about this TM500 system - the designers chose a very interesting way to power different modules. 

But I have one issue remaining - perhaps you all can advise. I obviously now have checked all the fuses and spares, and will have to order several since I have no 1.6A or 5A slow blo glass fuses. The schematic states the main line fuse is to be 4A slow blo, but the manual text says it's a 3A slow blo, and the actual fuse I took out of the rear fuse holder was a 2A slow blo  OK we can chock the 2A off to an impatient user, but there is a discrepancy in the manual. 3A or 4A? 

[bitseeker]

Well, a pragmatic approach would be to put in a 3A fuse. If you pop a few with no signs of malfunction in any of the modules, upgrade to 4A.

[MarkL]

There's SOOO many modules available.  SOOO much temptation...

Are you attempting to resist? In the TEA thread? 

No, not at all!  Resistance is futile.  I'm inviting all to join us and be one with the TE collect(ive).

I have a TM503 and TM501 and a modest collection of modules: FG504 func gen, AM503 current amp, AM502 diff amp, and DC503A counter.

Those familiar will note the mismatch of slots to modules, thus inducing a recurrent case of SMD (slot mismatch disorder).  I know a web site that can help.

[bitseeker]

Ah, OK. I see that you're doing just fine.

[tautech]

Maybe, maybe not.
As with any old equipment that may have had some twit twiddle with it you need to approach it with both eyes wide open. (was gunna add a wink but that's not right....well you know what I mean.  )

Oh I know mate, I always make sure when poking around in these things that the unit unplugged and the end of the cord is visible to my eye on the floor. I have a very good habit of looking for the end of the cord on the floor before sticking my hand inside. 

Chicken !

Man up and use Sue's method; Braille 

Seriously you need more HV stuff to work on and you gain methodologies and confidence and with the knowledge of "voltages present" it just becomes built into your psyche and you become safer in all that you do.

Remedy: more test equipment. 

[xrunner]

Remedy: more test equipment. 

I'll drink to that idea!   

So I had to open up the DC504, needs a lot of TLC. But behold the circa 1979 goodness inside. All 29 socketed ICs - many 7400 family like inverters, quad nand gates, D flip flops - it doesn't get any better than basic logic gates for a frequency counter design! 

[tggzzz]

This might be considered the "methadone equivalent" for fellow TEA sufferers: join a local Hackspace...

At my local Hackspace this month's haul donations have included:

• capacitance meters in a suspiciously Fluke-alike case
• an in-circuit capacitor ESR tester
• a working Tek DM63, a dual-beam analogue storage scope
• a working Tek 2245, even if it did take a few minutes to turn on the first time

And I don't feel any compunction to recap the 2245

[Rerouter]

So I had to open up the DC504

The white and yellow coax going to the rear of the board, what is he? just had a peek inside mine and i dont have him (assuming internal frequency source)

[xrunner]

The white and yellow coax going to the rear of the board, what is he? just had a peek inside mine and i dont have him (assuming internal frequency source)

It's explained on p. 1-8 of the manual. It's for an external osc. (clock). You'd have to wire in the ext. osc. to the unused pins on the back of the TM500 chassis.

But here's another weird thing. I was just checking that wire and on mine it's been wired to the wrong pads! I even checked another picture I found on the internet and that one was wired wrong also. 

Look at the picture - you can clearly see the marking on the pcb that says "EO". that's pin 14A which is what the manual says to wire to. Now, on the connector those pins and the ones above it are not connected to anything, so wiring it to the next pins above will do no harm. But it's very strange that mine and another one I found were wired that way, clearly not where the manual said. Mysteries, mysteries ... 

[AF6LJ]

Remedy: more test equipment. 

I'll drink to that idea!   

So I had to open up the DC504, needs a lot of TLC. But behold the circa 1979 goodness inside. All 29 socketed ICs - many 7400 family like inverters, quad nand gates, D flip flops - it doesn't get any better than basic logic gates for a frequency counter design! 

Not too bad, should be straight forward, and a fun job.

[xrunner]

Did the TEA party end? 

[AF6LJ]

Did the TEA party end? 

I don't think so....
Looks like an HP-8620 Sweeper is a gateway drug for sure.
Picked one up yesterday at TRW...
It generates RF Right now that is all I know.
Need to finish that 8569B....
Oh..
And I now have the .3-12.4GHZ converter for my 5245L...
I will have to see if it works.
 

[xrunner]

Looks like an HP-8620 Sweeper is a gateway drug for sure.
Picked one up yesterday at TRW...
It generates RF Right now that is all I know.

Doesn't that thing rotate that frequency scale around, like a drum, when you switch bands?

Well, I finished a basic restoration of the DC504 I got. Replaced the BNC and did a lot of cleaning - have I ever said how much I hate that adhesive that cal stickers use? Man that stuff can be a pain to remove, but it comes off given enough time and Goo Gone. Pic attached.

I also got another unit coming, an FG 501A for $49. Listed as:

"For parts or not working - No Output"

We shall see about that 

[AF6LJ]

Looks like an HP-8620 Sweeper is a gateway drug for sure.
Picked one up yesterday at TRW...
It generates RF Right now that is all I know.

Doesn't that thing rotate that frequency scale around, like a drum, when you switch bands?

Well, I finished a basic restoration of the DC504 I got. Replaced the BNC and did a lot of cleaning - have I ever said how much I hate that adhesive that cal stickers use? Man that stuff can be a pain to remove, but it comes off given enough time and Goo Gone. Pic attached.

I also got another unit coming, an FG 501A for $49. Listed as:

"For parts or not working - No Output"

We shall see about that 

Yes the drum does rotate, one of the panels with the scale on it came off and was in the bottom of the case. I'll have to fix that, and a knob had the plastic skirt disintegrate in my hand. I don't know what the deal with HP's plastic is...

The 5255 cleaned up nicely, I am not going to take it apart, but I did clean up a lot of the dirt.
I have to check the serial number on my 5345L to make sure I can use the converter, it has a warning on it saying not to use it in anything but a 5345L that is serial number prefix 402 or higher.

Your modules cleaned up nicely....

Lets see...
Now  I need that rare .01-4GHZ plug in directional couplers, diode detectors...
an amplifier....
I want an L-Band amplifier though...
Maybe 1-2GHZ..
And a reasonably nice solid state broadband amp for VHF and UHF...
RF is a Gateway Drug....
 

[bitseeker]

have I ever said how much I hate that adhesive that cal stickers use? Man that stuff can be a pain to remove, but it comes off given enough time and Goo Gone. Pic attached.

You can say that again! The only thing worse than buying TE with cal sticker goo is seeing a nice bit of kit where some barbarian gouged the sticker off the instrument panel with some brutal piece of medieval weapon of mass destruction.

[mmagin]

Is it TEA when you're slightly concerned about always having the right tuning tool, even though you only really use about 5 of them?

[Brumby]

I'm feeling underprivileged .... I only have 2.