TEK TM503 Project

[MED6753]

A local Facebook Marketplace find. Only $50 USD and we all know how much they go for on Evil Bay. TM503 with a DM501 DMM, FG501 Function Generator, and a PS503 Dual Supply. Unknown if it powers up. Seller got it from a storage unit and didn't have ability to test. It's damn dirty and will need a good clean up. And if the cabinet still looks that dull after cleaning then Papa Smurf's Paint Shop will be activated for the first time in almost 2 years. And there will be no attempt at power up until the main PSU as well as each plug-in is checked for shorts first. And of course will get a complete re-cap.

[bd139]

Oh now that was a winner. Interested in this one.

[Cubdriver]

Nice, Mike! $50 is a steal. Love that TM500/5000 stuff.

-Pat

[mansaxel]

Very, very nice. I have a TM503 but with the low distortion sine generator and the distortion analyser, complete with IM analytics option. Quite handy.

[Specmaster]

Nice one Mike, I can't say that I'd ever seen one before, but that looks pretty impressive, and I await your usual posts as you work your round it recapping and doing whatever is required to get up and running and looking splendid in Papa Smurf blue.

[MED6753]

Compare this photo to what I posted yesterday. The cover cleaned up so well that painting isn't required.



The power supply. Still needs to be cleaned then tested for shorts.



And now. Some porn. This is the DMM.



The function generator. I see beaded tants. They must go.



The power supply. More beaded tants.



The plug-in's have property tags from the Bronx Municipal Hospital in NYC. Never heard of that hospital but found out that it's now called Jacobi Hospital.

[Zenith]

Compare this photo to what I posted yesterday. The cover cleaned up so well that painting isn't required.

It's amazing what a soaking with a good dose of general purpose kitchen cleaner, scrubbing with a nail brush, and then a rinse will do.

Last summer I had three oscilloscope covers on the washing line drying in the wind. The neighbours gave me some odd looks.

[BU508A]

The power supply. Still needs to be cleaned then tested for shorts.

[MED6753]

It's tempting and I've used the dishwasher before to clean parts but I worry that the open frame power transformer won't like it. I'll come up with something to clean that PSU.

[Zenith]

I'm sure you've cleaned a lot of things like this before. This looks like accumulated dust rather than anything nasty, such as damp or worse, tobacco tar. I'd use a paint brush and vacuum cleaner, then a damp cloth.

I have heard of "brown" radios - that is ones caked in tobacco tar - having the chassis put in the shower, sprayed with bathroom mousse, left for 15 minutes for the mousse to do its work, and then rinsed off and put in an airing cupboard to dry. It seems less drastic than a dishwasher, but I can see how a lot could go wrong.

[mnementh]

The power supply. Still needs to be cleaned then tested for shorts.

Hey!!! Telling people to stick it in their dishwasher is my schtick!!!

mnem

[Specmaster]

It's tempting and I've used the dishwasher before to clean parts but I worry that the open frame power transformer won't like it. I'll come up with something to clean that PSU.

I'd never put any electronic bits in a dishwasher personally, as you say the tranny may not like that for a start and would give you an extra headache to deal with. Yes, I put cabinetry in a dishwasher before and it did a pretty good job.

[MED6753]

The PSU cleaned up well and no shorts were found.



Decided to check the DC voltages and the 11.5V measured 7.7V with 2VAC ripple. C35 is open and confirmed with the Peak tester. Submitted the order for total re-cap of the main PSU and the plug-in's.

[mansaxel]

It's tempting and I've used the dishwasher before to clean parts but I worry that the open frame power transformer won't like it. I'll come up with something to clean that PSU.

I've only ever gone to putting keycaps from keyboards in the dishwasher. The original IBM Model M and the Sun Type 5 keyboards have caps that remove with ease and de-griming them is a great step forward when your favourite keyboards are either vintage or expensive.

(Having said that, I do have a Unix Layout Type 5 keyboard, with optical mouse and mouse pad, NIB, somewhere in my garage. Probably would fetch a handy sum, if I could find someone who can cope with Larry owning SUN these days. )

[Zenith]

The PSU cleaned up well and no shorts were found.

A beautiful job, and no need for any over the top measures, quite likely to prove disappointing.

[Specmaster]

It's tempting and I've used the dishwasher before to clean parts but I worry that the open frame power transformer won't like it. I'll come up with something to clean that PSU.

I've only ever gone to putting keycaps from keyboards in the dishwasher. The original IBM Model M and the Sun Type 5 keyboards have caps that remove with ease and de-griming them is a great step forward when your favourite keyboards are either vintage or expensive.

(Having said that, I do have a Unix Layout Type 5 keyboard, with optical mouse and mouse pad, NIB, somewhere in my garage. Probably would fetch a handy sum, if I could find someone who can cope with Larry owning SUN these days. )

Never thought about doing that with mine, I find the best solution and easiest way is pull the caps and stick the in a bowl of hot water with washing up liquid soap, let them sit there for a few minutes and then give them a swirl around in the water. Take them out and place on a spread out tea towel and leave for around 20 minutes to dry, and they come up like new caps again.

[MED6753]

The PSU cleaned up well and no shorts were found.

A beautiful job, and no need for any over the top measures, quite likely to prove disappointing.

All it took was a soft brush to loosen the caked on dust. The project is now on hold until the replacement capacitors arrive next week. The cost of the capacitors exceeded what I paid for the unit by $7 USD. So I have $107 USD into it which is still much cheaper than typical Ebay. And my labor is super cheap.

[mnementh]

...And my labor is super cheap.

Yeah, they pay you in SmurfBerries.

mnem
*will work for draco-snax*

[MED6753]

The old C35.



https://www.youtube.com/watch?v=3at_Ev2kOoI

New C35.



Decided to see if any of the plug-in's work. The DMM works but is inaccurate. That reading should be 2.500V. Resistance is also very unstable. The function generator is DOA. No output. Didn't check the power supply yet.



After replacing the other 2 capacitors in the main supply I'll concentrate on fixing the DMM. The function generator will be a follow up as well as the power supply.

[bd139]

That last picture gave me nasty flashback of that fucking D81. That has the same chassis as the 3 slot TM500.

[tggzzz]

That last picture gave me nasty flashback of that fucking D81. That has the same chassis as the 3 slot TM500.

We know you like such things: you keep on coming back for more.

Unless, of course, you are just here for our company? (Newbury Sunday?)

[MED6753]

So today I attempted to calibrate the DCV and Ohms. It did not go well. All the internal voltages were checked as per the manual and were in spec. But the best I could do on DCV is +2.659V vs +2.501V. Definitely NFG.



The Ohms did initially calibrate well but every once in a while it goes wacko. There's nothing loose that I could find and my standard resistance box is fine. And who but only Tek would have the lowest resistance range at 2K ohms. Where is the 200 ohm range? Fluke and hp have it. Makes doing low resistance checks worthless.



Can't have enough DMM's? Yes you can. I'm not impressed with this DMM. I'm seriously considering throwing it into my parts stash. Going to troubleshoot the function generator next.

[tggzzz]

The Ohms did initially calibrate well but every once in a while it goes wacko.

Break out the freezer spray?
Wiggle all components?
DeOxit any connectors/switches?

[bd139]

That last picture gave me nasty flashback of that fucking D81. That has the same chassis as the 3 slot TM500.

We know you like such things: you keep on coming back for more.

Unless, of course, you are just here for our company? (Newbury Sunday?)

Alas I have no wheels and have the kids this weekend or I would.

[tggzzz]

That last picture gave me nasty flashback of that fucking D81. That has the same chassis as the 3 slot TM500.

We know you like such things: you keep on coming back for more.

Unless, of course, you are just here for our company? (Newbury Sunday?)

Alas I have no wheels and have the kids this weekend or I would.

Won't be too many years before your kids have you

Get a train to Newbury, then a taxi to Chieveley. I'm sure you could cadge a lift back to the station