Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
Flare:
--- Quote from: Flare on March 26, 2023, 10:28:40 am ---Has anyone got a suggestion for a replacement for the attached Iwatsu SS-6122 horizontal timing pot please? The board is cracked between the carbon trace and the legs. I think it's the same as the one in SS-5711 and SS-5710 as I think it's the same scope with an added OSD.
I believe the Iwatsu name for this part is: DRV147401. The case of the part states that it is an: Alps 749Y-50KB.
It's a 50k linear potentiometer with SPDT switch, the switch operates on the clockwise side, which is pretty unusual outside of scopes because practically all available ones seem to operate on the counterclockwise side, like a radio volume control. I think it only uses the CW open, CCW closed terminal, in order to light the uncalibrated LED. I don't expect to find anything with the same tiny slotted shaft, so whatever I get I'll have to grind down to size anyway. The leg size also shouldn't matter as it could just be wired to the board while hanging in its bracket.
Is there any good source for clockwise detent/switched pots in general outside of other scopes? Searching for them on electronics distributors is awful as many don't even have a parameter for switched pots and then if they do I need to go into the datasheet on each pot and look for the switch angle (which always seems to be 30° or 50° and I assume I would be looking for 270° or so). On a side note, I've found a parametric search worse than RS' one, Bourns own one feels like it's running on 56k.
I'll probably have to settle for a CCW switched volume knob in the end (the only difference should be the variable knob working in reverse direction) but I think it must be a fairly common type of part to replace in old gear, eg. I think Teks have a similar arrangement for their uncal LED.
--- End quote ---
Apologies, I forgot to offer up a glamour pic of the TE as payment for this request. I don't think the graticule illumination is working and the delay trace slower timebase seems to need the intensity turned up way too high to see anything other than the highlight, I didn't fully investigate before tearing it down to replace the pot. I don't know why the image is so horribly artifacted, the original picture from my phone before resizing looks that poor.
It's pretty cool looking 80s tech though imo, I mostly got it because I thought the clock and counter were cool ;D
m k:
So you opened it.
Was it a regular pot on top of not so regular something?
DC1MC:
I've bought an ANGENG SZ20 as a comfort purchase :palm:, the level of TE drought is terrible, anyways someone around Mannheim with a reasonable calibrator who wants to do a quick check/characterization ?
Cheers,
DC1MC
For risk takers:
https://www.aliexpress.com/item/1005005201649970.html
TERRA Operative:
I figured out how to use standard C-size cells in the THS700 series scopes, and keep full backwards compatibility with a completely stock appearance.
https://www.eevblog.com/forum/testgear/tek-ths720a-portable-scope-teardowndiscussion/msg4775885/#msg4775885
I have also ordered a new screen from China (still trying to source some polarisers that won't turn it blue and yellow instead of black and white. Got a bunch of TDS210 and TDS220 scopes to repair too. Damn STN/FSTN LCD screens and their extra filter requirements!) so this scope isn't far of actually being useable.
And now a THS720P has popped up on Yahoo Auctions, so I'll have a punt at that one too, see if I can nab it for a not stupid price. :D
Flare:
--- Quote from: m k on March 26, 2023, 11:44:05 am ---So you opened it.
Was it a regular pot on top of not so regular something?
--- End quote ---
I originally opened the back in situ in the hope I could repair it in place, as I'm pretty sure that the technically correct way to remove it is to remove that PCB, desolder the entire Horizontal timing assembly and then remove it from that. In the end there was just enough tolerance to get it out leaving the rest in place.
I've attached a picture of the insides, as you can see the crack fully separated. The wiper assembly actuates the switch on the rear which is inside the same casing. Also attached is a picture showing that due to it being switched, it doesn't have a regular track, the latched area of the switch is solid metal instead of carbon, for negligible resistance (I assume this is normal for switched pots).
If anyone has the service manual it would be great, I've just gotten the operating manual from Iwatsu Europe which I think I'll upload to Electrotanya as it's too large to host here.
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