| Electronics > Repair |
| Broken Faders on VideoComp VES-one genlock |
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| Overmann:
Years ago I was gifted a genlock for use with the Amiga line of computers. It powers on and appear to work, but the faders were falling apart. After years of being on the lookout I managed to find another VES-two (it's actually the VES-one, i misremembered. Thank you timeandfrequency for pointing it out), but sadly its faders were in even worse condition. Recently I've concluded that instead of looking for a third unit I might as well try to repair the two units that I have. The problem is I have very little knowledge when it comes to faders (and electronics in general). I do have some skill with a soldering iron, but thats about it. I am hoping that someone here, with knowledge on the subject, might be able to help me find a replacement part that i might solder on to the boards, or modify in some way to make them work. After disassembling one of the faders i found this writing: A, 035, 10k, Preh, E, S A, E and S are for the three pins. I also made this post with pictures of the faders: https://imgur.com/gallery/odd-unidentifiable-fader-QU0FJBw Do any of you know if there is a modern replacement for these faders? Any help or suggestion greatly appreciated. I think they are 10k, 70mm length, 50mm travel, linear, but thats not enough for me (as a layman) to find a replacement part. |
| timeandfrequency:
Hello Overmann, Uh, I could not even find a single picture of the Videocomp VES-TWO genlock on Google, I only found some information about the VES ONE. As far as I understand, PREH is a German manufacturer which now focuses on automotive parts and electronic systems Now let's find replacemement parts. Check out this one (6 units available) https://www.ebay.de/itm/123873406755 Perhaps ask the seller about the exact size of the part. IMO, they seem a bit too short (perhaps only 35 mm travel, 50 mm full lenght). Most of the PREH faders I could find are upright models :( Those in the VES TWO are of flat shape and are actually lying. But ask Greider if they dont have a few parts that matches your requirement. Furthermore, the part you describe has a 50 mm travel, and this is unfortunately rather uncommon. Standard travel course are 45 mm and 60 mm. Also check the other defective fader if they are exactely the same as the one you already dessoldered. Do you want only a genuine replacement part ? Or would a functional replacement suit too ? In the latter case, adapating another fader having similar mechanical size would certainly be possible and do the job. If a functional replacement is acceptable, the important features are : - the fader height - the fader resitive law As nothing is indicated on your fader, I would assume it is 'A' (linear), but this has to be verified - the fader total lenght (because too long might be a problem if other parts are located in vicinity. - the fader mechanical travel distance, but it's possible to cheat : 45 mm might do it, and 60 mm too, but in this case, it needs other cobblings to work properly (I we need too go that way, i'll be more specific in a later post) What is NOT important : - the fader total resistance value : as far as what you need is an 'A' law, the actual resistance value of the replacement part can be equal or above 10 k (because it's always possible to add a parallel fixed resistor so that it behaves as a 10 k fader) - the actual position of the pins (electrical connexions to the resistive track or the mecanical positioning pins), because it's always possible to drill new holes in the PCB and glue the fader at its' adequate position - mono or stereo fader : if you catch a stereo fader, just use one side. Some interesting parts that might be an acceptable replacement : 10 k (unknown law) 45 mm https://www.amazon.fr/lin%C3%A9airement-Potentiom%C3%A8tre-coulissant-coulissante-potentiom%C3%A8tre/dp/B07D42SYPH 10 k A 75 mm total lenght https://fr.aliexpress.com/item/32990553553.html 10 k A 60 mm travel https://sinolec.co.uk/en/slide-potentiometers/1211634-10k-ohm-slide-linear-slide-potentiometer-fader-with-dust-cover.html |
| Overmann:
This is very helpful, thank you timeandfrequency. You are correct in that this is the VES-one. I misremembered. Even the VES-one is pretty obscure, but it was in use as the center piece of the film-department of the school I went to back then. They had it in storage since the 90s, but it was in pretty rough shape. I suspect these faders just disintegrate with age. I don't mind a modern replacement at all. These faders do not appear to be of particularly high quality so If there is a modern, high quality replacement that I can use or modify to do the job then that would probably be the best way to go. I tried calling mouser for help finding a replacement, but they were only able to help if I was a corporate costumer making a bulk order. But I was able to find some that look like they might work, and one of those might the be same as the Alps you linked to in your post? https://no.mouser.com/ProductDetail/Alps-Alpine/RS45111A6A08?qs=m0BA540hBPd3sxZzJ%252BQ35g%3D%3D You think this might work, with some modifications? I also had these: https://no.mouser.com/ProductDetail/Alpha-Taiwan/RA4520F-10-20D1-B10K?qs=pp9WcCiiSR%252Bg%2F%252B8%252BL1mM0A%3D%3D https://no.mouser.com/ProductDetail/BI-Technologies-TT-Electronics/PS45G-C1SBR10KN?qs=XKNj3RTD%252B%252B89yqUQNM%252B6rw%3D%3D Id much rather buy new parts then NOS or used. :) |
| timeandfrequency:
Hello Overmann, Alps-Alpine is top-notch brand so it is probably the best choice. Alpha is OK too for your application. 'TT' is part of BI (Beckmann Industrial), which is also a renowed brand. Actually, the quality of the fader is not that important as it would be in an analog audio mixer : no video signal goes through the fader. The latter probably just provides a variable DC voltage to the actual video mixer assembly. As far as the parts you choose fit mecanically into the existing enclosure (check on the mecanical drawing for actual part dimension), you're on the safe side. Then you order the 10 k 'A' value part. I cannot give you any answer about the fact that a particular part will mecanically suit or not, because I don't know the height of the genuine part. What surprises me about the Mouser's page regarding the RS45111A6A08 part is that the description says 'Slide Potentiometers 10K OHM "B" TAPER' which speaks for a log law, and below the 'Taper' feature is mentionned as 'linear'. It's worth calling/emailing their customer service for an explanation. By the way, could you confirm that the genuine faders you need to replace are of 'A' law ? A basic measurment with a multimeter will tell you the truth. |
| Overmann:
I tried, and found that my multimeter must have broken since last time I used it. I must get a new one. But 'A' law signifies a linear taper? It must be linear if it's meants to smoothly transition from one video source to another, I think. But I'll put a new multimeter on the shopping list and check it out. It says B taper, but the documentation also describes it as linear. I'll also measure their height while I'm at it. It'll be great to finally replace these faders. If I'm lucky I'll have TWO working units and can have a go at some 90's video production :) Do you have some suggestion regarding how to identify which pins should be soldered to the PCB? The faders I'm replacing have three pins but some of the ones on mouser have more then that. Which are the important ones ? :P |
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