I have two Oscillators, an HP204C and an HP204D.
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The HP 204C has issues with the Main 300uF Capacitor (at least I think it is 300uF - it is so bad I can hardly tell what it is - but I can make out what looks like 300uF and I believe it is a 6VDC Cap). This cap is on the Power Board, not the Main Oscillator Board. I bought this off the eBay waistland. Seller said it was untested (but did not tell me they had been inside and pried the cover off because one of the screws was broken off. Also did not tell me they broke two of the NICAD Battery Terminals.. Still, I am going to fabricate new terminals out of Brass stock. My main issue is the set screws on the Frequency Dial seem to be stripped - or they are not Hex capable (and Torx Bits do not work either). Does anyone know what size and type of set screws are used on the HP204C?
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Second Oscillator seems fine inside, but the Frequencies are nowhere near what the dial says they should be. This oscillator also has set screws that will not loosen. Maybe it is because I am using Hex Bits and not the correct ones. Once again, I need to know what the correct size bits and type so I can figure out what size drill bit to use to drill them out. If I get too large a bit I run the risk of screwing up the hole threads... if I get too small, well small bits break more readily, that and too small a bit will result in a screw carcass that cannot be forced out after drilling..
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I tried downloading copies of the service manual - no help they just give an HP Part number for the dial and no info on what tools are required (so picking the wrench from a non existent tools list is not gonna happen).
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Such a quandry. I would really like to get these up and running. Help - please (pretty please).
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I tried calling my associate in Macon, Georgia (he is near the Macon Airport, just north of WR AFB. His phone is no longer valid ( makes sense since I haven't talked with him in 12 years). He was my Go To Guy for HP parts - His Warehouse was a 300,000 Sq Foot barn chock full of HP stuff. I now live in Phoenix, Arizona - that and my Aircraft is in Depot Repair so simply popping down to Georgia is not gonna happen either. If I find a good number for my associate I will surely post it here later (everyone can use an HP Parts Source.)
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My associate here in Phoenix is Jay Hoyl, but he does not have HP parts anymore. His son does not subscribe to seniors mentality that HP parts should be saved on scrapped fear... Oh well - I seem o be striking out everywhere...
..
Still... Help....
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The HP 204C has issues with the Main 300uF Capacitor (at least I think it is 300uF - it is so bad I can hardly tell what it is - but I can make out what looks like 300uF and I believe it is a 6VDC Cap). This cap is on the Power Board, not the Main Oscillator Board. I bought this off the eBay waistland. Seller said it was untested (but did not tell me they had been inside and pried the cover off because one of the screws was broken off. Also did not tell me they broke two of the NICAD Battery Terminals.. Still, I am going to fabricate new terminals out of Brass stock. My main issue is the set screws on the Frequency Dial seem to be stripped - or they are not Hex capable (and Torx Bits do not work either). Does anyone know what size and type of set screws are used on the HP204C?
..
Second Oscillator seems fine inside, but the Frequencies are nowhere near what the dial says they should be. This oscillator also has set screws that will not loosen. Maybe it is because I am using Hex Bits and not the correct ones. Once again, I need to know what the correct size bits and type so I can figure out what size drill bit to use to drill them out. If I get too large a bit I run the risk of screwing up the hole threads... if I get too small, well small bits break more readily, that and too small a bit will result in a screw carcass that cannot be forced out after drilling..
..
I tried downloading copies of the service manual - no help they just give an HP Part number for the dial and no info on what tools are required (so picking the wrench from a non existent tools list is not gonna happen).
..
Such a quandry. I would really like to get these up and running. Help - please (pretty please).
..
I tried calling my associate in Macon, Georgia (he is near the Macon Airport, just north of WR AFB. His phone is no longer valid ( makes sense since I haven't talked with him in 12 years). He was my Go To Guy for HP parts - His Warehouse was a 300,000 Sq Foot barn chock full of HP stuff. I now live in Phoenix, Arizona - that and my Aircraft is in Depot Repair so simply popping down to Georgia is not gonna happen either. If I find a good number for my associate I will surely post it here later (everyone can use an HP Parts Source.)
...
My associate here in Phoenix is Jay Hoyl, but he does not have HP parts anymore. His son does not subscribe to seniors mentality that HP parts should be saved on scrapped fear... Oh well - I seem o be striking out everywhere...
..
Still... Help....
I poked around in the manual and found indication that it's a hex Allen wrench, but didn't find size. Almost certain it's English as opposed to metric.
Get a set of Allen wrenches and find best fit. Drip a bit of WD-40 into each of the two knob holes and orient the dial so that gravity works for you. Let them soak. You might use a heat gun to help loosen, but use caution to avoid damage.
Drilling should be last absolute last resort when sockets are stripped. I don't know if easy-out bits would be available for set-screws so small.
I understand there's an HP user group, but I don't have details. I enjoy troubleshooting electronics if you reach that stage.
Good luck!
Get a set of Allen wrenches and find best fit. Drip a bit of WD-40 into each of the two knob holes and orient the dial so that gravity works for you. Let them soak. You might use a heat gun to help loosen, but use caution to avoid damage.
Drilling should be last absolute last resort when sockets are stripped. I don't know if easy-out bits would be available for set-screws so small.
I understand there's an HP user group, but I don't have details. I enjoy troubleshooting electronics if you reach that stage.
Good luck!
I have the 204D (same as the 204C with added features). That vintage HP used imperial sized hardware. Take a photo and indicate the parts in question and you'll get your answers. E