I recapped an old "Precise" model 610 RF generator.
There was a small 0.1mf oil filled cap in the osc circuit. The osc would not function with a new standard non oil cap. I put the old oil cap back in and all is well.
Help me to understand why that is.
Chuck

:I recapped an old "Precise" model 610 RF generator.
:There was a small 0.1mf oil filled cap in the osc circuit. The osc would not function with a new standard non oil cap. I put the old oil cap back in and all is well.
:Help me to understand why that is.
:Chuck
:PS does any one have a schematic for this RF gen?

::I recapped an old "Precise" model 610 RF generator.
::There was a small 0.1mf oil filled cap in the osc circuit. The osc would not function with a new standard non oil cap. I put the old oil cap back in and all is well.
::Help me to understand why that is.
::Chuck
::PS does any one have a schematic for this RF gen?
:
:
I will take a tab at it.
My suspicion is that your oil filled cap is a low ESR type or low leakage current type.
Oil filled capacitors were usually ordinary paper wax capacitors submerged in oil so that water vapor couldn't get to them and cause them to fail. Unless the oil has leaked out or they detach internally, they don't need to be replaced on a re-cap.

Best regards,

Bill Grimm

:::I recapped an old "Precise" model 610 RF generator.
:::There was a small 0.1mf oil filled cap in the osc circuit. The osc would not function with a new standard non oil cap. I put the old oil cap back in and all is well.
:::Help me to understand why that is.
:::Chuck
:::PS does any one have a schematic for this RF gen?
::
::Thanks Bill
:I will take a tab at it.
:My suspicion is that your oil filled cap is a low ESR type or low leakage current type.
:Oil filled capacitors were usually ordinary paper wax capacitors submerged in oil so that water vapor couldn't get to them and cause them to fail. Unless the oil has leaked out or they detach internally, they don't need to be replaced on a re-cap.
:
:Best regards,
:
:Bill Grimm
:

:::I recapped an old "Precise" model 610 RF generator.
:::There was a small 0.1mf oil filled cap in the osc circuit. The osc would not function with a new standard non oil cap. I put the old oil cap back in and all is well.
:::Help me to understand why that is.
:::Chuck
:::PS does any one have a schematic for this RF gen?
::
::Thanks Bill
:I will take a tab at it.
:My suspicion is that your oil filled cap is a low ESR type or low leakage current type.
:Oil filled capacitors were usually ordinary paper wax capacitors submerged in oil so that water vapor couldn't get to them and cause them to fail. Unless the oil has leaked out or they detach internally, they don't need to be replaced on a re-cap.
:
:Best regards,
:
:Bill Grimm
:Thanks Bill

Or perhaps the value was read wrong???

Clifton

:::I recapped an old "Precise" model 610 RF generator.
:::There was a small 0.1mf oil filled cap in the osc circuit. The osc would not function with a new standard non oil cap. I put the old oil cap back in and all is well.
:::Help me to understand why that is.
:::Chuck
:::PS does any one have a schematic for this RF gen?
::
::
:I will take a tab at it.
:My suspicion is that your oil filled cap is a low ESR type or low leakage current type.
:Oil filled capacitors were usually ordinary paper wax capacitors submerged in oil so that water vapor couldn't get to them and cause them to fail. Unless the oil has leaked out or they detach internally, they don't need to be replaced on a re-cap.
:
:Best regards,
:
:Bill Grimm
:

:Or perhaps the value was read wrong???
:
:Clifton
:The value is very clearly marked .1mfd

:
::::I recapped an old "Precise" model 610 RF generator.
::::There was a small 0.1mf oil filled cap in the osc circuit. The osc would not function with a new standard non oil cap. I put the old oil cap back in and all is well.
::::Help me to understand why that is.
::::Chuck
::::PS does any one have a schematic for this RF gen?
:::
:::
::I will take a tab at it.
::My suspicion is that your oil filled cap is a low ESR type or low leakage current type.
::Oil filled capacitors were usually ordinary paper wax capacitors submerged in oil so that water vapor couldn't get to them and cause them to fail. Unless the oil has leaked out or they detach internally, they don't need to be replaced on a re-cap.
::
::Best regards,
::
::Bill Grimm
::
:
:

It's hard to offer an useful opinion not knowing what the cap's exact circuit function is, but if the cap is being used as an RF timing component, 0.1 mF seems rather large. It's about the right value for a B+ bypass cap, but even a grossly wrong value there shouldn't prevent the circuit from working. And, a DC bus bypass cap wouldn't need to be oil-filled.

A 0.1 uF oil-filled cap wouldn't likely be physically "small" but I suppose that this is subjective. I vote for the "misread value theory". Could the part have been 0.1 nF (0.0001 uF)? Being a factor of a thousand off in a timing circuit would almost certainly prevent operation.

: It's hard to offer an useful opinion not knowing what the cap's exact circuit function is, but if the cap is being used as an RF timing component, 0.1 mF seems rather large. It's about the right value for a B+ bypass cap, but even a grossly wrong value there shouldn't prevent the circuit from working. And, a DC bus bypass cap wouldn't need to be oil-filled.
:
:A 0.1 uF oil-filled cap wouldn't likely be physically "small" but I suppose that this is subjective. I vote for the "misread value theory". Could the part have been 0.1 nF (0.0001 uF)? Being a factor of a thousand off in a timing circuit would almost certainly prevent operation.

It is definitely .1uf. Very clear, no scratch marks Above that it says:
"Lafayette"
"Oil Filled Cap"
"JCP-TMN-R"
One side is connected to the power supply. The other
side is marked "OUT SIDE OIL". That is connected thru a 2K ohm resister to the RF Band switch. I can't find a schematic for this RF Gen.
Chuck Harris

:: It's hard to offer an useful opinion not knowing what the cap's exact circuit function is, but if the cap is being used as an RF timing component, 0.1 mF seems rather large. It's about the right value for a B+ bypass cap, but even a grossly wrong value there shouldn't prevent the circuit from working. And, a DC bus bypass cap wouldn't need to be oil-filled.
::
::A 0.1 uF oil-filled cap wouldn't likely be physically "small" but I suppose that this is subjective. I vote for the "misread value theory". Could the part have been 0.1 nF (0.0001 uF)? Being a factor of a thousand off in a timing circuit would almost certainly prevent operation.
:
:It is definitely .1uf. Very clear, no scratch marks Above that it says:
:"Lafayette"
:"Oil Filled Cap"
:"JCP-TMN-R"
: One side is connected to the power supply. The other
:side is marked "OUT SIDE OIL". That is connected thru a 2K ohm resister to the RF Band switch. I can't find a schematic for this RF Gen.
The side that goes to the power supply does so thru a 22K res to the B+
:Chuck Harris
:
:

The only other thing that comes to mind is that your new capacitor was bad, mismarked, or you read the code on it incorrectly.

Back in the day when I was in electronics manufacturing we had "incoming inspection" on all parts (I was a design engineer for a military and commercial avionics manufacturer). A failure rate of around 2% was pretty normal for capacitors. Of course, 25 years of six-sigma supply chain management has driven that figure way down for high-rel applications, but I'd be willing to bet that the "sweep the floor and sell it" mentality still is common among hobbyist-targeted part vendors.

The only other thing that comes to mind is that the new cap was underrated for the DC voltage to which it was exposed, and it shorted and failed immediately after power-up. Not very likely.

:The only other thing that comes to mind is that your new capacitor was bad, mismarked, or you read the code on it incorrectly.
:
:Back in the day when I was in electronics manufacturing we had "incoming inspection" on all parts (I was a design engineer for a military and commercial avionics manufacturer). A failure rate of around 2% was pretty normal for capacitors. Of course, 25 years of six-sigma supply chain management has driven that figure way down for high-rel applications, but I'd be willing to bet that the "sweep the floor and sell it" mentality still is common among hobbyist-targeted part vendors.
:
:The only other thing that comes to mind is that the new cap was underrated for the DC voltage to which it was exposed, and it shorted and failed immediately after power-up. Not very likely.
:
:
:
Hi Chuck, interesting delema, Do you have a capacitor checker? It would be nice to check the value on both of the caps. I've replaced many oil caps with standard caps and have never had a problem. Strange problem indeed. If your set works fine and the cap looks good I would call it a day and leave it. Best Of Luck, George T

::The only other thing that comes to mind is that your new capacitor was bad, mismarked, or you read the code on it incorrectly.
::
::Back in the day when I was in electronics manufacturing we had "incoming inspection" on all parts (I was a design engineer for a military and commercial avionics manufacturer). A failure rate of around 2% was pretty normal for capacitors. Of course, 25 years of six-sigma supply chain management has driven that figure way down for high-rel applications, but I'd be willing to bet that the "sweep the floor and sell it" mentality still is common among hobbyist-targeted part vendors.
::
::The only other thing that comes to mind is that the new cap was underrated for the DC voltage to which it was exposed, and it shorted and failed immediately after power-up. Not very likely.
::
::
::
:Hi Chuck, interesting delema, Do you have a capacitor checker? It would be nice to check the value on both of the caps. I've replaced many oil caps with standard caps and have never had a problem. Strange problem indeed. If your set works fine and the cap looks good I would call it a day and leave it. Best Of Luck, George T
:Thanks to all of you. I do have a cap tester. Both caps test good. I will do as George says. Don't try to fix something that is not broken.
I do feel that Bill might be on to it. I have learned more about ESR caps in the past two days. This being an RF gen, the ESR of this cap good be very important for the high frequencies involved.
This is the joy of having this forum, so much to learn from one another.
Chuck Harris