Strange capacitors in PYE 84571/01 Compression Amplifier. Tantalum? Color coding? Manufacturer?

[Bjorn Andersson]

Is there anybody on the forum that recognise those strange looking capacitors?
Tantalum? Color Coding? Manufacturer?
I have never in my life seen any of those capacitor.
Did PYE perhaps made them?
I can see one regular drop shaped tantulum capacitor (C2 on the right side of the pcb).

 

[Khron]

Would reading those colours in either direction, give any credible (standard-ish) values?

https://www.engineersedge.com/instrumentation/capacitor_color_codes.htm

 

[Dreams]

Those are (most likely) tantalum, but that's all i know

 

[zamproject]

non brand but find this that look similar ?

https://www.radio741.com/68954-10uf-25v-radial-polarized-tantalum-capacitor-black-color.html

 

[RoadrunnerOZ]

Reading from the bottom up on the close-up looks like 6-blue, 8-grey, 5-green plus 2 for the red on top maybe unless the red is just marking the + end - could be 6.8 uF 2% - on cylindrical caps there are often four bands - 1st#, 2nd#, multiplier, tolerance. Like resistors.

 

[Bjorn Andersson]

Reading from the bottom up on the close-up looks like 6-blue, 8-grey, 5-green plus 2 for the red on top maybe unless the red is just marking the + end - could be 6.8 uF 2% - on cylindrical caps there are often four bands - 1st#, 2nd#, multiplier, tolerance. Like resistors.

That seems to be right (6.8uF).
Regarding to Khron´s link: https://www.engineersedge.com/instrumentation/capacitor_color_codes.htm
Found that value on C28 on another fuzzy schematic (probably a PYE 4060 Comp).

 

[ruffrecords]

Reading from the bottom up on the close-up looks like 6-blue, 8-grey, 5-green plus 2 for the red on top maybe unless the red is just marking the + end - could be 6.8 uF 2% - on cylindrical caps there are often four bands - 1st#, 2nd#, multiplier, tolerance. Like resistors.

Back in those days, nF was not in common use. Many caps were specified in pF so this could be 6800pF or 6.8nF - much more likely value to be a 2% part than a 6.8uF

Cheers

Ian

 

[Ike Zimbel]

40+ years ago I had a batch of ceramic caps in black plastic cases, 0.1uf, probably Mil-Spec...might be ceramic.

 

[BlindedByScience]

A guess - probably not ceramic with polarity marks on the PB. Tantalum is my first guess, could be electrolytic.

 

[RoadrunnerOZ]

Back in those days, nF was not in common use. Many caps were specified in pF so this could be 6800pF or 6.8nF - much more likely value to be a 2% part than a 6.8uF

Cheers

Ian

685 is 68 x 10*5 is 6,800,000pF - 6.8uF - 6.8nF would be blue, grey, red - but we have the green in between the grey and the red which doesn’t equate to a sensible value. Also the cap is polarised from the markings on the pc board making it some form of electrolytic. Easy way is to pull a cap and measure it.
I think the red spot is a polarity marker or it would probably be in line with the other 3 dots and on the side.

 

[OneRoomStudio]

Looks like a “silver film tantalum” capacitor to me (like these: https://www.amazon.com/6-8UF-Antique-Silver-Tantalum-Capacitor/dp/B0CRT4JCCV).

I’d guess the red dot is polarity and 6u8 is the value.

 

[RoadrunnerOZ]

Some early tantalums had odd casings - in an old Moog I’m servicing they use some that are black tubular axial with one end rounded and others that look like axial can electrolytic with a clear plastic tube cover - these all blew when someone plugged in the unit to 240V when it was set to 110V.

 

[Bjorn Andersson]

Some early tantalums had odd casings - in an old Moog I’m servicing they use some that are black tubular axial with one end rounded and others that look like axial can electrolytic with a clear plastic tube cover - these all blew when someone plugged in the unit to 240V when it was set to 110V.

Jesus!I I will measure the C28 cap and inform all of the value

 

[Bjorn Andersson]

The value of the C28 capacitor is 7,02uF and then i found out that that the TO-3 power transistor is broken in the PSU and the power supply was putting out approx 30 Volts to the electronics... And after that i found that someone have been cutting out transistor VT3 from the circuit... I put a substitute transistor in place of VT3 and then slowly ramped up the voltage to +16 Volt and the compressor works. Current consumption is about 180mA and the VT7 and VT9 output transistors gets to about 69 degrees with mounted heatsinks on them.

 

[OneRoomStudio]

The value of the C28 capacitor is 7,02uF and then i found out that that the TO-3 power transistor is broken in the PSU and the power supply was putting out approx 30 Volts to the electronics... And after that i found that someone have been cutting out transistor VT3 from the circuit... I put a substitute transistor in place of VT3 and then slowly ramped up the voltage to +16 Volt and the compressor works. Current consumption is about 180mA and the VT7 and VT9 output transistors gets to about 69 degrees with mounted heatsinks on them.

7.02uF is within 5% of 6.8uF, so I think it’s fair to say that was probably the correct marked-value.

In any case, congrats on getting it up and running!

 

[Bjorn Andersson]

7.02uF is within 5% of 6.8uF, so I think it’s fair to say that was probably the correct marked-value.

In any case, congrats on getting it up and running!

Thank you OneRoomStudio. And the compressor is still not even recapped! And it sounds smooooooth

 

[Richmix]

Is there anybody on the forum that recognise those strange looking capacitors?
Tantalum? Color Coding? Manufacturer?
I have never in my life seen any of those capacitor.
Did PYE perhaps made them?
I can see one regular drop shaped tantulum capacitor (C2 on the right side of the pcb).

I GUESS Tantalum due to the polarity marking but I have replaced those with a Wima 1.o uf film type with no ill effect. This circuit gets it harmonic color mainly from the transformers nd transistors anyway.

 

[johnchik]

Been over 40 years in the parts business and only thing I have seen like this were Military Tantalum style that were fully encased for humidity . probably some army surplus that they used