| Kustom IV Bass Power Supply Caps [message #28729] |
Wed, 03 August 2022 20:11  |
corona blue
Messages: 25
Registered: January 2015
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Junior Member |
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Hi everyone-
Been a long time since I have logged in here.
Great to see so many Kustom enthusiasts in the forum.
I am helping a friend repair his Kustom IV Bass head.
His technician is telling him that the two power supply caps have failed.
The caps in there are two 9800uf 100V G.E. caps.
I have looked at various schematic data I have on hand and it seems to me that there were different versions of the Kustom IV Bass head. The only schematic I have that shows power supply detail is for a version that had two separate power amp output channels. The value of those caps is shown at 9000uf 50V dc.
I am wondering if anyone here might have schematics for this Kustom IV Bass that has only a single power amp output channel so that I can confirm what the original spec was for these caps?
Also any suggestions on modern replacement caps would be welcome.
Thanks in advance,
corona blue
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| Re: Kustom IV Bass Power Supply Caps [message #28730 is a reply to message #28729] |
Thu, 04 August 2022 07:22  |
stevem
Messages: 4775
Registered: June 2004
Location: NY
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Senior Member |
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Hi.
I few months ago I picked up one of these monsters that needed repair, so I have learned a lot about them.
First off these amps as far as I know have two 5065 output boards and 8 output Transistors, this is what makes for the need of 9000 uf power supply rail filters.
The Kustom III models only had one output section for a rating of 135 watts.
Bending that this is a Kustom IV model then tag on the rear of the amp should say 270 watts RMS into a 4 ohm load because each outout section puts out 135 watts .
Note that this amp has only one speaker jack per output section, so to get the full 270 watts both need to be used.
In terms of replacement filter cans, newark electronics has them.
They are part number 69K1780.
They are 10,000 uf at 50 volts.
They are only 2 inches in diameter so you will need to rap cardboard and tape around them so to build them up and fit in the factory mounting clamps.
I would also clear silicone glue them down to the chassis.
These cost 42.25 each, but these size filters are what should be used.
Make sure that the fan in your amp still works, it should come on as soon as you turn the amp on as it's not controlled by a temperature sensor.
Keep us posted on there repair work.
[Updated on: Thu, 04 August 2022 08:46] Report message to a moderator |
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| Re: Kustom IV Bass Power Supply Caps [message #28733 is a reply to message #28729] |
Thu, 04 August 2022 17:05 |
stevem
Messages: 4775
Registered: June 2004
Location: NY
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Senior Member |
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Well if he can give us some of the PC board numbers we would have a better shot at figuring things out to help him.
One thing is for sure, GE brand caps are likely not original so the amp may now be getting its second set of power supply rail filters .
I agree Bill, I too have seen very few of these computer grade filters that Kustom used just outright fail, in fact many times I can reform them over the course of a weekend.
If this amp has only one output section then it's original filters would have been 4500uf and the larger GE made ones where installed as a upgrade.
Unfortunately that 100 volt rating is likely to be what lead to there demise.
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