1969 Kustom K200A-1 (Restoration) Three Questions (Power Section)

[nosaj]

Rectifier probably fried due to a leaky cap( AC leakage or shorted)
nosaj

[Rick Redrock]

Nosaj..... Very possible.... the filter cap that the red wire connected to, appears to be older (maybe original) than the one other one.... I guess since I'm doing all this other cap work, I should go ahead and replace them both to be on the safe side huh ?

Rick

[Rick Redrock]

Nosaj... I'm trying to share a link to a pic on my Facebook page.... Can you access it ?


Rick

[Rick Redrock]

Nosaj,,,, In testing both the 4500uf / 50vdc Filter Caps (out of circuit) , I get the following results:

Vloss = 0.6%
C = 5701uf
ESR = 0.06 ohms

Vloss = 1.3%
C = 5881
ESR = 0.06 ohms

[J M Fahey]

In my book, those are very functional caps.

Somebody might have higher standards than me, of course

I´m quite the "fuctionalist" guy, so *my* test would be:

* disconnect caps from power amp and any load

* wire transformer > bridge > caps

* turn amp ON, trough a bulb limiter, anything from 40W to 75W is fine.

* measure voltage across each cap

* turn amp OFF, wait 5 minutes, remeasure remaining voltages.
Did they catastrophically fall? (say to 15V or less?) or did they reasonably hold? (say around 30V).
Remember, no load of any kind, so only self discharge works.

THAT is your combined bridge - transformer - capacitor test

Post results.

[Rick Redrock]

Juan, I will do so !.... I am hoping the caps are good .... I had heard they could be a bit pricy, and they weren't kidden' ! $35-$75 a piece.... On a side note, I was looking into picking up an old (late 60s/early 70s) WEM 100 watt head.... When I started to research it a bit, the circuitry in the WEM is almost identical to the same era Kustom..... So I decided one headache at a time

[g1]

What is your cap tester (make & model)? Not sure what exactly the 'V loss' means in this particular case, sometimes it is dissipation. Have you compared that reading (vloss) to that of a known good cap (new)?
Caps that read high like that always make me a bit suspicious of possible leakage, depending on cap tester.

[nosaj]

Juan, I will do so !.... I am hoping the caps are good .... I had heard they could be a bit pricy, and they weren't kidden' ! $35-$75 a piece.... On a side note, I was looking into picking up an old (late 60s/early 70s) WEM 100 watt head.... When I started to research it a bit, the circuitry in the WEM is almost identical to the same era Kustom..... So I decided one headache at a time

If you HAD to change them a suitable replacement would be a 4700uf 63v cap which is more financially conservative.
nosaj

[Rick Redrock]

Well,,,,, I just got some time to work at my bench this weekend, and I'm afraid the transformer is bad ... I conducted the Filter Caps test as instructed, with a Dim Bulb Tester (150w light bulb)... As soon as power was turned on to the DUT, the light bulb went full glow ! I then disconnected both the CAPs and the rectifier, and no change.... it appears one side to the CT is completely shorted.... this was the side that was eventually powering the +40vdc to one of the filter cap.... Can anyone suggest a replacement transformer ? Before you go off on me, I know.... I should have started by testing the transformer/power supply section first !!! DOH ! Well, I now have all the circuit boards re-capped, tested, so I can't stop now ! Thanks guys ! I'm fricken learning, if nothing else ! :-)

[Rick Redrock]

HOLD THE PHONE ! - I am soooo sorry ! I had my DBT wired incorrectly ! It appears all is testing well now ! Getting +/- 40dc now ! I'm just waiting to see if the caps hold the charge after 5 minutes..... My apologies and thanks !

[Rick Redrock]

The Restoration is Complete ! I just wanted to thank all of you who chimed in and provided help and suggestions ! I couldn't have been so successful with this project if it wasn't for you guys !
I've attached a link to a little video I just posted on my Facebook page......

Thanks again ! Rick Redrock