BIG problems

[laatsch55]

Are those caps in the signal or feedback loop?



Both....

 

[laatsch55]

The box also contains 12 .33's and 12.27 emitter resistors...

 

[laatsch55]

And 4-410's with matching date codes.

 

[Michael F]

The box also contains 12 .33's and 12.27 emitter resistors...

You better send that box out ASAP before you start including power transformers, meters, handles etc..

 

[laatsch55]

I tend to get extreme in a goody box.

 

[Michael F]

Can you carefully cut off some of the ty raps and separate the wires for the photograph so I can get an idea what is going on here.

Were the Zoebel components stock on your amp or did you change them? The reason I ask is that the 224 value on the 2 green caps is wrong. That should be 104 (0.1uF not 0.22uF)

The resistor value appears correct at 10 ohms in parallel.

According to the schematic I have on hand, the caps are indeed .22mfd. The circuit only differs in the cap/resistor/post order.
Need I be concerned?

 

[laatsch55]

The .1uf poly pros yield better results in the Zoebel.

 

[laatsch55]

Michael, the goody box did indeed leave this morning. Shipping was 12.00

 

[Michael F]

Check the BR and leak test the power supply caps. DO NOT USE SIL_PADS, stick with mica and grease, way more effective and if there was ever an amp that DID NOT it's heatsink assembly LESS EFFECTIVE, it's this one.

I just looked into testing the BR and filter caps. It looks to be quite the procedure since I`ve only the 2 main caps.

Before attempting all of that, what king of voltages should I be getting on the AC secondary and rectified DC? According to the process outlined in the archived thread, the leak test is performed on a newly formed cap using the existing power supply.

The way I see, all transfo secondary wires ( big,thick,stiff) must be repositioned from BR and buss bar to one secondary winding and both center taps to the AC side of BR and then on to the DC side to one cap and paralled to the other under test via the 2K series resistor and then swap caps?


FWIW, there was no audible hum present on the outputs although I did not check for ripple voltage. Not wanting to sound like a wimp, I would sooner replace the caps and BR if the voltages don't measure correctly.
Also, should I disconnect the B+ and B- terminals on the caps to keep the half empty driver board from seeing any power while taking measurements?

 

[Michael F]

Michael, the goody box did indeed leave this morning. Shipping was 12.00

You da man! PM me the particulars.
THX

 

[laatsch55]

I just looked into testing the BR and filter caps. It looks to be quite the procedure since I`ve only the 2 main caps.

Before attempting all of that, what king of voltages should I be getting on the AC secondary and rectified DC? According to the process outlined in the archived thread, the leak test is performed on a newly formed cap using the existing power supply.

The way I see, all transfo secondary wires ( big,thick,stiff) must be repositioned from BR and buss bar to one secondary winding and both center taps to the AC side of BR and then on to the DC side to one cap and paralled to the other under test via the 2K series resistor and then swap caps?


FWIW, there was no audible hum present on the outputs although I did not check for ripple voltage. Not wanting to sound like a wimp, I would sooner replace the caps and BR if the voltages don't measure correctly.
Also, should I disconnect the B+ and B- terminals on the caps to keep the half empty driver board from seeing any power while taking measurements?

yES, UNHOOK ALL OUTBOTD POWER WIRES FROM THE CAPS. uNRECTIFIED SHOULd be 72 volts, rectified 100 plus +/- From the voltages you posted before your BR is fine, what caps do you have??

 

[Michael F]

yES, UNHOOK ALL OUTBOTD POWER WIRES FROM THE CAPS. uNRECTIFIED SHOULd be 72 volts, rectified 100 plus +/- From the voltages you posted before your BR is fine, what caps do you have??

No load measurements:

Secondary AC comes in at 77-0-77vac and +109.5 -0- -109.5vdc
Here is something interesting:the filter caps are 7500 mfd @ 100v, can you say under spec`d?
The cap manufacturer is "Callin" something or other, the last letters may be obscured.
They seem to be in good physical shape , no leaks or bulges and they seem to hold their charge forever, 100v after a couple of hours, I had to discharge them with a lightbulb.

 

[laatsch55]

109 +/- DC????? Oh my goodness, there's a 500 watter!! I'd say run em till you can spend more money on em.

 

[Michael F]

109 +/- DC????? Oh my goodness, there's a 500 watter!! I'd say run em till you can spend more money on em.

Is 109 that out of the ordinary? You don't seem concerned over the cap values so I wont be either. Would you consider the PS to be functioning properly then? A cap and bridge upgrade will have to wait a bit.

What's next Oh Wise Master?

 

[laatsch55]

The cap values are what they are, unless you want to spend 60.00 each ya gotta live with it. Phase later went to 9800 but that's as far as they went. I haven't seen 109 rail voltages in a 700 yet. 500 watts seems to come with rail voltages of 103.5 and higher. I would love to test that one. Power supply appears to be working , yes. Joe is the master, me but a yoeman.

 

[laatsch55]

While you wait, clean the white grease outta the sockets and pinch down the "tulip" ends where the TO-3 leads engage. It's pretty tedious getting all the white yuck outta there but it yields great results...

 

[Michael F]

The cap values are what they are, unless you want to spend 60.00 each ya gotta live with it. Phase later went to 9800 but that's as far as they went. I haven't seen 109 rail voltages in a 700 yet. 500 watts seems to come with rail voltages of 103.5 and higher. I would love to test that one. Power supply appears to be working , yes. Joe is the master, me but a yoeman.

OK. Is there something else I can test while I await the arrival of the CARE package, Oh Master(s)?

 

[laatsch55]

Have you got the board stripped of all that is coming?

 

[laatsch55]

Closely inspect all wiring going to the backwall and to the board. Replace any that have got any strands broke(which should be all of them).

 

[laatsch55]

How's it going Grasshopper....?