X-100 - Acceptable Voltages

[Dig22]

Hi,
I recapped my Fisher x-100 and it sounds amazing. But I'm wondering about the voltages. Are they too high or too low?
I should say many of the tubes might be original. I don't have a tube tester so I can't check. If someone can a tube tester recommendation in Los Angeles that would be greatly appreciated.

Here are my voltages. Can any of these be corrected with new tubes?

V1 (12ax7)
p6. schematic: 96v / my reading: 76v

V2 (12ax7)
p1 schematic: 150v / my reading: 175v
p6. schematic: 150v / my reading: 168v

V3 (7247)
p1 schematic: 167v / my reading: 180v
p3 schematic: 44v / my reading: 99v (is this too high?)

V4 (EL84)
p3 schematic: 44v / my reading: 44v
p7 schematic: 380v / my reading: 405v when turned on....399v after warming up
p9 schematic: 320v / my reading: 338v

V5 (EL84)
p3 schematic: 44v / my reading: 44v
p7 schematic: 380v / my reading: 405v when turned on....399v after warming up
p9 schematic: 326v / my reading: 347v

V6 (12ax7)
p1 schematic: 99v / my reading: 80v
p6. schematic: 96v / my reading: 83v

V7 (7247)
p1 no voltages listed / my reading: 149v
p6. no voltages listed / my reading: 147v

V8 (12ax7)
p1 schematic: 167v / my reading: 185v
p6. schematic: 100v / my reading: 94v

V9 (EL84)
p3 schematic: 44v / my reading: 44v
p7 schematic: 380v / my reading: 405v when turned on....399v after warming up

V10 (EL84)
p3 schematic: 44v / my reading: 44v
p7 schematic: 380v / my reading: 405v when turned on....399v after warming up

V11 (GZ34/ 5AR4)
p4 & 6 schematic: 730vac / my reading: 767vac (is this too high?)
p2 & 8 schematic: 5vac / my reading: 5.2

Any advice is appreciated. Thanks.

 

[Tim D]

Voltage on pin 3 of V3 is way too high. You should look for a cause. If you swap the tubes between the right and left channel (V3 with it's partner) does the voltage move with the tube? If not then I'd check the resistors on Pin 3 and on pin 6 to see if they are off spec by more than 10%. Is the amp working in this condition? Do you get balanced sound out of both channels?

The other voltages are likely high due to the higher line voltages of today. Have you measured what is your line voltage? A bucking transformer will help with that or you could add an in-rush limiter to the primary side of the power transformer or you could use a variac (permanently) to lower the voltages or you could try to live with it. My preference would be to add the in-rush limiter (a CL-80 or CL-90 would do).

 

[larryderouin]

Voltages in the manual are "BOGEY" values and are under IDEAL LAB conditions (new tubes, variac set to 117VAC, etc.) FISHER Allowed for +/-15% due to variances in components. Everything at a quick glance looks to be within 10% except V3 as TIM D noted. If you have a variac, set it up and verify 117VAC before turning on the 400, then adjust it after warmed up a couple minutes. You'll probably find that the line voltage to the 400 has dropped a volt or 2 due to loading of the variac. Make the adjustment with your meter attached to the leads on the end of the power cord inside the 400. Then retake your voltages. They should be closer to bogey.

Reference V3 & V8 (you mismarked V7 and V8. V8 is a 7247, not V7). Do what Tim said to check. If the tube is the culprit, get 2 new 7247/12DW7 and have them matched if possible.

 

[Dig22]

Voltages in the manual are "BOGEY" values and are under IDEAL LAB conditions (new tubes, variac set to 117VAC, etc.) FISHER Allowed for +/-15% due to variances in components. Everything at a quick glance looks to be within 10% except V3 as TIM D noted. If you have a variac, set it up and verify 117VAC before turning on the 400, then adjust it after warmed up a couple minutes. You'll probably find that the line voltage to the 400 has dropped a volt or 2 due to loading of the variac. Make the adjustment with your meter attached to the leads on the end of the power cord inside the 400. Then retake your voltages. They should be closer to bogey.

Reference V3 & V8 (you mismarked V7 and V8. V8 is a 7247, not V7). Do what Tim said to check. If the tube is the culprit, get 2 new 7247/12DW7 and have them matched if possible.

Thanks for input.

I goofed on V3:

V3 CORRECTION:
p1 schematic: 167v / my reading: 180v
p6 schematic: 100v / my reading: 99v

So.... I do have an elderly variac and tested voltages at 117 and 115. Both brought voltages down as suspected.

On the EL84s:
at 117V p3s averaged 42.5v
p9s averaged 332v

V3 & p8 (7247s)
at 117V p1 175V
p6 93 V

I'm wondering about voltages on the capacitor cans I replaced. What should voltages be? On the 100uf 160v cap, the voltage is only 42....

Lastly, On my original post in another forum (someone steered me to this Fisher Forum) someone posted a picture of their in rush limiter. What do you think?

Thanks again for you help.

 

[Dig22]

Voltage on pin 3 of V3 is way too high. You should look for a cause. If you swap the tubes between the right and left channel (V3 with it's partner) does the voltage move with the tube? If not then I'd check the resistors on Pin 3 and on pin 6 to see if they are off spec by more than 10%. Is the amp working in this condition? Do you get balanced sound out of both channels?

The other voltages are likely high due to the higher line voltages of today. Have you measured what is your line voltage? A bucking transformer will help with that or you could add an in-rush limiter to the primary side of the power transformer or you could use a variac (permanently) to lower the voltages or you could try to live with it. My preference would be to add the in-rush limiter (a CL-80 or CL-90 would do).

thanks. I replied in detail at post below.

 

[Dig22]

Thanks for input.

I goofed on V3:

V3 CORRECTION:
p1 schematic: 167v / my reading: 180v
p6 schematic: 100v / my reading: 99v

So.... I do have an elderly variac and tested voltages at 117 and 115. Both brought voltages down as suspected.

On the EL84s:
at 117V p3s averaged 42.5v
p9s averaged 332v

V3 & p8 (7247s)
at 117V p1 175V
p6 93 V

I'm wondering about voltages on the capacitor cans I replaced. What should voltages be? On the 100uf 160v cap, the voltage is only 42....

Lastly, On my original post in another forum (someone steered me to this Fisher Forum) someone posted a picture of their in rush limiter. What do you think?

Thanks again for you help.

I found another mistake in my hook up of the 100 @ 160v. I correct ad report back.

 

[Tim D]

Thanks for input.

I goofed on V3:

V3 CORRECTION:
p1 schematic: 167v / my reading: 180v
p6 schematic: 100v / my reading: 99v

So.... I do have an elderly variac and tested voltages at 117 and 115. Both brought voltages down as suspected.

On the EL84s:
at 117V p3s averaged 42.5v
p9s averaged 332v

V3 & p8 (7247s)
at 117V p1 175V
p6 93 V

I'm wondering about voltages on the capacitor cans I replaced. What should voltages be? On the 100uf 160v cap, the voltage is only 42....

Lastly, On my original post in another forum (someone steered me to this Fisher Forum) someone posted a picture of their in rush limiter. What do you think?

Thanks again for you help.

Regarding the in-rush limiter - yes that's the one.