Ceriatone HRM 50 Build - HELP NEEDED!!!

[martin manning]

The voltages look good except for V1, where the grids (pins 2 and 7) should be ~0 (like V2's). Look for a wiring error around there.

[xtian]

You guys concerned that his heater voltage has dropped to 5.4vac?

[martin manning]

Yes, there is something going on with the heater voltage. It was only 5.7-5.8 without tubes. Maybe some accidental contact somewhere. Maybe related to the ~1V on the V1 grids?

[passfan]

Over on the My Les Paul forum where he did the build he stated that he saw a flash in the area of V1. He thought it came from the 22uf cap and 2.2k dropping resistor down there. I suggested to him to bring the troubleshoot over here for more eyes and experience.

[amplifiednation]

V1 voltages are off. Those grids 4 should be 0v like Martin suggested. I think the V1b cathode looks high as well.

What kind of flash? Maybe try a different tube.

Was the last set of readings done without the bulb limiter? Were your heater voltages closer to 6.3v without tubes?

While you are testing for signal and getting this working initially I would make sure OD and PAB relays are set to off.

[The_Nuge]

Hi!

The last readings were all done without the limiter and the heater voltages were the same without tubes. One thought: The pilot light has a 47 Ohm resistor in one of the wires, as per Nik's email-instructions, which attaches to the same point as the heaters. Could this influence anything? Am I measuring wrong?

I'll triple check V1 tonight and report back!

Cheers!

[The_Nuge]

V1 voltages are off. Those grids 4 should be 0v like Martin suggested. I think the V1b cathode looks high as well.

What kind of flash? Maybe try a different tube.

Was the last set of readings done without the bulb limiter? Were your heater voltages closer to 6.3v without tubes?

While you are testing for signal and getting this working initially I would make sure OD and PAB relays are set to off.

How do I set the relays to off? Switches to "manual" at the back?

Thanks!

Es

[eazilyled]

How do I set the relays to off? Switches to "manual" at the back?

Thanks!

Es

Hi The_Nuge, see below for an excerpt from the manual for the switches at the back - with the footswitch unplugged I think you need to set the overdrive switch to manual and the boost switch to pedal. It may be easier to use the footswitch so that you are on the clean channel and the PAB boost is off:

OVERDRIVE two-way toggle switch manually switches between clean and overdrive channels. If you are using the foot pedal,
set this in the PEDAL position. If you are not using the included foot pedal, the toggle switch in the PEDAL position switches
the OTS to OVERDRIVE mode. In the MANUAL position, the OTS is in CLEAN mode.

PREAMP BOOST (aka – “PAB”) two-way toggle switch manually switches between boosted and normal configurations. In this
series of OTS amplifiers, the PAB accentuates midrange frequencies and attenuates low frequencies, making it great for cutting
through during a solo. Engaged, you will also notice an increase in gain and distortion characteristics. If you are using the foot
pedal, set this in the PEDAL position. If you are not using the included foot pedal, the toggle switch in the MANUAL position
switches the OTS to PREAMP BOOST mode. In the PEDAL position, the OTS is in normal mode.

[martin manning]

Es, don't worry about where the relays are for now. Focus on finding out why the V1 grids are not at zero volts, and why the filament voltage is low.

[passfan]

In short , with no foot switch plugged in ,flip both switches to pedal and your relays should be off

[amplifiednation]

Sorry to confuse with the relays. My thought was to keep V1 isolated and V2 out of the signal path while troubleshooting.

Your problem seems to lie at V1. I would check the connections there and examine your heater voltages as suggested

[ayan]

That sounds like a typo from Nik... Try 470 ohms. Dumble used 390 ohms in amps where the LED pilot light voltage was derived from the filament supply (to be more precise, a 390 ohm in series with a diode).

Cheers,

Gil

Hi!

The last readings were all done without the limiter and the heater voltages were the same without tubes. One thought: The pilot light has a 47 Ohm resistor in one of the wires, as per Nik's email-instructions, which attaches to the same point as the heaters. Could this influence anything? Am I measuring wrong?

I'll triple check V1 tonight and report back!

Cheers!

[The_Nuge]

Hi!

I've made some progress

Borrowed a proper multimeter from work, which I think makes things a bit easier an more accurate. Also bought some more fuses

1. I disconnected the pilot light and the heater wires and measured AC directly at the tranny: 6.2 VAC!

2. With the heater wires, but still no pilot, measured near tranny: 6.12VAC

3. Measurements between the heater wires at each tube, still no pilot light:
V1: 6.0VAC
V2: 6.0VAC
V3: 6.0VAC
V4: 6.05VAC
V5: 6.07VAC

I'll see if I can get a 470 Ohm resistor tomorrow!

On V1:
Pin 2 now reads ~ 0VDC
Pin 7 creeps from 0 to -0.2VDC over about 20 seconds mains are switched on.
I checked my wiring and found an anomaly: The cap between pin 7 and connection "B" (volume knob) is a 470pF according to the diagram. However the one supplied with the kit is marked "470K". Nik told me that this was indeed a 470pF, but according to my conversion table it's a 47pF...
Could his be causing problems?

Are "we" (that's really all you guys - hats off to all of you for being so suupportive!!!!) getting anywhere?

Cheers

Es

[martin manning]

Looks like you've solved the heater voltage issue, but why would the V1 pins 2 and 7 be different now? Is the meter you were using defective, or maybe the battery is low? I don't understand the negative voltage on pin 2, so be sure you have measured correctly. Are you getting any sound from the speaker? The 47 vs. 470pF will not prevent you from getting sound out of the amp or upset the voltages, so don't worry about that.

[The_Nuge]

It's alive!
I couldn't resist plugging a guitar in - and it actually makes guitar-like noises!

There is a problem with the "HI" input - lots of hissing and the signal only comes through when I wiggle the jack,
"LO" input seems to work OK. Will pull the input jacks to examine the further tomorrow.

Don't know about the multimeters - the one I have only has 2 AC ranges, 200VAC and 600VAC, maybe that explains why the heater values were "off". When I hook the pilot up again I'll compare the two. The one from work is about 20x more expensive
Would you also use a 470 Ohm resitor in one of the pilot light wires?

I measured pin 2 and 7 with the (expensive) multimeter with the COM-probe connected to the black bias point using the DC setting. Is that wrong?

Cheers

Es