Ceriatone HRM 50 Build - HELP NEEDED!!!

[The_Nuge]

Hi!

Firstly, let me introduce myself:

My name is Es, I live in Germany close to Stuttgart, am an automotive engineer by trade and I'm addicted to guitars and amps!

I joined the forum some weeks ago, before bying my kit, but haven't been active yet.

So here goes:

Bought a Ceriatone HRM 50 kit directly from Nik some weeks ago and I've been patiently soldering it up since. This is my first amp build BTW and I'm not an "electronics kind of person".

Got the amp finished yesterday, left the tube out and hooked it up to my light bulb limitier and speaker. The bulb went bright for less than a second and then dimmed. My understanding is that that's a good sign!
Then fitted tubes and hooked it up to mains and speaker with all the controls down. Checked and set bias to 37mA. Plugged in a guitar, and then ...

Nothing. Well not quite, I does hum!

I can't see any obvious defects, and these are my observations:

All tubes glow, but V3 glows much brighter than V1 and V2. Plate voltage on V3 is about 670V. The "right" plate voltage on V3 is lower than the left and can't be trimmed to be higher with the PI pot.

When switching fron "standby" to "operate" there's a little flash inside the power tubes.

The hum gets louder the higher the volume setting, and is louder through the high input. The hum changes when touching the chassis or guitar.

The guitar can be heard very faintly when strumming and then letting go of it.

I'll see if I can upload some pics!

Please help!!!

Cheers

Es

[The_Nuge]

Pics:

[img:600:399]http://www.mylespaul.com/forums/members ... c-0028.jpg[/img]
[img:600:399]http://www.mylespaul.com/forums/members ... c-0029.jpg[/img]
[IMG:600:399]http://www.mylespaul.com/forums/members ... c-0030.jpg[/img]
[IMG:600:399]http://www.mylespaul.com/forums/members ... c-0031.jpg[/img]
[IMG:600:399]http://www.mylespaul.com/forums/members ... c-0032.jpg[/img]
[IMG:600:399]http://www.mylespaul.com/forums/members ... c-0033.jpg[/img]
[IMG:600:399]http://www.mylespaul.com/forums/members ... c-0034.jpg[/img]
[IMG:600:399]http://www.mylespaul.com/forums/members ... c-0035.jpg[/img]
[IMG:600:399]http://www.mylespaul.com/forums/members ... c-0036.jpg[/img]

[rogb]

Hi there and welcome!

First of all please pay ENORMOUS attention to the lethal voltages present and discharge the PS caps before doing any work.
Best advice I can give for troubleshooting is to print out a copy of the layout you used then starting at the inputs work your way very slowly thru the build, highlighting with a highlight pen each wire and part you have checked.

Look also for cold or unsoldered joints.

Especially check ALL jack and relay wiring!

Make sure all components are the correct value and polarity oriented caps are the right way round. You may have to lift one end to measure the value correctly.

Put together an audio probe, do a search on here, and trace your audio signal through the circuit.

As you have found the D style is a VERY complex circuit for a first build, and there are many places you can make a mistake. Work back until you find the error!

Best of luck

[martin manning]

All tubes glow, but V3 glows much brighter than V1 and V2. Plate voltage on V3 is about 670V. The "right" plate voltage on V3 is lower than the left and can't be trimmed to be higher with the PI pot.

Something is wrong in the power supply- this 670V is more than 2x what it should be. Are you sure you are using the right primary voltage tap on the power transformer? Check the wiring carefully before powering up again.

[The_Nuge]

Thanks!
What's the best way of discharging the caps?
I disconnect the power cable and switch the amp back on - not 100% sure that does the trick though!

Cheers Es

[martin manning]

The caps should drain in a minute or two with the power switch off. Measure voltage at points K and L on the layout to be sure that they have. Better yet, measure the voltage to ground at the positive end of all six large filter caps... we know that there is some wiring issue, and there could be some charge remaining.

[The_Nuge]

All tubes glow, but V3 glows much brighter than V1 and V2. Plate voltage on V3 is about 670V. The "right" plate voltage on V3 is lower than the left and can't be trimmed to be higher with the PI pot.

Something is wrong in the power supply- this 670V is more than 2x what it should be. Are you sure you are using the right primary voltage tap on the power transformer? Check the wiring carefully before powering up again.

Hi!
I spent over an hour checking / re-tracing wiring yesterday, starting at the main transformer. I'm only through about a 1/4 of the amp, as I'm being very meticulous and also checking for continuity and resistor values, but the main transformer is hooked up as per diagram.
I can post some detailed pictures of that area if that would help!

Any other ideas?

Cheers

Es

[martin manning]

I would first confirm that the power supply voltages are correct. I'm still bothered by the very high reading you quoted above.

The Ceriatone layout is non-standard in that the output from the rectifier goes to the standby switch instead of the reservoir capacitors (2x 200uF). With this arrangement turning on the main power energizes the filaments, the bias supply, and the relay supply, but does not charge the reservoir capacitors.

So with the main power on, standby off, and no tubes installed check the AC filament voltage (to ground) on pins 2 and 7 of the power tube sockets (~3.5 VAC), the bias voltage at point E (about -50 VDC), and the relay supply at W-1 and W-2 (12 VDC).

If the above check out, turn the standby on and measure the DC voltage at point K, PS-1, PS-2, PS-3, and the voltage at the positive end of the last 22uF filter cap on the input end of the chassis.

[overtone]

Hi Es,
take it slow and careful, follow Martin's advice because Voltage readings tell more than photos at the moment.
The 670V reading makes no sense to me, maybe you can tell us how you measured that?
Just to rule out the obvious - did you really wire the mains transformer for 230V input, or do you have it set for USA voltage?
tony

[ToneMerc]

Just to rule out the obvious - did you really wire the mains transformer for 230V input, or do you have it set for USA voltage?
tony

Great observation, although looks like 120v is coiled maybe?

TM

[xtian]

Greetings and welcome.

Next time, please post high res photos. I can't zoom in to see details like the solder connections.

+1 on the strangely high voltages. Remove all your tubes before any further testing, and make sure the unloaded (i.e., no tubes) voltages are within spec before proceeding.

[The_Nuge]

I would first confirm that the power supply voltages are correct. I'm still bothered by the very high reading you quoted above.

The Ceriatone layout is non-standard in that the output from the rectifier goes to the standby switch instead of the reservoir capacitors (2x 200uF). With this arrangement turning on the main power energizes the filaments, the bias supply, and the relay supply, but does not charge the reservoir capacitors.

So with the main power on, standby off, and no tubes installed check the AC filament voltage (to ground) on pins 2 and 7 of the power tube sockets (~3.5 VAC), the bias voltage at point E (about -50 VDC), and the relay supply at W-1 and W-2 (12 VDC).

If the above check out, turn the standby on and measure the DC voltage at point K, PS-1, PS-2, PS-3, and the voltage at the positive end of the last 22uF filter cap on the input end of the chassis.

Hi Martin,

So I checked everything on the power supply, the tubes, the rear panel and the input jack and didn't find anything unusual.

Fired it up again with no tubes but a speaker connected, both with and without a light bulb limiter (which glowed brightly for an instant when flicking from standby to operate, but was otherwise almost "off") and measured these values

Limiter No Limiter
Heaters 2.7V 2.8-2.9V
Point E -43.7V -45.4V
W1 & 2 12V 11.96V
Point K 448V 485V
PS-1 452V 484V
PS-2 446V 477V
PS-3 404V 428V
22mF Cap 400V 428V
(on the side of the chassis, behind the foot switch jack)

I did check that I'm hooked up to the 240V side of the tranny I've got 234V coming out of the wall.

I think I might have had my multimeter set to AC when I measured those very high voltages the other day... Does that make sense?

Will check the V3 tube in another amp now to see if it's still OK.

Thanks for the help!

Es
Will chec

[martin manning]

Ok that looks reasonable.

Next put the power tubes in and bias them, then check the HT voltages again. To be safe, use the limiter at first, but if you get the same result (dim glow) take it out for the voltage measurements. The bias and relay supply look good, so you don't need to repeat those measurements. The voltages should come down a bit.

Next put all of the tubes in and get measurements on all pins. With that data we can get a good idea of where you are.

[The_Nuge]

Ok that looks reasonable.

Next put the power tubes in and bias them, then check the HT voltages again. To be safe, use the limiter at first, but if you get the same result (dim glow) take it out for the voltage measurements. The bias and relay supply look good, so you don't need to repeat those measurements. The voltages should come down a bit.

Next put all of the tubes in and get measurements on all pins. With that data we can get a good idea of where you are.

Hi!

So,
Did the limiter test again, removed it and biased the tubes (albeit with the preamp valves also installed). Got the following readings:
E -50.5V
K 453V
PS-1 450V
PS-2 428V
PS-3 326V
Cap 319V

V1
Pin 1: 187.7V
Pin 2: 75.7mV
Pin 3: 1,93V
Pin 4: 2.7VAC
Pin 5: 2.7VAC
Pin 6: 158V
Pin 7: 987mV
Pin 8: 2.55V
Pin 9: 2.7VAC


V2
Pin 1: 202V
Pin 2: -0.2mV???
Pin 3: 1,86V
Pin 4: 2.7VAC
Pin 5: 2.7VAC
Pin 6: 214V
Pin 7: 0.1mV???
Pin 8:1.67V
Pin 9: 2.7VAC


V3
Pin 1: 303V
Pin 2: 33.1V
Pin 3: 54.3V
Pin 4: 2.7VAC
Pin 5: 2.7VAC
Pin 6: 310V
Pin 7: 35.4V
Pin 8: 54.3V
Pin 9: 2.7VAC


V4
Pin 1: 43.4mV
Pin 2: 2.7VAC
Pin 3: 452V
Pin 4: 447V
Pin 5: -48.8V
Pin 6: 446V
Pin 7: 2.7VAC
Pin 8: 43.5mV

V5
Pin 1: 45.6mV
Pin 2: 2.7VAC
Pin 3: 447V
Pin 4: 446V
Pin 5: -48.9
Pin 6: 446V
Pin 7: 2.7VAC
Pin 8: 45.6mV


Hope these values help

BTW, I slipped off pin 6 with my multimeter when measuring it, which caused the HT fuse to blow... No smoke though, and I hope I can get a spare tomorrow!

Cheers

Es

[passfan]

Your getting close Es