Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Travis8 on September 14, 2023, 03:13:08 am

Title: AC15HW1 power issue
Post by: Travis8 on September 14, 2023, 03:13:08 am: Hi... my ac15hw1 doesnt turn on, no light on bulb or tubes..

I check fuses and looks ok, could be the rectifier? how can I check it?

thank
Title: Re: AC15HW1 power issue
Post by: Latole on September 14, 2023, 04:29:05 am: No power on led glow ? It directly connected to the Power transformer 6.3 volts secondary winding.

Check power transformer primary and secondary voltage
How do you check fuse ? There are many fuses. You must use a meter, not eyes .

Did you check internal fuse ? FS 1 ?
Title: Re: AC15HW1 power issue
Post by: Travis8 on September 14, 2023, 05:11:50 am: Quote from: Latole on September 14, 2023, 04:29:05 am
No power on led glow ? It directly connected to the Power transformer 6.3 volts secondary winding.

Check power transformer primary and secondary voltage
How do you check fuse ? There are many fuses. You must use a meter, not eyes .

Did you check internal fuse ? FS 1 ?

Schematic here ; https://el34world.com/charts/Schematics/files/Vox/Vox_ac15htvh1_handwired.pdf

I check the 3 fuses all look ok, no light from led.

I see right now that SL22 is disconected from one leg. Could be the issue?
Title: Re: AC15HW1 power issue
Post by: HotBluePlates on September 14, 2023, 06:20:07 am: Quote from: Travis8 on September 14, 2023, 05:11:50 am
I see right now that SL22 is disconected from one leg. Could be the issue?

Correct AC15HW1 schematic (https://music-electronics-forum.com/forum/schematic-requests/32725-vox-ac15hw1x-schematic-and-or-service-manual?p=446562#post446562)

Yes.

SL22 connects from the fuse F4 to one side of the power switch. With it open, no power can flow into the amp.

Some may choose to disconnect the thermistor SL22, but if so there must be some kind of jumper wire across it to complete the now-open connection.
Title: Re: AC15HW1 power issue
Post by: Loomer on September 14, 2023, 06:24:16 am: Quote from: Travis8 on September 14, 2023, 05:11:50 am
I check the 3 fuses all look ok, no light from led.

I see right now that SL22 is disconected from one leg. Could be the issue?

"Look ok" as in "buzz for continuity with a DMM"?

It might be my bad, but I can't seem to be able to locate SL22 on the schematic?
Title: Re: AC15HW1 power issue
Post by: sluckey on September 14, 2023, 06:44:38 am: Quote from: Loomer on September 14, 2023, 06:24:16 am
It might be my bad, but I can't seem to be able to locate SL22 on the schematic?
Look at the link posted by HBP. Latole posted a wrong schematic.
Title: Re: AC15HW1 power issue
Post by: Latole on September 14, 2023, 07:23:27 am: Quote from: sluckey on September 14, 2023, 06:44:38 am
[
Look at the link posted by HBP. Latole posted a wrong schematic.
[/quote]

Sorry , I update my post
Title: Re: AC15HW1 power issue
Post by: Latole on September 14, 2023, 07:24:30 am: To me "look" ok and are ok is not same thing.