The Amp Garage

Thank you for your insights. If the glue is not a problem then I'll leave it as is. I don't pretend to change or improve the amp's tone through modding, but since I actually have access to the PCB solder side I was considering to install good quality diodes to improve its reliability. But I'll stick...

My Jet City JCA50H — supposedly a clone or really close to the Soldano Hot Rod Plus — has a bulging Junzl HP capacitor so I'm recapping it. I have noticed the bias circuit diode is covered with the glue used to stick the capacitor to the board in the assembly process. I'm worried this glue may be co...

Yeah, low ESR for tube amp supplies is fine. In fact, it's what we tried to get for everything back when I was designing power supplies for a living. We could not get ESR low enough. Switching power supply caps really pointed up the need for low ESR in a big way. Is there a lot of low voltage logic...

That's interesting information, thank you so much. The device in which the low ESR capacitors caused problems had a pair of 7805 linear regulators. So low ESR would be fine for a tube amp filter caps, isn't it? Anyway I have more trust in the Nichicon brand and will probably use the LGN2H101MELA30 i...

I'm looking for snap-in capacitors measuring 25mm diameter and 35mm height for some Laney GH series amplifiers. One of the original parts is Samwha FL and the other one is Panasonic UP, both 100µF 500V. I can't find the Samwha FL, and Panasonic UP (discontinued) datasheet does not specify ESR, so I ...

Recapping went fine and the amp is roaring again. Bias caps (Arcolytic brand) were probably leaky since they measure 14µF, and two of the big filter caps were bulging in the bottom.

Thank you all! In addition to having a more reliable amplifier, I learned a few things.

Before the recap I took these measurements with the DC voltmeter. I used a 100W lightbulb as current limiter during all the process and it was mostly off, just a bit of light from the filament, no tubes installed, no speaker - just a 220 ohm 5W resistor soldered in parallel the output jack for OT pr...

From the technical documentation (page 4): Standards The following important international and national standards apply: 70-059-61/1A EN 60 12 IEC 60 257 CEE 4 DIN VDE 0820, Part 1 DIN VDE 0820, Part 2 DIN VDE 0820, Teil 3 UL 248-14 UL 512 CSA Standard C 22.2 No. 248.14 So no IEC60127 / UL 248 compl...

Thanks, I'll stick to F for HT fuse.

Although the amp came with a F1A fuse in HT (not sure if it has been replaced), both the manual and the rear panel indicate T1A.

Then we're talking about different amps. In the rear panel it just says "LOUDSPEAKER OUTPUTS" on top of two female jack connectors. No indication of external speaker. I also checked the manual (Master Volume And Lead Amplifiers Handbook) and it just says: "Parallel connected jacks for loudspeaker co...

It makes sense if one of them disconnects the other when it has a cable plugged. I have to look into this, thank you.

They are wired in parallel so if there is only one speaker connected the output would be shorted by the other connector. Am I missing something? Only one wired to short? (The JCMs I’ve had haven’t been wired to short to ground) I'm talking about the speaker jack outputs. I think they should be non-...

I'm about to order some fuses and I would like to know if 6.3mm x 32mm (presumably the same as 1-1/4" x 1/4") is the correct size for an early 80s JCM800 Mk2 Master Model 100W Lead. These ones seem to be good quality (250V): SIBA GZ series (70-059-61/1A): Slow blow (T), 1A SIBA GZ series (70-059-61 ...

While I wait for the components to arrive I've been experimenting with my less valuable amps, powering them (no tubes and no speakers), checking voltages and using the lightbulb current limiter to have an idea on what to expect. All worked as expected and now I'm more confident. Thank you! In order ...

3. I think the other folks covered this well already, as those are the bias supply filters. I wouldn't bother replacing them with film caps. A decent quality electrolytic would do quite well. You'll pay a big premium for axial leaded parts. It is worth looking to see if a radial electrolytic will f...