My HH ic 100s combo developed a loss of volume and was hissing. Having taken it out of the cab I saw that one of the large filtering caps had popped and was leaking some nice gooo. It doesn't appear to be a simple exchange as its encased in a metal strap and riveted to the chassis! Has anyone changed these? Is it better to change them as a pair? I suspect this is causing the hissing....but a lack of volume?
Thanks guys
Quote from: makjoh on April 20, 2020, 04:47:37 AM
My HH ic 100s combo developed a loss of volume and was hissing. Having taken it out of the cab I saw that one of the large filtering caps had popped and was leaking some nice gooo. It doesn't appear to be a simple exchange as its encased in a metal strap and riveted to the chassis! Has anyone changed these? Is it better to change them as a pair? I suspect this is causing the hissing....but a lack of volume?
Thanks guys
Your amp is mostly likely running on one rail, or close to it. This would cause exactly what you are talking about. You'll want to replace the pair as the other one is no doubt going to do the same soon-ish. What are the specs of these caps? They should say on the side of them. Also, a picture to show the metal strap you speak of would help.
I've heard folks really love these HH amps. I haven't played one myself, but always interested in seeing pics!
The cap clamps are riveted to the chassis, but there should be a screw you can loosen off, so you can remove the caps from the clamps.
(https://www.tubesandmore.com/sites/default/files/styles/uc_product/public/uc_products/s-h122.png?itok=o78Kv26O)
Quote from: joecool85 on April 20, 2020, 09:24:04 AM
Quote from: makjoh on April 20, 2020, 04:47:37 AM
My HH ic 100s combo developed a loss of volume and was hissing. Having taken it out of the cab I saw that one of the large filtering caps had popped and was leaking some nice gooo. It doesn't appear to be a simple exchange as its encased in a metal strap and riveted to the chassis! Has anyone changed these? Is it better to change them as a pair? I suspect this is causing the hissing....but a lack of volume?
Thanks guys
Your amp is mostly likely running on one rail, or close to it. This would cause exactly what you are talking about. You'll want to replace the pair as the other one is no doubt going to do the same soon-ish. What are the specs of these caps? They should say on the side of them. Also, a picture to show the metal strap you speak of would help.
I've heard folks really love these HH amps. I haven't played one myself, but always interested in seeing pics!
Thanks for the reply, the caps are 4700 uf 50 volts dc and I agree it makes sense to change them both while the amp is out of the chassis. I've sourced a pair and will try and get some pics uploaded
The riveted metal bands are going to be most annoying. Crazy way securing exchangeable parts to the chassis.
Do the caps need powering up on a variac like the recommend on valve amps?
Quote from: g1 on April 20, 2020, 02:13:47 PM
The cap clamps are riveted to the chassis, but there should be a screw you can loosen off, so you can remove the caps from the clamps.
(https://www.tubesandmore.com/sites/default/files/styles/uc_product/public/uc_products/s-h122.png?itok=o78Kv26O)
I wish it were that simple. But the metal band is riveted shut and riveted to the chassis
I'd suggest drilling out the rivet that holds the band together, assuming you can fit a drill bit in there, and replace with a nut/bolt. I mention it because I just drilled out a seized screw in a GK400RB two days ago, after trying just about everything else. Super frustrating.
EDIT: you may also be able to use a diagonal cutter to slice through the rivet.
SO drill out the clamping rivet and leave the clamp on the chassis. Install a new cap and replace the drilled rivet with a screw and nut.
ALthough, chances are a modern cap is considerably smaller than the original physically, so the clamp may become irrelevant.
All drilling of clamps done and capacitors replaced, both showing the required voltage but absolutely no sound from the amp now. Not a peep or even a squeak
Do u have the schematic?
Here's a schematic
Quote from: g1 on May 03, 2020, 12:21:41 PM
Here's a schematic
Many thanks g1 (wish I find that great Korg pedal)