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Post by driventone on Dec 14, 2021 22:28:04 GMT -7
Has anyone ever had trouble getting the back panel off of a Monza (or other) head cab? I unscrewed the chassis bolts and then took the four screws off the back, but the panel would not come off. I tried using the two chassis bolt rivets on the back side of the chassis to push the back off by pushing on the faceplate of the chassis, but that didn’t feel right and even a decent amount of pressure wasn’t getting me anywhere. So I put the head bolts back in and tightened them so I could flip the head on it’s face, back side up.
I tried gently prying with a flathead between the chassis and the panel (not enough pressure to hurt the chassis or tolex). I tried running the back side of a razor blade between the panel and all three sides of the cab, I tried tapping on it with a mallet in all directions. Then I even tried putting an angled pick into one of the holes on the backplate’s metal insert, grabbing the corner from the inside and pulling HARD. It. Will. Not. Budge.
I have taken apart 50+ amps, new and vintage. I’ve even disassembled a Mini Z head before for maintenance. I’ve never seen anything like this. The cab is very solid and I can see it’s a tight fit, but this is ridiculous. I’m 90% sure someone glued it, but I can’t IMAGINE why they would ever do that.
Has anyone ever run into anything like this before? Any tips for getting the panel off? Thank you.
-Ryan
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Post by driventone on Dec 14, 2021 22:31:56 GMT -7
Has anyone ever had trouble getting the back panel off of a Monza (or other) head cab? I unscrewed the chassis bolts and then took the four screws off the back, but the panel would not come off. I tried using the two chassis bolt rivets on the back side of the chassis to push the back off by pushing on the faceplate of the chassis, but that didn’t feel right and even a decent amount of pressure wasn’t getting me anywhere. So I put the head bolts back in and tightened them so I could flip the head on it’s face, back side up. I tried gently prying with a flathead between the chassis and the panel (not enough pressure to hurt the chassis or tolex). I tried running the back side of a razor blade between the panel and all three sides of the cab, I tried tapping on it with a mallet in all directions. Then I even tried putting an angled pick into one of the holes on the backplate’s metal insert, grabbing the corner from the inside and pulling HARD. It. Will. Not. Budge. I have taken apart 50+ amps, new and vintage. I’ve even disassembled a Mini Z head before for maintenance. I’ve never seen anything like this. The cab is very solid and I can see it’s a tight fit, but this is ridiculous. I’m 90% sure someone glued it, but I can’t IMAGINE why they would ever do that. Has anyone ever run into anything like this before? Any tips for getting the panel off? Thank you. -Ryan I forgot to mention - I know someone other than Dr. Z or his team has been in there before - there’s a master volume knob on the back where the 4 ohm speaker output used to be…
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Post by iluvpunz on Dec 14, 2021 22:34:25 GMT -7
Put the chassis bolts back in. You can drop the chassis onto the tubes and cause damage. Lay the head on the its front. With the screws out of the back cover keep applying constant pressure at the top of the back cover at the corners and it will eventually pop loose.
I've had this happen with a couple of Dr Z heads. The panel is tight.
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Post by driventone on Dec 14, 2021 23:52:01 GMT -7
Put the chassis bolts back in. You can drop the chassis onto the tubes and cause damage. Lay the head on the its front. With the screws out of the back cover keep applying constant pressure at the top of the back cover at the corners and it will eventually pop loose. I've had this happen with a couple of Dr Z heads. The panel is tight. Thank you. Yeah, I didn’t want the chassis flopping around when I turned the head, so I put the bolts back in tight before doing that. I know there’s the little guide blocks for the chassis to rest on, but the pots on the front would rest on the front panel, etc., it’s not a good situation. And you’re right - I was worried about the tubes too. Good suggestion - I’ll try applying pressure to create leverage at the top of the panel and see if I can get it to pop out. Thanks!
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Post by Chilly Gibbons (Todd T.) on Dec 15, 2021 4:04:12 GMT -7
Keep us updated, they can be really “tight, tight, tight” as Tuco Salamanca (Breaking Bad) would say.
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Post by KeithA on Dec 15, 2021 4:12:32 GMT -7
I assume you bought it used so you can’t rule out a previous owner doing something silly like gluing it, but I even doubt that.
Most likely it’s a case that the black paint used on the wooden inside is stuck to the underside of the rear panel (this happens with installed speakers sometimes, too). This is why running a knife along the sides is not helping.
In the past people have used a hair dryer to heat up the area to loosen up the connection. It may be a little harder with a rear panel as the contact spots you are trying to affect are below the panel.
However, I’d try the heat angle first before anything else.
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Post by lowbudget on Dec 15, 2021 9:08:10 GMT -7
I assume you bought it used so you can’t rule out a previous owner doing something silly like gluing it, but I even doubt that. Most likely it’s a case that the black paint used on the wooden inside is stuck to the underside of the rear panel (this happens with installed speakers sometimes, too). This is why running a knife along the sides is not helping. In the past people have used a hair dryer to heat up the area to loosen up the connection. It may be a little harder with a rear panel as the contact spots you are trying to affect are below the panel. However, I’d try the heat angle first before anything else. This right here. Just use a little heat and keep working it and eventually it’ll pop loose. By the way, judicious use of the mallet was and is a good idea.
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Post by driventone on Dec 15, 2021 16:41:16 GMT -7
I assume you bought it used so you can’t rule out a previous owner doing something silly like gluing it, but I even doubt that. Most likely it’s a case that the black paint used on the wooden inside is stuck to the underside of the rear panel (this happens with installed speakers sometimes, too). This is why running a knife along the sides is not helping. In the past people have used a hair dryer to heat up the area to loosen up the connection. It may be a little harder with a rear panel as the contact spots you are trying to affect are below the panel. However, I’d try the heat angle first before anything else. I know, I jest about the back panel being glued. The only thing I could think of was an angry amp "tech", but i can't imagine anyone being that malicious, especially when the thing would possibly end up on their own bench again someday.
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Post by driventone on Dec 15, 2021 16:56:14 GMT -7
Thanks everyone, lots of great tips. By the way, "judicious use of the mallet" is my new favorite phrase. lowbudget I’m going to use that! Well, it gave up the fight today! I think the hair dryer was the key. That crossed my mind for a second, but then I wondered if that could hurt the tolex adhesive (remember, I've dealt with a lot of old Fenders, some with peeling tolex). That was silly of me. Even with my wife's hair dryer on full heat, it doesn't even get as hot as the power and rectifier tubes probably do. Anyway, I ran the hair dryer over the sides and bottom several times, pressed the panel upwards, and tapped it with the mallet. Repeated a few times with no luck. I went down to the garage, and found just the right Allen key that was beefy enough to take some pressure, but small enough to fit between the panel and the chassis. I used a pair of vice grips to hold onto it, and yanked (gently, of course). It popped out on the first try! I think the hair dryer loosened it up. KeithA - you were right - a little of the paint actually came off the wood and stuck to the tolex! Glad I got it apart - thank you all for the help. I wanted to get in there for two things: 1. I've only seen the inside of a Z Mini chassis in person. Z Chassis are like nothing I've ever seen - very cool to look at the craftsmanship. 2. Curious what has been done with the MV Mod on the back... Are the 4 ohm taps from the OT taped up in there? Did they leave the jack and just tape it up? Wondering if it's a hack job. I'll find out and report back, for entertainment purposes. Cheers!
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Post by Chilly Gibbons (Todd T.) on Dec 15, 2021 17:39:49 GMT -7
Glad you got that sucker off. Can you post an image of the inside of the chassis? I’m not sure if the Z sanctioned mod used one of the speaker jacks for the MV pot or not.
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Post by Don A on Dec 15, 2021 20:47:48 GMT -7
I'd like to see a gut shot as well (if it's permitted here). I have a 2011 Monza that had a master added on the rear panel supposedly by Dr. Z Amps and it's a red chicken head knob and it was mounted in a hole that was drilled for it, not in a speaker jack hole.
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Post by driventone on Dec 15, 2021 23:58:30 GMT -7
Hey dona,
Spoiler alert: mine was not done by Z. I have been in touch with Dr. Z and Don in repairs over the last couple weeks. (They are awesome guys, so helpful and patient.) I have wanted a Monza with a PPIMV or the mod for a very long time, and I decided now is the time. I first asked Dr. Z about the possibility of getting one through the Legacy Amp program. Then Z was nice enough to check for me if they had a 1x10 cab, Monza chassis, etc. but no dice.
I saw this Monza head come up at Guitar Center in Texas, and I had it shipped to me. While it was en-route, I sent Z the picture and he said no way, they drill a hole, they don’t ever repurpose the 4 ohm speaker output. He asked Don in repairs, who confirmed that there’s a near 100% chance that was not done by Z.
They gave me an RA number - the plan was to send them the Monza head, and get a new faceplate with the MV in front, and they would also go through and undo whatever had been done previously, check the amp, etc. once I got it back, I was going to try and get a 1x10 combo cab and Red Fang… I know, a tall order. Super rare without the amp in it.
However, I found an un-modded Monza combo that looks just like yours, and it’s on its way to Z for the PPIMV with new faceplate.
I’m not sure what the plan is yet for the head. I will tell you this, the MV works well and it does sound really good. Everything seems to work great. I’ll drop the chassis out tomorrow and try to take some pictures.
-Ryan
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Post by Don A on Dec 16, 2021 5:49:33 GMT -7
These amps are awesome with the PPIMV! I've mentioned elsewhere on this forum that I played a non-master Monza about 10 years ago and found it to be way too loud with the volume at about 9:00!
Although I prefer the practicality of the PPIMV on the front, I like the look of it on the rear- the front panel looks great with 3 knobs and the large Monza logo.
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