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Technik-Service Hollis Explorer

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If you have any querries please contact me under:



We give you a 100% Guarantee, if you are not satisfied, you will get your money back!


Wir are official *  Service- Partner of

AUP Germany, our technicians are well trained and work according to all valid regulations


*AUP - Hollis has finished all business operations. There is no more service available. We offer you maintanance as long we have the necessary service-kits.


We are in the process of providing the most important spare parts / service kits for the Explorer.


First results are available. All O-rings, directional valves (Mushrooms) Quadring for Scrubber(!) are now available.


Solenoid, Scrubber, HUD, Handset available! Price on request.

For example: Quadring price: 29€





As your Service- Station for the Hollis Explorer,

we offer you:


- any necesarry service; maintanance


Conversion: *
- eCCR
all prices on request

Repair LSS Modul:

- LSS Modul housing pressure stabilisation
- Replacement batteries
- new fusion-bonded epoxy. Price: 298€


Repair Handset:
- Replacement screen (violett screen with stripes?) 89€
- Replacement battery, 69€
- Turn on - off problems, Replacement Reed C. 89€

Repair HUD:
- Replacement micro-vibration-motor 89€
- Sealing housing  36€
- Sealing cable glands  29€, 
all prices excl.TAX, excl. shipping


Problems with the Hollis Explorer and their solution…


by Jürgen Scharm, Tauchbasis Ilsesee, Sept. 2017 ©


As you know the Hollis Explorer is no longer produced, which is why

I would like to give you some information, as well as an offer to solve

 technical issues with your Explorer. Many of you are frustrated because

 the problems with the electronic have not yet been solved. Your

LSS Modules were changed several times by Hollis, but the error is still

not solved or got even worse. In advance, I can tell you, every information

you got until today is definitely wrong or not the whole truth. The source

of the different errors/system failures were found by us 2 years ago and

at this time we offered Hollis a solution to the problem. This was at the

 end of 2014.

What happened?

First some information about how things started, how the system failure structure

builds up, and where we are today. We will explain to you the cause of the different failures, the possible breakdowns and their reasons before or during the dive, if you are interested – ask me! We also offer you the possibility to send us your Electronic for repair or replacement. We give you a 100% guarantee, if it don`t work or you are not satisfied, you get your money back without any discussion.

We (Tauchbasis Ilsesee) were joining the Hollis Explorer program from the beginning here in Germany. At this time, we had three Explorers. The first three Explorer Instructors were trained by Chris Ullmann with us. Now we own six Explorers and all are running without any issues now for 2 years after we modified our LSS-Modules.  Since one year we have two eCCR Units in operation and these Explorers have already done many dives deeper than 40m (120ft.) without any problems. Currently, one of our experimental Explorer is equipped with MAV`s and FMCL and is ready to use  for TRIMIX. No issues since six month.

Already from the beginning we also had problems with the LSS Module, the Handset and the HUD. Some of the issues were suddenly varying battery status, lost battery capacity, flickering or displays with stripes, defective HUD, defective vibration…. COMMS ERROR etc… i am sure you all know that.


Hollis tried to get a solution by exchanging the electronics (LSS Modules) and

or software updates.

At the beginning, they thought that defective batteries of the supplier and or

software errors in the control of the sensor module were the cause. Also

our Instructor Trainer, just like AUP Germany, denied a possible design fault

and, maybe as a result of their own technical understanding, they said these

are mistakes caused by Users.

Because of this, I was pretty angry at that time and felt challenged. For more

than thirty years, I have worked in various technical fields in industry and I

knew that this assumption was absolutely wrong. Diving with Rebreathers has

 been my passion for more than 20 years. I have built some eCCR and mCCR

 for myself. As I wrote before, currently we have an eCCR Explorer with

FMCL and MAV`s in use and it works without any issues.

Meanwhile, I claim that no one can tell me anything new about the Explorer, except the constructors themselves. To me, it was immediately clear, that the type of failures/errors and their reproducibility can`t be caused by the User under certain conditions.

My experience told me, that something with the intern power supply could not be o.k I didn`t know that I was right, however later, I found out that a faulty construction of the LSS housing was responsible for all these issues!


At that time at Tauchbasis Ilsesee, we were a Service and Training Center for the Hollis Explorer and the issues with our Explorers got me down. I had to decide: either we are moving to another manufacturer, e.g. Poseidon, or I'll find out what`s going wrong and where the issues came from. I would like to say very clearly, I was and I am absolutely convinced of the possibilities of the Hollis Explorer and so I decided to keep going with the Hollis Explorer. The troubleshooting began.

In addition to Tauchbasis Ilsesee, I am the owner of a company near Landsberg, which deals with the maintenance of all kinds of diving equipment.  Here, we also carry out some rebreather rebuilds, maintenance and repair of different types of rebreathers. I wanted to find the error. The necessary technical background and knowledge were available. At the end of 2014, I began analyzing the design and the logic of the Hollis Explorer and opened the first defective LSS, which have been kindly supplied by AUP Germany. Perhaps more from despair as from good will ;-) In the meantime the defective LSS -Modules stacked up to the ceiling at AUP Germany.

O.K, after some electronic tests we tried to evaluate the logic chains of the corresponding codes. The codes showed us, that the different failures could only be caused by malfunctions of the installed batteries. Now the question arose, how a battery, which works in thousands of other devices without any problem, is constantly failing here. The question could be answered very quickly. The environment, water and pressure must be the key. That is the only important difference to other devices.


We started with pressure tests under water and after that, for the very first time we could find small water traces on the electronic contacts of one battery. It was the third battery, placed under two others at the bottom of the housing. Not easy to find. Impossible to see it from outside. Then we could prove, that the design of the LSS housing was not able to hold the pressure back and water was penetrating the system (capillary effect).  As a result, the batteries or their electronic protective circuits get damaged by current leaks, electrical short circuited or discharged…(water does not fit well with electrical components especially salt water ;-)) These influences led inevitably to the well-known malfunctions of the entire electronics due to voltage stress peaks, high discharge currents, etc. Those voltage peaks can also lead to damage in the Sensor Module.

Electronics, whose batteries were still intact at the beginning, showed the same failures after a few dives below 30 m (90ft). At first, only some kind of failures most of you describe, but later, all the known issues came up. At first the diagnosis was not easy because the quantity of in-coming water was so little that we did not recognize it at first. We found more traces of electro-chemical reactions on the control elements of the batteries after we opened several LSS Modules.


Now it was proven, all issues had to be caused by water which had been penetrating into the housing under pressure and sometimes this led to a malfunction of the batteries. The problem was, that the incoming water was not always observed in the same place or quantity. So it happened, that a few electronics still ran without problems for a few years and others showed the known issues very quickly. But, be aware, almost 100% were and are affected! Dive time, duration, frequency of dives and depth: all those things do matter. The thing that we noticed first was, that Explorers used in salt water, were more affected than others. However, the first issues were always the same. Changed charging times and / or suddenly varying batteries status as well as connection problems to the Sensor Module. During dive sudden red light (bailout warning) because of dropped battery charging status. Already at this time, (at the end of 2014!) we informed AUP Germany what the problem is: a misconstruction of the LSS housing. The pressure stability of the LSS housing and the type of potting caused all the known issues. This time, they ignored us, because they did not understand the problem, maybe because of their own technical knowledge and their advisor told them that we were wrong.



The Sensor Module malfunction could not be connected (…COMS FAILED) to the LSS Module or a complete shut-down with red alert (bail-out) during the dive is caused by the following:

1. The batteries are discharged because of voltage peaks caused by water in the LSS. That can happen within a few minutes.

2. The Sensor Module shut down because the constant charging current to the Sensor Module depends on the charging status of the main batteries in the LSS Module. Without this supply, the Sensor Module shuts down within 30 sec. and starts a resetting program when the charging current from the LSS Module is back.


It is the same procedure to reset your Sensor Module. Put the Sensor Module on the LSS and turn the LSS Module on. Then hold the Sensor Module 30cm over the LSS Module, the infrared connection will fail after 25 – 30 sec. because the charging current of the LSS is missing. Otherwise, if the charging status of the batteries inside the LSS Module is down, there is no infrared connection to the Sensor Module possible because there is no charging current to it. Sometimes it takes more than one minute until it is connected. That depends on a defect inside the Sensor Module (the ferrit core or the condensers) caused by some voltage peaks some time before. Only after the charging of the condensers is completed will the infrared LED communicate with the LSS. That is why I strongly recommend that all LSS Modules should be changed by us immediately.

Now you know why many of you have reported a connection error "…COMMS FAIL.." at the beginning of the Pre-dive Sequence even though you have charged your LSS Module as well.


At this point a hint.

Many "wannabe technicians" have been and are still talking about the Hollis Explorer, but they have no idea. If you ever find yourself in your basement with a lamp in your hand to bring the sensor module to life by light pulse, you have fallen foul of such a specialist. I was told this at the beginning, and you will not believe it, I felt into the trap too, because it is a dangerous half-knowledge which sounds logical for a technician at first.  On second thought it sounds unbelievable and after the analysis of the switching logic our electronic engineer quickly found out that this is absolute rubbish. This optical element in the sensor module is actually an IR interface that receives various control signals from the LSS, but its function has no significance without an incoming charging current from the LSS.  Due to insufficient battery power, the sensor module discharges within 30 sec. and a reset should be performed after the current returns. Some of those experts reported "miraculous" resurrection rituals in Egypt, according to which the sun once again brought the unit back to life after it shone on the electronics a long time. We also took this statement and examined it. The reason for this was presumably due to the fact that the extreme solar radiation heated the unit, the electronics being heated up with the batteries and the remaining moisture egressed. This reestablished the correct voltage paths and the communication to the Sensor Module could start again. Furthermore, the heat of the sun probably ensured that the battery voltage rose briefly above the switching voltage and the Sensor Module was again powered. Each of you knows this – it is a simple physical process. Did you never try to improve the battery of a torchlight to get some volts back if you put in on a heater? Ok, ok..  that was in the early eighties, long time before of the battery technique of today ;-)

Well, I do not want to go into the subject of these "experts" anymore.


You can send me a message to the explorer@tauchbasis-ilsesee.de  if you have also recommended such "miracle techniques".


As a certified Hollis service technician and former AUP service partner, we have the necessary manufacturer codes to be able to read errors in the system or, for example, to be able to reset the individual components by means of software.

I can promise to you, a lamp of any kind is not part of it ;-)


Back to the LSS module of Hollis Explorer.

Only after various pressure tests we could reproduce the error and realized that we can solve the problem if we find a simple way to stabilize the housing against the pressure under water without changing the design and pot it with another, more suitable potting compound. We found a German manufacturer of epoxy resins, which helped us a lot in the selection. Then we tested these modified LSS Modules for one year and offered this to Hollis via AUP Germany as a solution. We get no answer. Later, during our correspondence with Mr. Nick Hollis, we found out, that the manager of AUP Germany did not pass some important information to him.

After a long correspondence recently with Nick Hollis, I assume that he was badly advised by some third party. Meanwhile, he regrets this. If he had received our information, things would have been different.


Back to now.

Meanwhile, we helped a lot of Hollis Explorer divers with our solution and they never had any problems with the modified LSS module or with their entire unit! Every Explorer, modified by us, runs without any problems.


Something else at this point. Actually, I did not want to go public here, but when I read your problems and see the anger and despair, that annoys me very much. That is why we decided to offer you a service station for the Hollis Explorer and carry out the usual repairs needed by the Explorer. We are able to repair your Handset, HUD and LSS Module. Sensor Modules unfortunately not. But we always have some on stock. During the last few years I have only had one on the table which was really down. But this one was delivered by a customer who told me, that one of the “Specialists” I talked about before, tried to repair his Electronic. Usually the Sensor Modules can be restored by a reset, if you know how to do this. In most cases the Module works again. And, what I said before, the reason why it doesn`t connect to the LSS is not caused by the Sensor Module itself.

Something else. I do not want to have any discussions about CE or omitted warranty of the manufacturer. These things are all known, lying on the table. You must be clear that there is no longer a manufacturer who supports you by now. Under German law, Hollis could only be held responsible against his distributor. You must assert warranty claims against the seller if you want it to do so. Other countries may have different law but here, I am talking about German law.


The motive of some people seems to be very clear and why they constantly told this nonsense to you. Either their technical understanding was not enough to see the things itself correctly, or they are still afraid of warranty claims or being held legally responsible for product defects. (german law)


A further statement on the discussion Mark 1 or Mark 2 elektronic:

Both have advantages and disadvantages. The MK 1 is better and more stable than the MK 2 after it has been pressure stabilized and newly potted by us. We have several MK 2’s and the type of cable ducts as well as the sealing of the LSS Module cover with only one O-ring, leave great doubts about the durability. We have thoroughly tested these and have come to the conclusion that in total, the version MK 1 with our modification is the better choice. With missing CE, the version MK 2 falls away for use in commercial education anyway. (German law!)


If you need help and do not want to mess around any longer, get in touch with us.


Our offer is addressed to those who want to experience beautiful dives with their Explorer in the future and not to any back seat driver who has no idea of the technology ... We give you a 100% success guarantee on the work we have carried out. The CE will not be extinguished during our repair as there are no major changes in the function or design of the device. All work is carried out under the regulations of VDE (German). The relevant functional materials we use like batteries, screens, vibration motors, etc. are identical to the genuine parts.


Contact us at explorer@tauchbasis-ilsesee.de


1. Send us an e-mail, describe the error, wait for response. Do not send your electronic without the authorization from us.

2. Send us your complete electronic free of charge.

3. We carry out an initial check with error analysis and get back in touch with you within three days.

4. You will receive an offer for repair or replacement. If we are not able to repair it, you get your item(s) back within one week. (you only have to pay for shipment).


We hope that the Explorer will soon have a comeback under new management. It is one of the most versatile rebreathers on the market. No other Rebreather can be used as eCCR, mCCR, eSCR or even as it was built for,

 a rebreather for recreational diving, simple and safe ;-)


If you have any queries, get in touch with me: explorer@tauchbasis-ilsesee.de



Jürgen M. Scharm, Tauchbasis Ilsesee, Sept. 2017

* Conversions or conversion-kits

... are not CE certified and will be sold by us for demo and development purposes only! We strongly recommend, not to use it for real diving. Diving with converted equipment is at your own risk and do not correspond to your diving- association. We assume no liability!